The Influence of Dietary Nitrate on Nitrate Concentration in Egg Yolk and Albumenl H . W . L E E , A. W . ADAMS AND F . E . CUNNINGHAM
Department of Dairy and Poultry Science, Kansas State University, Manhattan, Kansas 66506 (Received for publication July 3, 1974)
ABSTRACT Sodium nitrate (from 0 to 2,000 p.p.m.) was added to the drinking water of 32-week old S.C. White Leghorn pullets. Eggs collected once a week for 8 weeks were analyzed for nitrate content. Increasing levels of nitrate in the drinking water resulted in increasing levels of nitrate in albumen and yolk. Higher levels of nitrate were found in the yolk than in the albumen. When birds were started on the experiment, nitrate in the drinking water was reflected by immediate increases in nitrate content of the eggs. The nitrate content of eggs from birds receiving 1,000 p.p.m. NaN0 3 (728 p.p.m. N O , ) exceeded the 45 p.p.m. permissible level of nitrate in drinking water for human beings. POULTRY SCIENCE 54: 475-478, 1975
INTRODUCTION LOCAL egg processor recently discovered nitrates in his dried egg albumen. Ingestion of foodstuffs with a high level of nitrate could cause methemoglobinemia, particularly in children (Rosenfield and Huston, 1950), and in certain circumstances nitrites react with amines to form the carcinogenic compound, nitrosamine, in test animals. A government select panel is now investigating alleged health hazards related to use of nitrate preservatives in processed meats. Numerous studies have dealt with the influence of dietary nitrate. Those studies primarily investigated the relationship of dietary nitrate to growth responses in such animals as swine (Tollett et al., 1960), rats (Smith etal., 1961), cattle (Weichenthal et al., 1963), sheep (Seerley et al., 1965). Interference with thyroid function in rats was reported by Bloomfield et al. (1961). Nitrate in forage was studied by Wiseman and Jacobson (1965) and by Smith and Sund (1965). Effects of nitrate on growth rate of birds have been reported by Sell and Roberts
A
1. Contribution No. 894, Dairy and Poultry Science Department, Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas 66506.
(1963), Sunde (1964), Adams et al. (1966, 1969), Arends et al. (1967), and Marrett and Sunde (1968). Effects on liver vitamin A and beta-carotene were reported by Emerick and Olson (1962), Sell and Roberts (1963), Adams et al. (1966). Susceptibility of birds to nitrite toxicity was reported by Adams et al. (1966, 1969) and Marrett and Sunde (1968). Adams et al. (1969) found in their study with turkeys that nitrate ion rather than sodium was responsible for the adverse effects. Methods for determining nitrates in milk and milk products have been reported by Hami (1951) and Manning et al. (1968), in meat and meat products by Landmann et al. (1960) and Follett and Ratcliff (1963), in baby foods by Kamm et al. (1965), in spinach by Phillips (1968), and in potatoes by Heisler et al. (1974). The method of choice seems to by the one involving reduction of nitrate and then determination of nitrite by measuring the red color formed by diazotization with sulfanilic acid and coupling with 1-naphthylamine. Nitrate content can be obtained by recalculating to nitrate equivalent. Direct determination of nitrate by colorimetric method employs phenolsulfonic acid which develops a yellow color upon nitration forming nitrophenoldi-sulfonic acid. That method seems to have some disadvantage due to the inter-
475
476
H. W. LEE, A. W. ADAMS AND F. E. CUNNINGHAM
