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Animal Science Journal (2015) 86, 891–896
doi: 10.1111/asj.12377
ORIGINAL ARTICLE Estimation of the optimal standardized ileal digestible lysine requirement for primiparous lactating sows fed diets supplemented with crystalline amino acids Meng SHI,1 Jianjun ZANG,1 Zhongchao LI,1 Chuanxin SHI,1 Ling LIU,1 Zhengpeng ZHU2 and Defa LI1 1
State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing, and 2The New Hope Liuhe Co., Ltd, Chengdu, China
ABSTRACT This experiment was conducted to determine the optimal standardized ileal digestible lysine (SID Lys) level in diets fed to primiparous sows during lactation. A total of 150 (Landrace × Large White) crossbred gilts (weighing 211.1 ± 3.5 kg with a litter size of 11.1 ± 0.2) were fed lactation diets (3325 kcal metabolizable energy (ME)/kg) containing SID Lys levels of 0.76, 0.84, 0.94, 1.04 or 1.14%, through 28 days lactation. Gilts were allocated to treatments based on their body weight and backfat thickness 48 h after farrowing. Gilt body weight loss was significantly (P < 0.05) decreased by increasing dietary SID Lys levels. Fitted broken-line (P < 0.05) and quadratic plot (P < 0.05) analysis of body weight loss indicated that the optimal SID Lys for primiparous sows was 0.85 and 1.01%, respectively. Average daily feed intake (ADFI), weaningto-estrus interval and subsequent conception rate were not affected by dietary SID Lys levels. Increasing dietary lysine had no effect on litter performances. Protein content in milk was increased by dietary SID Lys (P < 0.05). Dietary SID Lys tended to increase concentrations of serum insulin-like growth factor I (P = 0.066). These results of this experiment indicate that the optimal dietary SID Lys for lactating gilts was at least 0.85%, which approaches the recommendation of 0.84% that is estimated by the National Research Council (2012).
Key words: body weight loss, gilt, lactation, litter performance, SID Lysine.
INTRODUCTION Lysine (Lys) is the first-limiting amino acid in typical corn-soybean meal diets fed to lactating sows (Soltwedel et al. 2006). Parity influences Lys requirement and the magnitude of the response in subsequent litter size to previous lactation Lys (protein) intake (Yang et al. 2000). For example, primiparous sows have to use a greater proportion of dietary nutrients for maternal growth than multiparous sows (Whittemore 1996). Yang et al. (2009) suggested that a higher Lys intake than recommended by the NRC (1998) could improve sow performance during lactation. Several studies have been conducted to estimate the effect of Lys (protein) levels in diets on the performance of lactating sows (Knabe et al. 1996; Tritton et al. 1996; Sauber et al. 1998; Touchette et al. 1998; Yang et al. 2000) with Lys supplied from intact protein sources. However, for economic and environmental reasons, a reduction in dietary crude protein (CP) and supplementation with crystalline amino acids (AA) is a desirable goal for the pig industry (Kerr et al. 1995). © 2015 Japanese Society of Animal Science
However, few studies have determined the optimum dietary Lys requirement on the basis of standardized ileal digestible (SID) AA for primiparous sows supplied with crystalline AA. Ileal digestibility coefficients for AA have been expressed as total or apparent by the authors listed above. Compared with apparent or true ileal digestibility (AID or TID), SID values have been suggested as the best choice to be used for routine feed formulation (Stein et al. 2007), because they are additive in mixed diets and there is no need to measure the specific endogenous AA loss (Stein et al. 2005). The objective of the present study was to estimate the optimum SID Lys required to minimize weight loss or optimize litter
Correspondence: Defa Li, State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing 100193, China. (Email: [email protected]) Received 18 July 2014; accepted for publication 28 October 2014.
892 M. SHI et al.
weight at weaning of primiparous sows fed diets supplemented with crystalline AA.
heat pad and an infrared heat lamp. The temperature in the farrowing house was maintained at a minimum of 20°C with heat lamps providing supplemental heat for the pigs. Gilts were allowed ad libitum access to feed and water from parturition (day 1) until weaning (day 28). Several gilts were culled because of death during parturition, lack of milk, having died, disease during lactation or failure to observe estrus, so the total numbers of gilts recorded in each of the five treatments in the present study were 22, 23, 20, 25 and 22, respectively. On day 2 post partum, gilts were allotted to one of five dietary treatments based on body weight (BW) (211 ± 3.5 kg) and backfat thickness (27.8 ± 3.5 mm). All dietary treatments were based on corn, soybean meal and wheat bran. Five lactation diets (3325 kcal of ME/kg) were formulated to contain SID Lys contents of 0.76, 0.84, 0.94, 1.04 and 1.14%, respectively (Table 1) by adding crystalline Lys to the diet at the expense of corn. Pigs were cross-fostered among gilts irrespective of dietary treatment until 48 h after parturition to standardize litters to at least 10 pigs. On day 1 of birth, pigs received 200 mg of iron (iron dextran solution), ears were notched, teeth were cut and tails and navel cords were docked. Male pigs were castrated on day 7. Ten gilts per treatment were milked manually on day 21 of lactation. Gilts were separated from their litters for a minimum of 30 min before milking. All gilts were milked
MATERIALS AND METHODS The animal care and experimental procedures were approved by the Institutional Animal Care and Use Committee of China Agriculture University (Beijing, China). The experiment was carried out at the National Feed Engineering Technology Research Center of the Ministry of Agriculture Feed Industry Center Animal Testing Base (Hebei, China).
