Performance of Chicks Fed Diets Formulated to Minimize Excess Levels of Essential Amino Acids P . W . WALDROUP, R. J. MITCHELL, J. R. PAYNE AND K. R. HAZEN
Department of Animal Sciences, University of Arkansas, Fayetteville, Arkansas 72701 (Received for publication April 29, 1975)
ABSTRACT Studies were conducted in which levels of essential amino acids in excess of the minimum requirements were minimized in broiler diets composed of commercially available feedstuffs and synthetic amino acid supplements. Growth rate and efficiency of feed utilization of chicks fed such diets were equal to that attained by chicks fed diets formulated by conventional means when grown under conditions where heat stress was not a factor and significantly improved when fed under conditions of heat stress. Improvements were obtained in efficiency of protein and calorie utilization using this technique of formulation. POULTRY SCIENCE 55: 243-253, 1976
LMQUIST (1952) stated that "when dietary protein is in exact balance and in sufficient quantity the rate of tissue synthesis and the efficiency of utilization of the diet for growth will approach a maximum. However, if a slight amino acid deficit exists the animal will attempt to compensate by consuming more of the diet, in which case the rate of growth may attain the maximum but the efficiency of the diet may not." The importance of balanced amino acid patterns in broiler diets is well documented. Askelson and Balloun (1965) concluded from studies in which broiler chicks were fed diets ranging in crude protein from 18 to 22 percent that improvement in performance associated with increased protein levels was the result of improved essential amino acid balance and could be accomplished equally as well through amino acid supplementation. Fisher et al. (1960) described an imbalanced diet as one which contained an excess amount of some essential amino acids while one essential amino acid was present in amounts less than that required for optimum protein synthesis and growth. Smith and Scotl (1965a, b, c) showed that supplementing a deficient diet with an essential amino acid mixture devoid of the deficient amino acid Published with the approval of the Director of the Arkansas Agricultural Experiment Station.
243
had an adverse effect upon growth. Sugahara et al. (1969) and Velu et al. (1970) demonstrated that a protein source with a good amino acid balance fed at suboptimal levels had little or no depressing effect upon feed intake by chicks; however, if a poorly balanced protein was fed, feed consumption was reduced. Velu et al. (1971) further demonstrated that protein utilization of a balanced diet remained constant as protein intake increased from a deficiency to adequacy for maximum growth. Harper et al. (1970) reported that amino acid degradation systems did not respond readily to excess amino acids when dietary protein levels were low. The ingestion of excesses of individual amino acids at low protein intake levels often results in accumulation of these amino acids in the body fluids and may trigger the reduction in feed intake that is characteristic of amino acid imbalance. Salmon (1958) stated that when a single amino acid is present in an animal's diet at levels not capable of supporting maximum synthesis of tissue proteins any amino acid not fully utilized is in excess and must be eliminated from the body. Intheprocess there is a wasting of the most limiting essential amino acid which increases the severity of the deficiency. Lewis (1969) concluded that in most instances an excess of an essential amino acid will impose a limitation upon the
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
A
244
WALDROUP, MITCHELL, PAYNE AND HAZEN
It is now generally accepted that the altered plasma and tissue amino acid pattern which develops during an imbalance produces the adverse affect on appetite. The mechanism by which the altered amino acid pattern affects the appetite regulating centers is still unknown. Evidence indicates that two possible mechanisms may be responsible for the reduced level of circulating target amino acids
in the plasma brought about by the consumption of an imbalanced diet. Harper and Rogers (1965) proposed the anabolic theory which states that a surplus of amino acids stimulates synthesis or suppresses breakdown of protein in the liver so that more of the limiting amino acid is retained in the liver in the imbalanced than in the control group. The concentration of the limiting amino acid in the plasma is thereby reduced, leading to an altered amino acid pattern and subsequently to a depressed feed intake. The catabolic theory proposed by Lewis and D'Mello (1967) states than an excess of an agent amino acid enhances general catabolism and excretion of amino acids and thereby inadvertently encourages the loss of the target amino acid. This mechanism may lead to a deranged pattern of free amino acids in plasma and tissue and to a depression of growth rate and feed intake. The anabolic form of imbalanced response can be regarded as being brought about by the addition of an incomplete mixture of amino acids to a diet limiting in the amino acid not added and is characterized by a homeostatic response to prevent undue loss of the limiting amino acid. The catabolic version can be considered to be brought about by excess doses of single amino acids, particularly lysine, leucine, threonine and methionine. In such instances the target or limiting amino acid is lost through renal or oxidative pathways, as indicated by various workers. Jones et al. (1967) and Nesheim (1968) reported that kidney arginase activity was increased by excess dietary lysine. Austic and Nesheim (1970) reported increased arginase activity in chicks fed diets containing amino acids in excess other than lysine. Savage (1972) reported that the addition of lysine to a diet composed largely of casein protein which contains approximately twice as much lysine as arginine depressed chick growth, increased kidney arginase activity and exaggerated arginine deficiency symptoms. Nesheim et al. (1972) discussed the increased degradation
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
efficiency of nutrient utilization proportional to the magnitude of deviation from a perfect balance. There are also recognized instances when a dietary excess of an amino acid or a mixture of amino acids will precipitate an ill effect which is totally disproportionate to the degree of imbalance. Such is the case with the interaction existing between lysine and arginine (D'Mello and Lewis, 1970a), leucine and valine and to some extent leucine and isoleucine (D'Mello and Lewis, 1970b) and threonine and tryptophan (D'Mello and Lewis, 1970c). These are apparently actual interactions between target and agent amino acids as advanced by Lewis (1965) and not adverse effects precipitated by administering massive doses of amino acid as described by Anderson etal. (1951) and Almquist (1952). D'Mello and Lewis (1970c) concluded that it is impossible to determine the chick's actual requirement for essential amino acids unless the diet is in good amino acid balance since the amino acid pattern of the diet will affect the chick's response to supplementation. Allen et al. (1970) reported that the addition of one percent lysine to a diet presently adequate in this amino acid would increase the chick's arginine requirement by approximately 50 percent. It was shown by D'Mello and Lewis (1971) that excess lysine, leucine and threonine precipitated drops in plasma levels of arginine, valine and isoleucine and tryptophan, respectively, along with (but at some later time) decreased growth rate and feed consumption. These ill effects were remedied only by the addition of the target amino acid.
AMINO ACIDS FOR CHICKS
It is readily apparent that amino acids in excess of the actual needs of the chick enter the bloodstream and by some mechanism inhibit feed intake and thus limit the rate of growth. Since the growth potential of a chick is governed to a great extent by the amount of feed the animal will voluntarily consume, the possibility exists that performance of broiler chicks under commercial conditions could be improved by limiting the amounts of amino acids present at levels greater than actually needed. This may be quite easy to do on a small scale with purified diets but because of the ubiquitous nature of some amino acids in practical feedstuffs may be difficult to attain under commercial conditions. Trials were conducted in this laboratory to study means by which the amounts of essential amino acids in a broiler diet might be minimized and still maintain acceptable performance. Ingredients were limited to widely available feedstuffs and feed grade methionine and lysine supplements. EXPERIMENT 1 Materials and Methods. The first study was an exploratory trial conducted to determine the feasibility of reducing the levels of excess
essential amino acids using practical type diets and to examine the response of chicks in terms of voluntary feed consumption and weight gains. In this and all following studies in this report, the amino acid levels suggested by the Arkansas Agricultural Extension Service (1966), scaled in proportion to the dietary energy level being used, were used as minimum requirements. These restrictions have supported adequate performance in our laboratory for several years. The diets were formulated by linear programming using the IBM MPS-360 system (Waldroup, 1973). Ingredients were assigned prices currently in effect in Fayetteville, Arkansas. Using a dietary energy level of 3080 M.E. kcal./kg., three amino acid series were formulated. In the first series, no supplemental methionine or lysine were allowed so that only intact feedstuffs were used as a source of dietary amino acids. In the second series, the minimum requirements for the sulfur amino acids were removed and the diets formulated with intact ingredients to meet the needs for the other essential amino acids. A feed grade DL-methionine supplement was then added to bring the methionine and total sulfur amino acid levels to the minimum specifications. In the third series, the minimum specifications for the sulfur amino acids and lysine were removed and the remainder of the nutrients supplied from intact ingredients. Supplemental DL methionine and a feed grade lysine HC1 supplement were then used to meet the minimums for these amino acids. In addition to the three amino acid series, there were two types of basal diets used. In the first basal series yellow corn and soybean meal were the only intact protein sources and in the second series corn, soybean meal and 5 percent of a Peruvian anchovy fish meal were used as the intact protein sources. As a result of this method of formulation, the diets contained a wide range of protein and essential amino acid levels, while still
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
of arginine by kidney arginase largely to urea and ornithine when dietary excesses of lysine were fed. They concluded from this and other work that excess levels of some amino acids may increase the degradation of other amino acids, thus increasing the chick's need for the degraded amino acid(s). According to D'Mello and Lewis (1970a, b, c) an interaction exists between agent and target amino acids which increases the bird's need for the target amino acid when the agent amino acid is present in the diet in excess. Further, if the agent amino acids were present in the diet at levels no higher than that required for maximum protein synthesis, the requirement for the target amino acid would be less than that required under "normal" conditions.