ference of chloride and nitrite (Holden, 1970). A.O.A.C. xylenol method is time consuming. Precipitating agents for protein and fat in the samples seem to depend on the nature of the sample. Diven et al. (1962) found mercuric chloride satisfactory for serum samples, Manning et al. (1968) reported zinc hydroxide best for milk, Follett and Ratcliff (1963) reported aluminum potassium sulfate best for meat, and Kamm etal. (1965) reported aluminum potassium sulfate satisfactory for baby foods. For the reduction of nitrate, zinc dust was used in the study of Diven etal. (1962). Follett and Ratcliff (1963) reported zinc dust was not accurate as a reducing agent for nitrate and employed a cadmium column. Kamm et al. (1965) and Manning et al. (1968) successfully used the cadmium column with modification. The efficiency of cadmium column was about 5 to 6 times that of the zinc dust. The purpose of this study was to determine the influence of nitrate, administered at various levels to laying hens in the drinking water, on nitrate composition of eggs. MATERIALS AND METHODS Six birds were randomly assigned to each of six blocks. Each block had three cages. Birds in each block were fed sodium nitrate (added to the drinking water) at different rates. Once a week the water bottle was refilled. Levels of sodium nitrate were: 0 p.p.m., 125 p.p.m., 250 p.p.m., 500 p.p.m., 1000 p.p.m., and 2000 p.p.m. Stock solution of 90,000 p.p.m. sodium nitrate was prepared in the laboratory and diluted on the poultry farm of Kansas State University. Egg samples from each block of birds were collected once a week for 8 weeks and kept in the cooler at 4.5-5.5° C. (40-42° F.) until analyzed for nitrate. The feed was also analyzed for nitrate content. Reduction of nitrate in a cadmium column and subsequent analysis of nitrite by azo dye formation in acidic media by diazotization
and coupling with l-naphthylamine was used in this study as follows: Nitrate Determination. Reagents: saturated mercuric chloride solution. Sulfanilamide solution . . . 0.2% sulfanilamide in 20% HC1, l-naphthylamine . . . 0.02% 1naphthylamine solution, prepared fresh every week. Nitrite Standard Solution. N a N 0 2 (99.7% Baker's analyzed reagent) 0.4298 gm. was dissolved in one liter and, by serial dilution, solutions of 0.001 mg. nitrogen/1 ml. were prepared. Reduction Column. A modification of the technique of Follett and Ratcliff (1963) as modified by Kamm et al. (1965) was used. A funnel stem of inside diameter 2.5 mm. and 5 cm. high was adapted to serve as the cadmium reduction column. Metallic cadmium was prepared by the method described by Kamm et al. (1965). Extraction of Egg Sample. Four eggs from each block of birds receiving different nitrate levels were broken and their whites separated from yolks. Yolk and albumen samples were mixed separately and 5 gm. of each was used for extraction. 80 ml. of 80° C. water was added, mixed thoroughly, then transferred to 100 ml. volumetric flask. The beaker was rinsed with additional hot water, which was added to the 100 ml. volumetric flask. The samples were kept at room temperature for 1 hour and were shaken occasionally. Then saturated mercuric chloride (0.5 ml.) was added. After filtering through No. 42 Whatman filter paper, a 5 ml. aliquot was passed through a cadmium funnel. The aliquot was collected in a 50 ml. volumetric flask, and nitrate-free H 2 0 was added. Then 1 ml. of each reagent, sulfanilamide solution and l-naphthylamine solution was
477
DIET NITRATE AND EGG NITRATE
added, made up to volume, mixed again, and allowed to stand in the dark until the pink color developed. Absorbance was determined at 520 nm. with a Bausch & Lomb Spectronic 20. Nitrite contents were determined by comparisons with a standard curve. The efficiency of the cadmium column was checked by passing a known concentration of nitrite solution through the column. RESULTS AND DISCUSSION Absorbance was converted into mg. N/gm. of sample, and then to p.p.m. N a N 0 3 . The basis of conversion was: 1. mg. N / 5 ml. x 100/5 gm. x 100 = mg. N/100 gm. sample. 2. N a N 0 3 ... (23 + 14 + 48) = 85 N / N a N O j = 14/85 = 1/6.07 3. p.p.m. = mg. N x 20 x 20 x 10 = mg. N/lOOOgm. p.p.m. N a N 0 3 = mg. N x 24000.