Animals, dietary treatments and management A total of 150 (Landrace × Large White crossbred) gilts were bred with semen obtained from purebred Duroc boars. During gestation, gilts were housed in individual gestation stalls (0.65 m × 2.2 m), and were fed 2.0 kg/day from mating until day 80 of gestation and 3.0 kg/day after day 80 of gestation. The gestation diet was a corn, wheat bran and soybean meal based diet formulated to provide 3000 kcal/kg metabolizable energy (ME), 15.5% crude protein (CP), 0.67% SID Lys, 0.80% Ca and 0.70% P. On day 110 of gestation, gilts were moved into the farrowing room and placed in farrowing crates (2.0 × 3.0 m2) equipped with a piglet creep area which was fitted with a
Table 1 Ingredient composition and chemical analysis of lactation diets (as-fed, %)
Item
Dietary SID Lys (%) 0.76
Ingredient (%) Corn Soybean meal Wheat bran Soybean oil Limestone Salt Dicalcium phosphate L-lysine (78%)† L-threonine (98.5%) MHA (84%)‡ Analyzed composition (%)§ Crude protein Calcium Phosphorus Lysine (lys) Threonine (Thr) Methionine (Met) Tryptophan (Trp) Valine Calculated composition ME (kcal/kg) SID Lys (%) SID Thr (%) SID Met (%) SID Trp (%)
0.84
0.94
1.04
1.14
60.78 21.00 11.31 2.80 1.64 0.60 0.84 0.00 0.06 0.03
64.50 24.80 5.20 1.50 1.64 0.60 0.84 0.00 0.00 0.00
64.30 24.77 5.20 1.60 1.64 0.60 0.84 0.13 0.00 0.00
64.00 25.00 5.14 1.60 1.64 0.60 0.84 0.26 0.00 0.00
64.50 24.30 5.10 1.70 1.64 0.60 0.84 0.40 0.00 0.00
17.45 0.95 0.63 0.91 0.67 0.28 0.20 0.86
17.58 0.94 0.62 1.02 0.67 0.28 0.20 0.86
17.63 0.94 0.62 1.13 0.67 0.28 0.20 0.86
17.72 0.95 0.64 1.20 0.67 0.28 0.20 0.86
17.69 0.96 0.62 1.38 0.67 0.28 0.20 0.86
3340 0.76 0.56 0.24 0.17
3336 0.84 0.56 0.24 0.17
3332 0.94 0.56 0.24 0.17
3327 1.04 0.56 0.24 0.17
3324 1.14 0.56 0.24 0.17
†L-lysine, L-threonine and L-valine were provided by Changchun Dacheng Bio Technology Development Company (Changchun, China). ‡MHA, DL-methionine hydroxy analogue (84%) was provided by Novus International, St. Louis, MO, USA. §Supplied per kg diet: vitamin A, 12 000 IU; vitamin D3, 2000 IU; vitamin E, 24 IU; vitamin K3, 2.0 mg; thiamin, 2.0 mg; riboflavin, 6.0 mg; pyridoxine, 4.0 mg; vitamin B12, 24 μg; niacin, 30 mg; pantothenic acid, 20 mg; folic acid, 3.6 mg; biotin, 0.40 mg; choline, 0.40 g; iron, 96 mg; copper, 8.0 mg; zinc, 120 mg; manganese, 40 mg; iodine, 0.56 mg; selenium, 0.30 mg; phytase, 120 mg. SID, standardized ileal digestible; ME, metabolizable energy.
© 2015 Japanese Society of Animal Science
Animal Science Journal (2015) 86, 891–896
LYSINE REQUIREMENTS FOR LACTATING GILTS
approximately 2 h after the morning feeding. Milk was collected from the first and last productive glands on both sides of the body. Each gland was milked until approximately 20 mL of milk was collected. Samples were collected by infusing 10 IU oxytocin via a jugular catheter. Milk was immediately frozen at −20°C. Gilts were bled via vena cava puncture on day 21 postfarrowing to determine concentrations of glucose, serum urea nitrogen, insulin, insulin-like growth factor I (IGF-I) and luteinizing hormone. Gilts were given feed at 07.00 hours, allowed 1 h to consume to satiety, and residual feed was removed. Gilts were bled 3 h later at 11.00 hours. Blood was collected using a 10 mL plain, blood collection tube (Greiner Bio-One GmbH, Kremsmunster, Austria). Blood samples were held in ice-cold tubes and centrifuged at 3000 × g at 4°C for 20 min using a TDL-5-A Shanghai Anting Scientific Instrument Centrifuge (Shanghai, China). All serum samples were stored at −20°C until needed for analysis. Feed intake was determined weekly. Within 48 h of farrowing and at weaning (day 28), gilts were weighed, and loin eye area and back fat thickness (P2, 6 cm from the midline at the head of the last rib) were measured concurrently with an ultrasonic device (Piglog105; SFK Technology A/S, Herlev, Denmark). Piglets were weighed at days 0, 14 and 28. The percentage of piglet mortality was also recorded. On day 28 of lactation, gilts were moved back to the breeding barn and housed in gestation stalls and fed the same gestation diet as used previously. Gilts were checked for signs of estrus daily for 10 days after weaning and detection of estrus was conducted using boar stimuli for 15 min. The weaning to estrus interval was recorded when gilts were first observed to show a positive response to the back-pressure test (immobilization reflex). If estrus was observed, the gilts were again mated with semen from Duroc boars and conception rate recorded.
Collection and sampling The content of SID AA and ME in the ingredients were determined previously in our laboratory (Deng 2012; Ni 2012; Zhang 2012) using growing-finishing pigs. The SID AAs were determined using pigs surgically equipped with a T-cannula in the distal ileum. The basal ileal endogenous losses were measured by feeding a nitrogen-free diet. The content of ME and SID Lys were calculated by multiplying the ME and SID AA content of the individual ingredients by their inclusion level in the diets, then summing the products. All diets were supplemented with crystalline L-amino acids to achieve AA recommendations for primiparous sows (NRC 1998). Samples of ingredients and feed were taken at the beginning and the end of the experiment and stored at −20°C for the determination of their nutrient composition at the certified laboratory of the Ministry Feed Safety and Bioefficiency Evaluation Center (China Agricultural University, Beijing, China). Analysis for dry matter (DM), CP, Ca and total P was conducted according to the methods of AOAC (2003). Gross energy was measured by an Automatic Adiabatic Oxygen Bomb Calorimeter (Parr 6300 Calorimeter; Moline, IL, USA). AAs except for methionine and tryptophan in the diets were measured using ion-exchange chromatography with an Automatic Amino Acid Analyzer (L-8800; Hitachi Automatic Amino Acid Analyzer, Tokyo, Japan) after hydrolyzing with 6 mol/L HCl at 110°C for 24 h. Dietary methionine was measured after oxidation with performic acid and subsequent hydrolysis with HCl while tryptophan Animal Science Journal (2015) 86, 891–896
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was determined after alkaline hydrolysis at 120°C for 16 h (AOAC 2003) with separation using reverse-phase Highperformance liquid chromatography (HPLC) (Waters 2690, Milford, MA, USA). Milk samples were analyzed for DM, CP, fat and lactose using an Infrared Milk Analyzer (Milko Scan 133B Analyzer, Foss Electric, Hillerød, Denmark). Multi-type reagents (Arkray Inc., Saitama, Japan) were available and used to determine glucose and serum urea nitrogen by an Automated Chemistry Analyzer (Spotchem EZ SP-4430; Arkray Inc., Saitama, Japan). A swine insulin kit (Endocrine Technologies Inc., Newark, CA, USA) was used and the concentration was determined in duplicate according to the instructions for an ELISA using Biolog MicroStation System (Biolog Inc., Hayward, CA, USA). Serum IGF-I concentrations were analyzed in triplicate (Frey et al. 1994), following an extraction of serum using 0.1 mol/L glycyl glycine in a ratio of 1:1. Serum luteinizing hormone concentrations were measured using a heterologous double antibody radioimmunoassay (Dial et al. 1983).
Statistical analysis Data were analyzed using the GLM procedure of SAS (1999) with gilt as the experimental unit. Single-degree-of-freedom contrasts were performed using the solution statement in the GLM procedure of SAS to determine linear and quadratic effects of treatment. The inflection point was calculated using the solution option of SAS to determine the SID Lys requirement for gilt body weight changes, litter weight and serum metabolites. When quadratic responses were found in the data (P ≤ 0.05), the breaks were estimated using a broken line analysis, with the NLIN procedure of SAS (Robbins et al. 2006). All values are reported as least square means. The significance level was set at P ≤ 0.05, and a tendency was considered when 0.05 < P ≤ 0.10.
