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Effect of Levels and Sources of Dietary Protein in Pullet Grower Diet on Subsequent Performance1
Effect of Levels and Sources of Dietary Protein in Pullet Grower Diet on Subsequent Performance* S. M. KIM AND J. MCGINNIS
Department of Animal Sciences, Washington State University, Pullman 99163 (Received for publication July 22, 1975)
POULTRY SCIENCE 55: 895-905, 1976
INTRODUCTION
P
UBLISHED results on the effect of grower diet on subsequent performance of laying chickens show wide differences in experimental design and results. Different protein and energy levels, ages, strains and management procedures are some of the predominant factors involved in causing differences in experimental design and results. Blaylock (1956) suggested that the protein requirement of light breed growing pullets from 12-20 weeks of age is as low as 12%. Since then the protein requirement of growing pullets has been extensively studied. Berg and Bearse (1958) suggested that growing
1. Scientific Paper No. 4470. College of Agriculture Research Center, Washington State University. Project 1922.
pullets require not more than 15% protein from 8-12 weeks of age, less than 13% from 12-16 weeks and less than 12% from 16-20 weeks. They also reported that White Leghorn pullets developed normally with a wide energy /protein (M.E. kcal./kg.:% protein) ratio ranging from 166/1 to 224/1. According to Bullock et al. (1963), reducing protein content of a growing diet from 15 to 10.5% for replacement pullets from 9-20 weeks of age had no adverse effects on subsequent egg production, egg weight or mortality. Sunde and Bird (1959) reported that the use of a growing diet containing 11.3% protein from 10-20 weeks of age gave satisfactory egg production and egg size. The report by Lillie and Denton (1966) suggested that 12% protein fed from hatching time to 20 weeks of age was adequate for subsequent egg production, feed per dozen eggs and egg weight, even though the pullets fed 12% protein growing diet had significant lighter
895
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ABSTRACT An experiment was conducted using 1,100 White Leghorn pullets to study the effect of two dietary protein levels (12 and 15%) from 12-20 weeks of age on subsequent laying performance. The effect of replacing protein concentrates such as soybean meal and meat and bone meal with triticale or alfalfa (dehydrated or sun-cured) was studied. The effect of adding lysine or methionine or both to grower diets in which cereal grains were the only sources of protein on growth and subsequent performance was also studied. The performance criteria were body weight, feed consumption, egg production, egg weight, age at 50% production rate and mortality. Compared with pullets fed 12% protein grower diets, those fed 15% protein grower diets were heavier by 15 and 14 g. per bird at 20 and 32 weeks of age, respectively. The latter consumed 0.8 and 2.5 g. more feed per bird per day during the 12-20 and 21-32 week period, respectively. Pullets fed the higher protein grower diet laid 1.8% more eggs on a hen-day basis and their eggs were 0.1 g. heavier during the 23-32 week period than those of pullets fed the lower protein diet. There was a difference of 1.7 days when the two groups reached 50% production. The differences for body weight at 20 weeks of age, feed consumption during the laying period and age at 50% production rate were statistically significant (P < 0.05). Replacing the protein contributed by soybean meal and meat and bone meal with grain or alfalfa in the grower diet did not cause any adverse effects on growth and subsequent performance as layers. The results also suggest that added lysine or methionine or both were not required when corn and triticale provided all of the 12 or 15% protein in the grower diets.
896
S. M. KIM AND J. MCGINNIS
in which corn and triticale supplied all the dietary protein. PROCEDURE White Leghorn pullets of the H&N strain, hatched June 14, 1973, were used in this experiment. They were raised in confinement in a open-front house from hatching to 12 weeks of age. A practical type chick starter diet containing 21% protein was fed from hatching to 8 weeks of age, and thereafter a 12% protein grower diet (Table 1) was fed from 8-12 weeks of age. At 12 weeks of age, the pullets were randomly distributed into 110 groups of 10 pullets each. These pullets were group-weighed and placed in double-decked cages of approximately 51 x 61 cm. in dimension. The cages were located in a windowless house and a declining photoperiod was employed from 12-20 weeks of age to simulate the changing natural day-length during the period from September 6 to November 1. The photoperiod was decreased weekly so that the photoperiod was 9 hours per day during the last week of the experimental growing period. Twenty-two experimental grower diets were employed, with 13 containing 12% dietary protein and nine, 15% protein. All diets were formulated to have 0.75% calcium and 0.50% phosphorus. Diet 1 with 12% protein and diet 14 with 15% protein were practical types of grower diets composed principally of corn, soybean meal and meat and bone meal and were used as controls at each dietary protein level. The rest of the diets did not contain any protein concentrate with the exception of diets 6 and 19 where the effect of adding soybean meal to corn-triticale was tested. The triticale used in this experiment was analyzed to contain 18% crude protein. In diets 2 and 15, all the protein was derived from a combination of corn and triticale. By supplementing lysine and methionine, singly or in combination, to
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body weights at 8 and 20 weeks of age in comparison with those fed 16 or 20% protein at different ages. Foster (1971) fed only whole wheat (11.5% protein) to growing pullets from 89-134 days of age. Although the pullets fed whole wheat had lighter body weight at the end of the growing period and delayed sexual maturity their ultimate egg production, egg weight and feed consumption were comparable to those fed a mixed grower diet containing 14.6% protein. Wright et al. (1968) found significant delays in sexual maturity of the pullets fed a 10% protein diet from 8-18 weeks of age in comparison with the pullets fed 16% protein diet, yet no significant difference in egg production was found between the two groups of pullets. A grower diet with a protein level as low as 9.27% was fed to replacement pullets from 8-18 weeks of age by Douglas et al. (1973). Their reports indicated that the pullets raised on 9.27% protein diet had significantly lighter body weights at 20 weeks of age and consumed significantly less feed in comparison with the pullets grown on a 14% protein diet. They laid fewer total eggs, mainly due to a delay in onset of egg production compared with the pullets fed a 14% protein grower diet. Information on the nutritional value of triticale for poultry is limited. Reports by Sell et al. (1962) and Fernandez and McGinnis (1974) suggested that lysine is the first limiting amino acid for chicks. Although Sell et al. (1962) indicated that methionine is also limiting in triticale for chicks, Fernandez and McGinnis (1974) and Marquez and Avila (1974) suggested that threonine is the second limiting amino acid in triticale for chicks. No information on feeding value of triticale for growing pullets is available. Therefore, part of the experiment reported in this paper was conducted to study the utilization of triticale by growing pullets and the effect of adding lysine or methionine or both to grower diets
0.46 0.23 0.21
0.46 0.18 0.20 '
— —
6.27 2.00 0.% 0.59 0.40 0.25 0.10
—
89.43
1
— —
1.00 1.00 0.40 0.25 0.05 0.05
—
2.00 5.50
89.75
— —
Grower diet 1
0.34 0.22 0.22
— —
1.14 1.20 0.40 0.25 0.10
—
59.82 37.09
2
6
0.39 0.22 0.22
0.48 0.36 0.21
0.34 0.37 0.22
— 0.49 0.22 0.22
—
0.15 0.15
— 0.15
0.15
3.00
69.94 24.00
1.15 1.16 0.40 0.25 0.10
—
62.50 34.10
5
0.40 0.22 0.17
—
1.33 0.40 0.25 0.10
—
—
34.59
—
63.33
7 6 3
Diet number of experiment
1.14 1.21 0.40 0.25 0.10
—
61.17 35.59
4
1.14 1.20 0.40 0.25 0.10
1.14 1.20 0.40 0.25 0.10
—
61.17 35.59
3
'Grower diet refers to pre-experimental grower diet which was fed to all pullets during 8-12 weeks 2 Vitamin premix in grower diet supplied the following per kg. of diet: vitamin A, 5,500 I.U.; v niacin, 17.6 mg.; choline chloride, 449.4 mg.; calcium pantothenate, 3.3 mg.; ethoxyquin, 125.4 premix in the experimental diet supplied the following per kg. of diet: vitamin A, 4,400 I.U.; vi riboflavin, 4.4 mg.; niacin, 11 mg.; pantothenic acid. 6.06 mg.; vitamin B12, 0.0055 rag.; and ethoxyqu 'Mineral premix at a level of 0.05% in the diet supplied the following mg./kg. of diet: Mn, 50 Co, 0.5.
