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Daily Protein Intake Requirement of Laying Hens1
354
P. G. JOHNSON AND J. A. BOWERS
1954. Flavor studies. Origin of chicken flavor. J. Ag. Food Chem. 2: 364-367. Schermerhorn, E. P., and W. J. Stadelman, 1964. Treating hen carcasses with polyphosphates to control hydration and cooking losses. Food Technol. 18: 101-102. Tallan, H. H., S. Moore and W. H. Stein, 1954. Studies on the free amino acids and related compounds in the tissues of the cat. J. Biol. Chem. 211:927-939.
Tarladgis, B. G., B. M. Watts, M. T. Younathan and L. Dungan, 1960. A distillation method for the quantitative determination of malonaldehyde in rancid foods. J. Am. Oil Chem. Soc. 37: 403-406. Tims, M. J., and B. M. Watts, 1958. Protection of cooked meats with phosphates. Food Technol. 12: 240-243. Yemm, E. W., and E. C. Cocking, 1955. The determination of amino acids with ninhydrin. Analyst, 80: 209-213.
ROLLIN H . THAYER, G. E . HUBBELL, J. A. KASBOHM, R. D . MORRISON AND E . C . NELSON
Departments of Animal Sciences and Industry, Mathematics and Statistics, and Oklahoma State University, Stillwater, Oklahoma 74074
Biochemistry,
(Received for publication May 25, 1973)
ABSTRACT Two feeding trials were conducted with commercial hybrid pullets housed in individual cages. In these feeding trials (1) graded levels of protein intakes ranging from 14 to 19 grams per pullet per day were provided on an ad libitum feeding basis over the first 20-weeks of the laying period, (2) amino acid requirements were fully met through strict attention to amino acid balance pattern, and (3) the pullets were allowed to meet protein intake requirements without being limited by energy intake. This was accomplished by manipulating ration levels of dietary weight, dietary volume, dietary protein, and dietary energy. Comparisons were made on egg production, egg weight, and body weight gain among the pullets fed the different protein intake levels. There were no differences in egg production or egg weight regardless of protein intake. A protein intake level of 14 grams per pullet per day was adequate to support egg production, and egg weight, but did not produce body weight gains comparable to the body weight gains produced by protein intakes of 15 to 19 grams per pullet per day. Even so, body weight gain with the 14 gram protein intake level was substantial, and this protein intake level could be recommended for use under practical feeding conditions. However, the pullets seemed to consume 15 grams of protein per pullet per day as a minimum, and this protein intake level might be more satisfactory under marginal management conditions. POULTRY SCIENCE 53: 354-364, 1974
INTRODUCTION
UMEROUS studies have been conducted to determine the protein requirement of layer hens for egg production both from the standpoint of the percentage of protein in the layer ration, and grams of protein intake per hen per day. A comparison of the data from the different studies leads to the conclusion that the results obtained are not in full agreement. In general, these studies indicate that a satisfactory level of egg production
N
1. This research was supported in part by a grantin-aid from Farmland Industries, Inc., Kansas City, Missouri.
can be supported by dietary protein levels ranging from 11 to 19 percent, although results differ in some respects from study to study in terms of egg production, egg weight, and body weight change. Smith (1967) found no differences in egg production when rations were fed which contained protein levels of 11, 15 and 19 percent. However, Britzman and Carlson (1965) concluded that a layer ration with a protein content of 11 percent would support egg production for a period of 5 or 6 months, but at a level 10 percent below that obtained with a protein level of 16 percent. Miller et al. (1957) observed that laying hens main-
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Daily Protein Intake Requirement of Laying Hens
PROTEIN INTAKE OF LAYERS
Egg weight and body weight data also differed among the several studies which were reported. Some research workers concluded that egg weight increased with increases in the dietary protein level (Smith, 1967; Quisenberry and Bradley, 1962; Reid et al, 1963; Bray et al, 1965). However, Berg and Bearse (1957) observed that egg weight increased with an increase in dietary protein (above 14 percent) at a dietary energy level of 1450 kilocalories of metabolizable energy per pound, but was depressed when the 14 percent dietary protein level was fed in combination with a dietary energy level