RESULTS Gilt performance The average daily feed intake was not significantly affected by dietary lysine (Table 2) and gilts averaged 4.56 kg/day. Actual SID Lys intakes in the five treatments were 33.6, 36.1, 40.2, 46.0 and 55.0 g/day corresponding to 40.8, 45.2, 49.6, 55.4 and 66.7 g/day of total Lys. Overall, gilts lost weight during the 28-day lactation, and the average gilt weight loss during lactation was 27.0 ± 5.5 kg. Gilt BW loss decreased with increasing dietary SID Lys supply (linear, P < 0.05; quadratic, P < 0.01; Table 2). Regression analysis showed that a linear-plateau relationship existed between Lys intake and BW loss (platform value 0.85%, R2 = 0.95). Based on quadratic analysis, BW loss was minimized at 1.01% dietary SID Lys (BW loss = 84.62 (SID Lys)2– 170.7 (SID Lys) + 111.1, R2 = 0.93). The loin eye area at weaning increased quadratically (P < 0.01) with dietary SID Lys. Based on quadratic analysis, loin eye area at weaning maximized at 1.02% dietary SID Lys (loin eye area = 56.6 (SID Lys)2–115.2 (SID Lys) + 67.7, R2 = 0.74). The extent of the loin eye area loss corresponded quadratically (P < 0.05, 8.30 vs. © 2015 Japanese Society of Animal Science
894 M. SHI et al.
4.76 cm2) with increasing dietary SID Lys levels, and was minimized at 1.02% dietary SID Lys based on the quadratic analysis. Dietary SID Lys did not affect back fat loss, weaning to estrus interval or conception rate. The average backfat loss, weaning to estrus interval and conception rate were 8.6 mm, 5.1 days and 88.1%, respectively.
Litter performance Increasing dietary Lys had no effect on the number of pigs weaned or litter growth with an average of 10.5 pigs weaned per litter and an average litter growth rate of 2.11 kg/day (Table 3). Piglet mortality was not affected by dietary SID Lys levels with the average mortality of 5.5%.
Milk composition Milk protein increased linearly (P < 0.05) with the increasing dietary SID Lys levels and the average content of milk protein was 4.80% (P = 0.051) and increasing Lys had no effect on the percentage of DM,
fat or lactose in milk. The average DM, fat and lactose in milk were 17.0, 6.33 and 4.27%, respectively (Table 4).
Gilt serum metabolites IGF-I concentration of gilts fed the 0.76% SID Lys diet tended to be lower than those of the other groups (P = 0.066, Table 5). Dietary SID Lys levels had no effect on concentrations of serum urea nitrogen, luteinizing hormone, insulin or glucose.
DISCUSSION The results of the present study show that different indicators (BW loss, muscle mass and milk protein) results in different values of requirements. The daily SID Lys intake increased with increasing dietary SID Lys levels while the BW loss of gilts decreased. Mahan et al. (1971), Tokach et al. (1992) and Touchette et al. (1998) reported that increasing dietary lysine reduced sow weight loss during lactation. For BW loss, the broken line and quadratic models showed the broken
Table 2 Effects of SID lysine levels on lactating gilt body weight loss, feed intake, weaning to estrus interval and conception rate
Item
No. of gilts Body weight (kg) At farrowing At weaning Weight loss Backfat thickness (mm) At farrowing At weaning Backfat loss Loin eye area (cm2) At farrowing At weaning Loin eye area loss ADFI (kg) Total SID Lys intake (g/day) Weaning to estrus interval (day) Conception rate (%)
Dietary SID Lys (%)
SEM
0.76
0.84
0.94
1.04
1.14
22
23
20
25
22
206.9 176.1 30.7
211.5 179.1 26.5
212.0 178.9 25.9
212.7 181.1 25.2
212.5 178.2 26.5
P-value Treatment
Linear
Quadratic
3.5 3.9 1.1
0.981 0.782 0.041
0.872 0.401 0.038
0.794 0.454 0.009
29.12 20.71 8.45
28.45 19.23 9.23
29.36 19.05 10.36
25.82 18.32 7.52
26.45 18.97 7.44
3.48 2.05 1.98
0.543 0.401 0.599
0.762 0.189 0.904
0.687 0.182 0.181
51.98 43.79 8.19 4.48 33.55 5.07 87.7
52.11 43.82 8.30 4.44 36.14 5.29 88.0
56.07 51.31 4.76 4.39 40.20 5.20 89.3
53.02 48.21 4.81 4.62 46.02 4.92 87.0
51.86 45.63 6.23 4.83 54.96 5.25 88.3
3.89 2.63 0.89 1.87 1.98 1.56 –
0.665 0.001 0.025 0.342 0.001 0.951 –
0.512 0.490 0.278 0.081 0.001 0.952 –
0.232 0.001 0.030 0.113 0.211 0.991 –
SID Lys, standardized ileal digestible lysine; ADFI, average daily feed intake.
Table 3 Effects of SID lysine levels on litter performance (days 1 to 28)
Item
No. of gilts No. piglets suckled/litter No. piglets weaned/litter Piglet mortality (%) Initial litter weight (kg) Litter weight at weaning (kg) Litter growth (kg/day)
Dietary SID Lys (%)
SEM
0.76
0.84
0.94
1.04
1.14
22 11.3 10.3 8.54 17.9 76.6 2.10
23 10.7 9.9 6.65 17.3 75.3 2.10
20 10.9 10.5 4.13 17.3 73.8 2.02
25 11.4 10.8 5.58 18.8 80.4 2.16
22 11.1 10.8 2.71 18.1 79.6 2.17
0.45 0.18 1.92 0.72 2.90 0.09
P-value Treatment
Linear
Quadratic
0.734 0.541 0.252 0.975 0.640 0.884
0.752 0.152 0.044 0.876 0.301 0.554
0.813 0.292 0.121 0.765 0.440 0.710
SID Lys, standardized ileal digestible lysine.
© 2015 Japanese Society of Animal Science
Animal Science Journal (2015) 86, 891–896
LYSINE REQUIREMENTS FOR LACTATING GILTS
Table 4
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Effects of SID lysine levels in lactation on gilt milk composition
Item
Dietary SID Lys (%)
No. of gilts Dry matter (%) Protein (%) Fat (%) Lactose (%)
SEM
0.76
0.84
0.94
1.04
1.14
7 16.23 4.31 6.27 4.43
7 16.68 4.43 6.32 4.09
6 17.25 4.85 6.28 4.21
8 17.84 5.21 6.44 4.29
7 17.01 5.19 6.36 4.33
0.15 0.06 0.05 0.03
P-value Treatment
Linear
Quadratic
0.051 0.029 0.744 0.412
0.090 0.010 0.483 0.154
0.072 0.229 0.759 0.310
SID Lys, standardized ileal digestible lysine.