Ground corn Ground triticale Ground wheat Alfalfa (sun-cured) Alfalfa (dehydrated) Soybean meal Meat and bone meal Limestone Dical. phosphate Salt, iodized Vitamin premix 2 Mineral premix 3 Amprol premix Lysine HC1 DL-methionine Calculated analysis: Lysine (%) Methionine (%) Cystine (%)
Ingredient
TABLE 1.—Percentage composition of pre-experimental grower diet and 12% protei
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898
S. M. KIM AND J. MCGINNIS
Each of the 22 experimental grower diets was fed to five groups of 10 pullets each from 12-20 weeks of age. Data on body weight at 12 and 20 weeks of age and feed consumption were collected and mortality was recorded as it occurred. When the pullets were 20 weeks old they were moved to individual laying cages. At the time of transfer, the photoperiod was increased to provide 14 hours of light per day and the photoperiod was kept constant during the egg production period. Following the experimental growing phase, all pullets were fed the same laying diet shown in Table 2 for a period of 12 weeks to determine the effects of grower diets on subsequent feed consumption, body weight gain, age at 50% production, egg production and egg weight. All eggs produced by each group during two days of every week, starting from 23 weeks of age, were saved for determination of egg weight. All birds were weighed at 32 weeks of age and at this time the experiment was terminated. The data obtained were submitted to analysis of variance and the different treatment means within each dietary protein level of grower diet were compared using Duncan's
new multiple range test according to the procedures outlined by Steel and Torrie (1960). The different treatment means between the two dietary protein levels for each of the 9 dietary protein sources were compared using the least significant difference. Then the mean of 9 treatments containing 12% protein (excluding diets 7, 11, 12 and 13) was compared with that of 15% protein using single degree of freedom comparisons (Steel and Torrie, 1960).
RESULTS Body Weight. The results on body weights at 20 and 32 weeks of age are presented in Table 3. The body weight at the beginning of the experiment was not included because they had the same starting weights. Regardless of the dietary protein level of the grower diet, the corn-triticale diet supported pullet growth comparable to the corn-soy-meat control diet without significant differences in body weights at 20 and 32 weeks of age. Supplementing the corn-triticale diet with lysine or methionine or both did not improve pullet growth over the unsupplemented corntriticale diet at either protein level. Replacing 3% of the grain portion of the corn-triticale diet with soybean meal did not exert any beneficial effect on growth at either of the two protein levels. When the protein in the 12% diet was derived from corn and sun-cured alfalfa, the pullets grew at a significantly (P < 0.05) lower rate in comparison with any of the other dietary regimes except the one with the highest level of dehydrated alfalfa. The diets containing graded levels of alfalfa, both suncured and dehydrated, supported pullet growth comparable to the corn-soy-meat control or the corn-triticale diet. When the three diets containing graded levels of suncured alfalfa were compared as a group with those containing dehydrated alfalfa, no
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the corn-triticale diet, the effect of amino acid additions was studied (diets 3-5 and 16-18). The supplementary synthetic amino acids were included as a part of the dietary protein. All the dietary protein was derived from corn and sun-cured alfalfa in diet 7. By adding graded levels of alfalfa, either sun-cured or dehydrated, at levels supplying 1, 2 and 3% protein, the effect of replacing corn and triticale with alfalfa on growth and subsequent performance was studied. The suncured alfalfa (variety Washoe) used in the study was the first cutting grown under irrigation and analyzed to contain 18.4% protein (N x 6.25). Dietary composition and the contents of lysine, methionine and cystine are presented in Tables 1 and 2.
1.16 1.12 0.40 0.25 0.10
—— 0.49 0.25 0.26
1.13 1.18 0.40 0.25 0.10 0.20 0.20 0.63 0.44 0.25
1.14 1.17 0.40 0.25 0.10
— 0.20
1.14 1.17 0.40 0.25 0.10 0.20
— 0.63 0.24 0.26
1.14
1.17 0.40 0.25 0.10
— —
0.44 0.24 0.26
13.24 2.50 0.94
0.33 0.40 0.25 0.10
— —
0.68 0.27 0.25
—
'Vitamin premix in the experimental grower diet and the laying diet supplied the following pe D 3 , 1,100 I.C.U.; vitamin E. 4.4 I.U.; riboflavin, 4.4 mg.; niacin, 11 mg.; pantothenic acid, 6.06 62 mg. 2 Mineral premix supplied the following in mg. per kg. of diet: Mn, 100; Fe, 100; Ca, 120; Cu, 10; Z
0.43 0.44 0.26
— —
— — — —
— — — —
— — — —
— — — — 3.00
37.03 56.94
30.51 66.03
28.71 68.03
28.71 68.03
26.91 70.03
82.24
Ground corn Ground triticale Alfalfa (sun-cured) Alfalfa (dehydrated) Soybean meal Meat and bone meal Limestone Dicalcium phosphate Salt, iodized Vitamin premix' Mineral premix 2 Lysine HC1 DL-methionine Calculated analysis: Lysine (%) Methionine (%) Cystine(%)
— — —
16
15
14
Ingredient
Diet number of experimental grower diets 18 19 17
TABLE 2.—Percentage composition of 15% protein experimental grower d
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— *
— 1285 16
1222cd 1270
13
—
—
1256abc
12
—
—
1275ab
—
—
11
NS
1236b
1275ab 1186d
10,22 7
NS
1279ab
1268abc
9,21
NS
* *
1277ab
1247bc
8,20
NS
Significance
NS NS NS
15%'
At 20 weeks 1295a 1320a 1308a 1302a 1283ab 1264ab
1293ab 1261abc 1251bc 1259abc 1302a 1275ab
12%'
1, 14 2, 15 3, 16 4, 17 5, 18 6, 19
Diet number
of experimental grower diets on body weight
3
2
Means within each column having a common letter are not significantly different (P < 0.05). Refers to comparison between the two protein levels of the same protein sources. NS: nonsignific Does not include diets 7, 11, 12 and 13.