For statistical analysis mg. N / 5 gm. sample was used. The feed contained no nitrate as ascertained by qualitative test with N, N ' -diphenyl benzidine. Significantly more (P < .01) nitrates were concentrated in yolks rather than in whites (Table 1). The different levels of nitrate in the drinking water resulted in different levels of nitrate in egg whites and yolks in the order of linear increase from 125 to 2000 p.p.m. Interaction between level of nitrate in the water and duration of treatment was not significant (Table 2). Standard deviation was highest with the highest level of nitrate. Control treatment (0 p.p.m.) had least standard deviation. Efficiency of the reduction column might partially explain this result. Data in Table 1 show nitrate content of albumen and yolk from hens fed 1,000 p.p.m. N a N 0 3 (728 p.p.m. N 0 3 ) exceeded 45 p.p.m. of nitrate permissible in drinking water for human beings (Anonymous, 1962). However, reports suggest levels of nitrate comparable
TABLE 1.—Mean values' and standard deviation for nitrate concentration in eggs produced by hens receiving various levels of nitrate in the drinking water Level of NaNOj (p.p.m.) Control 125 (91)2 250 (182) 500 (364) 1000 (728) 2000(1456)
Albumen Mean 0.15 (6.7) 0.26(11.5) 0.50(21.8) 0.70(30.8) 1.02(45.8) 1.49(65.3)
Yolk St. dev.
Mean
St. dev.
0.06 0.14 0.17 0.20 0.31 0.43
0.20 (8.7) 0.35 (15.5) 0.55 (24.3) 0.98 (42.7) 1.47 (64.5) 2.37(103.5)
0.10 0.10 0.07 0.17 0.37 0.57
'Mean values for the 8 week period expressed as mg. N/5 gm. sample. Values in parenthesis indicate levels of NOj in p.p.m.
2
TABLE 2.—Analysis of variance
Source
d.f.
S.S.
M.S.
F (calculated)
Sig. diff.
Treatment Week Treat, x week
5 6 30
30.39 1.42 1.41
6.08 0.24 0.05
86.85 3.42 0.71
.01 .01 None
White x yolk Treat, x WXY* Error
1 5 36
1.89 1.82 2.54
1.89 0.36 0.07
27.00 5.14
.01 .01
Total
83
39.47
*WXY . . . Intraction of egg white and yolk.
478
H. W. L E E , A. W. ADAMS AND F. E. CUNNINGHAM
to that level (728 p.p.m.) and higher occur frequently in water supplies normally used by human beings and livestock (Smith, 1965; Hileman and Sabbe, 1968; Shaw and Wiley, 1969). REFERENCES Adams, A. W., R. J. Emerick and C. W. Carlson, 1966. Effects of nitrate and nitrite in the drinking water on chicks, poults and laying hens. Poultry Sci. 45: 1215-1222. Adams, A. W., J. L. West and A. J. Kahrs, 1969. Some effects on turkeys of nitrate in the drinking water. Poultry Sci. 48: 1222-1229. Anonymous, 1962. U.S. Public Health Service Drinking Water Standards. U.S. Dept. Health, Education and Welfare, Washington, D.C. Arends, L. G., E. W. Kienholz and C. F. Nockels, 1969. Growth stimulation effects of sodium nitrate for bronze turkeys. Poultry Sci. 46: 1228. Bloomfield, R. A., C. W. Welsch, G. B. Garner and M. E. Muhrer, 1961. Effect of dietary nitrate on thyroid function. Science, 134: 1690. Diven, R. H., W. J. Pistor, R. E. Reed, R. J. Trautman and R. E. Watts, 1962. The determination of serum or plasma nitrate and nitrite. Am. J. Vet. Res. 23: 497-499. Emerick, R. J., and O. E. Olson, 1962. Effect of nitrate and nitrite on vitamin A storage in the rat. J. Nutrition, 78: 73-77. Follett, M. J., and P. W. Ratcliff, 1963. Determination of nitrite and nitrate in meat products. J. Sci. Food Agr. 14: 138-144. Hanni, H., 1951. Zur methodik der nitrit und nitratbestimmung in milch und milchprodukten. Mitt. Gebiete Lebemsm. Hyg. (Bern) 42: 114. Hileman, L. H., and W. E. Sabbe, 1968. Nitrate-nitrogen in domestic water supplies. University of Arkansas, Ark. Farm Res. 17: 6. Holden, W. S., 1970. Water Treatment and Examination. Edited for The Society For Water Treatment and Examination. Williams and Wilkin Co., Baltimore. p. 157. Heisler, E. G., J. Siciliano, S. Krulick, W. L. Porter and J. W. White, 1974. Nitrate and nitrite content of market potatoes. J. Agr. FoodChem. 21: 970-973. Kamm, L., G. G. McKeown and D. M. Smith, 1965. New colorimetric method for the determination of the nitrate and nitrite content of baby foods. J. Assoc. Offic. Anal. Chemists, 48: 892-897. Landmann, W. A., M. Saeed, K. Pih and D. M.