Table 5
Effects of SID Lysine levels in lactation on gilt blood metabolites and hormones on day 21
Item
No. of gilts Luteinizing hormone (mIU/mL) IGF-I (ng/mL) Insulin (μIU/mL) Glucose (mmol/L) Serum urea nitrogen (mmol/L)
Dietary SID Lys (%)
SEM
0.76
0.84
0.94
1.04
1.14
6 10.36 147.3 14.51 4.31 2.67
8 12.5 178.5 17.25 4.5 3.71
7 14.55 174.6 14.34 6.22 2.48
7 11.96 179.0 13.75 4.77 3.83
8 14.15 180.9 16.51 5.58 3.29
0.74 9.8 0.36 0.96 0.34
P-value Treatment
Linear
Quadratic
0.083 0.066 0.383 0.722 0.024
0.157 0.125 0.521 0.452 0.633
0.344 0.223 0.610 0.716 0.825
SID Lys, standardized ileal digestible lysine; IGF-1, insulin-like growth factor I.
point and quadratic minimum of dietary SID Lys were 0.85% and 1.01%, respectively. In the present study, loin eye area at weaning was highest at the 1.02% dietary SID Lys (54 g/day total lysine) content based on the quadratic analysis as well as loin eye area loss was lowest at this level. This is close to the estimation of gilt BW loss which minimized at 1.01% and was obtained from the same quadratic model. The result was close to Touchette et al. (1998) who indicated that lactating gilts have the capacity to utilize dietary lysine levels of up to 58 g/day total lysine to minimize loss of body protein reserves. Pettigrew (1993) developed a prediction equation to estimate the lysine requirement for litter growth: lysine (g/day) = −8.38 + 26 (litter average daily gain, kg/day). Given a litter growth of 2.11 kg/day in the present study, the total Lys requirement for litter growth would be 46.5 g/day. Other prediction equations such as in NRC (2012) which estimated the SID Lys requirement needed for maximum litter growth suggest SID Lys requirements (g/day) = 0.015 litter growth rate (g/day) + 3.978, and the SID Lys requirement in the present study would be 35.6 g/day. In the present study, the broken point of dietary SID Lys were 0.85% for maternal BW loss, corresponding to 45.7 g of total Lys or 36.5 g SID Lys per day. Our results based on the broken line analysis fit the results of studies above. Estimates of requirement are affected by the statistical methodology. The present experiment agrees with Kendall et al. (2007) who reported that estimates of requirement would be affected by the statistical Animal Science Journal (2015) 86, 891–896
methodology used in the study with derived estimates from broken-line models almost always resulting in requirement estimates lower than those estimated from quadratic models. Linear broken line models fit the ascending and plateau portions of the curve well and the break-point of two lines is selected as the requirement. However, it assumes that the dose response of a nutrient is linear until the requirement is met and above which no significant change in response can be expected. Therefore, the broken-line model may underestimate the requirement (Robbins et al. 2006). Quadratic models can effectively estimate increases and decreases, and the shape of the curve represents the response to graded concentrations of a nutrient up to the point to meet the requirements (Pesti et al. 2009). They are more accurate to describe the physiological course than linear models (Robbins et al. 2006). However, the quadratic estimation of the maximum amount of AA requirement are commonly overestimated (Baker 1986). To facilitate comparison with sources in the literature and decrease the population variation, both linear broken line and quadratic models are presented in the present study. Lower dietary SID Lys (0.76%) may cause body reserve mobilization of primiparous sows to maintain milk yield for the maintenance of litter growth. Increasing SID Lys intake had no effect on litter performance in the present study. This confirms that sows will mobilize body tissues to provide additional energy and nutrients to support maximum milk yield if there are deficiencies in the diet (Sauber et al. 1998). © 2015 Japanese Society of Animal Science
896 M. SHI et al.
Conclusion On the basis of this study, minimized weight loss using estimates provided by the linear broken-line and quadratic model were 0.85 and 1.01%, respectively, while 1.02% optimized loin eye area loss. The present study suggests that SID Lys is at least 0.85% for lactating gilts fed a corn, wheat bran and soybean meal based diet with the estimated daily feed intake of 4.56 kg containing 3325 kcal/kg of ME. The dietary SID Lys of the present study approaches the recommendation (0.84%) of NRC (2012) for gilts.
ACKNOWLEDGMENTS We thank Changchun Dacheng Bio Technology Development Company (Changchun, China) for the generous gift of the feed grade L-lysine HCL and threonine used in the present study. DL-methionine hydroxy analogue (84%) was provided by Novus International, St. Louis, MO, USA.
REFERENCES AOAC. 2003. Official Methods of Analysis, 17th edn. Association of Official Analytical Chemists (AOAC), Arlington, VA. Baker DH. 1986. Problems and pitfalls in animal experiments designed to establish dietary requirements for essential nutrients. Journal of Nutrition 116, 2339–2349. Deng Y. 2012. Evaluation of energy value and amino acid digestibility of simulated corns for growing pigs. Master Candidate. China Agricultural University Thesis, Beijing, China. Dial GD, Dial OK, Bevier GW, Glenn SD, Dzuik PJ. 1983. Estrous behavior and circadian discharge of luteinizing hormone in the prepubertal gilt in response to exogenous estrogen. Biology of Reproduction 29, 1047–1056. Frey RS, Hathaway MR, Dayton WR. 1994. Comparison of the effectiveness of various procedures for reducing or eliminating insulin-like growth factor binding protein interference with insulin-like growth factor-1 radioimmunoassays on porcine sera. Journal of Endocrinology 140, 229–237. Kendall DC, Gaines AM, Kerr BJ, Allee GL. 2007. True ileal digestible tryptophan to lysine ratios in ninety to one hundred twenty five kilogram barrows. Journal of Animal Science 85, 3004–3012. Kerr BJ, McKeith FK, Easter RA. 1995. Effects on performance and carcass characteristics of nursery to finisher pigs fed reduced crude protein, amino acid-supplemented diets. Journal of Animal Science 73, 433–440. Knabe DA, Brendemuhl JH, Chiba LI, Dove CR. 1996. Supplemental lysine for sows nursing large litters. Journal of Animal Science 74, 1635–1640. Mahan DC, Becker DE, Jensen AH. 1971. Effect of protein levels and opaque-2 corn on sow and litter performance during the first and second lactation periods. Journal of Animal Science 32, 470–475. Ni J. 2012. Prediction regression equations of energy values of corn, soybean meal and wheat bran for pigs. Ph. D.