245
246
WALDROUP, MITCHELL, PAYNE AND HAZEN
chicks, were assigned to each of the test diets for a 10 day feeding period. The experimental diets and tap water were fed ad libitum with a 14 hour light period. Individual weight gains and pen feed consumption data were subjected to the analysis of variance as outlined by Steel and Torrie (1960) with significant differences between treatment means determined by the multiple range test of Duncan (1955). Results. The results of this study (Table 2) indicated that there were no statistically significant differences in voluntary feed consumption or weight gains among chicks fed the different experimental diets. While one might theoretically anticipate improved feed consumption or body weight gains by chicks fed the diets with a minimum of essential amino acids, these chicks were not under temperature stress nor were any amino acids
TABLE 1.—Composition of diets (Trial 1) Ingredient Yellow corn Soybean meal (50 protein) Fish meal (65 protein) Soybean oil Dical phosphate Limestone Salt Vitamin premix 1 Trace minerals' Sand DL-methionine (98) Lysine HC1 (98)
Calculated Analysis M.E. kcal./kg. Protein % Lysine % Meth + Cys % Essential amino acids % Excess amino acids %
5
6
46.19
57.27
64.77
4 50.74
60.97
64.90
45.00 0.00 4.58 1.77 0.64 0.40 0.50 0.10 0.82
33.92 0.00 3.32 1.84 0.66 0.40 0.50 0.10 1.86
26.42 0.00 2.51 1.92 0.66 0.40 0.50 0.10 2.27
35.26 5.00 3.88 1.02 0.58 0.40 0.50 0.10 2.53
25.03 5.00 2.78 1.12 0.57 0.40 0.50 0.10 3.41
21.10 5.00 2.36 1.14 0.58 0.40 0.50 0.10 3.64
0.00 0.00
0.13 0.00
0.22 0.24
0.00 0.00
0.12 0.00
0.17 0.12
100.00
100.00
100.00
100.00
100.00
100.00
3080 26.92 1.60 0.80 14.56 147.07
3080 22.23 1.23 0.80 12.11 122.32
3080 19.04 1.23 0.80 10.77 108.78
3080 25.59 1.54 0.80 13.91 140.50
3080 21.25 1.23 0.80 11.67 117.87
3080 19.59 1.23 0.80 10.94 110.50
1
2
1. As outlined by Waldroup et al. (1974).
3
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
meeting the same minimum amino acid restrictions (Table 1). Protein levels ranged from a high of 26.9 percent to a low of 19.0 percent. Analytical values were in close agreement with these calculated levels. The sum of the calculated essential amino acid content ranged from 14.6 percent to 10.8 percent. The sum of the essential amino acid levels required was 9.9 percent, so the final diets contained from 108.8 to 147.1 percent more essential amino acids than the minimum levels specified. Female chicks of a broiler strain were fed a standard chick starter mash from day-old to 7 days of age, at which time they were weighed and divided into weight groups with a 2 gram weight range. The chicks were then assigned to compartments in electrically heated battery brooders in such a manner as to equalize as nearly as possible the initial weights. Six pens, each containing eight
247
AMINO ACIDS FOR CHICKS
TABLE 2.—Effect
Basal diet 1 1. 2. 3. 4. 5. 6.
C-S C-S C-S C-S-F C-S-F C-S-F
1. 2. 3. 4. 5. 6.
of diets with different levels of essential amino acids on broiler performance (Trial 1)
Protein
E.A.A. 2
7-17 day weight gain 6
26.92 22.23 19.04 25.59 21.25 19.59
14.56 12.11 10.77 13.91 11.67 10.94
269 278 264 277 272 273
%
%
7-17 day feed /bird (g.) 6 511 525 484 496 490 487
Gain: feed 6
P.E.R. 3 ' 5
C.E.R. 4 6
0.526 0.529 0.546 0.558 0.555 0.561
1.95d 2.38bc 2.85a 2.18c 2.57b 2.86a
5.85 5.82 5.64 5.51 5.54 5.48
C-S = corn-soybean meal; C-S-F = corn-soybean meal-fish meal. E.A.A. = % of essential amino acids in diet. P.E.R. = Protein Efficiency Ratio. C.E.R. = Caloric Efficiency Ratio. Means having the same common letter do not differ significantly (P S 0.05). Where common letters are not given, differences did not reach a level of statistical significance. select feed grade lysine and methionine supplements if their cost justified their usage. No minimum protein levels were imposed. In the second series the minimums for sulfur amino acids and lysine were removed, the diets formulated to meet the needs for the other amino acids and then the remainder of the lysine and sulfur amino acid requirements were met with the addition of the feed grade supplements. Sexed broiler chicks were grown to seven days of age on a standard chick starter feed, weighed and divided into weight groups and assigned to compartments in battery brooders as previously described. Eight pens of chicks, each consisting of four male and four female chicks, were fed each experimental diet from 7 to 21 days of age. Feed consumption, body weight gains and efficiency of feed utilization were statistically analyzed as previously described.
EXPERIMENT 2 Materials and Methods. Using the same amino acidrenergy ratios described for Experiment 1, diets were formulated to contain 3080, 3300 and 3520 M.E. kcal./kg. (Table 3). Two amino acid series were formulated within each energy level. In the first series, diets were formulated to meet all amino acid minimums but the computer was allowed to
Results. Over the three different dietary energy levels tested 3080, 3300 and 3520 M.E. kcal./kg.) there were no significant differences in weight gain, feed consumption, or feed efficiency ratio that could be attributed to the differences in essential amino acid content of the diet (Table 4). Although both series of diets were formulated to meet the same minimum amino acid levels, the
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
in excessive imbalance, particularly the lysine-argine or leucine-isoleucine-valine groups. Calculations were made of the efficiency of nutrient utilization (Table 2). A Protein Efficiency Ratio (P.E.R.) was calculated as the grams of body weight gain per gram of protein consumed. As seen in Table 2 there was an improvement in efficiency of conversion of protein to body tissues by minimizing the levels of essential amino acids. A Caloric Efficiency Ratio (C.E.R.) was calculated as the M.E. kilocalories required to produce a gram of weight gain. No statistically significant differences were seen among the various dietary treatments in efficiency of energy utilization (Table 2). The fact that satisfactory performance could be attained by formulating the diets in this manner prompted further study.
248
WALDROUP, MITCHELL, PAYNE AND HAZEN
TABLE 3.—Composition of diets (Trial 2) Ingredient Yellow corn Soybean meal (50 protein) Soybean oil Dical phosphate Limestone Vitamin premix 1 Salt Trace minerals' DL-methionine (98%) Lysine HC1 (98%) Total
2
3
4'
5
6
68.16
48.76
60.91
41.25
53.66
35.92 4.15 1.88 0.67 0.50 0.40 0.10 0.12 0.00
26.14 2.17 1.92 0.67 0.50 0.40 0.10 0.23 0.25
39.14 8.20 2.08 0.67 0.50 0.40 0.10 0.15 0.00
28.94 6.40 2.12 0.67 0.50 0.40 0.10 0.26 0.37
42.37 12.26 2.27 0.67 0.50 0.40 0.10 0.18 0.00
31.75 10.63 2.32 0.67 0.50 0.40 0.10 0.30 0.39
100.00
100.00
100.00
100.00
100.00
100.00
3080 22.71 1.23 0.80 12.84 129.70
3080 18.94 1.23 0.80 10.71 108.18
3300 23.68 1.31 0.85 13.36 128.83
3300 19.66 1.31 0.85 11.06 106.65
3520 24.65 1.40 0.91 13.91 127.15
3520 20.38 1.40 0.91 11.49 105.03
1. As given in Table 1. TABLE 4.—Effect of diets with different levels of energy and essential amino acids on broiler performance (Trial 2)
M.E. kcal./kg.
% Protein
% E.A.A. 1
1. 3080 2. 3080 Avg.
22.71 18.94
12.84 10.71
3. 3300 4. 3300 Avg.
23.68 19.66
13.36 11.06
5. 3520 6. 3520 Avg.
24.65 20.38
13.91 11.49
Average 1,3, 5 Average 2 , 4 , 6
7-21 day weight gain (g.) 4 218 222 220a 240 228 234b
Gain: feed 4
P.E.R. 2 4
C.E.R.3-4
0.606 0.592
2.67 3.16
5.08 5.20
0.598b
2.92
5.14
0.657 0.649
2.78 3.31
5.02 5.08
0.653a
3.05
5.05
237 234
0.684 0.657
2.79 3.25
5.14 5.35
236b
0.671
3.02
5.24
232 228
0.649 0.632
2.75b 3.24a
5.08 5.21
1. E.A.A. = % of essential amino acids in diet. 2. P.E.R. = Protein Efficiency Ratio. 3. C.E.R. = Caloric Efficiency Ratio. 4. Means having the same common letter do not differ significantly (P < 0.05). Where common letters are not given, differences did not reach a level of statistical significance.
diets formulated to supply minimum levels of excess amino acids contained an average of 4.0 percent less protein than those formulated by more conventional means. As a
result, protein utilization (P.E.R.) was improved as in Experiment 1 as a consequence of formulating to minimize excess levels of essential amino acids (Table 4). Efficiency
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
Calculated Analysis M.E. kcal./kg. Protein % Lysine % Meth + Cyst % Essential amino acid % Escess amino acid %
1 56.26
249
AMINO ACIDS FOR CHICKS
EXPERIMENT 3 Materials and Methods. This study was conducted for a full eight week growout period under conditions similar to those encountered in commercial broiler production. The starter diets containing 3080 and 3520 M.E. kcal./kg. with "normal" and "low" essential amino acid content (Diets 1, 2, 5, and 6, Table 3) were used for the period of day old to 4 weeks of age and finisher diets of the same energy levels but adjusted for the recommended amino acid levels (Table 5) were fed from 4 to 8 weeks of age.