1
Corn + soy + meat Corn + triticale Corn + triticale + lysine Corn + triticale + methionine Corn + triticale + lysine + methionine Corn + triticale + soy Corn + triticale + alfalfa (sun-cured) 1% protein Corn + triticale + alfalfa (sun-cured) 2% protein Corn + triticale + alfalfa (sun-cured) 3% protein Corn + alfalfa (sun-cured) Corn + triticale + alfalfa (dehydrated) 1% protein Corn + triticale + alfalfa (dehydrated) 2% protein Corn + triticale + alfalfa (dehydrated) 3% protein Over-all 3 Standard error of a mean
Dietary protein source
TABLE 3.—Effects
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PROTEIN AND SUBSEQUENT PERFORMANCE
Feed Consumption. All groups of pullets, regardless of dietary treatments, consumed comparable amounts of feed during the 12-20 week growing period (Table 4). However, the pullets fed the corn-sun-cured alfalfa grower diet consumed significantly (P < 0.05) more feed than many of the other groups even though they had the lightest body weight at 20 weeks of age. Generally, the pullets fed diets containing alfalfa consumed slightly more feed in comparison with the pullets fed the diets without alfalfa. No significant difference was found between the two different levels of dietary protein in feed consumption during the growing period. However, the pullets fed the 15% protein grower diets
consumed significantly (P < 0.05) more feed than their counterparts fed the 12% protein grower diets during the 12 weeks of laying period (diets 14-22 vs. diets 1-10, excluding diet 7). No marked differences in feed intake during the laying period were observed among different treatments within each grower diet protein level. Egg Production and Egg Weight. The egg production data showing the percent egg production on a hen-day basis for the 10 week period, counting from 23 weeks of age, are summarized in Table 5. The pullets grown on the corn-triticale diet laid at the same rate as the groups fed corn-soy-meat control at both levels of protein. Pullets fed the grower diets supplemented with lysine or methionine or both were not different in egg production rates from those fed diets without amino acid supplementation at both dietary protein levels. Pullets raised on diets with 3% soybean meal replacing grain portion had a slightly lower production rate and a slightly heavier egg weight in comparison with those grown on diets containing only corn and triticale at both dietary protein levels, but the difference was not significant in either case. In spite of significantly lighter body weight at the end of the growing period, the pullets grown on corn-sun-cured alfalfa diet had an egg production rate and egg weight comparable to those of other groups grown on other dietary regimes. Sun-cured alfalfa in the grower diets was equal to dehydrated alfalfa in supporting subsequent egg production and egg weight. The only significant (P < 0.05) effect of grower diet protein level on egg production was observed in the diets where 3% soybean meal replaced grain portion in the formula at both protein levels. Otherwise, there were no significant differences in egg production between the two protein levels of the grower diet for the other eight dietary regimes. This general lack of effect of grower protein level
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appreciable differences were found in regard to pullet growth. In spite of the results showing no significant differences among seven independent comparisons out of nine involving the two dietary protein levels, the pullets fed 15% protein diets had slightly but significantly (P < 0.05) heavier body weight at 20 weeks of age in comparison with those fed the 12% protein diets (diets 14-22 vs. diets 1-10, excluding diet 7). After 12 weeks on the same laying diet, there were virtually no significant differences in body weight among all the groups of pullets within each dietary protein level of the grower diet. The pullets fed the corn-sun-cured alfalfa grower diet and the diet with the highest level of dehydrated alfalfa gained more body weight than any of the other groups of pullets during the laying period. The significant difference in body weight found at the end of the growing period between the pullets fed 12% protein diets and those fed 15% protein diets was not found at 32 weeks of age. This was partly due to large error term within each treatment at 32 weeks of age, although the actual difference was still 14 g. (1665-1651) in comparison with 15 g. (1285-1270) at 20 weeks of age (Table 3).
901
Dietary protein source Corn + soy + meat Corn + triticale Corn + triticale + lysine Corn + triticale + methionine Corn + triticale + lysine + methionine Corn + triticale + soy Corn + triticale + alfalfa (sun-cured) 1% protein Corn + triticale + alfalfa (sun-cured) 2% protein Corn + triticale + alfalfa (sun-cured) 3% protein Corn + alfalfa (sun-cured) Corn + triticale + alfalfa (dehydrated) 1% protein Corn + triticale + alfalfa (dehydrated) 2% protein Corn + triticale + alfalfa (dehydrated) 3% protein Over-all 3 Standard error of a mean '• 2,3 See Footnotes in Table 3.
* —
— NS
63.7ab
— — — — 62.5
66.9ab 67.7a 63.3bc 62.3bcd 65.2ab 61.7
10,22 7 11 12 13 1.00
NS
64.8a
63.9bc
9,21
—
—
NS
63.4ab
60.9cd
14 15 16 17 18 19
consumption
Growing period (12-20 weeks) Significance 2 15%> 12%> NS 62.0ab 59.6d 63.6ab 59.9d * NS 62.7ab 61.7cd 61.led NS 60.4b 61.8ab NS 60.8cd NS 60.4b 60.9cd
of experimental grower diets on feed
8,20
1, 2, 3, 4, 5, 6,
Diet number
TABLE 4.—Effects
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49.9ab 49.4
— NS
— 67.4
64.4abcd 65.6
13
49.3ab
—
—
68.4ab
11
49.4a
—
—
66.7abc
11
49.5
—
—
—
—
50.0a
49.6ab 48.6b
—
—
NS
67.2a
69.5a 61.9cd
10,22 7
49.7a
49.0ab
NS
65.8a
65.8abcd
9,21
49.7a
50.1a
NS
67.1a
67.7abc
8,20
49.4a 49.5a 49.7a 49.4a 48.5a 49.7a
*
15%'
NS NS NS NS NS
68.1a 68.6a 68.5a 67.1a 66.2a 67.6a
65.7abcd 65.5abcd 65.8abcd 62.6bcd 67.6abc 60.4d
1, 14 2, 15 3, 16 4, 17 5, 18 6, 19
12%'
Egg weight (g.) a
49. lab 48.8ab 48.9ab 49.3ab 49.6ab 50.1a
Significance 2
15%'
12%'
Diet number
% Egg production »
of experimental grower diets on egg production, egg weight an
a
0.44 1.94 Average egg production or egg weight of pooled data for a period of 10 weeks (from 23-32 weeks o 123 See footnotes in Table 3.