Doty, 1960. The determination of nitrate in meat and meat products. J. Assoc. Offic. Anal. Chemists, 43: 531-535. Manning, P. B., S. T. Coulter and R. Jenness, 1968. Determination of nitrate and nitrite in milk and dry milk products. J. Dairy Sci. 51: 1725-1730. Marrett, L. E., and M. L. Sunde, 1968. The use of turkey poults and chickens as test animals for nitrate and nitrite toxicity. Poultry Sci. 47: 511-519. Phillips, W. E. J., 1968. Changes in nitrate and nitrite contents of fresh and processed spinach during storage. J. Agr. Food Chem. 16: 88-91. Rosenfield, A. B., and R. Huston, 1950. Infant methemoglobinemia in Minnesota due to nitrates in well water. Minn. Med. 33: 787. Seerley, R. W., R. J. Emerick, L. B. Embry and O. E. Olson, 1965. Effect of nitrate or nitrite administered continuously in drinking water for swine and sheep. J. Animal Sci. 24: 1014-1019. Sell, J. L.,and W. K. Roberts, 1963. Effects of dietary nitrate on the chick: growth, liver vitamin A storage and thyroid weight. J. Nutrition, 79: 171-178. Shaw, E. C , and P. Wiley, 1969. Nitrate ion concentration in well water. California Agric. Exp. Sta. California Agric. 23: 11. Smith, G. S., A. L. Neumann and E. E. Hatfield, 1961. Carotene utilization and vitamin A nutrition as influenced by dietary nitrite and "high nitrate" silage laboratory studies. J. Animal Sci. 20: 683-684. Smith, D., and J. M. Sund, 1965. Nitrate in forage, influence of storage of growth and soil nitrogen on nitrate content of herbage of alfalfa, red clover, Ladino clover, trefoil, and gromegrass. J. Agr. Food Chem. 13: 81-84. Smith, J. C , 1965. Nitrate problems in water related to soils, plants and water. Water Forum, 42-52. College of Agriculture, University of Missouri, Special Report No. 56. Sunde, M. L., 1964. The use of the turkey poults as a test animal for nitrite toxicity. Poultry Sci. 43: 1368. Tollett, J. T., D. E. Becker, A. H. Jensen and S. W. Terrill, 1960. Effect of dietary nitrate on growth and reproductive performance of swine. J. Animal Sci. 19: 1297. Weichenthal, B. A., L. B. Embry, R. J. Emerick and F. W. Whetzal, 1963. Influence of sodium nitrate, vitamin A and protein level on feedlot performance and vitamin A status of fattening cattle. J. Animal Sci. 22: 979-984. Wiseman, H. G., and W. C. Jacobson, 1965. Nitrate in plant material, determination of nitrate in silages and forages. J. Agr. Food Chem. 13: 36-39.