© 2015 Japanese Society of Animal Science
Candidate. China Agricultural University Dissertation, Beijing, China. NRC. 1998. Nutrient Requirements of Swine, 10th Rev. edn. National Academy Press, Washington, DC, USA. NRC. 2012. Nutrient Requirements of Swine, 11th Rev. edn. National Academy Press, Washington, DC, USA. Pesti GM, Vedenov D, Cason JA, Billard L. 2009. A comparison of methods to estimate nutritional requirements from experimental data. British Poultry Science 50, 16–32. Pettigrew JE. 1993. Amino acid nutrition of gestating and lactating sows. Biokyowa Technical Reviews-5. St. Louis, Missouri USA. Robbins KR, Saxton AM, Southern LL. 2006. Estimation of nutrient requirements using broken-line regression analysis. Journal of Animal Science 84 (Suppl), E155–E165. SAS. 1999. SAS User’s Guide: Statistics. Version 8.02. SAS Inst. Inc., Cary, NC. Sauber TE, Stahly TS, Williams NH, Ewan RC. 1998. Effect of lean growth genotype and dietary amino acid regimen on the lactational performance of sows. Journal of Animal Science 76, 1098–1111. Soltwedel KT, Easter RA, Pettigrew JE. 2006. Evaluation of the order of limitation of lysine, threonine, and valine, as determined by plasma urea nitrogen, in corn-soybean meal diets of lactating sows with high body weight loss. Journal of Animal Science 84, 1734–1741. Stein HH, Fuller MF, Moughan PJ, Seve B, Mosenthin R, Jansman AJM, et al. 2007. Definition of apparent, true, and standardized ileal digestibility of amino acids in pigs. Journal of Animal Science 109, 282–285. Stein HH, Pedersen C, Wirt AR, Bohlke RA. 2005. Additivity of values for apparent and standardized ileal digestibility of amino acids in mixed diets fed to growing pigs. Journal of Animal Science 83, 2387–2395. Tokach MD, Pettigrew JE, Crooker BA, Dial GD, Sower AF. 1992. Quantitative influence of lysine and energy intake on yield of milk components in the primiparous sow. Journal of Animal Science 70, 1864–1872. Touchette KJ, Allee GL, Newcomb MD, Boyd RD. 1998. The lysine requirement of lactating primiparous sows. Journal of Animal Science 76, 1091–1097. Tritton SM, King RH, Campbella RG, Edwards AC, Hughes PE. 1996. The effects of dietary protein and energy levels of diets offered during lactation on the lactational and subsequent reproductive performance of first-litter sows. Animal Science 62, 573–579. Whittemore CT. 1996. Nutrition reproduction interactions in primiparous sows. Livestock Production Science 46, 65–83. Yang H, Pettigrew JE, Johnston LJ, Shurson GC, Wheaton JE, White ME, et al. 2000. Effects of dietary lysine intake during lactation on blood metabolites, hormones, and reproductive performance in primiparous sows. Journal of Animal Science 78, 1001–1009. Yang YX, Heo S, Jin Z, Choi JY, Yoon SY, Yang BK, Chae BJ. 2009. Effects of lysine intake during late gestation and lactation on blood metabolites, hormones, milk composition and reproductive performance in primiparous and multiparous sows. Animal Reproduction Science 112, 199– 214. Zhang Z. 2012. Modeling of energy value and digestibility of amino acid of wheat bran for growing pigs. Master Candidate. China Agricultural University Thesis, Beijing, China.
Animal Science Journal (2015) 86, 891–896
Animal Science Journal (2015) 86, 891–896
doi: 10.1111/asj.12377
ORIGINAL ARTICLE Estimation of the optimal standardized ileal digestible lysine requirement for primiparous lactating sows fed diets supplemented with crystalline amino acids Meng SHI,1 Jianjun ZANG,1 Zhongchao LI,1 Chuanxin SHI,1 Ling LIU,1 Zhengpeng ZHU2 and Defa LI1 1
State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing, and 2The New Hope Liuhe Co., Ltd, Chengdu, China
ABSTRACT This experiment was conducted to determine the optimal standardized ileal digestible lysine (SID Lys) level in diets fed to primiparous sows during lactation. A total of 150 (Landrace × Large White) crossbred gilts (weighing 211.1 ± 3.5 kg with a litter size of 11.1 ± 0.2) were fed lactation diets (3325 kcal metabolizable energy (ME)/kg) containing SID Lys levels of 0.76, 0.84, 0.94, 1.04 or 1.14%, through 28 days lactation. Gilts were allocated to treatments based on their body weight and backfat thickness 48 h after farrowing. Gilt body weight loss was significantly (P < 0.05) decreased by increasing dietary SID Lys levels. Fitted broken-line (P < 0.05) and quadratic plot (P < 0.05) analysis of body weight loss indicated that the optimal SID Lys for primiparous sows was 0.85 and 1.01%, respectively. Average daily feed intake (ADFI), weaningto-estrus interval and subsequent conception rate were not affected by dietary SID Lys levels. Increasing dietary lysine had no effect on litter performances. Protein content in milk was increased by dietary SID Lys (P < 0.05). Dietary SID Lys tended to increase concentrations of serum insulin-like growth factor I (P = 0.066). These results of this experiment indicate that the optimal dietary SID Lys for lactating gilts was at least 0.85%, which approaches the recommendation of 0.84% that is estimated by the National Research Council (2012).
Key words: body weight loss, gilt, lactation, litter performance, SID Lysine.
INTRODUCTION Lysine (Lys) is the first-limiting amino acid in typical corn-soybean meal diets fed to lactating sows (Soltwedel et al. 2006). Parity influences Lys requirement and the magnitude of the response in subsequent litter size to previous lactation Lys (protein) intake (Yang et al. 2000). For example, primiparous sows have to use a greater proportion of dietary nutrients for maternal growth than multiparous sows (Whittemore 1996). Yang et al. (2009) suggested that a higher Lys intake than recommended by the NRC (1998) could improve sow performance during lactation. Several studies have been conducted to estimate the effect of Lys (protein) levels in diets on the performance of lactating sows (Knabe et al. 1996; Tritton et al. 1996; Sauber et al. 1998; Touchette et al. 1998; Yang et al. 2000) with Lys supplied from intact protein sources. However, for economic and environmental reasons, a reduction in dietary crude protein (CP) and supplementation with crystalline amino acids (AA) is a desirable goal for the pig industry (Kerr et al. 1995). © 2015 Japanese Society of Animal Science
However, few studies have determined the optimum dietary Lys requirement on the basis of standardized ileal digestible (SID) AA for primiparous sows supplied with crystalline AA. Ileal digestibility coefficients for AA have been expressed as total or apparent by the authors listed above. Compared with apparent or true ileal digestibility (AID or TID), SID values have been suggested as the best choice to be used for routine feed formulation (Stein et al. 2007), because they are additive in mixed diets and there is no need to measure the specific endogenous AA loss (Stein et al. 2005). The objective of the present study was to estimate the optimum SID Lys required to minimize weight loss or optimize litter
Correspondence: Defa Li, State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing 100193, China. (Email: [email protected]) Received 18 July 2014; accepted for publication 28 October 2014.