Results. No significant differences in growth rate or feed consumption were observed that could be related to the amino acid status of the diet, even though the diets
TABLE 5.—Composition of finisher diets (Trial 3) Ingredient Yellow corn Soybean meal (50 protein) Alfalfa meal (17 protein) Soybean oil Dical phosphate Limestone Salt Vitamin mix1 Trace minerals 1 DL-methionine (98%) Lysine HC1 (98%) Total Calculated Analysis M.E. kcal./kg. Protein % Lysine % Meth + Cys % Essential amino acid %
•As given in Table 1.
1
2
4
66.11
68.78
3 43.59
51.04
25.44
23.67
31.44
26.42
2.81 2.12 1.87 0.55 0.40 0.50 0.10 0.10 0.00
2.48 1.46 1.88 0.56 0.40 0.50 0.10 0.12 0.06
5.46 15.60 2.26 0.46 0.40 0.50 0.10 0.18 0.00
4.54 13.81 2.28 0.50 0.40 0.50 0.10 0.23 0.18
100.00
100.00
100.00
100.00
3080 18.92 0.99 0.72 10.60
3080 18.15 0.99 0.72 10.31
3520 20.39 1.14 0.83 11.39
3520 18.29 1.14 0.83 10.58
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
The chicks were housed in a wood frame building containing 16 pens, each 7.43 M 2 in size. Each of the diets was assigned to four pens with 40 male and 40 female chicks placed in each pen. Rice hulls were used as litter and infrared brooder lamps were used as a source of heat. Ceiling fans controlled by a time-temperature thermostat were used to regulate air flow. The chicks were started in the first week of June so it was anticipated that heat stress might be encountered during the period of 4 to 8 weeks of age. This did not prove to be so as the temperature during the months of June and July was moderate and heat stress was not an apparent factor. The chicks were group weighed by sex and total pen feed consumption was determined. The data were analyzed as previously described.
of energy utilization was similar for all diets with no statistically significant differences noted. As expected, chicks fed the diets containing the higher energy levels consumed less feed, grew at a faster rate, and converted the feed to gain more efficiently than those fed at lower energy levels. However, there were no significant interactions observed between the dietary energy level and the amino acid status of the diet.
250
WALDROUP, MITCHELL, PAYNE AND HAZEN
EXPERIMENT 4 Materials and Methods. The purpose of this study was to compare the effectiveness of several methods of feed formulation during summer heat stress. Four systems were TABLE 6.—Effect
compared (Table 7). These were (1) a conventional least-cost formulation without any minimum protein level established (Diets A and E); (2) formulation to minimize excess essential amino acid levels by making maximum usage of synthetic methionine and lysine supplements (Diets B and F); (3) least-cost formulation without minimum protein levels but with minimum amino acid levels increased by 10%, a practice frequently recommended to combat problems with reduced feed intake (Diets C and G); and (4) least-cost formulation to meet minimum amino acid needs with a protein minimum based on energy:protein ratios (M.E. kcal./kg. -r% protein) of 132:1 for starter diets and 156:1 for finisher diets (Diets D and H). An energy level of 3080 M.E. kcal./kg. was used in diets fed during the first 4 weeks (starter period) with 3190 M.E. kcal./kg. used during the last 4 weeks (finisher period). Each diet was fed to four groups of 40 males and 40 females in the floor pen facility described in Experiment 3. The trial was initiated during the last week of May and hot weather stress was observed during the latter part of the growth period. The data were collected and analyzed as previously described.
of diets with different levels of energy and essential amino acids on broiler performance (Trial 3)
M.E. kcal./kg.
% Protein S/F1
0-56 day weight gain (g.) 4
Gain: feed 4
P.E.R. 2 4
C.E.R.3-4
1. 3080 2. 3080
22.7/18.9 18.9/18.1
1429 1463
0.425 0.435
2.13 2.36
7.24 7.09
1446a 1554 1516
0.429
2.25
7.17
24.7/20.4 20.4/18.3
0.469 0.498
2.13 2.63
7.50 7.08
15356
0.483
2.38
7.29
1492 1489
0.446b 0.462a
2.13b 2.50a
7.37b 7.09a
Avg. 3. 3520 4. 3520 Avg.
Average 1 , 3 Average 2 , 4
1. S/F = Starter diet/Finisher diet. 2. P.E.R. = Protein Efficiency Ratio. 3. C.E.R. = Caloric Efficiency Ratio. 4. Means having the same common letter do not differ significantly (P < 0.05). Where common letters are not given, differences did not reach a level of statistical significance.
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
formulated to minimize the excess levels of essential amino acids were lower in total protein content than those formulated by conventional least-cost programming (Table 6). Chicks fed the higher energy level grew at a more rapid rate and consumed less feed but there was no significant interaction between energy level and amino acid status. Chicks fed the diets containing the lower protein level with a reduced excess of essential amino acids converted their feed to gain more efficiently with an improvement in caloric utilization (C.E.R.) as seen in Table 6. This supports the hypothesis that excess levels of amino acids are detrimental to efficient energy utilization, perhaps because of their greater heat of digestion. Efficiency of protein utilization (P.E.R.) was again improved by formulating to minimize excess levels of amino acids (Table 6) even though the difference in protein content of the finisher diets was not as great as previously seen in the starter diets.
251
AMINO ACIDS FOR CHICKS
TABLE 7.—Composition of diets (Experiment 4) Ingredient Yellow corn Soybean meal (49 protein) Fish meal (65 protein) Animal fat Dical phosphate Limestone Salt Vitamin premix1 Trace minerals1 Alfalfa meal (20) DL-methionine Lysine HC1
Starter diets (0-4 wks.) B D 63.16 64.41 58.36 55.51
Calculated Analysis M.E. kcal./kg. 3080 Protein % 20.94 Lysine % 1.13 Meth + Cys % 0.87 1. As given in Table 1.
27.57 1.50 1.82 1.63 0.86 0.40 0.50 0.10 1.00 0.18 0.03 100.00
32.35 1.50 3.11 1.61 0.85 0.40 0.50 0.10 1.00 0.22 0.00 100.00
3080 3080 3080 20.44 22.44 23.30 1.13 1.24 1.31 0.87 0.95 0.87
Results. Broilers fed the diets formulated to minimize excesses of essential amino acids had the greatest weight gain during the 56 day feeding period, followed in order by those fed the diet formulated with a 110% increase in minimum amino acid levels, those fed the least-cost diet with normal amino acid levels but with no protein minimum, and broilers fed the diets with minimum protein levels TABLE 8.—Effects Formulation method 1. Least cost, no protein minimum 2. Low essential amino acid levels 3. Least cost, 110% of minimum amino acid 4. Least cost, fixed protein levels
34.83 1.50 3.60 1.60 0.85 0.40 0.50 0.10 1.00 0.11 0.00 100.00
62.69
65.85
57.52
H 57.50
26.20 0.00 4.78 1.88 0.80 0.40 0.50 0.10 2.50 0.15 0.00 100.00
24.00 0.00 4.00 1.89 0.82 0.40 0.50 0.10 2.18 0.18 0.08 100.00
29.81 0.00 5.87 1.87 0.77 0.40 0.50 0.10 2.97 0.19 0.00 100.00
29.95 0.00 5.83 1.86 0.77 0.40 0.50 0.10 2.98 0.11 0.00 100.00
3190 3190 3190 3190 19.07 18.08 20.51 20.50 1.00 1.00 1.10 1.11 0.77 0.77 0.85 0.77
imposed (Table 8). The same order was followed in regards to efficiency of feed utilization (gainrfeed ratios) protein utilization (P.E.R.) and energy utilization (C.E.R.). These data, in conjunction with the results of the previous experiments, demonstrate that broiler chicks can be grown effectively on diets formulated to meet essential amino acid needs without regard to a protein mini-
of different methods of feed formulation on broiler performance (Trial 4) % Protein S/F1
0-56 day weight gain (g.) 4
Gain: feed
P.E.R. 2 - 4
C.E.R. 3 4
20.9/19.0
1476ab
0.425ab
2.19cd
7.18
20.4/18.0
1535a
0.444a
2.37a
6.97
22.4/20.5
1512ab
0.434ab
2.07bc
7.08
23.3/20.5
1436b
0.414b
1.95c
7.42
1. S/F = Starter diet/Finisher diet. 2. P.E.R. = Protein Efficiency Ratio. 3. C.E.R. = Caloric Efficiency Ratio. 4. Means having the same common letter do not differ significantly (P < 0.05). Where common letters are not given, differences did not reach a level of statistical significance.
