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The Effect of Dietary Vitamin A, Ambient Temperature and Rearing Location on Growth, Feed Conversion and Vitamin Liver Storage of White Leghorn Pullets
The Effect of Dietary Vitamin A, Ambient Temperature and Rearing Location on Growth, Feed Conversion and Vitamin Liver Storage of White Leghorn Pullets A. A. KURNICK,* B. W. HEYWANG, B. J. HULETT, M. G. VAVICH AND B. L. REID Poultry Research Branch, Animal Husbandry Research Division, Agricultural Research Service, Glendale, Arizona and Departments of Agricultural Biochemistry and Poultry Science, University of Arizona, Tucson (Received for publication June 1, 1964)
Although chick growth is usually employed as the criterion for determining vitamin A requirement, Olsen et al. (1959) * Present address: The Ray Ewing Company, Division of Hoffmann-La-Roche Inc. Pasadena, California. Arizona Agricultural Experiment Station Technical Article No. 886.
reported that, in short term experiments, growth may not be reliable and that liver storage was superior in assessing vitamin A utilization. Seven long-term experiments were designed to examine the relationship between the level of dietary vitamin A and environmental temperature on growth of White Leghorn pullets. EXPERIMENTAL
Approximately 5200 commercial strain White Leghorn pullet chicks were used in 7 experiments to determine the vitamin A requirement during the first 20 weeks of age. Five experiments were conducted with chicks hatched during periods of high ambient temperature (May-August) and two experiments were conducted with chicks hatched during the cooler part of the year (November). Four of the experiments were conducted at the U.S.D.A. Southwest Poultry Experiment Station, Glendale, Arizona, and three were conducted at the Poultry Research Center, University of Arizona, Tucson. Location of experiments, date of hatch, length of experiments, average ambient temperatures, and other information are shown in Table 1. All chicks were fed to a low vitamin A, white corn-soybean meal diet for a one or two week depletion period. Rubin and Bird (1941) indicated that the liver was
1582
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
AN evaluation of vitamin requirement -£*- data indicates that the minimum amount of vitamin A needed for growth of chicks is approximately 1,000 U.S.P. units per pound of diet (Almquist, 1953). Results of the experiments evaluated varied greatly as did the source of vitamin A activity used. Thornton and Whittet (1962) reported that neither growth rate nor feed efficiency of White Leghorn chicks was influenced by vitamin A levels ranging from 800 to 3200 U.S.P. units per pound of diet. Harms et al. (1955) indicated no differences in growth rate during the first four weeks of age when undepleted chicks were fed diets containing 500 to 4,000 U.S.P. units of vitamin A per pound. Scott el al. (1957) found that 400 to 600 U.S.P. units of vitamin A per pound of diet were sufficient for normal growth and survival of White Leghorn chicks. The poultry subcommittee of the National Research Council (1960) has listed the minimum requirement for vitamin A as 1200 U.S.P. units per pound of diet for starting and growing chickens.
1583
VITAMIN A REQUIREMENT TABLE 1.—Summary of vitamin A experiments
Exper. number
Location of experiment Tucson
1 2 3 4 5 6
Glendale
X
May June
x(L)
July
x(L) X X
x(L) x(L)
7
Month of hatch
Length of depletion (days)
Length of growth period (wks.)
68 70 108 119 145 155 101
9 9 10 10 10 10 10
Ave. temp. during growth period Max.
Min. (°F.)