892 M. SHI et al.
weight at weaning of primiparous sows fed diets supplemented with crystalline AA.
heat pad and an infrared heat lamp. The temperature in the farrowing house was maintained at a minimum of 20°C with heat lamps providing supplemental heat for the pigs. Gilts were allowed ad libitum access to feed and water from parturition (day 1) until weaning (day 28). Several gilts were culled because of death during parturition, lack of milk, having died, disease during lactation or failure to observe estrus, so the total numbers of gilts recorded in each of the five treatments in the present study were 22, 23, 20, 25 and 22, respectively. On day 2 post partum, gilts were allotted to one of five dietary treatments based on body weight (BW) (211 ± 3.5 kg) and backfat thickness (27.8 ± 3.5 mm). All dietary treatments were based on corn, soybean meal and wheat bran. Five lactation diets (3325 kcal of ME/kg) were formulated to contain SID Lys contents of 0.76, 0.84, 0.94, 1.04 and 1.14%, respectively (Table 1) by adding crystalline Lys to the diet at the expense of corn. Pigs were cross-fostered among gilts irrespective of dietary treatment until 48 h after parturition to standardize litters to at least 10 pigs. On day 1 of birth, pigs received 200 mg of iron (iron dextran solution), ears were notched, teeth were cut and tails and navel cords were docked. Male pigs were castrated on day 7. Ten gilts per treatment were milked manually on day 21 of lactation. Gilts were separated from their litters for a minimum of 30 min before milking. All gilts were milked
MATERIALS AND METHODS The animal care and experimental procedures were approved by the Institutional Animal Care and Use Committee of China Agriculture University (Beijing, China). The experiment was carried out at the National Feed Engineering Technology Research Center of the Ministry of Agriculture Feed Industry Center Animal Testing Base (Hebei, China).
Animals, dietary treatments and management A total of 150 (Landrace × Large White crossbred) gilts were bred with semen obtained from purebred Duroc boars. During gestation, gilts were housed in individual gestation stalls (0.65 m × 2.2 m), and were fed 2.0 kg/day from mating until day 80 of gestation and 3.0 kg/day after day 80 of gestation. The gestation diet was a corn, wheat bran and soybean meal based diet formulated to provide 3000 kcal/kg metabolizable energy (ME), 15.5% crude protein (CP), 0.67% SID Lys, 0.80% Ca and 0.70% P. On day 110 of gestation, gilts were moved into the farrowing room and placed in farrowing crates (2.0 × 3.0 m2) equipped with a piglet creep area which was fitted with a
Table 1 Ingredient composition and chemical analysis of lactation diets (as-fed, %)
Item
Dietary SID Lys (%) 0.76
Ingredient (%) Corn Soybean meal Wheat bran Soybean oil Limestone Salt Dicalcium phosphate L-lysine (78%)† L-threonine (98.5%) MHA (84%)‡ Analyzed composition (%)§ Crude protein Calcium Phosphorus Lysine (lys) Threonine (Thr) Methionine (Met) Tryptophan (Trp) Valine Calculated composition ME (kcal/kg) SID Lys (%) SID Thr (%) SID Met (%) SID Trp (%)
0.84
0.94
1.04
1.14
60.78 21.00 11.31 2.80 1.64 0.60 0.84 0.00 0.06 0.03
64.50 24.80 5.20 1.50 1.64 0.60 0.84 0.00 0.00 0.00
64.30 24.77 5.20 1.60 1.64 0.60 0.84 0.13 0.00 0.00
64.00 25.00 5.14 1.60 1.64 0.60 0.84 0.26 0.00 0.00
64.50 24.30 5.10 1.70 1.64 0.60 0.84 0.40 0.00 0.00
17.45 0.95 0.63 0.91 0.67 0.28 0.20 0.86
17.58 0.94 0.62 1.02 0.67 0.28 0.20 0.86
17.63 0.94 0.62 1.13 0.67 0.28 0.20 0.86
17.72 0.95 0.64 1.20 0.67 0.28 0.20 0.86
17.69 0.96 0.62 1.38 0.67 0.28 0.20 0.86
3340 0.76 0.56 0.24 0.17
3336 0.84 0.56 0.24 0.17
3332 0.94 0.56 0.24 0.17
3327 1.04 0.56 0.24 0.17
3324 1.14 0.56 0.24 0.17
†L-lysine, L-threonine and L-valine were provided by Changchun Dacheng Bio Technology Development Company (Changchun, China). ‡MHA, DL-methionine hydroxy analogue (84%) was provided by Novus International, St. Louis, MO, USA. §Supplied per kg diet: vitamin A, 12 000 IU; vitamin D3, 2000 IU; vitamin E, 24 IU; vitamin K3, 2.0 mg; thiamin, 2.0 mg; riboflavin, 6.0 mg; pyridoxine, 4.0 mg; vitamin B12, 24 μg; niacin, 30 mg; pantothenic acid, 20 mg; folic acid, 3.6 mg; biotin, 0.40 mg; choline, 0.40 g; iron, 96 mg; copper, 8.0 mg; zinc, 120 mg; manganese, 40 mg; iodine, 0.56 mg; selenium, 0.30 mg; phytase, 120 mg. SID, standardized ileal digestible; ME, metabolizable energy.
© 2015 Japanese Society of Animal Science
Animal Science Journal (2015) 86, 891–896
LYSINE REQUIREMENTS FOR LACTATING GILTS
approximately 2 h after the morning feeding. Milk was collected from the first and last productive glands on both sides of the body. Each gland was milked until approximately 20 mL of milk was collected. Samples were collected by infusing 10 IU oxytocin via a jugular catheter. Milk was immediately frozen at −20°C. Gilts were bled via vena cava puncture on day 21 postfarrowing to determine concentrations of glucose, serum urea nitrogen, insulin, insulin-like growth factor I (IGF-I) and luteinizing hormone. Gilts were given feed at 07.00 hours, allowed 1 h to consume to satiety, and residual feed was removed. Gilts were bled 3 h later at 11.00 hours. Blood was collected using a 10 mL plain, blood collection tube (Greiner Bio-One GmbH, Kremsmunster, Austria). Blood samples were held in ice-cold tubes and centrifuged at 3000 × g at 4°C for 20 min using a TDL-5-A Shanghai Anting Scientific Instrument Centrifuge (Shanghai, China). All serum samples were stored at −20°C until needed for analysis. Feed intake was determined weekly. Within 48 h of farrowing and at weaning (day 28), gilts were weighed, and loin eye area and back fat thickness (P2, 6 cm from the midline at the head of the last rib) were measured concurrently with an ultrasonic device (Piglog105; SFK Technology A/S, Herlev, Denmark). Piglets were weighed at days 0, 14 and 28. The percentage of piglet mortality was also recorded. On day 28 of lactation, gilts were moved back to the breeding barn and housed in gestation stalls and fed the same gestation diet as used previously. Gilts were checked for signs of estrus daily for 10 days after weaning and detection of estrus was conducted using boar stimuli for 15 min. The weaning to estrus interval was recorded when gilts were first observed to show a positive response to the back-pressure test (immobilization reflex). If estrus was observed, the gilts were again mated with semen from Duroc boars and conception rate recorded.