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
28.50 1.50 2.18 1.63 0.86 0.40 0.50 0.10 1.00 0.17 0.00 100.00
Finisher diets (4-8 wks.)
252
WALDROUP, MITCHELL, PAYNE AND HAZEN
The results of the studies in this report, using ingredients similar to those used in commercial broiler production in the United States, support the hypothesis proposed by numerous workers that amino acids in excess of the needs by the chick may impair feed intake and growth rate, especially under heat stress conditions. Through the increased usage of commercially available synthetic amino acids, diets may be formulated having minimal excesses of these amino acids and may result in improved performance under heat stress without impairing performance under more moderate environmental conditions. REFERENCES Allen, N. K., D. H. Baker and H. M. Scott, 1970. Quantitative impairment of arginine utilization by graded levels of dietary lysine. Poultry Sci. 49: 1363.
Almquist, H. J., 1952. Utilization of amino acids by chicks. Arch. Biochem. Biophys. 59: 197-202. Anderson, J. O., G. F. Combs, A. C. Graschke and G. M. Briggs, 1951. Effects on chicks' growth of amino acid imbalances in diets containing low and adequate levels of niacin and pyridoxine. J. Nutr. 45: 345-360. Arkansas Agricultural Extension Service, 1966. Suggested restrictions for poultry diets. University of Arkansas, Little Rock, Ark. Askelson, C. E., and S. L. Balloun, 1965. Influence of dietary protein level and amino acid composition on chick performance. Poultry Sci. 44: 193-197. Austic, R. E., and M. C. Nesheim, 1970. Role of kidney arginase in variations of the arginine requirements of chicks. J. Nutr. 100: 855-867. D'Mello, J. P. F., and D. Lewis, 1970a. Amino acid interactions in chick nutrition. 1. The interrelationship between lysine and arginine. Br. Poultry Sci. 11: 299-311. D'Mello, J. P. F., and D. Lewis, 1970b. Amino acid interactions in chick nutrition. 2. Interrelationships between leucine, isoleucine and valine. Br. Poultry Sci. 11: 313-323. D'Mello, J. P. F., and D. Lewis, 1970c. Amino acid interactions in chick nutrition. 3. Interdependence in amino acid requirements. Br. Poultry Sci. 11: 367-385. D'Mello, J. P. F., and D. Lewis, 1971. Amino acid interactions in chick nutrition. 4. Growth, food intake and plasma amino acid patterns. Br. Poultry Sci. 12: 345-358. Duncan, D. B., 1955. Multiple range and multiple f test. Biometrics, 11: 1-42. Fisher, H., P. A. Griminger, G. A. Leveille and R. Shapiro, 1960. Quantitative aspects of lysine deficiency and amino acid imbalances. J. Nutr. 71: 213-220. Greene, D. E., 1961. Factors influencing the growth of chicks fed crystalline amino acid diets with special reference to a growth stimulating factor in intact proteins. Diss. Abstracts, 21: 1312. Harper, A. E., N. J. Benevenga andR. M. Wohlhueter, 1970. Effects of ingestion of disproportional amounts of amino acids. Physiol. Rev. 50: 428-558. Harper, A. E., and Q. R. Rogers, 1965. Amino acid imbalance. Proc. Nutr. Soc. 24: 173-190. Jones, J. D., S. J. Petersburg and P. C. Burnett, 1967. The mechanism of the lysine-arginine antagonism in the chick: Effect of lysine on digestion kidney arginase and liver transamidose. J. Nutr. 93: 103116. Lewis, D., 1965. The concept of agent and target in amino acid interactions. Proc. Nutr. Soc. 24: 196-209.
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
mum. Obviously one must consider the needs of a nitrogen pool for formation of the dispensible amino acids but this does not appear to be a problem when using diets composed principally of corn and soybean meal. Some indications of ratios for dispensible/indispensible amino acid needs have been reported for purified or semi-purified diets. Stucki and Harper (1961) examined the optimum ratios of indispensable dispensable amino acids for chicks. Their results suggested that best growth of chicks resulted when about 33 percent of the dietary nitrogen in a purified diet came from dispensible amino acids. Greene (1961) reported that for maximum performance of chicks fed a crystalline amino acid diet an optimum ration of essential to non-specific nitrogen was 1.7:1. Sugahara and Ariyoshi (1968) noted an optimum dispensible :dispensible amino ratio for optimum growth of chicks of 1.5:1 while for optimum feed efficiency it was 1:1. As additional sources of supplemental amino acids become available for commercial usage this may become a necessary consideration in formulating diets.
AMINO ACIDS FOR CHICKS
of the amino acid content of fish meal proteins by chick growth assay. 2. The effects of amino acid imbalances upon estimations of amino acid availability by chick growth assay. Poultry Sci. 44: 408-413. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Co., New York, N.Y. Stucki, W. P., and A. E. Harper, 1961. Importance of dispensible amino acids for normal growth of chicks. J. Nutr. 74: 377-383. Sugahara, M., and S. Ariyoshi, 1968. The role of dispensible amino acids for the maximum growth of chick. Agr. Biol. Chem. 32: 153-160. Sugahara, M., D. H. Baker and H. M. Scott, 1969. Effects of different patterns of excess amino acids on performance of chicks fed amino acid-deficient diets. J. Nutr. 97: 29-32. Velu, J. G., D. H. Baker and H. M. Scott, 1970. Amino acid balance and body composition changes in the young chick. Poultry Sci. 49: 1448. Velu, J. G., D. H. Baker and H. M. Scott, 1971. Protein and energy utilization by chicks fed graded levels of a balanced mixture of crystalline amino acids. J. Nutr. 101: 1249-1256. Waldroup, P. W„ 1973. Using the MPS/360 linear programming system for feed formulation. University of Arkansas Bookstore, Fayetteville, Arkansas. Waldroup, P. W., R. J. Mitchell and K. R. Hazen, 1974. The phosphorus needs of finishing broilers in relationship to dietary nutrient density levels. Poultry Sci. 53: 1655-1663.
NEWS AND NOTES (Continued from page 242) ration of the Mid-Atlantic Rift," "Towards a Human Scientist," "The Emergence of Biochemistry," "Income Distribution and Economic Equity in the United States," and "Mapping the Grand Canyon." Prominent among the symposia are those concerned with food and population issues that will be of general interest to all agricultural scientists. Some of these symposium topics are (with arranger given in parenthesis): Food, Nutrition and Population Policy (R. Ravelle); Feasibility and Impact of Urban Food Production (S. Leiderman); Wind, Weather and Dryland Farming (W. Roberts); Climate and Plant Productivity (E. Lemon); Crop Productivity—Research Imperatives (M. Lamborg); Elemental Pathways Along the Food Chain (H. Cannon); Malthus Thwarted—So Far
(J. Horsfall); Energy and Food Production: Contemporary Technology and Alternatives (G. Salzman); Unappreciated Indigenous Foods of Exceptional Nutritional Value (M. Whiting); Plant Germplasm Resources—American Independence, Past and Future (G. Wilkes); and The Ecology of Famine (F. Bang). In addition, this meeting provides an excellent opportunity to gain a " state of art" overview of many diverse scientific fields that are relevant to agricultural and biological scientists. No other scientific meeting in the U.S. offers an opportunity comparable to the A.A.A.S. meetings for interacting with the leaders from other disciplines or for influencing the public image of science.