Corn + soy + meat Corn + triticale Corn + triticale + lysine Corn + triticale + methionine Corn + triticale Corn + triticale + soy Corn + triticale + alfalfa (suncured) 1% protein Corn + triticale + alfalfa (suncured) 2% protein Corn + triticale + alfalfa (suncured) 3% protein Corn + alfalfa (sun-cured) Corn + triticale + alfalfa (dehydrated) 1% protein Corn + triticale + alfalfa (dehydrated) 2% protein Corn + triticale + alfalfa (dehydrated) 3 % protein Over-all 3 Standard error of a mean
Dietary protein sources
TABLE 5.—Effects
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904
S. M. KIM AND J. MCGINNIS
Age at 50% Production Rate. The effects of dietary treatments on sexual development as indicated by age at 50% lay are summarized in Table 5. Pullets fed the 12% protein grower diet containing 3% soybean meal required the longest period of time to reach 50% egg production. Pullets fed the diets containing the highest level of sun-cured alfalfa at 15% dietary protein level (diet 22) reached 50% production at the youngest age. The difference between the youngest and the oldest
ages in reaching 50% egg production was five days in the 12% protein groups and 3.8 days in the 15% protein groups. Compared with pullets fed the 12% protein grower diets, those fed the 15% protein diets reached 50% egg production rate earlier by an average of 1.7 days, and this difference was significant (P < 0.05). Mortality. Mortality was low and only six pullets died out of 1,100 started during the combined growing and laying periods. Mortality was not related to dietary treatments. DISCUSSION The results of this experiment confirm some of the early reports (Blaylock, 1956; Berg, 1959; Bullock et al, 1963; Lillie and Denton, 1966; Foster, 1971; Holmquist and Carlson, 1972; and Magruder and Coune, 1973) showing that hen-day egg production and egg size were not significantly affected by protein levels of the grower diet. Whether the effects were statistically significant or not, most of the above authors reported delayed sexual maturity and lower body weight up to the point-of-lay due to protein restriction by one way or another, which are confirmed by the data in this study. Even though effects of different grower diets were attributed to dietary protein levels and sources, other variables such as energy content or amino acid composition of each diet might have affected the over-all experimental results. Nevertheless, Berg (1959) reported that the energy level of the developing rations have no effect on body weight, rate of peak production, egg size or sexual maturity. Pullets fed the high protein grower diets with significantly heavier body weights at the end of the growing period consumed significantly more feed without laying either more or heavier eggs during the laying period. In other words, they consumed more feed in
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on egg production resulted in no significant differences in the over-all comparison of egg production between 12 and 15% protein level in grower diets. In addition to considering over-all egg production rates, the peak production attained by hens is also interesting. In this experiment, a comparison of the peak rates for a one-week period on Diets 1-10 showed a low of 78.0% for Diet 6 and a high of 86.6% for Diet 10, with an average of 82.95% for Diets 1-10 (12% protein). For Diets 14-22 the low was 80.5% for Diet 20 and a high of 88.6% for Diet 19, with an average of 83.90% for Diets 14-22. Peak production for all treatments was reached between 27 and 29 weeks of age. No marked differences in weight were found among different treatments within each dietary protein level of the grower diets. None of the statistical comparisons between the two dietary protein levels for nine different protein sources showed significance. A further examination of egg weights for the last week of the trial (32 weeks of age) showed remarkably similar values for all treatments. For Diets 1-10 the average egg weight was 51.1 for Diet 3 to 53.0 for Diet 8, with the average for Diets 1-10 (12% protein) being 52.3 grams. For diets 14-22, the corresponding weights were a low of 50.9 for Diet 18, a high of 52.9 for Diet 20, and an average of 52.2 grams for Diets 14-22 (15% protein). All of these figures are based on eggs produced during two days of the 32nd week.
PROTEIN AND SUBSEQUENT PERFORMANCE
REFERENCES Berg, L. R., 1959. Protein, energy and method of feeding as factors in the nutrition of developing White Leghorn pullets. Poultry Sci. 38: 158-165. Berg, L. R., and G. E. Bearse, 1958. Protein and energy studies with developing White Leghorn pullets. Poultry Sci. 37: 1340-1346. Blaylock, L. G., 1956. The protein requirements of growing birds. Poultry Sci. 35: 1133. Bullock, D. W., T. R. Morris and S. Fox, 1963. Protein and energy restriction for replacement pullets. Br. Poultry Sci. 4: 227-237. Douglas, C. R., H. R. Wilson, R. H. Harms and T.
S. Powell, 1973. Laying house performance of pullets grown on wire versus litter floors and nine versus fourteen percent protein diets. Poultry Sci. 52: 2023. Fernandez, R., and J. McGinnis, 1974. Nutritive value of triticale for young chicks and effect of different amino acid supplements on growth. Poultry Sci. 53: 47-53. Foster, W. H., 1971. The use of low-protein rations including the feeding of only whole wheat to two breeds of replacement pullets. Br. Poultry Sci. 12: 333-343. Holmquist, C , and C. W. Carlson, 1972. Effects of various pullet grower diets on subsequent layer performance. Poultry Sci. 51: 1820. Lillie.R. J., and C. A. Denton, 1966. Effect of nutrient restriction on White Leghorns in the grower and subsequent layer periods. Poultry Sci. 45: 810-818. Magruder, N. D., and F. L. Coune, 1973. Feeding replacement pullets on four diet regimes. Poultry Sci. 52: 2055-2056. Marquez, V. A., and C. E. Avila, 1974. Effect of amino acid supplementation to triticale diets. Poultry Sci. 53: 1231-1233. Sell, J. L., G. C. Hodgson and L. H. Shebeski, 1962. Triticale as a potential component of chick rations. Can. J. Anim. Sci. 42: 158-166. Steel, G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., New York, NY. Sunde, M. L., and H. R. Bird, 1959. The protein requirements of growing pullets. Poultry Sci. 38: 48-55. Wright, C. F., B. L. Damron, P. W. Waldroup and R. H. Harms, 1968. The performance of laying hens fed normal and low protein diets between eight and eighteen weeks of age. Poultry Sci. 47: 635-638.
NEWS AND NOTES (Continued from page 873) from each member society. They are established on a rotational basis, so that, in the future, each member will serve a term of six years, rotating to the Chairmanship of the Committee during his or her last two years. Each Committee is charged with specific responsibilities and the Chairman of each Committee will report to the C.I.S.P. annually. A.A.A.S. NOTES The Section O (Agriculture) Committee met on
February 20 with the Editor of Science, Philip H. Abelson. The Committee expressed concern about the tone, and especially the inaccuracies, of recent items in the News and Comment Section of Science concerning agricultural science. Dr. Abelson asked for assistance of Section O in giving agricultural science a more positive image in the pages of Science. He said he would be pleased to receive as many as six suggestions for articles on the agricultural sciences each year. Since the normal
(Continued on page 917)
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order to maintain their relatively heavy body weight established during the growing period, resulting in reduced feed efficiency for egg production and egg size. The heavy body weight of the pullets at the end of the growing period does not necessarily mean better performance during the laying period. Unlike some of the reports on work with chicks by Sell et al. (1962), Fernandez and McGinnis (1974), the data suggest that lysine or methionine, or both, were not limiting amino acids when corn and triticale provided all of the 12 or 15% dietary protein in a grower diet. In addition, these observations demonstrate further that pullets may be raised from 12-20 weeks with a dietary protein level of no more than 12% without impairing their egg production potential.