Collection and sampling The content of SID AA and ME in the ingredients were determined previously in our laboratory (Deng 2012; Ni 2012; Zhang 2012) using growing-finishing pigs. The SID AAs were determined using pigs surgically equipped with a T-cannula in the distal ileum. The basal ileal endogenous losses were measured by feeding a nitrogen-free diet. The content of ME and SID Lys were calculated by multiplying the ME and SID AA content of the individual ingredients by their inclusion level in the diets, then summing the products. All diets were supplemented with crystalline L-amino acids to achieve AA recommendations for primiparous sows (NRC 1998). Samples of ingredients and feed were taken at the beginning and the end of the experiment and stored at −20°C for the determination of their nutrient composition at the certified laboratory of the Ministry Feed Safety and Bioefficiency Evaluation Center (China Agricultural University, Beijing, China). Analysis for dry matter (DM), CP, Ca and total P was conducted according to the methods of AOAC (2003). Gross energy was measured by an Automatic Adiabatic Oxygen Bomb Calorimeter (Parr 6300 Calorimeter; Moline, IL, USA). AAs except for methionine and tryptophan in the diets were measured using ion-exchange chromatography with an Automatic Amino Acid Analyzer (L-8800; Hitachi Automatic Amino Acid Analyzer, Tokyo, Japan) after hydrolyzing with 6 mol/L HCl at 110°C for 24 h. Dietary methionine was measured after oxidation with performic acid and subsequent hydrolysis with HCl while tryptophan Animal Science Journal (2015) 86, 891–896
893
was determined after alkaline hydrolysis at 120°C for 16 h (AOAC 2003) with separation using reverse-phase Highperformance liquid chromatography (HPLC) (Waters 2690, Milford, MA, USA). Milk samples were analyzed for DM, CP, fat and lactose using an Infrared Milk Analyzer (Milko Scan 133B Analyzer, Foss Electric, Hillerød, Denmark). Multi-type reagents (Arkray Inc., Saitama, Japan) were available and used to determine glucose and serum urea nitrogen by an Automated Chemistry Analyzer (Spotchem EZ SP-4430; Arkray Inc., Saitama, Japan). A swine insulin kit (Endocrine Technologies Inc., Newark, CA, USA) was used and the concentration was determined in duplicate according to the instructions for an ELISA using Biolog MicroStation System (Biolog Inc., Hayward, CA, USA). Serum IGF-I concentrations were analyzed in triplicate (Frey et al. 1994), following an extraction of serum using 0.1 mol/L glycyl glycine in a ratio of 1:1. Serum luteinizing hormone concentrations were measured using a heterologous double antibody radioimmunoassay (Dial et al. 1983).
Statistical analysis Data were analyzed using the GLM procedure of SAS (1999) with gilt as the experimental unit. Single-degree-of-freedom contrasts were performed using the solution statement in the GLM procedure of SAS to determine linear and quadratic effects of treatment. The inflection point was calculated using the solution option of SAS to determine the SID Lys requirement for gilt body weight changes, litter weight and serum metabolites. When quadratic responses were found in the data (P ≤ 0.05), the breaks were estimated using a broken line analysis, with the NLIN procedure of SAS (Robbins et al. 2006). All values are reported as least square means. The significance level was set at P ≤ 0.05, and a tendency was considered when 0.05 < P ≤ 0.10.
RESULTS Gilt performance The average daily feed intake was not significantly affected by dietary lysine (Table 2) and gilts averaged 4.56 kg/day. Actual SID Lys intakes in the five treatments were 33.6, 36.1, 40.2, 46.0 and 55.0 g/day corresponding to 40.8, 45.2, 49.6, 55.4 and 66.7 g/day of total Lys. Overall, gilts lost weight during the 28-day lactation, and the average gilt weight loss during lactation was 27.0 ± 5.5 kg. Gilt BW loss decreased with increasing dietary SID Lys supply (linear, P < 0.05; quadratic, P < 0.01; Table 2). Regression analysis showed that a linear-plateau relationship existed between Lys intake and BW loss (platform value 0.85%, R2 = 0.95). Based on quadratic analysis, BW loss was minimized at 1.01% dietary SID Lys (BW loss = 84.62 (SID Lys)2– 170.7 (SID Lys) + 111.1, R2 = 0.93). The loin eye area at weaning increased quadratically (P < 0.01) with dietary SID Lys. Based on quadratic analysis, loin eye area at weaning maximized at 1.02% dietary SID Lys (loin eye area = 56.6 (SID Lys)2–115.2 (SID Lys) + 67.7, R2 = 0.74). The extent of the loin eye area loss corresponded quadratically (P < 0.05, 8.30 vs. © 2015 Japanese Society of Animal Science
894 M. SHI et al.
4.76 cm2) with increasing dietary SID Lys levels, and was minimized at 1.02% dietary SID Lys based on the quadratic analysis. Dietary SID Lys did not affect back fat loss, weaning to estrus interval or conception rate. The average backfat loss, weaning to estrus interval and conception rate were 8.6 mm, 5.1 days and 88.1%, respectively.
Litter performance Increasing dietary Lys had no effect on the number of pigs weaned or litter growth with an average of 10.5 pigs weaned per litter and an average litter growth rate of 2.11 kg/day (Table 3). Piglet mortality was not affected by dietary SID Lys levels with the average mortality of 5.5%.
Milk composition Milk protein increased linearly (P < 0.05) with the increasing dietary SID Lys levels and the average content of milk protein was 4.80% (P = 0.051) and increasing Lys had no effect on the percentage of DM,
fat or lactose in milk. The average DM, fat and lactose in milk were 17.0, 6.33 and 4.27%, respectively (Table 4).
Gilt serum metabolites IGF-I concentration of gilts fed the 0.76% SID Lys diet tended to be lower than those of the other groups (P = 0.066, Table 5). Dietary SID Lys levels had no effect on concentrations of serum urea nitrogen, luteinizing hormone, insulin or glucose.
DISCUSSION The results of the present study show that different indicators (BW loss, muscle mass and milk protein) results in different values of requirements. The daily SID Lys intake increased with increasing dietary SID Lys levels while the BW loss of gilts decreased. Mahan et al. (1971), Tokach et al. (1992) and Touchette et al. (1998) reported that increasing dietary lysine reduced sow weight loss during lactation. For BW loss, the broken line and quadratic models showed the broken
Table 2 Effects of SID lysine levels on lactating gilt body weight loss, feed intake, weaning to estrus interval and conception rate
Item
No. of gilts Body weight (kg) At farrowing At weaning Weight loss Backfat thickness (mm) At farrowing At weaning Backfat loss Loin eye area (cm2) At farrowing At weaning Loin eye area loss ADFI (kg) Total SID Lys intake (g/day) Weaning to estrus interval (day) Conception rate (%)
Dietary SID Lys (%)
SEM
0.76
0.84
0.94
1.04
1.14
22
23
20
25
22
206.9 176.1 30.7
211.5 179.1 26.5
212.0 178.9 25.9
212.7 181.1 25.2
212.5 178.2 26.5
P-value Treatment
Linear
Quadratic
3.5 3.9 1.1
0.981 0.782 0.041
0.872 0.401 0.038
0.794 0.454 0.009
29.12 20.71 8.45
28.45 19.23 9.23
29.36 19.05 10.36
25.82 18.32 7.52
26.45 18.97 7.44
3.48 2.05 1.98
0.543 0.401 0.599
0.762 0.189 0.904
0.687 0.182 0.181
51.98 43.79 8.19 4.48 33.55 5.07 87.7
52.11 43.82 8.30 4.44 36.14 5.29 88.0
56.07 51.31 4.76 4.39 40.20 5.20 89.3
53.02 48.21 4.81 4.62 46.02 4.92 87.0
51.86 45.63 6.23 4.83 54.96 5.25 88.3
3.89 2.63 0.89 1.87 1.98 1.56 –
0.665 0.001 0.025 0.342 0.001 0.951 –
0.512 0.490 0.278 0.081 0.001 0.952 –
0.232 0.001 0.030 0.113 0.211 0.991 –
SID Lys, standardized ileal digestible lysine; ADFI, average daily feed intake.