91-112 83-105 64-107 64-100 51-86 54-77 97-115
51-88 64-82 51-86 50-82 26-58 42-64 65-86
(L)—indicates experiments that were continued past the 9-10 week growth period.
depleted of vitamin A during the first 2 weeks after hatching unless appreciable quantities of dietary vitamin A were available. After the depletion period, the chicks were weighed and randomly placed in pens of 65 chicks each. Duplicate pens were randomly assigned to each of the experimental treatments. The experimental diets were produced from a basal diet (Table 2) by adding the required amount of a commercial stabilized vitamin A supplement containing 10,000 U.S.P. units of vitamin A per gram. Feed and water were supplied ad libitum. The chicks were weighed every two or three TABLE 2.—Basal diet Ingredient
%
White corn, ground Soybean meal (44% protein) Dried whey (12% protein) Salt Ground limestone Dicalcium phosphate MnSCv5H 2 0 (Tech. 70%) Vitamin & antibiotic mix1
54.00 37.00 2.00 0.50 2.25 2.25 0.02 2.00
1 Supplied the following per pound of diet: 700 I.C.U. vitamin D3, 2.0 mg. riboflavin, 12.5 mg. niacin, 5.0 mg.
weeks. However, only the 9 or 10, and 20 week weights are reported. Liver vitamin A determinations (Ames et al., 1954) were made on 20 representative birds from each treatment at the end of the 9th or 10th week of the growing period. Four of the 7 experiments were continued through 20 weeks. Performance of these pullets during the laying period will be reported later. RESULTS AND DISCUSSION The 9 week body weight of pullets (experiments 1 and 2) indicated that growth was not significantly influenced by the various levels of dietary vitamin A (Table 3). Body weights of pullets fed a diet containing 500 U.S.P. units of vitamin A per pound were 13 percent heavier than pullets fed the diet containing the 250 U.S.P. unit level in experiments 5 and 7 (statistically significant at the 0.05 level of probability). Significantly heavier weights were obtained for pullets fed the diet containing 750 U.S.P. units of vitamin A compared with pullets fed 500 U.S.P. units only in experiment 7. In general, increasing the dietary vitamin A level above 750 U.S.P. per pound produced a slight, but not a statistically significant, improvement in
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
August November November June (following year)
7 7 14 14 14 17 14
Ave. wt. at start of treat. (gm.)
1584
KURNICK, HEYWANG, HULETT, VAVICH AND REID TABLE 3.—Effect of dietary vitamin A level on body weight of White Leghorn pullets at 9 or 10 weeks of age Experiment number
Vit. A U.S.P. \ units per lb.
1
2
3
4
5
6
7
Average weight
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
250 500 750 1,000 1,250 1,500 3,000
—
—
.—
621"* 642" 653" 640" 643" 649"
683" 683" 694" 697"
765" 779" 788" 793" 785" 783"
785" 795" 780" 826"
713" 806b 850b° 860b° 863b° 856b° 880b°
875" 904" 906" 907"
568" 647b 683" 684° 690°d 708d 700"1
— •
—
— —
— —
641 740 762 766 774 748 752
ergy requirement during cold weather. Pullets hatched in November required 12% more feed per pound of gain than pullets hatched during the summer. The higher daily intake of vitamin A during cold weather did not improve growth rate (Table 3) nor feed conversion (Table 4) of chicks fed diets containing 250 units of vitamin A per pound. However, feed conversion in chicks hatched during June (experiment 7) and fed 250 or 500 U.S.P. units of vitamin A per pound of diet was statistically lower than for chicks fed 750 U.S.P. units, whereas no statistical difference for feed conversion was observed in chicks hatched during November (experiment 5) at Glendale.
growth rate of pullets (Table 3). This weight increase in pullets was observed in tests conducted during both high and low ambient temperatures. Ten-week body weights of pullets hatched and reared at Tucson during the cooler months (experiment 6) were approximately 30% higher than those of pullets hatched and reared during the summer months (experiment 2). Feed conversion of chicks was not influenced significantly by the feeding level of dietary vitamin A except in experiment 7 (Table 4). Considerable differences in feed conversion were found among the various hatches; however, most of the differences could be attributed to the increased en-
TABLE 4.—Effect of dietary vitamin A on feed conversion of White Leghorn pullets to 9 or 10 weeks of age Vit. A U.S.P. units per lb. 250 500 750 1,000 1,250 1,500 3,000
Experiment number 1
2
3
4
5
6
7
Ave.