SEPTEMBER 5-11, 1976. FIFTH EUROPEAN POULTRY CONFERENCE, MALTA
Department of Dairy and Poultry Science, Kansas State University, Manhattan, Kansas 66506 (Received for publication July 3, 1974)
ABSTRACT Sodium nitrate (from 0 to 2,000 p.p.m.) was added to the drinking water of 32-week old S.C. White Leghorn pullets. Eggs collected once a week for 8 weeks were analyzed for nitrate content. Increasing levels of nitrate in the drinking water resulted in increasing levels of nitrate in albumen and yolk. Higher levels of nitrate were found in the yolk than in the albumen. When birds were started on the experiment, nitrate in the drinking water was reflected by immediate increases in nitrate content of the eggs. The nitrate content of eggs from birds receiving 1,000 p.p.m. NaN0 3 (728 p.p.m. N O , ) exceeded the 45 p.p.m. permissible level of nitrate in drinking water for human beings. POULTRY SCIENCE 54: 475-478, 1975
INTRODUCTION LOCAL egg processor recently discovered nitrates in his dried egg albumen. Ingestion of foodstuffs with a high level of nitrate could cause methemoglobinemia, particularly in children (Rosenfield and Huston, 1950), and in certain circumstances nitrites react with amines to form the carcinogenic compound, nitrosamine, in test animals. A government select panel is now investigating alleged health hazards related to use of nitrate preservatives in processed meats. Numerous studies have dealt with the influence of dietary nitrate. Those studies primarily investigated the relationship of dietary nitrate to growth responses in such animals as swine (Tollett et al., 1960), rats (Smith etal., 1961), cattle (Weichenthal et al., 1963), sheep (Seerley et al., 1965). Interference with thyroid function in rats was reported by Bloomfield et al. (1961). Nitrate in forage was studied by Wiseman and Jacobson (1965) and by Smith and Sund (1965). Effects of nitrate on growth rate of birds have been reported by Sell and Roberts
A
1. Contribution No. 894, Dairy and Poultry Science Department, Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas 66506.
(1963), Sunde (1964), Adams et al. (1966, 1969), Arends et al. (1967), and Marrett and Sunde (1968). Effects on liver vitamin A and beta-carotene were reported by Emerick and Olson (1962), Sell and Roberts (1963), Adams et al. (1966). Susceptibility of birds to nitrite toxicity was reported by Adams et al. (1966, 1969) and Marrett and Sunde (1968). Adams et al. (1969) found in their study with turkeys that nitrate ion rather than sodium was responsible for the adverse effects. Methods for determining nitrates in milk and milk products have been reported by Hami (1951) and Manning et al. (1968), in meat and meat products by Landmann et al. (1960) and Follett and Ratcliff (1963), in baby foods by Kamm et al. (1965), in spinach by Phillips (1968), and in potatoes by Heisler et al. (1974). The method of choice seems to by the one involving reduction of nitrate and then determination of nitrite by measuring the red color formed by diazotization with sulfanilic acid and coupling with 1-naphthylamine. Nitrate content can be obtained by recalculating to nitrate equivalent. Direct determination of nitrate by colorimetric method employs phenolsulfonic acid which develops a yellow color upon nitration forming nitrophenoldi-sulfonic acid. That method seems to have some disadvantage due to the inter-
475
476
H. W. LEE, A. W. ADAMS AND F. E. CUNNINGHAM