Table 3 Effects of SID lysine levels on litter performance (days 1 to 28)
Item
No. of gilts No. piglets suckled/litter No. piglets weaned/litter Piglet mortality (%) Initial litter weight (kg) Litter weight at weaning (kg) Litter growth (kg/day)
Dietary SID Lys (%)
SEM
0.76
0.84
0.94
1.04
1.14
22 11.3 10.3 8.54 17.9 76.6 2.10
23 10.7 9.9 6.65 17.3 75.3 2.10
20 10.9 10.5 4.13 17.3 73.8 2.02
25 11.4 10.8 5.58 18.8 80.4 2.16
22 11.1 10.8 2.71 18.1 79.6 2.17
0.45 0.18 1.92 0.72 2.90 0.09
P-value Treatment
Linear
Quadratic
0.734 0.541 0.252 0.975 0.640 0.884
0.752 0.152 0.044 0.876 0.301 0.554
0.813 0.292 0.121 0.765 0.440 0.710
SID Lys, standardized ileal digestible lysine.
© 2015 Japanese Society of Animal Science
Animal Science Journal (2015) 86, 891–896
LYSINE REQUIREMENTS FOR LACTATING GILTS
Table 4
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Effects of SID lysine levels in lactation on gilt milk composition
Item
Dietary SID Lys (%)
No. of gilts Dry matter (%) Protein (%) Fat (%) Lactose (%)
SEM
0.76
0.84
0.94
1.04
1.14
7 16.23 4.31 6.27 4.43
7 16.68 4.43 6.32 4.09
6 17.25 4.85 6.28 4.21
8 17.84 5.21 6.44 4.29
7 17.01 5.19 6.36 4.33
0.15 0.06 0.05 0.03
P-value Treatment
Linear
Quadratic
0.051 0.029 0.744 0.412
0.090 0.010 0.483 0.154
0.072 0.229 0.759 0.310
SID Lys, standardized ileal digestible lysine.
Table 5
Effects of SID Lysine levels in lactation on gilt blood metabolites and hormones on day 21
Item
No. of gilts Luteinizing hormone (mIU/mL) IGF-I (ng/mL) Insulin (μIU/mL) Glucose (mmol/L) Serum urea nitrogen (mmol/L)
Dietary SID Lys (%)
SEM
0.76
0.84
0.94
1.04
1.14
6 10.36 147.3 14.51 4.31 2.67
8 12.5 178.5 17.25 4.5 3.71
7 14.55 174.6 14.34 6.22 2.48
7 11.96 179.0 13.75 4.77 3.83
8 14.15 180.9 16.51 5.58 3.29
0.74 9.8 0.36 0.96 0.34
P-value Treatment
Linear
Quadratic
0.083 0.066 0.383 0.722 0.024
0.157 0.125 0.521 0.452 0.633
0.344 0.223 0.610 0.716 0.825
SID Lys, standardized ileal digestible lysine; IGF-1, insulin-like growth factor I.
point and quadratic minimum of dietary SID Lys were 0.85% and 1.01%, respectively. In the present study, loin eye area at weaning was highest at the 1.02% dietary SID Lys (54 g/day total lysine) content based on the quadratic analysis as well as loin eye area loss was lowest at this level. This is close to the estimation of gilt BW loss which minimized at 1.01% and was obtained from the same quadratic model. The result was close to Touchette et al. (1998) who indicated that lactating gilts have the capacity to utilize dietary lysine levels of up to 58 g/day total lysine to minimize loss of body protein reserves. Pettigrew (1993) developed a prediction equation to estimate the lysine requirement for litter growth: lysine (g/day) = −8.38 + 26 (litter average daily gain, kg/day). Given a litter growth of 2.11 kg/day in the present study, the total Lys requirement for litter growth would be 46.5 g/day. Other prediction equations such as in NRC (2012) which estimated the SID Lys requirement needed for maximum litter growth suggest SID Lys requirements (g/day) = 0.015 litter growth rate (g/day) + 3.978, and the SID Lys requirement in the present study would be 35.6 g/day. In the present study, the broken point of dietary SID Lys were 0.85% for maternal BW loss, corresponding to 45.7 g of total Lys or 36.5 g SID Lys per day. Our results based on the broken line analysis fit the results of studies above. Estimates of requirement are affected by the statistical methodology. The present experiment agrees with Kendall et al. (2007) who reported that estimates of requirement would be affected by the statistical Animal Science Journal (2015) 86, 891–896
methodology used in the study with derived estimates from broken-line models almost always resulting in requirement estimates lower than those estimated from quadratic models. Linear broken line models fit the ascending and plateau portions of the curve well and the break-point of two lines is selected as the requirement. However, it assumes that the dose response of a nutrient is linear until the requirement is met and above which no significant change in response can be expected. Therefore, the broken-line model may underestimate the requirement (Robbins et al. 2006). Quadratic models can effectively estimate increases and decreases, and the shape of the curve represents the response to graded concentrations of a nutrient up to the point to meet the requirements (Pesti et al. 2009). They are more accurate to describe the physiological course than linear models (Robbins et al. 2006). However, the quadratic estimation of the maximum amount of AA requirement are commonly overestimated (Baker 1986). To facilitate comparison with sources in the literature and decrease the population variation, both linear broken line and quadratic models are presented in the present study. Lower dietary SID Lys (0.76%) may cause body reserve mobilization of primiparous sows to maintain milk yield for the maintenance of litter growth. Increasing SID Lys intake had no effect on litter performance in the present study. This confirms that sows will mobilize body tissues to provide additional energy and nutrients to support maximum milk yield if there are deficiencies in the diet (Sauber et al. 1998). © 2015 Japanese Society of Animal Science
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Conclusion On the basis of this study, minimized weight loss using estimates provided by the linear broken-line and quadratic model were 0.85 and 1.01%, respectively, while 1.02% optimized loin eye area loss. The present study suggests that SID Lys is at least 0.85% for lactating gilts fed a corn, wheat bran and soybean meal based diet with the estimated daily feed intake of 4.56 kg containing 3325 kcal/kg of ME. The dietary SID Lys of the present study approaches the recommendation (0.84%) of NRC (2012) for gilts.
ACKNOWLEDGMENTS We thank Changchun Dacheng Bio Technology Development Company (Changchun, China) for the generous gift of the feed grade L-lysine HCL and threonine used in the present study. DL-methionine hydroxy analogue (84%) was provided by Novus International, St. Louis, MO, USA.
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