(Continued on page 263)
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
Lewis, D., 1969. Amino acid interactions in nutrition, especially between arginine and lysine. Biological Interrelationships and Nutrition, 15: 157-158. Lewis, D., and J. P. F. D'Mello, 1967. Growth and dietary amino acid balance. In: Growth and Development of Mammals, G. A. Lodge and G. E. Ramming (Ed.) Butterworth's, London, England. Nesheim, M. C , 1968. Genetic variation in arginine and lysine utilization. Fed. Proc. 27: 1210-1214. Nesheim, M. C , R. E. Austic and S. Wang, 1972. Amino acids in avian nutrition 4. Dietary factors influencing amino acid degradation. Poultry Sci. 51: 28-35. Salmon, W. P., 1958. The significance of amino acid imbalance in nutrition. Am. J. Clinical Nutr. 6: 487-494. Savage, J. E., 1972. Amino acids in avian nutrition. 5. Amino acid and mineral interrelationships. Poultry Sci. 51:35-43. Smith, R. E., and H. M. Scott, 1965a. Use of free amino acid concentrations in blood plasma in evaluating the amino acid adequacy of intact proteins for chick growth. 1. Free amino acid patterns of blood plasma of chicks fed unheated and heated fishmeal proteins. J. Nutr. 86: 37-44. Smith, R. E., and H. M. Scott, 1965b. Use of free amino acid concentrations in blood plasma in evaluating the amino acid adequacy of intact proteins for chick growth. 2. Free amino acid patterns of blood plasma of chicks fed sesame and raw, heated and overheated soybean meals. J. Nutr. 86: 45-50. Smith, R. E., and H. M. Scott, 1965c. Measurement
253
Department of Animal Sciences, University of Arkansas, Fayetteville, Arkansas 72701 (Received for publication April 29, 1975)
ABSTRACT Studies were conducted in which levels of essential amino acids in excess of the minimum requirements were minimized in broiler diets composed of commercially available feedstuffs and synthetic amino acid supplements. Growth rate and efficiency of feed utilization of chicks fed such diets were equal to that attained by chicks fed diets formulated by conventional means when grown under conditions where heat stress was not a factor and significantly improved when fed under conditions of heat stress. Improvements were obtained in efficiency of protein and calorie utilization using this technique of formulation. POULTRY SCIENCE 55: 243-253, 1976
LMQUIST (1952) stated that "when dietary protein is in exact balance and in sufficient quantity the rate of tissue synthesis and the efficiency of utilization of the diet for growth will approach a maximum. However, if a slight amino acid deficit exists the animal will attempt to compensate by consuming more of the diet, in which case the rate of growth may attain the maximum but the efficiency of the diet may not." The importance of balanced amino acid patterns in broiler diets is well documented. Askelson and Balloun (1965) concluded from studies in which broiler chicks were fed diets ranging in crude protein from 18 to 22 percent that improvement in performance associated with increased protein levels was the result of improved essential amino acid balance and could be accomplished equally as well through amino acid supplementation. Fisher et al. (1960) described an imbalanced diet as one which contained an excess amount of some essential amino acids while one essential amino acid was present in amounts less than that required for optimum protein synthesis and growth. Smith and Scotl (1965a, b, c) showed that supplementing a deficient diet with an essential amino acid mixture devoid of the deficient amino acid Published with the approval of the Director of the Arkansas Agricultural Experiment Station.
243
had an adverse effect upon growth. Sugahara et al. (1969) and Velu et al. (1970) demonstrated that a protein source with a good amino acid balance fed at suboptimal levels had little or no depressing effect upon feed intake by chicks; however, if a poorly balanced protein was fed, feed consumption was reduced. Velu et al. (1971) further demonstrated that protein utilization of a balanced diet remained constant as protein intake increased from a deficiency to adequacy for maximum growth. Harper et al. (1970) reported that amino acid degradation systems did not respond readily to excess amino acids when dietary protein levels were low. The ingestion of excesses of individual amino acids at low protein intake levels often results in accumulation of these amino acids in the body fluids and may trigger the reduction in feed intake that is characteristic of amino acid imbalance. Salmon (1958) stated that when a single amino acid is present in an animal's diet at levels not capable of supporting maximum synthesis of tissue proteins any amino acid not fully utilized is in excess and must be eliminated from the body. Intheprocess there is a wasting of the most limiting essential amino acid which increases the severity of the deficiency. Lewis (1969) concluded that in most instances an excess of an essential amino acid will impose a limitation upon the
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
A
244
WALDROUP, MITCHELL, PAYNE AND HAZEN
It is now generally accepted that the altered plasma and tissue amino acid pattern which develops during an imbalance produces the adverse affect on appetite. The mechanism by which the altered amino acid pattern affects the appetite regulating centers is still unknown. Evidence indicates that two possible mechanisms may be responsible for the reduced level of circulating target amino acids
in the plasma brought about by the consumption of an imbalanced diet. Harper and Rogers (1965) proposed the anabolic theory which states that a surplus of amino acids stimulates synthesis or suppresses breakdown of protein in the liver so that more of the limiting amino acid is retained in the liver in the imbalanced than in the control group. The concentration of the limiting amino acid in the plasma is thereby reduced, leading to an altered amino acid pattern and subsequently to a depressed feed intake. The catabolic theory proposed by Lewis and D'Mello (1967) states than an excess of an agent amino acid enhances general catabolism and excretion of amino acids and thereby inadvertently encourages the loss of the target amino acid. This mechanism may lead to a deranged pattern of free amino acids in plasma and tissue and to a depression of growth rate and feed intake. The anabolic form of imbalanced response can be regarded as being brought about by the addition of an incomplete mixture of amino acids to a diet limiting in the amino acid not added and is characterized by a homeostatic response to prevent undue loss of the limiting amino acid. The catabolic version can be considered to be brought about by excess doses of single amino acids, particularly lysine, leucine, threonine and methionine. In such instances the target or limiting amino acid is lost through renal or oxidative pathways, as indicated by various workers. Jones et al. (1967) and Nesheim (1968) reported that kidney arginase activity was increased by excess dietary lysine. Austic and Nesheim (1970) reported increased arginase activity in chicks fed diets containing amino acids in excess other than lysine. Savage (1972) reported that the addition of lysine to a diet composed largely of casein protein which contains approximately twice as much lysine as arginine depressed chick growth, increased kidney arginase activity and exaggerated arginine deficiency symptoms. Nesheim et al. (1972) discussed the increased degradation
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
efficiency of nutrient utilization proportional to the magnitude of deviation from a perfect balance. There are also recognized instances when a dietary excess of an amino acid or a mixture of amino acids will precipitate an ill effect which is totally disproportionate to the degree of imbalance. Such is the case with the interaction existing between lysine and arginine (D'Mello and Lewis, 1970a), leucine and valine and to some extent leucine and isoleucine (D'Mello and Lewis, 1970b) and threonine and tryptophan (D'Mello and Lewis, 1970c). These are apparently actual interactions between target and agent amino acids as advanced by Lewis (1965) and not adverse effects precipitated by administering massive doses of amino acid as described by Anderson etal. (1951) and Almquist (1952). D'Mello and Lewis (1970c) concluded that it is impossible to determine the chick's actual requirement for essential amino acids unless the diet is in good amino acid balance since the amino acid pattern of the diet will affect the chick's response to supplementation. Allen et al. (1970) reported that the addition of one percent lysine to a diet presently adequate in this amino acid would increase the chick's arginine requirement by approximately 50 percent. It was shown by D'Mello and Lewis (1971) that excess lysine, leucine and threonine precipitated drops in plasma levels of arginine, valine and isoleucine and tryptophan, respectively, along with (but at some later time) decreased growth rate and feed consumption. These ill effects were remedied only by the addition of the target amino acid.
AMINO ACIDS FOR CHICKS
It is readily apparent that amino acids in excess of the actual needs of the chick enter the bloodstream and by some mechanism inhibit feed intake and thus limit the rate of growth. Since the growth potential of a chick is governed to a great extent by the amount of feed the animal will voluntarily consume, the possibility exists that performance of broiler chicks under commercial conditions could be improved by limiting the amounts of amino acids present at levels greater than actually needed. This may be quite easy to do on a small scale with purified diets but because of the ubiquitous nature of some amino acids in practical feedstuffs may be difficult to attain under commercial conditions. Trials were conducted in this laboratory to study means by which the amounts of essential amino acids in a broiler diet might be minimized and still maintain acceptable performance. Ingredients were limited to widely available feedstuffs and feed grade methionine and lysine supplements. EXPERIMENT 1 Materials and Methods. The first study was an exploratory trial conducted to determine the feasibility of reducing the levels of excess
essential amino acids using practical type diets and to examine the response of chicks in terms of voluntary feed consumption and weight gains. In this and all following studies in this report, the amino acid levels suggested by the Arkansas Agricultural Extension Service (1966), scaled in proportion to the dietary energy level being used, were used as minimum requirements. These restrictions have supported adequate performance in our laboratory for several years. The diets were formulated by linear programming using the IBM MPS-360 system (Waldroup, 1973). Ingredients were assigned prices currently in effect in Fayetteville, Arkansas. Using a dietary energy level of 3080 M.E. kcal./kg., three amino acid series were formulated. In the first series, no supplemental methionine or lysine were allowed so that only intact feedstuffs were used as a source of dietary amino acids. In the second series, the minimum requirements for the sulfur amino acids were removed and the diets formulated with intact ingredients to meet the needs for the other essential amino acids. A feed grade DL-methionine supplement was then added to bring the methionine and total sulfur amino acid levels to the minimum specifications. In the third series, the minimum specifications for the sulfur amino acids and lysine were removed and the remainder of the nutrients supplied from intact ingredients. Supplemental DL methionine and a feed grade lysine HC1 supplement were then used to meet the minimums for these amino acids. In addition to the three amino acid series, there were two types of basal diets used. In the first basal series yellow corn and soybean meal were the only intact protein sources and in the second series corn, soybean meal and 5 percent of a Peruvian anchovy fish meal were used as the intact protein sources. As a result of this method of formulation, the diets contained a wide range of protein and essential amino acid levels, while still
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
of arginine by kidney arginase largely to urea and ornithine when dietary excesses of lysine were fed. They concluded from this and other work that excess levels of some amino acids may increase the degradation of other amino acids, thus increasing the chick's need for the degraded amino acid(s). According to D'Mello and Lewis (1970a, b, c) an interaction exists between agent and target amino acids which increases the bird's need for the target amino acid when the agent amino acid is present in the diet in excess. Further, if the agent amino acids were present in the diet at levels no higher than that required for maximum protein synthesis, the requirement for the target amino acid would be less than that required under "normal" conditions.