905
Department of Animal Sciences, Washington State University, Pullman 99163 (Received for publication July 22, 1975)
POULTRY SCIENCE 55: 895-905, 1976
INTRODUCTION
P
UBLISHED results on the effect of grower diet on subsequent performance of laying chickens show wide differences in experimental design and results. Different protein and energy levels, ages, strains and management procedures are some of the predominant factors involved in causing differences in experimental design and results. Blaylock (1956) suggested that the protein requirement of light breed growing pullets from 12-20 weeks of age is as low as 12%. Since then the protein requirement of growing pullets has been extensively studied. Berg and Bearse (1958) suggested that growing
1. Scientific Paper No. 4470. College of Agriculture Research Center, Washington State University. Project 1922.
pullets require not more than 15% protein from 8-12 weeks of age, less than 13% from 12-16 weeks and less than 12% from 16-20 weeks. They also reported that White Leghorn pullets developed normally with a wide energy /protein (M.E. kcal./kg.:% protein) ratio ranging from 166/1 to 224/1. According to Bullock et al. (1963), reducing protein content of a growing diet from 15 to 10.5% for replacement pullets from 9-20 weeks of age had no adverse effects on subsequent egg production, egg weight or mortality. Sunde and Bird (1959) reported that the use of a growing diet containing 11.3% protein from 10-20 weeks of age gave satisfactory egg production and egg size. The report by Lillie and Denton (1966) suggested that 12% protein fed from hatching time to 20 weeks of age was adequate for subsequent egg production, feed per dozen eggs and egg weight, even though the pullets fed 12% protein growing diet had significant lighter
895
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ABSTRACT An experiment was conducted using 1,100 White Leghorn pullets to study the effect of two dietary protein levels (12 and 15%) from 12-20 weeks of age on subsequent laying performance. The effect of replacing protein concentrates such as soybean meal and meat and bone meal with triticale or alfalfa (dehydrated or sun-cured) was studied. The effect of adding lysine or methionine or both to grower diets in which cereal grains were the only sources of protein on growth and subsequent performance was also studied. The performance criteria were body weight, feed consumption, egg production, egg weight, age at 50% production rate and mortality. Compared with pullets fed 12% protein grower diets, those fed 15% protein grower diets were heavier by 15 and 14 g. per bird at 20 and 32 weeks of age, respectively. The latter consumed 0.8 and 2.5 g. more feed per bird per day during the 12-20 and 21-32 week period, respectively. Pullets fed the higher protein grower diet laid 1.8% more eggs on a hen-day basis and their eggs were 0.1 g. heavier during the 23-32 week period than those of pullets fed the lower protein diet. There was a difference of 1.7 days when the two groups reached 50% production. The differences for body weight at 20 weeks of age, feed consumption during the laying period and age at 50% production rate were statistically significant (P < 0.05). Replacing the protein contributed by soybean meal and meat and bone meal with grain or alfalfa in the grower diet did not cause any adverse effects on growth and subsequent performance as layers. The results also suggest that added lysine or methionine or both were not required when corn and triticale provided all of the 12 or 15% protein in the grower diets.
896
S. M. KIM AND J. MCGINNIS
in which corn and triticale supplied all the dietary protein. PROCEDURE White Leghorn pullets of the H&N strain, hatched June 14, 1973, were used in this experiment. They were raised in confinement in a open-front house from hatching to 12 weeks of age. A practical type chick starter diet containing 21% protein was fed from hatching to 8 weeks of age, and thereafter a 12% protein grower diet (Table 1) was fed from 8-12 weeks of age. At 12 weeks of age, the pullets were randomly distributed into 110 groups of 10 pullets each. These pullets were group-weighed and placed in double-decked cages of approximately 51 x 61 cm. in dimension. The cages were located in a windowless house and a declining photoperiod was employed from 12-20 weeks of age to simulate the changing natural day-length during the period from September 6 to November 1. The photoperiod was decreased weekly so that the photoperiod was 9 hours per day during the last week of the experimental growing period. Twenty-two experimental grower diets were employed, with 13 containing 12% dietary protein and nine, 15% protein. All diets were formulated to have 0.75% calcium and 0.50% phosphorus. Diet 1 with 12% protein and diet 14 with 15% protein were practical types of grower diets composed principally of corn, soybean meal and meat and bone meal and were used as controls at each dietary protein level. The rest of the diets did not contain any protein concentrate with the exception of diets 6 and 19 where the effect of adding soybean meal to corn-triticale was tested. The triticale used in this experiment was analyzed to contain 18% crude protein. In diets 2 and 15, all the protein was derived from a combination of corn and triticale. By supplementing lysine and methionine, singly or in combination, to
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body weights at 8 and 20 weeks of age in comparison with those fed 16 or 20% protein at different ages. Foster (1971) fed only whole wheat (11.5% protein) to growing pullets from 89-134 days of age. Although the pullets fed whole wheat had lighter body weight at the end of the growing period and delayed sexual maturity their ultimate egg production, egg weight and feed consumption were comparable to those fed a mixed grower diet containing 14.6% protein. Wright et al. (1968) found significant delays in sexual maturity of the pullets fed a 10% protein diet from 8-18 weeks of age in comparison with the pullets fed 16% protein diet, yet no significant difference in egg production was found between the two groups of pullets. A grower diet with a protein level as low as 9.27% was fed to replacement pullets from 8-18 weeks of age by Douglas et al. (1973). Their reports indicated that the pullets raised on 9.27% protein diet had significantly lighter body weights at 20 weeks of age and consumed significantly less feed in comparison with the pullets grown on a 14% protein diet. They laid fewer total eggs, mainly due to a delay in onset of egg production compared with the pullets fed a 14% protein grower diet. Information on the nutritional value of triticale for poultry is limited. Reports by Sell et al. (1962) and Fernandez and McGinnis (1974) suggested that lysine is the first limiting amino acid for chicks. Although Sell et al. (1962) indicated that methionine is also limiting in triticale for chicks, Fernandez and McGinnis (1974) and Marquez and Avila (1974) suggested that threonine is the second limiting amino acid in triticale for chicks. No information on feeding value of triticale for growing pullets is available. Therefore, part of the experiment reported in this paper was conducted to study the utilization of triticale by growing pullets and the effect of adding lysine or methionine or both to grower diets
0.46 0.23 0.21
0.46 0.18 0.20 '
— —
6.27 2.00 0.% 0.59 0.40 0.25 0.10
—
89.43
1
— —
1.00 1.00 0.40 0.25 0.05 0.05
—
2.00 5.50
89.75
— —
Grower diet 1
0.34 0.22 0.22
— —
1.14 1.20 0.40 0.25 0.10
—
59.82 37.09
2
6
0.39 0.22 0.22
0.48 0.36 0.21
0.34 0.37 0.22
— 0.49 0.22 0.22
—
0.15 0.15
— 0.15
0.15
3.00
69.94 24.00
1.15 1.16 0.40 0.25 0.10
—
62.50 34.10
5
0.40 0.22 0.17
—
1.33 0.40 0.25 0.10
—
—
34.59
—
63.33
7 6 3
Diet number of experiment
1.14 1.21 0.40 0.25 0.10
—
61.17 35.59
4
1.14 1.20 0.40 0.25 0.10
1.14 1.20 0.40 0.25 0.10
—
61.17 35.59
3
'Grower diet refers to pre-experimental grower diet which was fed to all pullets during 8-12 weeks 2 Vitamin premix in grower diet supplied the following per kg. of diet: vitamin A, 5,500 I.U.; v niacin, 17.6 mg.; choline chloride, 449.4 mg.; calcium pantothenate, 3.3 mg.; ethoxyquin, 125.4 premix in the experimental diet supplied the following per kg. of diet: vitamin A, 4,400 I.U.; vi riboflavin, 4.4 mg.; niacin, 11 mg.; pantothenic acid. 6.06 mg.; vitamin B12, 0.0055 rag.; and ethoxyqu 'Mineral premix at a level of 0.05% in the diet supplied the following mg./kg. of diet: Mn, 50 Co, 0.5.