ference of chloride and nitrite (Holden, 1970). A.O.A.C. xylenol method is time consuming. Precipitating agents for protein and fat in the samples seem to depend on the nature of the sample. Diven et al. (1962) found mercuric chloride satisfactory for serum samples, Manning et al. (1968) reported zinc hydroxide best for milk, Follett and Ratcliff (1963) reported aluminum potassium sulfate best for meat, and Kamm etal. (1965) reported aluminum potassium sulfate satisfactory for baby foods. For the reduction of nitrate, zinc dust was used in the study of Diven etal. (1962). Follett and Ratcliff (1963) reported zinc dust was not accurate as a reducing agent for nitrate and employed a cadmium column. Kamm et al. (1965) and Manning et al. (1968) successfully used the cadmium column with modification. The efficiency of cadmium column was about 5 to 6 times that of the zinc dust. The purpose of this study was to determine the influence of nitrate, administered at various levels to laying hens in the drinking water, on nitrate composition of eggs. MATERIALS AND METHODS Six birds were randomly assigned to each of six blocks. Each block had three cages. Birds in each block were fed sodium nitrate (added to the drinking water) at different rates. Once a week the water bottle was refilled. Levels of sodium nitrate were: 0 p.p.m., 125 p.p.m., 250 p.p.m., 500 p.p.m., 1000 p.p.m., and 2000 p.p.m. Stock solution of 90,000 p.p.m. sodium nitrate was prepared in the laboratory and diluted on the poultry farm of Kansas State University. Egg samples from each block of birds were collected once a week for 8 weeks and kept in the cooler at 4.5-5.5° C. (40-42° F.) until analyzed for nitrate. The feed was also analyzed for nitrate content. Reduction of nitrate in a cadmium column and subsequent analysis of nitrite by azo dye formation in acidic media by diazotization
and coupling with l-naphthylamine was used in this study as follows: Nitrate Determination. Reagents: saturated mercuric chloride solution. Sulfanilamide solution . . . 0.2% sulfanilamide in 20% HC1, l-naphthylamine . . . 0.02% 1naphthylamine solution, prepared fresh every week. Nitrite Standard Solution. N a N 0 2 (99.7% Baker's analyzed reagent) 0.4298 gm. was dissolved in one liter and, by serial dilution, solutions of 0.001 mg. nitrogen/1 ml. were prepared. Reduction Column. A modification of the technique of Follett and Ratcliff (1963) as modified by Kamm et al. (1965) was used. A funnel stem of inside diameter 2.5 mm. and 5 cm. high was adapted to serve as the cadmium reduction column. Metallic cadmium was prepared by the method described by Kamm et al. (1965). Extraction of Egg Sample. Four eggs from each block of birds receiving different nitrate levels were broken and their whites separated from yolks. Yolk and albumen samples were mixed separately and 5 gm. of each was used for extraction. 80 ml. of 80° C. water was added, mixed thoroughly, then transferred to 100 ml. volumetric flask. The beaker was rinsed with additional hot water, which was added to the 100 ml. volumetric flask. The samples were kept at room temperature for 1 hour and were shaken occasionally. Then saturated mercuric chloride (0.5 ml.) was added. After filtering through No. 42 Whatman filter paper, a 5 ml. aliquot was passed through a cadmium funnel. The aliquot was collected in a 50 ml. volumetric flask, and nitrate-free H 2 0 was added. Then 1 ml. of each reagent, sulfanilamide solution and l-naphthylamine solution was
477
DIET NITRATE AND EGG NITRATE
added, made up to volume, mixed again, and allowed to stand in the dark until the pink color developed. Absorbance was determined at 520 nm. with a Bausch & Lomb Spectronic 20. Nitrite contents were determined by comparisons with a standard curve. The efficiency of the cadmium column was checked by passing a known concentration of nitrite solution through the column. RESULTS AND DISCUSSION Absorbance was converted into mg. N/gm. of sample, and then to p.p.m. N a N 0 3 . The basis of conversion was: 1. mg. N / 5 ml. x 100/5 gm. x 100 = mg. N/100 gm. sample. 2. N a N 0 3 ... (23 + 14 + 48) = 85 N / N a N O j = 14/85 = 1/6.07 3. p.p.m. = mg. N x 20 x 20 x 10 = mg. N/lOOOgm. p.p.m. N a N 0 3 = mg. N x 24000.