3.64" 3.69" 3.58" 3.68"
3.38" 3.16 b 3.05" 3.07° 3.06° 3.03° 2.99°
3.49 3.28f 3.16f 3.15f 3.15f 3.03 3.05
Pounds feed per pound gain 2.79"* 2.77" 2.73" 2.75" 2.71" 2.73"
2.83" 2.79" 2.82" 2.77"
3.12" 3.05" 3.06" 3.06" 3.05" 3.07"
3.40" 3.38" 3.40" 3.29"
3.60" 3.54" 3.39" 3.38" 3.44" 3.34" 3.42"
* Means without a common letter are significantly different at the .05 level of probability. f Averages represented in all 7 experiments.
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
* Means without a common letter are significantly different at the .05 level of probability. t Averages represented in all 7 experiments.
1585
VITAMIN A REQUIREMENT TABLE 5.—Liver storage of vitamin A in micrograms per liver, of White Leghorn pullet s fed various levels of stabilized vitamin A Expt. No. 1 3 5 7
U.S.P. units of vitamin A per pound of diet 500 A
250 A
3.5 + 5.7 + 9.3 + 4.8 +
6.5 + 2.3* 3.2 + 0.2
0.5 0.6 2.3 0.1
750 A
l,OO0A
13.0+1.8 17.2 + 2.4
21.3 + 29.9 + 27.0 + 13.6 +
8.4+1.0
2.8 3.4 4.7 1.7
1,250 A 27.4+ 64.4+ 73.4 + 31.0+
3,000 A
1,500 A
3.7 5.8 11.0 4.0
66.9+ 117.0 + 91.2 + 54.6 +
8.4 15.0 16.0 17.0
336+44 470 + 46 673 + 73 435 + 95
* Standard deviation.
conducted in the summer than in the liver of pullets fed the same dietary vitamin A level during the winter (Table 5). This may be explained by the increased feed consumption and thus greater ingestion of vitamin A during the cooler months. Pullets reared in four of the original 7 experiments were continued on test through 20 weeks of age. Feed conversions and body weights of pullets at the end of the 20-week rearing period are shown in Table 6. Pullets fed the diet containing 500 U.S.P. of vitamin A per pound were the lowest in body weight in each of the four experiments; the differences being statistically significant only in experiment 7. In general, there was an increase in average body weight when the dietary vitamin A was increased above 500 units.
TABLE 6.—Effect of dietary vitamin A on growth and feed consumption of While Leghorn pullets to 20 weeks of age Experiment numbers Vit. A U.S.P. per lb.
500 750 ,000 ,250 3,000
Body wt. (gms.) 1,265"* 1,281" 1,292" 1,298"
Average temp. (°F.) Max. Min.
Pounds feed/ pounds gain 7.44" 7.30" 7.50" 7.38"
Body wt. (gms.)
Pounds feed/ pounds gain
•D J Body wt. (gms.)
Pounds Ifeed/ eea ^ pounds gain
1,420" 1,492" 1,508" 1,490" 1,451"
7.40" 7.10" 6.91" 7.26" 7.60"
1,425" 1,434" 1,443" 1,479"
9.77" 10.10" 10.34" 9.61"
97° 67°
•D ,
Body
wt. (gms.) 1,317" 1,379» l,390 b l,410 b l,427 b °
67° 51°
* Means without a common letter are significantly different at the .05 level of probability.