Ground corn Ground triticale Ground wheat Alfalfa (sun-cured) Alfalfa (dehydrated) Soybean meal Meat and bone meal Limestone Dical. phosphate Salt, iodized Vitamin premix 2 Mineral premix 3 Amprol premix Lysine HC1 DL-methionine Calculated analysis: Lysine (%) Methionine (%) Cystine (%)
Ingredient
TABLE 1.—Percentage composition of pre-experimental grower diet and 12% protei
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898
S. M. KIM AND J. MCGINNIS
Each of the 22 experimental grower diets was fed to five groups of 10 pullets each from 12-20 weeks of age. Data on body weight at 12 and 20 weeks of age and feed consumption were collected and mortality was recorded as it occurred. When the pullets were 20 weeks old they were moved to individual laying cages. At the time of transfer, the photoperiod was increased to provide 14 hours of light per day and the photoperiod was kept constant during the egg production period. Following the experimental growing phase, all pullets were fed the same laying diet shown in Table 2 for a period of 12 weeks to determine the effects of grower diets on subsequent feed consumption, body weight gain, age at 50% production, egg production and egg weight. All eggs produced by each group during two days of every week, starting from 23 weeks of age, were saved for determination of egg weight. All birds were weighed at 32 weeks of age and at this time the experiment was terminated. The data obtained were submitted to analysis of variance and the different treatment means within each dietary protein level of grower diet were compared using Duncan's
new multiple range test according to the procedures outlined by Steel and Torrie (1960). The different treatment means between the two dietary protein levels for each of the 9 dietary protein sources were compared using the least significant difference. Then the mean of 9 treatments containing 12% protein (excluding diets 7, 11, 12 and 13) was compared with that of 15% protein using single degree of freedom comparisons (Steel and Torrie, 1960).
RESULTS Body Weight. The results on body weights at 20 and 32 weeks of age are presented in Table 3. The body weight at the beginning of the experiment was not included because they had the same starting weights. Regardless of the dietary protein level of the grower diet, the corn-triticale diet supported pullet growth comparable to the corn-soy-meat control diet without significant differences in body weights at 20 and 32 weeks of age. Supplementing the corn-triticale diet with lysine or methionine or both did not improve pullet growth over the unsupplemented corntriticale diet at either protein level. Replacing 3% of the grain portion of the corn-triticale diet with soybean meal did not exert any beneficial effect on growth at either of the two protein levels. When the protein in the 12% diet was derived from corn and sun-cured alfalfa, the pullets grew at a significantly (P < 0.05) lower rate in comparison with any of the other dietary regimes except the one with the highest level of dehydrated alfalfa. The diets containing graded levels of alfalfa, both suncured and dehydrated, supported pullet growth comparable to the corn-soy-meat control or the corn-triticale diet. When the three diets containing graded levels of suncured alfalfa were compared as a group with those containing dehydrated alfalfa, no
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the corn-triticale diet, the effect of amino acid additions was studied (diets 3-5 and 16-18). The supplementary synthetic amino acids were included as a part of the dietary protein. All the dietary protein was derived from corn and sun-cured alfalfa in diet 7. By adding graded levels of alfalfa, either sun-cured or dehydrated, at levels supplying 1, 2 and 3% protein, the effect of replacing corn and triticale with alfalfa on growth and subsequent performance was studied. The suncured alfalfa (variety Washoe) used in the study was the first cutting grown under irrigation and analyzed to contain 18.4% protein (N x 6.25). Dietary composition and the contents of lysine, methionine and cystine are presented in Tables 1 and 2.
1.16 1.12 0.40 0.25 0.10
—— 0.49 0.25 0.26
1.13 1.18 0.40 0.25 0.10 0.20 0.20 0.63 0.44 0.25
1.14 1.17 0.40 0.25 0.10
— 0.20
1.14 1.17 0.40 0.25 0.10 0.20
— 0.63 0.24 0.26
1.14
1.17 0.40 0.25 0.10
— —
0.44 0.24 0.26
13.24 2.50 0.94
0.33 0.40 0.25 0.10
— —
0.68 0.27 0.25
—
'Vitamin premix in the experimental grower diet and the laying diet supplied the following pe D 3 , 1,100 I.C.U.; vitamin E. 4.4 I.U.; riboflavin, 4.4 mg.; niacin, 11 mg.; pantothenic acid, 6.06 62 mg. 2 Mineral premix supplied the following in mg. per kg. of diet: Mn, 100; Fe, 100; Ca, 120; Cu, 10; Z
0.43 0.44 0.26
— —
— — — —
— — — —
— — — —
— — — — 3.00
37.03 56.94
30.51 66.03
28.71 68.03
28.71 68.03
26.91 70.03
82.24
Ground corn Ground triticale Alfalfa (sun-cured) Alfalfa (dehydrated) Soybean meal Meat and bone meal Limestone Dicalcium phosphate Salt, iodized Vitamin premix' Mineral premix 2 Lysine HC1 DL-methionine Calculated analysis: Lysine (%) Methionine (%) Cystine(%)
— — —
16
15
14
Ingredient
Diet number of experimental grower diets 18 19 17
TABLE 2.—Percentage composition of 15% protein experimental grower d
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— *
— 1285 16
1222cd 1270
13
—
—
1256abc
12
—
—
1275ab
—
—
11
NS
1236b
1275ab 1186d
10,22 7
NS
1279ab
1268abc
9,21
NS
* *
1277ab
1247bc
8,20
NS
Significance
NS NS NS
15%'
At 20 weeks 1295a 1320a 1308a 1302a 1283ab 1264ab
1293ab 1261abc 1251bc 1259abc 1302a 1275ab
12%'
1, 14 2, 15 3, 16 4, 17 5, 18 6, 19
Diet number
of experimental grower diets on body weight
3
2
Means within each column having a common letter are not significantly different (P < 0.05). Refers to comparison between the two protein levels of the same protein sources. NS: nonsignific Does not include diets 7, 11, 12 and 13.