For statistical analysis mg. N / 5 gm. sample was used. The feed contained no nitrate as ascertained by qualitative test with N, N ' -diphenyl benzidine. Significantly more (P < .01) nitrates were concentrated in yolks rather than in whites (Table 1). The different levels of nitrate in the drinking water resulted in different levels of nitrate in egg whites and yolks in the order of linear increase from 125 to 2000 p.p.m. Interaction between level of nitrate in the water and duration of treatment was not significant (Table 2). Standard deviation was highest with the highest level of nitrate. Control treatment (0 p.p.m.) had least standard deviation. Efficiency of the reduction column might partially explain this result. Data in Table 1 show nitrate content of albumen and yolk from hens fed 1,000 p.p.m. N a N 0 3 (728 p.p.m. N 0 3 ) exceeded 45 p.p.m. of nitrate permissible in drinking water for human beings (Anonymous, 1962). However, reports suggest levels of nitrate comparable
TABLE 1.—Mean values' and standard deviation for nitrate concentration in eggs produced by hens receiving various levels of nitrate in the drinking water Level of NaNOj (p.p.m.) Control 125 (91)2 250 (182) 500 (364) 1000 (728) 2000(1456)
Albumen Mean 0.15 (6.7) 0.26(11.5) 0.50(21.8) 0.70(30.8) 1.02(45.8) 1.49(65.3)
Yolk St. dev.
Mean
St. dev.
0.06 0.14 0.17 0.20 0.31 0.43
0.20 (8.7) 0.35 (15.5) 0.55 (24.3) 0.98 (42.7) 1.47 (64.5) 2.37(103.5)
0.10 0.10 0.07 0.17 0.37 0.57
'Mean values for the 8 week period expressed as mg. N/5 gm. sample. Values in parenthesis indicate levels of NOj in p.p.m.
2
TABLE 2.—Analysis of variance
Source
d.f.
S.S.
M.S.
F (calculated)
Sig. diff.
Treatment Week Treat, x week
5 6 30
30.39 1.42 1.41
6.08 0.24 0.05
86.85 3.42 0.71
.01 .01 None
White x yolk Treat, x WXY* Error
1 5 36
1.89 1.82 2.54
1.89 0.36 0.07
27.00 5.14
.01 .01
Total
83
39.47
*WXY . . . Intraction of egg white and yolk.
478
H. W. L E E , A. W. ADAMS AND F. E. CUNNINGHAM
to that level (728 p.p.m.) and higher occur frequently in water supplies normally used by human beings and livestock (Smith, 1965; Hileman and Sabbe, 1968; Shaw and Wiley, 1969). REFERENCES Adams, A. W., R. J. Emerick and C. W. Carlson, 1966. Effects of nitrate and nitrite in the drinking water on chicks, poults and laying hens. Poultry Sci. 45: 1215-1222. Adams, A. W., J. L. West and A. J. Kahrs, 1969. Some effects on turkeys of nitrate in the drinking water. Poultry Sci. 48: 1222-1229. Anonymous, 1962. U.S. Public Health Service Drinking Water Standards. U.S. Dept. Health, Education and Welfare, Washington, D.C. Arends, L. G., E. W. Kienholz and C. F. Nockels, 1969. Growth stimulation effects of sodium nitrate for bronze turkeys. Poultry Sci. 46: 1228. Bloomfield, R. A., C. W. Welsch, G. B. Garner and M. E. Muhrer, 1961. Effect of dietary nitrate on thyroid function. Science, 134: 1690. Diven, R. H., W. J. Pistor, R. E. Reed, R. J. Trautman and R. E. Watts, 1962. The determination of serum or plasma nitrate and nitrite. Am. J. Vet. Res. 23: 497-499. Emerick, R. J., and O. E. Olson, 1962. Effect of nitrate and nitrite on vitamin A storage in the rat. J. Nutrition, 78: 73-77. Follett, M. J., and P. W. Ratcliff, 1963. Determination of nitrite and nitrate in meat products. J. Sci. Food Agr. 14: 138-144. Hanni, H., 1951. Zur methodik der nitrit und nitratbestimmung in milch und milchprodukten. Mitt. Gebiete Lebemsm. Hyg. (Bern) 42: 114. Hileman, L. H., and W. E. Sabbe, 1968. Nitrate-nitrogen in domestic water supplies. University of Arkansas, Ark. Farm Res. 17: 6. Holden, W. S., 1970. Water Treatment and Examination. Edited for The Society For Water Treatment and Examination. Williams and Wilkin Co., Baltimore. p. 157. Heisler, E. G., J. Siciliano, S. Krulick, W. L. Porter and J. W. White, 1974. Nitrate and nitrite content of market potatoes. J. Agr. FoodChem. 21: 970-973. Kamm, L., G. G. McKeown and D. M. Smith, 1965. New colorimetric method for the determination of the nitrate and nitrite content of baby foods. J. Assoc. Offic. Anal. Chemists, 48: 892-897. Landmann, W. A., M. Saeed, K. Pih and D. M.