105° 76°
Pounds feed/ \ pounds gain 5.85" 6.13" 6.10" 5.95" 5.91"
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
There was a responsive increase in liver storage of vitamin A as the dietary vitamin A level was increased from 250 to 3,000 U.S.P. units per pound (Table 5). These data agree with the work of Reid et al. (1955) in which it was reported that the amount of vitamin A stored in the liver of chicks was an indication of the amount of the vitamin in the feed. Shellenberger et al. (1960) found only minor amounts of vitamin A in the liver with the feeding of 400 U.S.P. units vitamin A, and marked deposition of the vitamin with 1,750 or 2,000 U.S.P. units of vitamin A per pound of diet. An interaction was observed between season of hatch and vitamin A stored in the liver. Appreciably less vitamin A was stored in the livers of pullets from studies
1586
K U R N I C K , H E Y W A N G , H U L E T T , VAVICH AND R E I D
Feed conversion of pullets grown to 20weeks was not significantly different regardless of location (Table 6). Very small differences in feed conversion were observed within each experiment. However, considerable differences were found between the four experiments. I n general, these differences could be accounted for by season of the year. Considerably more feed per unit gain was required for pullets reared during the cooler p a r t of the year. SUMMARY Approximately 5,200 commercial strain White Leghorn pullet chicks were used in 7 experiments to determine the vitamin A requirement of chicks grown in a subtropical, semi-arid climate. I n general, increasing the dietary vitamin A from 500 to 3,000 U.S.P. units per pound of diet produced a numerical, b u t not a statistically significant, improvement in growth rate to 10 or 20 weeks of age. Differences in feed
conversion among the various vitamin A treatments were small and not statistically different except in one experiment. I n every instance, there was a responsive increase in vitamin A stored in the liver of pullets as their dietary vitamin A increased. Chicks reared during the cooler periods showed more liver vitamin A than those fed during hot weather. REFERENCES Almquist, H. J., 1953. Evaluation of vitamin requirement data. Poultry Sci. 32: 122-128. Ames, S. R., H. A. Risley and P. L. Harris, 1954. Simplified procedure for extraction and determination of vitamin A in liver. Anal. Chem. 26: 1378-1381. Harms, R. H., B. L. Reid and J. R. Couch, 1955. Storage of vitamin A in chick livers as a criterion of stability, availability, and dietary level. Poultry Sci. 34: 1125-1133. National Research Council, 1960. Nutrient requirement for domestic animals. No. 1 Nutrient requirement for poultry. Olsen, E. M., J. O. Harvey, D. C. Hill and H. D. Branion, 1959. Distribution of carotene and vitamin A in the tissues of chicks following administration of carotene. Poultry Sci. 38: 688693. Reid, B. L., H. K. Daugherty and J. R. Couch, 1955. The stability of vitamin A in mixed feeds and premixes. Poultry Sci. 34: 603-608. Rubin, M., and H. R. Bird, 1941. Some experiments on the physiology of vitamin A storage in the chick. Poultry Sci. 20: 291-297. Scott, M. L., F. W. Hill, L. C. Norris, G. F. Heuser, R. D. Reynalds, E. H. Parsons and H. E. Butters, 1957. New information on the vitamin A requirements of chickens, ducks and pheasants, Proc. 1957 Cornell Nutrition Conference for Feed Manufacturers: 132-136. Shellenberger, T. E., D. B. Parrish and P. E. Stanford, 1960. Effect of vitamin A level of diet on feed conversion and utilization of energy by growing chickens. Poultry Sci. 39:1413-1417. Thornton, P. A., and W. A. Whittet, 1962. The influence of dietary energy level, energy source, breed and sex on vitamin A requirement in the chick. Poultry Sci. 41: 32-36.
M A Y 5-8. P O U L T R Y B R E E D E R S O F A M E R I C A M E E T I N G A N D ROUNDTABLE, H O T E L P R E S I D E N T , KANSAS CITY, MO.
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As would be expected, the first 250 U.S.P. increment added to the diet containing 500 U.S.P. units of vitamin A resulted in the largest increase in body weight. Pullets fed 250 U.S.P. units of vitamin A per pound of diet throughout the first 10 weeks of experiment 7 were divided into two equal groups and fed 1,000 or 1,250 U.S.P. units of vitamin A for the next 10 weeks. At the end of the twentieth week, body weights averaged 1,294 grams for each group. Body weights were not statistically different from pullets fed 500 U.S.P. units of vitamin A throughout the 20-week experiment, but were significantly lower t h a n body weight of pullets fed dietary vitamin A above 500 U.S.P. units per pound.