245
246
WALDROUP, MITCHELL, PAYNE AND HAZEN
chicks, were assigned to each of the test diets for a 10 day feeding period. The experimental diets and tap water were fed ad libitum with a 14 hour light period. Individual weight gains and pen feed consumption data were subjected to the analysis of variance as outlined by Steel and Torrie (1960) with significant differences between treatment means determined by the multiple range test of Duncan (1955). Results. The results of this study (Table 2) indicated that there were no statistically significant differences in voluntary feed consumption or weight gains among chicks fed the different experimental diets. While one might theoretically anticipate improved feed consumption or body weight gains by chicks fed the diets with a minimum of essential amino acids, these chicks were not under temperature stress nor were any amino acids
TABLE 1.—Composition of diets (Trial 1) Ingredient Yellow corn Soybean meal (50 protein) Fish meal (65 protein) Soybean oil Dical phosphate Limestone Salt Vitamin premix 1 Trace minerals' Sand DL-methionine (98) Lysine HC1 (98)
Calculated Analysis M.E. kcal./kg. Protein % Lysine % Meth + Cys % Essential amino acids % Excess amino acids %
5
6
46.19
57.27
64.77
4 50.74
60.97
64.90
45.00 0.00 4.58 1.77 0.64 0.40 0.50 0.10 0.82
33.92 0.00 3.32 1.84 0.66 0.40 0.50 0.10 1.86
26.42 0.00 2.51 1.92 0.66 0.40 0.50 0.10 2.27
35.26 5.00 3.88 1.02 0.58 0.40 0.50 0.10 2.53
25.03 5.00 2.78 1.12 0.57 0.40 0.50 0.10 3.41
21.10 5.00 2.36 1.14 0.58 0.40 0.50 0.10 3.64
0.00 0.00
0.13 0.00
0.22 0.24
0.00 0.00
0.12 0.00
0.17 0.12
100.00
100.00
100.00
100.00
100.00
100.00
3080 26.92 1.60 0.80 14.56 147.07
3080 22.23 1.23 0.80 12.11 122.32
3080 19.04 1.23 0.80 10.77 108.78
3080 25.59 1.54 0.80 13.91 140.50
3080 21.25 1.23 0.80 11.67 117.87
3080 19.59 1.23 0.80 10.94 110.50
1
2
1. As outlined by Waldroup et al. (1974).
3
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
meeting the same minimum amino acid restrictions (Table 1). Protein levels ranged from a high of 26.9 percent to a low of 19.0 percent. Analytical values were in close agreement with these calculated levels. The sum of the calculated essential amino acid content ranged from 14.6 percent to 10.8 percent. The sum of the essential amino acid levels required was 9.9 percent, so the final diets contained from 108.8 to 147.1 percent more essential amino acids than the minimum levels specified. Female chicks of a broiler strain were fed a standard chick starter mash from day-old to 7 days of age, at which time they were weighed and divided into weight groups with a 2 gram weight range. The chicks were then assigned to compartments in electrically heated battery brooders in such a manner as to equalize as nearly as possible the initial weights. Six pens, each containing eight
247
AMINO ACIDS FOR CHICKS
TABLE 2.—Effect
Basal diet 1 1. 2. 3. 4. 5. 6.
C-S C-S C-S C-S-F C-S-F C-S-F
1. 2. 3. 4. 5. 6.
of diets with different levels of essential amino acids on broiler performance (Trial 1)
Protein
E.A.A. 2
7-17 day weight gain 6
26.92 22.23 19.04 25.59 21.25 19.59
14.56 12.11 10.77 13.91 11.67 10.94
269 278 264 277 272 273
%
%
7-17 day feed /bird (g.) 6 511 525 484 496 490 487
Gain: feed 6
P.E.R. 3 ' 5
C.E.R. 4 6
0.526 0.529 0.546 0.558 0.555 0.561
1.95d 2.38bc 2.85a 2.18c 2.57b 2.86a
5.85 5.82 5.64 5.51 5.54 5.48
C-S = corn-soybean meal; C-S-F = corn-soybean meal-fish meal. E.A.A. = % of essential amino acids in diet. P.E.R. = Protein Efficiency Ratio. C.E.R. = Caloric Efficiency Ratio. Means having the same common letter do not differ significantly (P S 0.05). Where common letters are not given, differences did not reach a level of statistical significance. select feed grade lysine and methionine supplements if their cost justified their usage. No minimum protein levels were imposed. In the second series the minimums for sulfur amino acids and lysine were removed, the diets formulated to meet the needs for the other amino acids and then the remainder of the lysine and sulfur amino acid requirements were met with the addition of the feed grade supplements. Sexed broiler chicks were grown to seven days of age on a standard chick starter feed, weighed and divided into weight groups and assigned to compartments in battery brooders as previously described. Eight pens of chicks, each consisting of four male and four female chicks, were fed each experimental diet from 7 to 21 days of age. Feed consumption, body weight gains and efficiency of feed utilization were statistically analyzed as previously described.
EXPERIMENT 2 Materials and Methods. Using the same amino acidrenergy ratios described for Experiment 1, diets were formulated to contain 3080, 3300 and 3520 M.E. kcal./kg. (Table 3). Two amino acid series were formulated within each energy level. In the first series, diets were formulated to meet all amino acid minimums but the computer was allowed to
Results. Over the three different dietary energy levels tested 3080, 3300 and 3520 M.E. kcal./kg.) there were no significant differences in weight gain, feed consumption, or feed efficiency ratio that could be attributed to the differences in essential amino acid content of the diet (Table 4). Although both series of diets were formulated to meet the same minimum amino acid levels, the
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
in excessive imbalance, particularly the lysine-argine or leucine-isoleucine-valine groups. Calculations were made of the efficiency of nutrient utilization (Table 2). A Protein Efficiency Ratio (P.E.R.) was calculated as the grams of body weight gain per gram of protein consumed. As seen in Table 2 there was an improvement in efficiency of conversion of protein to body tissues by minimizing the levels of essential amino acids. A Caloric Efficiency Ratio (C.E.R.) was calculated as the M.E. kilocalories required to produce a gram of weight gain. No statistically significant differences were seen among the various dietary treatments in efficiency of energy utilization (Table 2). The fact that satisfactory performance could be attained by formulating the diets in this manner prompted further study.
248
WALDROUP, MITCHELL, PAYNE AND HAZEN
TABLE 3.—Composition of diets (Trial 2) Ingredient Yellow corn Soybean meal (50 protein) Soybean oil Dical phosphate Limestone Vitamin premix 1 Salt Trace minerals' DL-methionine (98%) Lysine HC1 (98%) Total
2
3
4'
5
6
68.16
48.76
60.91
41.25
53.66
35.92 4.15 1.88 0.67 0.50 0.40 0.10 0.12 0.00
26.14 2.17 1.92 0.67 0.50 0.40 0.10 0.23 0.25
39.14 8.20 2.08 0.67 0.50 0.40 0.10 0.15 0.00
28.94 6.40 2.12 0.67 0.50 0.40 0.10 0.26 0.37
42.37 12.26 2.27 0.67 0.50 0.40 0.10 0.18 0.00
31.75 10.63 2.32 0.67 0.50 0.40 0.10 0.30 0.39
100.00
100.00
100.00
100.00
100.00
100.00
3080 22.71 1.23 0.80 12.84 129.70
3080 18.94 1.23 0.80 10.71 108.18
3300 23.68 1.31 0.85 13.36 128.83
3300 19.66 1.31 0.85 11.06 106.65
3520 24.65 1.40 0.91 13.91 127.15
3520 20.38 1.40 0.91 11.49 105.03
1. As given in Table 1. TABLE 4.—Effect of diets with different levels of energy and essential amino acids on broiler performance (Trial 2)
M.E. kcal./kg.
% Protein
% E.A.A. 1
1. 3080 2. 3080 Avg.
22.71 18.94
12.84 10.71
3. 3300 4. 3300 Avg.
23.68 19.66
13.36 11.06
5. 3520 6. 3520 Avg.
24.65 20.38
13.91 11.49
Average 1,3, 5 Average 2 , 4 , 6
7-21 day weight gain (g.) 4 218 222 220a 240 228 234b
Gain: feed 4
P.E.R. 2 4
C.E.R.3-4
0.606 0.592
2.67 3.16
5.08 5.20
0.598b
2.92
5.14
0.657 0.649
2.78 3.31
5.02 5.08
0.653a
3.05
5.05
237 234
0.684 0.657
2.79 3.25
5.14 5.35
236b
0.671
3.02
5.24
232 228
0.649 0.632
2.75b 3.24a
5.08 5.21
1. E.A.A. = % of essential amino acids in diet. 2. P.E.R. = Protein Efficiency Ratio. 3. C.E.R. = Caloric Efficiency Ratio. 4. Means having the same common letter do not differ significantly (P < 0.05). Where common letters are not given, differences did not reach a level of statistical significance.
diets formulated to supply minimum levels of excess amino acids contained an average of 4.0 percent less protein than those formulated by more conventional means. As a
result, protein utilization (P.E.R.) was improved as in Experiment 1 as a consequence of formulating to minimize excess levels of essential amino acids (Table 4). Efficiency
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
Calculated Analysis M.E. kcal./kg. Protein % Lysine % Meth + Cyst % Essential amino acid % Escess amino acid %
1 56.26
249
AMINO ACIDS FOR CHICKS
EXPERIMENT 3 Materials and Methods. This study was conducted for a full eight week growout period under conditions similar to those encountered in commercial broiler production. The starter diets containing 3080 and 3520 M.E. kcal./kg. with "normal" and "low" essential amino acid content (Diets 1, 2, 5, and 6, Table 3) were used for the period of day old to 4 weeks of age and finisher diets of the same energy levels but adjusted for the recommended amino acid levels (Table 5) were fed from 4 to 8 weeks of age.