Doty, 1960. The determination of nitrate in meat and meat products. J. Assoc. Offic. Anal. Chemists, 43: 531-535. Manning, P. B., S. T. Coulter and R. Jenness, 1968. Determination of nitrate and nitrite in milk and dry milk products. J. Dairy Sci. 51: 1725-1730. Marrett, L. E., and M. L. Sunde, 1968. The use of turkey poults and chickens as test animals for nitrate and nitrite toxicity. Poultry Sci. 47: 511-519. Phillips, W. E. J., 1968. Changes in nitrate and nitrite contents of fresh and processed spinach during storage. J. Agr. Food Chem. 16: 88-91. Rosenfield, A. B., and R. Huston, 1950. Infant methemoglobinemia in Minnesota due to nitrates in well water. Minn. Med. 33: 787. Seerley, R. W., R. J. Emerick, L. B. Embry and O. E. Olson, 1965. Effect of nitrate or nitrite administered continuously in drinking water for swine and sheep. J. Animal Sci. 24: 1014-1019. Sell, J. L.,and W. K. Roberts, 1963. Effects of dietary nitrate on the chick: growth, liver vitamin A storage and thyroid weight. J. Nutrition, 79: 171-178. Shaw, E. C , and P. Wiley, 1969. Nitrate ion concentration in well water. California Agric. Exp. Sta. California Agric. 23: 11. Smith, G. S., A. L. Neumann and E. E. Hatfield, 1961. Carotene utilization and vitamin A nutrition as influenced by dietary nitrite and "high nitrate" silage laboratory studies. J. Animal Sci. 20: 683-684. Smith, D., and J. M. Sund, 1965. Nitrate in forage, influence of storage of growth and soil nitrogen on nitrate content of herbage of alfalfa, red clover, Ladino clover, trefoil, and gromegrass. J. Agr. Food Chem. 13: 81-84. Smith, J. C , 1965. Nitrate problems in water related to soils, plants and water. Water Forum, 42-52. College of Agriculture, University of Missouri, Special Report No. 56. Sunde, M. L., 1964. The use of the turkey poults as a test animal for nitrite toxicity. Poultry Sci. 43: 1368. Tollett, J. T., D. E. Becker, A. H. Jensen and S. W. Terrill, 1960. Effect of dietary nitrate on growth and reproductive performance of swine. J. Animal Sci. 19: 1297. Weichenthal, B. A., L. B. Embry, R. J. Emerick and F. W. Whetzal, 1963. Influence of sodium nitrate, vitamin A and protein level on feedlot performance and vitamin A status of fattening cattle. J. Animal Sci. 22: 979-984. Wiseman, H. G., and W. C. Jacobson, 1965. Nitrate in plant material, determination of nitrate in silages and forages. J. Agr. Food Chem. 13: 36-39.
SEPTEMBER 5-11, 1976. FIFTH EUROPEAN POULTRY CONFERENCE, MALTA