Although chick growth is usually employed as the criterion for determining vitamin A requirement, Olsen et al. (1959) * Present address: The Ray Ewing Company, Division of Hoffmann-La-Roche Inc. Pasadena, California. Arizona Agricultural Experiment Station Technical Article No. 886.
reported that, in short term experiments, growth may not be reliable and that liver storage was superior in assessing vitamin A utilization. Seven long-term experiments were designed to examine the relationship between the level of dietary vitamin A and environmental temperature on growth of White Leghorn pullets. EXPERIMENTAL
Approximately 5200 commercial strain White Leghorn pullet chicks were used in 7 experiments to determine the vitamin A requirement during the first 20 weeks of age. Five experiments were conducted with chicks hatched during periods of high ambient temperature (May-August) and two experiments were conducted with chicks hatched during the cooler part of the year (November). Four of the experiments were conducted at the U.S.D.A. Southwest Poultry Experiment Station, Glendale, Arizona, and three were conducted at the Poultry Research Center, University of Arizona, Tucson. Location of experiments, date of hatch, length of experiments, average ambient temperatures, and other information are shown in Table 1. All chicks were fed to a low vitamin A, white corn-soybean meal diet for a one or two week depletion period. Rubin and Bird (1941) indicated that the liver was
1582
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
AN evaluation of vitamin requirement -£*- data indicates that the minimum amount of vitamin A needed for growth of chicks is approximately 1,000 U.S.P. units per pound of diet (Almquist, 1953). Results of the experiments evaluated varied greatly as did the source of vitamin A activity used. Thornton and Whittet (1962) reported that neither growth rate nor feed efficiency of White Leghorn chicks was influenced by vitamin A levels ranging from 800 to 3200 U.S.P. units per pound of diet. Harms et al. (1955) indicated no differences in growth rate during the first four weeks of age when undepleted chicks were fed diets containing 500 to 4,000 U.S.P. units of vitamin A per pound. Scott el al. (1957) found that 400 to 600 U.S.P. units of vitamin A per pound of diet were sufficient for normal growth and survival of White Leghorn chicks. The poultry subcommittee of the National Research Council (1960) has listed the minimum requirement for vitamin A as 1200 U.S.P. units per pound of diet for starting and growing chickens.
1583
VITAMIN A REQUIREMENT TABLE 1.—Summary of vitamin A experiments
Exper. number
Location of experiment Tucson
1 2 3 4 5 6
Glendale
X
May June
x(L)
July
x(L) X X
x(L) x(L)
7
Month of hatch
Length of depletion (days)
Length of growth period (wks.)
68 70 108 119 145 155 101
9 9 10 10 10 10 10
Ave. temp. during growth period Max.
Min. (°F.)
91-112 83-105 64-107 64-100 51-86 54-77 97-115
51-88 64-82 51-86 50-82 26-58 42-64 65-86
(L)—indicates experiments that were continued past the 9-10 week growth period.
depleted of vitamin A during the first 2 weeks after hatching unless appreciable quantities of dietary vitamin A were available. After the depletion period, the chicks were weighed and randomly placed in pens of 65 chicks each. Duplicate pens were randomly assigned to each of the experimental treatments. The experimental diets were produced from a basal diet (Table 2) by adding the required amount of a commercial stabilized vitamin A supplement containing 10,000 U.S.P. units of vitamin A per gram. Feed and water were supplied ad libitum. The chicks were weighed every two or three TABLE 2.—Basal diet Ingredient
%
White corn, ground Soybean meal (44% protein) Dried whey (12% protein) Salt Ground limestone Dicalcium phosphate MnSCv5H 2 0 (Tech. 70%) Vitamin & antibiotic mix1