1
Corn + soy + meat Corn + triticale Corn + triticale + lysine Corn + triticale + methionine Corn + triticale + lysine + methionine Corn + triticale + soy Corn + triticale + alfalfa (sun-cured) 1% protein Corn + triticale + alfalfa (sun-cured) 2% protein Corn + triticale + alfalfa (sun-cured) 3% protein Corn + alfalfa (sun-cured) Corn + triticale + alfalfa (dehydrated) 1% protein Corn + triticale + alfalfa (dehydrated) 2% protein Corn + triticale + alfalfa (dehydrated) 3% protein Over-all 3 Standard error of a mean
Dietary protein source
TABLE 3.—Effects
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PROTEIN AND SUBSEQUENT PERFORMANCE
Feed Consumption. All groups of pullets, regardless of dietary treatments, consumed comparable amounts of feed during the 12-20 week growing period (Table 4). However, the pullets fed the corn-sun-cured alfalfa grower diet consumed significantly (P < 0.05) more feed than many of the other groups even though they had the lightest body weight at 20 weeks of age. Generally, the pullets fed diets containing alfalfa consumed slightly more feed in comparison with the pullets fed the diets without alfalfa. No significant difference was found between the two different levels of dietary protein in feed consumption during the growing period. However, the pullets fed the 15% protein grower diets
consumed significantly (P < 0.05) more feed than their counterparts fed the 12% protein grower diets during the 12 weeks of laying period (diets 14-22 vs. diets 1-10, excluding diet 7). No marked differences in feed intake during the laying period were observed among different treatments within each grower diet protein level. Egg Production and Egg Weight. The egg production data showing the percent egg production on a hen-day basis for the 10 week period, counting from 23 weeks of age, are summarized in Table 5. The pullets grown on the corn-triticale diet laid at the same rate as the groups fed corn-soy-meat control at both levels of protein. Pullets fed the grower diets supplemented with lysine or methionine or both were not different in egg production rates from those fed diets without amino acid supplementation at both dietary protein levels. Pullets raised on diets with 3% soybean meal replacing grain portion had a slightly lower production rate and a slightly heavier egg weight in comparison with those grown on diets containing only corn and triticale at both dietary protein levels, but the difference was not significant in either case. In spite of significantly lighter body weight at the end of the growing period, the pullets grown on corn-sun-cured alfalfa diet had an egg production rate and egg weight comparable to those of other groups grown on other dietary regimes. Sun-cured alfalfa in the grower diets was equal to dehydrated alfalfa in supporting subsequent egg production and egg weight. The only significant (P < 0.05) effect of grower diet protein level on egg production was observed in the diets where 3% soybean meal replaced grain portion in the formula at both protein levels. Otherwise, there were no significant differences in egg production between the two protein levels of the grower diet for the other eight dietary regimes. This general lack of effect of grower protein level
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appreciable differences were found in regard to pullet growth. In spite of the results showing no significant differences among seven independent comparisons out of nine involving the two dietary protein levels, the pullets fed 15% protein diets had slightly but significantly (P < 0.05) heavier body weight at 20 weeks of age in comparison with those fed the 12% protein diets (diets 14-22 vs. diets 1-10, excluding diet 7). After 12 weeks on the same laying diet, there were virtually no significant differences in body weight among all the groups of pullets within each dietary protein level of the grower diet. The pullets fed the corn-sun-cured alfalfa grower diet and the diet with the highest level of dehydrated alfalfa gained more body weight than any of the other groups of pullets during the laying period. The significant difference in body weight found at the end of the growing period between the pullets fed 12% protein diets and those fed 15% protein diets was not found at 32 weeks of age. This was partly due to large error term within each treatment at 32 weeks of age, although the actual difference was still 14 g. (1665-1651) in comparison with 15 g. (1285-1270) at 20 weeks of age (Table 3).
901
Dietary protein source Corn + soy + meat Corn + triticale Corn + triticale + lysine Corn + triticale + methionine Corn + triticale + lysine + methionine Corn + triticale + soy Corn + triticale + alfalfa (sun-cured) 1% protein Corn + triticale + alfalfa (sun-cured) 2% protein Corn + triticale + alfalfa (sun-cured) 3% protein Corn + alfalfa (sun-cured) Corn + triticale + alfalfa (dehydrated) 1% protein Corn + triticale + alfalfa (dehydrated) 2% protein Corn + triticale + alfalfa (dehydrated) 3% protein Over-all 3 Standard error of a mean '• 2,3 See Footnotes in Table 3.
* —
— NS
63.7ab
— — — — 62.5
66.9ab 67.7a 63.3bc 62.3bcd 65.2ab 61.7
10,22 7 11 12 13 1.00
NS
64.8a
63.9bc
9,21
—
—
NS
63.4ab
60.9cd
14 15 16 17 18 19
consumption
Growing period (12-20 weeks) Significance 2 15%> 12%> NS 62.0ab 59.6d 63.6ab 59.9d * NS 62.7ab 61.7cd 61.led NS 60.4b 61.8ab NS 60.8cd NS 60.4b 60.9cd
of experimental grower diets on feed
8,20
1, 2, 3, 4, 5, 6,
Diet number
TABLE 4.—Effects
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49.9ab 49.4
— NS
— 67.4
64.4abcd 65.6
13
49.3ab
—
—
68.4ab
11
49.4a
—
—
66.7abc
11
49.5
—
—
—
—
50.0a
49.6ab 48.6b
—
—
NS
67.2a
69.5a 61.9cd
10,22 7
49.7a
49.0ab
NS
65.8a
65.8abcd
9,21
49.7a
50.1a
NS
67.1a
67.7abc
8,20
49.4a 49.5a 49.7a 49.4a 48.5a 49.7a
*
15%'
NS NS NS NS NS
68.1a 68.6a 68.5a 67.1a 66.2a 67.6a
65.7abcd 65.5abcd 65.8abcd 62.6bcd 67.6abc 60.4d
1, 14 2, 15 3, 16 4, 17 5, 18 6, 19
12%'
Egg weight (g.) a
49. lab 48.8ab 48.9ab 49.3ab 49.6ab 50.1a
Significance 2
15%'
12%'
Diet number
% Egg production »
of experimental grower diets on egg production, egg weight an
a
0.44 1.94 Average egg production or egg weight of pooled data for a period of 10 weeks (from 23-32 weeks o 123 See footnotes in Table 3.