Results. No significant differences in growth rate or feed consumption were observed that could be related to the amino acid status of the diet, even though the diets
TABLE 5.—Composition of finisher diets (Trial 3) Ingredient Yellow corn Soybean meal (50 protein) Alfalfa meal (17 protein) Soybean oil Dical phosphate Limestone Salt Vitamin mix1 Trace minerals 1 DL-methionine (98%) Lysine HC1 (98%) Total Calculated Analysis M.E. kcal./kg. Protein % Lysine % Meth + Cys % Essential amino acid %
•As given in Table 1.
1
2
4
66.11
68.78
3 43.59
51.04
25.44
23.67
31.44
26.42
2.81 2.12 1.87 0.55 0.40 0.50 0.10 0.10 0.00
2.48 1.46 1.88 0.56 0.40 0.50 0.10 0.12 0.06
5.46 15.60 2.26 0.46 0.40 0.50 0.10 0.18 0.00
4.54 13.81 2.28 0.50 0.40 0.50 0.10 0.23 0.18
100.00
100.00
100.00
100.00
3080 18.92 0.99 0.72 10.60
3080 18.15 0.99 0.72 10.31
3520 20.39 1.14 0.83 11.39
3520 18.29 1.14 0.83 10.58
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
The chicks were housed in a wood frame building containing 16 pens, each 7.43 M 2 in size. Each of the diets was assigned to four pens with 40 male and 40 female chicks placed in each pen. Rice hulls were used as litter and infrared brooder lamps were used as a source of heat. Ceiling fans controlled by a time-temperature thermostat were used to regulate air flow. The chicks were started in the first week of June so it was anticipated that heat stress might be encountered during the period of 4 to 8 weeks of age. This did not prove to be so as the temperature during the months of June and July was moderate and heat stress was not an apparent factor. The chicks were group weighed by sex and total pen feed consumption was determined. The data were analyzed as previously described.
of energy utilization was similar for all diets with no statistically significant differences noted. As expected, chicks fed the diets containing the higher energy levels consumed less feed, grew at a faster rate, and converted the feed to gain more efficiently than those fed at lower energy levels. However, there were no significant interactions observed between the dietary energy level and the amino acid status of the diet.
250
WALDROUP, MITCHELL, PAYNE AND HAZEN
EXPERIMENT 4 Materials and Methods. The purpose of this study was to compare the effectiveness of several methods of feed formulation during summer heat stress. Four systems were TABLE 6.—Effect
compared (Table 7). These were (1) a conventional least-cost formulation without any minimum protein level established (Diets A and E); (2) formulation to minimize excess essential amino acid levels by making maximum usage of synthetic methionine and lysine supplements (Diets B and F); (3) least-cost formulation without minimum protein levels but with minimum amino acid levels increased by 10%, a practice frequently recommended to combat problems with reduced feed intake (Diets C and G); and (4) least-cost formulation to meet minimum amino acid needs with a protein minimum based on energy:protein ratios (M.E. kcal./kg. -r% protein) of 132:1 for starter diets and 156:1 for finisher diets (Diets D and H). An energy level of 3080 M.E. kcal./kg. was used in diets fed during the first 4 weeks (starter period) with 3190 M.E. kcal./kg. used during the last 4 weeks (finisher period). Each diet was fed to four groups of 40 males and 40 females in the floor pen facility described in Experiment 3. The trial was initiated during the last week of May and hot weather stress was observed during the latter part of the growth period. The data were collected and analyzed as previously described.
of diets with different levels of energy and essential amino acids on broiler performance (Trial 3)
M.E. kcal./kg.
% Protein S/F1
0-56 day weight gain (g.) 4
Gain: feed 4
P.E.R. 2 4
C.E.R.3-4
1. 3080 2. 3080
22.7/18.9 18.9/18.1
1429 1463
0.425 0.435
2.13 2.36
7.24 7.09
1446a 1554 1516
0.429
2.25
7.17
24.7/20.4 20.4/18.3
0.469 0.498
2.13 2.63
7.50 7.08
15356
0.483
2.38
7.29
1492 1489
0.446b 0.462a
2.13b 2.50a
7.37b 7.09a
Avg. 3. 3520 4. 3520 Avg.
Average 1 , 3 Average 2 , 4
1. S/F = Starter diet/Finisher diet. 2. P.E.R. = Protein Efficiency Ratio. 3. C.E.R. = Caloric Efficiency Ratio. 4. Means having the same common letter do not differ significantly (P < 0.05). Where common letters are not given, differences did not reach a level of statistical significance.
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
formulated to minimize the excess levels of essential amino acids were lower in total protein content than those formulated by conventional least-cost programming (Table 6). Chicks fed the higher energy level grew at a more rapid rate and consumed less feed but there was no significant interaction between energy level and amino acid status. Chicks fed the diets containing the lower protein level with a reduced excess of essential amino acids converted their feed to gain more efficiently with an improvement in caloric utilization (C.E.R.) as seen in Table 6. This supports the hypothesis that excess levels of amino acids are detrimental to efficient energy utilization, perhaps because of their greater heat of digestion. Efficiency of protein utilization (P.E.R.) was again improved by formulating to minimize excess levels of amino acids (Table 6) even though the difference in protein content of the finisher diets was not as great as previously seen in the starter diets.
251
AMINO ACIDS FOR CHICKS
TABLE 7.—Composition of diets (Experiment 4) Ingredient Yellow corn Soybean meal (49 protein) Fish meal (65 protein) Animal fat Dical phosphate Limestone Salt Vitamin premix1 Trace minerals1 Alfalfa meal (20) DL-methionine Lysine HC1
Starter diets (0-4 wks.) B D 63.16 64.41 58.36 55.51
Calculated Analysis M.E. kcal./kg. 3080 Protein % 20.94 Lysine % 1.13 Meth + Cys % 0.87 1. As given in Table 1.
27.57 1.50 1.82 1.63 0.86 0.40 0.50 0.10 1.00 0.18 0.03 100.00
32.35 1.50 3.11 1.61 0.85 0.40 0.50 0.10 1.00 0.22 0.00 100.00
3080 3080 3080 20.44 22.44 23.30 1.13 1.24 1.31 0.87 0.95 0.87
Results. Broilers fed the diets formulated to minimize excesses of essential amino acids had the greatest weight gain during the 56 day feeding period, followed in order by those fed the diet formulated with a 110% increase in minimum amino acid levels, those fed the least-cost diet with normal amino acid levels but with no protein minimum, and broilers fed the diets with minimum protein levels TABLE 8.—Effects Formulation method 1. Least cost, no protein minimum 2. Low essential amino acid levels 3. Least cost, 110% of minimum amino acid 4. Least cost, fixed protein levels
34.83 1.50 3.60 1.60 0.85 0.40 0.50 0.10 1.00 0.11 0.00 100.00
62.69
65.85
57.52
H 57.50
26.20 0.00 4.78 1.88 0.80 0.40 0.50 0.10 2.50 0.15 0.00 100.00
24.00 0.00 4.00 1.89 0.82 0.40 0.50 0.10 2.18 0.18 0.08 100.00
29.81 0.00 5.87 1.87 0.77 0.40 0.50 0.10 2.97 0.19 0.00 100.00
29.95 0.00 5.83 1.86 0.77 0.40 0.50 0.10 2.98 0.11 0.00 100.00
3190 3190 3190 3190 19.07 18.08 20.51 20.50 1.00 1.00 1.10 1.11 0.77 0.77 0.85 0.77
imposed (Table 8). The same order was followed in regards to efficiency of feed utilization (gainrfeed ratios) protein utilization (P.E.R.) and energy utilization (C.E.R.). These data, in conjunction with the results of the previous experiments, demonstrate that broiler chicks can be grown effectively on diets formulated to meet essential amino acid needs without regard to a protein mini-
of different methods of feed formulation on broiler performance (Trial 4) % Protein S/F1
0-56 day weight gain (g.) 4
Gain: feed
P.E.R. 2 - 4
C.E.R. 3 4
20.9/19.0
1476ab
0.425ab
2.19cd
7.18
20.4/18.0
1535a
0.444a
2.37a
6.97
22.4/20.5
1512ab
0.434ab
2.07bc
7.08
23.3/20.5
1436b
0.414b
1.95c
7.42
1. S/F = Starter diet/Finisher diet. 2. P.E.R. = Protein Efficiency Ratio. 3. C.E.R. = Caloric Efficiency Ratio. 4. Means having the same common letter do not differ significantly (P < 0.05). Where common letters are not given, differences did not reach a level of statistical significance.