54.00 37.00 2.00 0.50 2.25 2.25 0.02 2.00
1 Supplied the following per pound of diet: 700 I.C.U. vitamin D3, 2.0 mg. riboflavin, 12.5 mg. niacin, 5.0 mg.
weeks. However, only the 9 or 10, and 20 week weights are reported. Liver vitamin A determinations (Ames et al., 1954) were made on 20 representative birds from each treatment at the end of the 9th or 10th week of the growing period. Four of the 7 experiments were continued through 20 weeks. Performance of these pullets during the laying period will be reported later. RESULTS AND DISCUSSION The 9 week body weight of pullets (experiments 1 and 2) indicated that growth was not significantly influenced by the various levels of dietary vitamin A (Table 3). Body weights of pullets fed a diet containing 500 U.S.P. units of vitamin A per pound were 13 percent heavier than pullets fed the diet containing the 250 U.S.P. unit level in experiments 5 and 7 (statistically significant at the 0.05 level of probability). Significantly heavier weights were obtained for pullets fed the diet containing 750 U.S.P. units of vitamin A compared with pullets fed 500 U.S.P. units only in experiment 7. In general, increasing the dietary vitamin A level above 750 U.S.P. per pound produced a slight, but not a statistically significant, improvement in
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
August November November June (following year)
7 7 14 14 14 17 14
Ave. wt. at start of treat. (gm.)
1584
KURNICK, HEYWANG, HULETT, VAVICH AND REID TABLE 3.—Effect of dietary vitamin A level on body weight of White Leghorn pullets at 9 or 10 weeks of age Experiment number
Vit. A U.S.P. \ units per lb.
1
2
3
4
5
6
7
Average weight
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
(gms.)
250 500 750 1,000 1,250 1,500 3,000
—
—
.—
621"* 642" 653" 640" 643" 649"
683" 683" 694" 697"
765" 779" 788" 793" 785" 783"
785" 795" 780" 826"
713" 806b 850b° 860b° 863b° 856b° 880b°
875" 904" 906" 907"
568" 647b 683" 684° 690°d 708d 700"1
— •
—
— —
— —
641 740 762 766 774 748 752
ergy requirement during cold weather. Pullets hatched in November required 12% more feed per pound of gain than pullets hatched during the summer. The higher daily intake of vitamin A during cold weather did not improve growth rate (Table 3) nor feed conversion (Table 4) of chicks fed diets containing 250 units of vitamin A per pound. However, feed conversion in chicks hatched during June (experiment 7) and fed 250 or 500 U.S.P. units of vitamin A per pound of diet was statistically lower than for chicks fed 750 U.S.P. units, whereas no statistical difference for feed conversion was observed in chicks hatched during November (experiment 5) at Glendale.
growth rate of pullets (Table 3). This weight increase in pullets was observed in tests conducted during both high and low ambient temperatures. Ten-week body weights of pullets hatched and reared at Tucson during the cooler months (experiment 6) were approximately 30% higher than those of pullets hatched and reared during the summer months (experiment 2). Feed conversion of chicks was not influenced significantly by the feeding level of dietary vitamin A except in experiment 7 (Table 4). Considerable differences in feed conversion were found among the various hatches; however, most of the differences could be attributed to the increased en-
TABLE 4.—Effect of dietary vitamin A on feed conversion of White Leghorn pullets to 9 or 10 weeks of age Vit. A U.S.P. units per lb. 250 500 750 1,000 1,250 1,500 3,000
Experiment number 1
2
3
4
5
6
7
Ave.