Corn + soy + meat Corn + triticale Corn + triticale + lysine Corn + triticale + methionine Corn + triticale Corn + triticale + soy Corn + triticale + alfalfa (suncured) 1% protein Corn + triticale + alfalfa (suncured) 2% protein Corn + triticale + alfalfa (suncured) 3% protein Corn + alfalfa (sun-cured) Corn + triticale + alfalfa (dehydrated) 1% protein Corn + triticale + alfalfa (dehydrated) 2% protein Corn + triticale + alfalfa (dehydrated) 3 % protein Over-all 3 Standard error of a mean
Dietary protein sources
TABLE 5.—Effects
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904
S. M. KIM AND J. MCGINNIS
Age at 50% Production Rate. The effects of dietary treatments on sexual development as indicated by age at 50% lay are summarized in Table 5. Pullets fed the 12% protein grower diet containing 3% soybean meal required the longest period of time to reach 50% egg production. Pullets fed the diets containing the highest level of sun-cured alfalfa at 15% dietary protein level (diet 22) reached 50% production at the youngest age. The difference between the youngest and the oldest
ages in reaching 50% egg production was five days in the 12% protein groups and 3.8 days in the 15% protein groups. Compared with pullets fed the 12% protein grower diets, those fed the 15% protein diets reached 50% egg production rate earlier by an average of 1.7 days, and this difference was significant (P < 0.05). Mortality. Mortality was low and only six pullets died out of 1,100 started during the combined growing and laying periods. Mortality was not related to dietary treatments. DISCUSSION The results of this experiment confirm some of the early reports (Blaylock, 1956; Berg, 1959; Bullock et al, 1963; Lillie and Denton, 1966; Foster, 1971; Holmquist and Carlson, 1972; and Magruder and Coune, 1973) showing that hen-day egg production and egg size were not significantly affected by protein levels of the grower diet. Whether the effects were statistically significant or not, most of the above authors reported delayed sexual maturity and lower body weight up to the point-of-lay due to protein restriction by one way or another, which are confirmed by the data in this study. Even though effects of different grower diets were attributed to dietary protein levels and sources, other variables such as energy content or amino acid composition of each diet might have affected the over-all experimental results. Nevertheless, Berg (1959) reported that the energy level of the developing rations have no effect on body weight, rate of peak production, egg size or sexual maturity. Pullets fed the high protein grower diets with significantly heavier body weights at the end of the growing period consumed significantly more feed without laying either more or heavier eggs during the laying period. In other words, they consumed more feed in
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on egg production resulted in no significant differences in the over-all comparison of egg production between 12 and 15% protein level in grower diets. In addition to considering over-all egg production rates, the peak production attained by hens is also interesting. In this experiment, a comparison of the peak rates for a one-week period on Diets 1-10 showed a low of 78.0% for Diet 6 and a high of 86.6% for Diet 10, with an average of 82.95% for Diets 1-10 (12% protein). For Diets 14-22 the low was 80.5% for Diet 20 and a high of 88.6% for Diet 19, with an average of 83.90% for Diets 14-22. Peak production for all treatments was reached between 27 and 29 weeks of age. No marked differences in weight were found among different treatments within each dietary protein level of the grower diets. None of the statistical comparisons between the two dietary protein levels for nine different protein sources showed significance. A further examination of egg weights for the last week of the trial (32 weeks of age) showed remarkably similar values for all treatments. For Diets 1-10 the average egg weight was 51.1 for Diet 3 to 53.0 for Diet 8, with the average for Diets 1-10 (12% protein) being 52.3 grams. For diets 14-22, the corresponding weights were a low of 50.9 for Diet 18, a high of 52.9 for Diet 20, and an average of 52.2 grams for Diets 14-22 (15% protein). All of these figures are based on eggs produced during two days of the 32nd week.
PROTEIN AND SUBSEQUENT PERFORMANCE
REFERENCES Berg, L. R., 1959. Protein, energy and method of feeding as factors in the nutrition of developing White Leghorn pullets. Poultry Sci. 38: 158-165. Berg, L. R., and G. E. Bearse, 1958. Protein and energy studies with developing White Leghorn pullets. Poultry Sci. 37: 1340-1346. Blaylock, L. G., 1956. The protein requirements of growing birds. Poultry Sci. 35: 1133. Bullock, D. W., T. R. Morris and S. Fox, 1963. Protein and energy restriction for replacement pullets. Br. Poultry Sci. 4: 227-237. Douglas, C. R., H. R. Wilson, R. H. Harms and T.
S. Powell, 1973. Laying house performance of pullets grown on wire versus litter floors and nine versus fourteen percent protein diets. Poultry Sci. 52: 2023. Fernandez, R., and J. McGinnis, 1974. Nutritive value of triticale for young chicks and effect of different amino acid supplements on growth. Poultry Sci. 53: 47-53. Foster, W. H., 1971. The use of low-protein rations including the feeding of only whole wheat to two breeds of replacement pullets. Br. Poultry Sci. 12: 333-343. Holmquist, C , and C. W. Carlson, 1972. Effects of various pullet grower diets on subsequent layer performance. Poultry Sci. 51: 1820. Lillie.R. J., and C. A. Denton, 1966. Effect of nutrient restriction on White Leghorns in the grower and subsequent layer periods. Poultry Sci. 45: 810-818. Magruder, N. D., and F. L. Coune, 1973. Feeding replacement pullets on four diet regimes. Poultry Sci. 52: 2055-2056. Marquez, V. A., and C. E. Avila, 1974. Effect of amino acid supplementation to triticale diets. Poultry Sci. 53: 1231-1233. Sell, J. L., G. C. Hodgson and L. H. Shebeski, 1962. Triticale as a potential component of chick rations. Can. J. Anim. Sci. 42: 158-166. Steel, G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., New York, NY. Sunde, M. L., and H. R. Bird, 1959. The protein requirements of growing pullets. Poultry Sci. 38: 48-55. Wright, C. F., B. L. Damron, P. W. Waldroup and R. H. Harms, 1968. The performance of laying hens fed normal and low protein diets between eight and eighteen weeks of age. Poultry Sci. 47: 635-638.
NEWS AND NOTES (Continued from page 873) from each member society. They are established on a rotational basis, so that, in the future, each member will serve a term of six years, rotating to the Chairmanship of the Committee during his or her last two years. Each Committee is charged with specific responsibilities and the Chairman of each Committee will report to the C.I.S.P. annually. A.A.A.S. NOTES The Section O (Agriculture) Committee met on
February 20 with the Editor of Science, Philip H. Abelson. The Committee expressed concern about the tone, and especially the inaccuracies, of recent items in the News and Comment Section of Science concerning agricultural science. Dr. Abelson asked for assistance of Section O in giving agricultural science a more positive image in the pages of Science. He said he would be pleased to receive as many as six suggestions for articles on the agricultural sciences each year. Since the normal
(Continued on page 917)
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order to maintain their relatively heavy body weight established during the growing period, resulting in reduced feed efficiency for egg production and egg size. The heavy body weight of the pullets at the end of the growing period does not necessarily mean better performance during the laying period. Unlike some of the reports on work with chicks by Sell et al. (1962), Fernandez and McGinnis (1974), the data suggest that lysine or methionine, or both, were not limiting amino acids when corn and triticale provided all of the 12 or 15% dietary protein in a grower diet. In addition, these observations demonstrate further that pullets may be raised from 12-20 weeks with a dietary protein level of no more than 12% without impairing their egg production potential.
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