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
28.50 1.50 2.18 1.63 0.86 0.40 0.50 0.10 1.00 0.17 0.00 100.00
Finisher diets (4-8 wks.)
252
WALDROUP, MITCHELL, PAYNE AND HAZEN
The results of the studies in this report, using ingredients similar to those used in commercial broiler production in the United States, support the hypothesis proposed by numerous workers that amino acids in excess of the needs by the chick may impair feed intake and growth rate, especially under heat stress conditions. Through the increased usage of commercially available synthetic amino acids, diets may be formulated having minimal excesses of these amino acids and may result in improved performance under heat stress without impairing performance under more moderate environmental conditions. REFERENCES Allen, N. K., D. H. Baker and H. M. Scott, 1970. Quantitative impairment of arginine utilization by graded levels of dietary lysine. Poultry Sci. 49: 1363.
Almquist, H. J., 1952. Utilization of amino acids by chicks. Arch. Biochem. Biophys. 59: 197-202. Anderson, J. O., G. F. Combs, A. C. Graschke and G. M. Briggs, 1951. Effects on chicks' growth of amino acid imbalances in diets containing low and adequate levels of niacin and pyridoxine. J. Nutr. 45: 345-360. Arkansas Agricultural Extension Service, 1966. Suggested restrictions for poultry diets. University of Arkansas, Little Rock, Ark. Askelson, C. E., and S. L. Balloun, 1965. Influence of dietary protein level and amino acid composition on chick performance. Poultry Sci. 44: 193-197. Austic, R. E., and M. C. Nesheim, 1970. Role of kidney arginase in variations of the arginine requirements of chicks. J. Nutr. 100: 855-867. D'Mello, J. P. F., and D. Lewis, 1970a. Amino acid interactions in chick nutrition. 1. The interrelationship between lysine and arginine. Br. Poultry Sci. 11: 299-311. D'Mello, J. P. F., and D. Lewis, 1970b. Amino acid interactions in chick nutrition. 2. Interrelationships between leucine, isoleucine and valine. Br. Poultry Sci. 11: 313-323. D'Mello, J. P. F., and D. Lewis, 1970c. Amino acid interactions in chick nutrition. 3. Interdependence in amino acid requirements. Br. Poultry Sci. 11: 367-385. D'Mello, J. P. F., and D. Lewis, 1971. Amino acid interactions in chick nutrition. 4. Growth, food intake and plasma amino acid patterns. Br. Poultry Sci. 12: 345-358. Duncan, D. B., 1955. Multiple range and multiple f test. Biometrics, 11: 1-42. Fisher, H., P. A. Griminger, G. A. Leveille and R. Shapiro, 1960. Quantitative aspects of lysine deficiency and amino acid imbalances. J. Nutr. 71: 213-220. Greene, D. E., 1961. Factors influencing the growth of chicks fed crystalline amino acid diets with special reference to a growth stimulating factor in intact proteins. Diss. Abstracts, 21: 1312. Harper, A. E., N. J. Benevenga andR. M. Wohlhueter, 1970. Effects of ingestion of disproportional amounts of amino acids. Physiol. Rev. 50: 428-558. Harper, A. E., and Q. R. Rogers, 1965. Amino acid imbalance. Proc. Nutr. Soc. 24: 173-190. Jones, J. D., S. J. Petersburg and P. C. Burnett, 1967. The mechanism of the lysine-arginine antagonism in the chick: Effect of lysine on digestion kidney arginase and liver transamidose. J. Nutr. 93: 103116. Lewis, D., 1965. The concept of agent and target in amino acid interactions. Proc. Nutr. Soc. 24: 196-209.
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
mum. Obviously one must consider the needs of a nitrogen pool for formation of the dispensible amino acids but this does not appear to be a problem when using diets composed principally of corn and soybean meal. Some indications of ratios for dispensible/indispensible amino acid needs have been reported for purified or semi-purified diets. Stucki and Harper (1961) examined the optimum ratios of indispensable dispensable amino acids for chicks. Their results suggested that best growth of chicks resulted when about 33 percent of the dietary nitrogen in a purified diet came from dispensible amino acids. Greene (1961) reported that for maximum performance of chicks fed a crystalline amino acid diet an optimum ration of essential to non-specific nitrogen was 1.7:1. Sugahara and Ariyoshi (1968) noted an optimum dispensible :dispensible amino ratio for optimum growth of chicks of 1.5:1 while for optimum feed efficiency it was 1:1. As additional sources of supplemental amino acids become available for commercial usage this may become a necessary consideration in formulating diets.
AMINO ACIDS FOR CHICKS
of the amino acid content of fish meal proteins by chick growth assay. 2. The effects of amino acid imbalances upon estimations of amino acid availability by chick growth assay. Poultry Sci. 44: 408-413. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Co., New York, N.Y. Stucki, W. P., and A. E. Harper, 1961. Importance of dispensible amino acids for normal growth of chicks. J. Nutr. 74: 377-383. Sugahara, M., and S. Ariyoshi, 1968. The role of dispensible amino acids for the maximum growth of chick. Agr. Biol. Chem. 32: 153-160. Sugahara, M., D. H. Baker and H. M. Scott, 1969. Effects of different patterns of excess amino acids on performance of chicks fed amino acid-deficient diets. J. Nutr. 97: 29-32. Velu, J. G., D. H. Baker and H. M. Scott, 1970. Amino acid balance and body composition changes in the young chick. Poultry Sci. 49: 1448. Velu, J. G., D. H. Baker and H. M. Scott, 1971. Protein and energy utilization by chicks fed graded levels of a balanced mixture of crystalline amino acids. J. Nutr. 101: 1249-1256. Waldroup, P. W„ 1973. Using the MPS/360 linear programming system for feed formulation. University of Arkansas Bookstore, Fayetteville, Arkansas. Waldroup, P. W., R. J. Mitchell and K. R. Hazen, 1974. The phosphorus needs of finishing broilers in relationship to dietary nutrient density levels. Poultry Sci. 53: 1655-1663.
NEWS AND NOTES (Continued from page 242) ration of the Mid-Atlantic Rift," "Towards a Human Scientist," "The Emergence of Biochemistry," "Income Distribution and Economic Equity in the United States," and "Mapping the Grand Canyon." Prominent among the symposia are those concerned with food and population issues that will be of general interest to all agricultural scientists. Some of these symposium topics are (with arranger given in parenthesis): Food, Nutrition and Population Policy (R. Ravelle); Feasibility and Impact of Urban Food Production (S. Leiderman); Wind, Weather and Dryland Farming (W. Roberts); Climate and Plant Productivity (E. Lemon); Crop Productivity—Research Imperatives (M. Lamborg); Elemental Pathways Along the Food Chain (H. Cannon); Malthus Thwarted—So Far
(J. Horsfall); Energy and Food Production: Contemporary Technology and Alternatives (G. Salzman); Unappreciated Indigenous Foods of Exceptional Nutritional Value (M. Whiting); Plant Germplasm Resources—American Independence, Past and Future (G. Wilkes); and The Ecology of Famine (F. Bang). In addition, this meeting provides an excellent opportunity to gain a " state of art" overview of many diverse scientific fields that are relevant to agricultural and biological scientists. No other scientific meeting in the U.S. offers an opportunity comparable to the A.A.A.S. meetings for interacting with the leaders from other disciplines or for influencing the public image of science.
(Continued on page 263)
Downloaded from http://ps.oxfordjournals.org/ by guest on June 10, 2015
Lewis, D., 1969. Amino acid interactions in nutrition, especially between arginine and lysine. Biological Interrelationships and Nutrition, 15: 157-158. Lewis, D., and J. P. F. D'Mello, 1967. Growth and dietary amino acid balance. In: Growth and Development of Mammals, G. A. Lodge and G. E. Ramming (Ed.) Butterworth's, London, England. Nesheim, M. C , 1968. Genetic variation in arginine and lysine utilization. Fed. Proc. 27: 1210-1214. Nesheim, M. C , R. E. Austic and S. Wang, 1972. Amino acids in avian nutrition 4. Dietary factors influencing amino acid degradation. Poultry Sci. 51: 28-35. Salmon, W. P., 1958. The significance of amino acid imbalance in nutrition. Am. J. Clinical Nutr. 6: 487-494. Savage, J. E., 1972. Amino acids in avian nutrition. 5. Amino acid and mineral interrelationships. Poultry Sci. 51:35-43. Smith, R. E., and H. M. Scott, 1965a. Use of free amino acid concentrations in blood plasma in evaluating the amino acid adequacy of intact proteins for chick growth. 1. Free amino acid patterns of blood plasma of chicks fed unheated and heated fishmeal proteins. J. Nutr. 86: 37-44. Smith, R. E., and H. M. Scott, 1965b. Use of free amino acid concentrations in blood plasma in evaluating the amino acid adequacy of intact proteins for chick growth. 2. Free amino acid patterns of blood plasma of chicks fed sesame and raw, heated and overheated soybean meals. J. Nutr. 86: 45-50. Smith, R. E., and H. M. Scott, 1965c. Measurement
253