3.64" 3.69" 3.58" 3.68"
3.38" 3.16 b 3.05" 3.07° 3.06° 3.03° 2.99°
3.49 3.28f 3.16f 3.15f 3.15f 3.03 3.05
Pounds feed per pound gain 2.79"* 2.77" 2.73" 2.75" 2.71" 2.73"
2.83" 2.79" 2.82" 2.77"
3.12" 3.05" 3.06" 3.06" 3.05" 3.07"
3.40" 3.38" 3.40" 3.29"
3.60" 3.54" 3.39" 3.38" 3.44" 3.34" 3.42"
* Means without a common letter are significantly different at the .05 level of probability. f Averages represented in all 7 experiments.
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
* Means without a common letter are significantly different at the .05 level of probability. t Averages represented in all 7 experiments.
1585
VITAMIN A REQUIREMENT TABLE 5.—Liver storage of vitamin A in micrograms per liver, of White Leghorn pullet s fed various levels of stabilized vitamin A Expt. No. 1 3 5 7
U.S.P. units of vitamin A per pound of diet 500 A
250 A
3.5 + 5.7 + 9.3 + 4.8 +
6.5 + 2.3* 3.2 + 0.2
0.5 0.6 2.3 0.1
750 A
l,OO0A
13.0+1.8 17.2 + 2.4
21.3 + 29.9 + 27.0 + 13.6 +
8.4+1.0
2.8 3.4 4.7 1.7
1,250 A 27.4+ 64.4+ 73.4 + 31.0+
3,000 A
1,500 A
3.7 5.8 11.0 4.0
66.9+ 117.0 + 91.2 + 54.6 +
8.4 15.0 16.0 17.0
336+44 470 + 46 673 + 73 435 + 95
* Standard deviation.
conducted in the summer than in the liver of pullets fed the same dietary vitamin A level during the winter (Table 5). This may be explained by the increased feed consumption and thus greater ingestion of vitamin A during the cooler months. Pullets reared in four of the original 7 experiments were continued on test through 20 weeks of age. Feed conversions and body weights of pullets at the end of the 20-week rearing period are shown in Table 6. Pullets fed the diet containing 500 U.S.P. of vitamin A per pound were the lowest in body weight in each of the four experiments; the differences being statistically significant only in experiment 7. In general, there was an increase in average body weight when the dietary vitamin A was increased above 500 units.
TABLE 6.—Effect of dietary vitamin A on growth and feed consumption of While Leghorn pullets to 20 weeks of age Experiment numbers Vit. A U.S.P. per lb.
500 750 ,000 ,250 3,000
Body wt. (gms.) 1,265"* 1,281" 1,292" 1,298"
Average temp. (°F.) Max. Min.
Pounds feed/ pounds gain 7.44" 7.30" 7.50" 7.38"
Body wt. (gms.)
Pounds feed/ pounds gain
•D J Body wt. (gms.)
Pounds Ifeed/ eea ^ pounds gain
1,420" 1,492" 1,508" 1,490" 1,451"
7.40" 7.10" 6.91" 7.26" 7.60"
1,425" 1,434" 1,443" 1,479"
9.77" 10.10" 10.34" 9.61"
97° 67°
•D ,
Body
wt. (gms.) 1,317" 1,379» l,390 b l,410 b l,427 b °
67° 51°
* Means without a common letter are significantly different at the .05 level of probability.
105° 76°
Pounds feed/ \ pounds gain 5.85" 6.13" 6.10" 5.95" 5.91"
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 9, 2016
There was a responsive increase in liver storage of vitamin A as the dietary vitamin A level was increased from 250 to 3,000 U.S.P. units per pound (Table 5). These data agree with the work of Reid et al. (1955) in which it was reported that the amount of vitamin A stored in the liver of chicks was an indication of the amount of the vitamin in the feed. Shellenberger et al. (1960) found only minor amounts of vitamin A in the liver with the feeding of 400 U.S.P. units vitamin A, and marked deposition of the vitamin with 1,750 or 2,000 U.S.P. units of vitamin A per pound of diet. An interaction was observed between season of hatch and vitamin A stored in the liver. Appreciably less vitamin A was stored in the livers of pullets from studies
1586
K U R N I C K , H E Y W A N G , H U L E T T , VAVICH AND R E I D
Feed conversion of pullets grown to 20weeks was not significantly different regardless of location (Table 6). Very small differences in feed conversion were observed within each experiment. However, considerable differences were found between the four experiments. I n general, these differences could be accounted for by season of the year. Considerably more feed per unit gain was required for pullets reared during the cooler p a r t of the year. SUMMARY Approximately 5,200 commercial strain White Leghorn pullet chicks were used in 7 experiments to determine the vitamin A requirement of chicks grown in a subtropical, semi-arid climate. I n general, increasing the dietary vitamin A from 500 to 3,000 U.S.P. units per pound of diet produced a numerical, b u t not a statistically significant, improvement in growth rate to 10 or 20 weeks of age. Differences in feed
conversion among the various vitamin A treatments were small and not statistically different except in one experiment. I n every instance, there was a responsive increase in vitamin A stored in the liver of pullets as their dietary vitamin A increased. Chicks reared during the cooler periods showed more liver vitamin A than those fed during hot weather. REFERENCES Almquist, H. J., 1953. Evaluation of vitamin requirement data. Poultry Sci. 32: 122-128. Ames, S. R., H. A. Risley and P. L. Harris, 1954. Simplified procedure for extraction and determination of vitamin A in liver. Anal. Chem. 26: 1378-1381. Harms, R. H., B. L. Reid and J. R. Couch, 1955. Storage of vitamin A in chick livers as a criterion of stability, availability, and dietary level. Poultry Sci. 34: 1125-1133. National Research Council, 1960. Nutrient requirement for domestic animals. No. 1 Nutrient requirement for poultry. Olsen, E. M., J. O. Harvey, D. C. Hill and H. D. Branion, 1959. Distribution of carotene and vitamin A in the tissues of chicks following administration of carotene. Poultry Sci. 38: 688693. Reid, B. L., H. K. Daugherty and J. R. Couch, 1955. The stability of vitamin A in mixed feeds and premixes. Poultry Sci. 34: 603-608. Rubin, M., and H. R. Bird, 1941. Some experiments on the physiology of vitamin A storage in the chick. Poultry Sci. 20: 291-297. Scott, M. L., F. W. Hill, L. C. Norris, G. F. Heuser, R. D. Reynalds, E. H. Parsons and H. E. Butters, 1957. New information on the vitamin A requirements of chickens, ducks and pheasants, Proc. 1957 Cornell Nutrition Conference for Feed Manufacturers: 132-136. Shellenberger, T. E., D. B. Parrish and P. E. Stanford, 1960. Effect of vitamin A level of diet on feed conversion and utilization of energy by growing chickens. Poultry Sci. 39:1413-1417. Thornton, P. A., and W. A. Whittet, 1962. The influence of dietary energy level, energy source, breed and sex on vitamin A requirement in the chick. Poultry Sci. 41: 32-36.
M A Y 5-8. P O U L T R Y B R E E D E R S O F A M E R I C A M E E T I N G A N D ROUNDTABLE, H O T E L P R E S I D E N T , KANSAS CITY, MO.
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As would be expected, the first 250 U.S.P. increment added to the diet containing 500 U.S.P. units of vitamin A resulted in the largest increase in body weight. Pullets fed 250 U.S.P. units of vitamin A per pound of diet throughout the first 10 weeks of experiment 7 were divided into two equal groups and fed 1,000 or 1,250 U.S.P. units of vitamin A for the next 10 weeks. At the end of the twentieth week, body weights averaged 1,294 grams for each group. Body weights were not statistically different from pullets fed 500 U.S.P. units of vitamin A throughout the 20-week experiment, but were significantly lower t h a n body weight of pullets fed dietary vitamin A above 500 U.S.P. units per pound.