of 1100 kilocalories. In addition, Lillie and Denton (1967) found that a 14 percent protein level was adequate for egg production, but not for the maintenance of egg weight or body weight, and that a 16 to 18 percent protein level was required to support these two responses. In contrast to these finding, Hochreich et al (1957) reported that there were no differences in egg weight among eggs laid by hens fed dietary protein levels of 15.7, 17.0, and 18.3 percent; and Thornton et al. (1957) found no effect on body weight when dietary levels of 11, 13, 15 and 17 percent were fed. Other research workers have approached the problem of determining the protein requirement of layer hens from the standpoint of grams of protein intake per hen per day. Novacek and Carlson (1969) stated that the protein requirement of layer hens was not more than 11.3 grams per day for a 4.4 pound hen at a level of 60 percent egg production. Manoukas and Young (1969) reported that a total intake of 14.4 to 15 grams of protein per hen per day supported optimum egg production. Blaylock et al. (1967) concluded that no more than 14 grams of protein intake per hen per day were required to support egg production up to a level of 80 percent. Nivas and Sunde (1969) provided layer hens with protein intakes of 14, 16, and 18 grams per day. They reported that egg production was lower when protein intake was 14 to 16 grams per hen per day as compared to an intake of 18 to 20 grams; egg weight increased as protein intake increased above a 14 to 16 gram intake; and body weight increased as protein intake increased above 14 grams per hen per day. Gleaves et al (1968) indicated that more than 16 grams of protein per hen per day is required for optimum egg production. Data published by Tonkinson et al. (1968) sets the protein intake requirement at 17.5 grams of protein per hen per day with a daily energy intake of 343 kilocalories. Touchburn and Naber (1962)
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tained in batteries laid at a rate of approximately 70 percent when the layer ration contained a protein level of 12.5 percent and energy levels of either 640 or 785 kilocalories of productive energy per pound. However, when a dietary energy level of 930 kilocalories was fed, it was found that egg production dropped to 55 percent. Heywang et al. (1955) reported the optimum dietary protein level for layers to be 15 percent. Lillie and Denton (1967) compared dietary protein levels of 12, 14 and 16 percent. They found that when the 12 percent protein level was fed egg production was significantly lower than that obtained with the 14 percent protein level, but was equivalent to that obtained with the 16 percent protein level. Berg and Bearse (1957) designed a study in which two dietary energy levels (1100 and 1450 kilocalories of metabolizable energy per lb.) were combined with dietary protein levels of 14, 16 and 18 percent. It was apparent from the data obtained that a dietary protein level of 14 percent depressed egg production at a dietary energy level of 1450 kilocalories. Dietary protein levels of 16 and 18 percent produced essentially the same rate of lay, although there was a slight advantage in favor of the 18 percent protein level. With a dietary energy level of 1100 kilocalories per pound, rate of lay was equivalent for both the 14 and 18 percent dietary protein levels.
355
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THAYER, HUBBELL, KASBOHM, MORRISON AND NELSON
EXPERIMENTAL PROCEDURE General. Two feeding trials were conducted in a windowless caged layer laboratory which contained 576 individual wire cages arranged in twenty-four blocks with twenty-four cages per block. Each cage was equipped with an automatic waterer, a feeder, and a feed storage container. The individual feed storage containers made it possible to weigh the feed separately for each pullet, and permitted an individual pullet to be considered as an experimental unit. Artificial light was supplied by incandes-
cent lights which were controlled by automatic time clocks. In both feeding trials the pullets received 14 hours of continuous light and 10 hours of continuous darkness until egg production reached 50 percent. At this point, the length of daily light was increased by 15 minutes each week until the pullets were receiving 17 hours of continuous light and 7 hours of darkness each day. The pullets remained on this lighting schedule until the end of the experiment. Environmental temperature during the two feeding trials varied from a high of 32° C. (90° F.) in the late summer and early fall to a low of 15° C. (60° F.) in the winter months. The two feeding trials were conducted over a span of two years with each feeding trial being initiated in September of one year and terminated in January or February of the following year. The hybrid pullets used in the first feeding trial were DeKalb 131 while those used in the second were H&N Nick Chicks. The age of the pullets at the beginning of the feeding trials was 22 weeks for Feeding Trial 1, and 20 weeks for Feeding Trial 2. The pullets used in both feeding trials were grown in floor pens on litter, and fed a series of pullet replacement grower rations developed through research at Oklahoma State University. The experimental diets as listed in Table 1 for the two feeding trials were selected to illustrate typical diet composition within each feeding trial. Estimated intakes of feed weight, energy, protein, and feed volume per hen per day for each diet are listed in Table 2. The formulation procedures followed, and the amino acid ratio standard used for all diets were those described in detail by Gleaves et al. (1963). In order to keep the amino acid pattern as uniform as possible from diet to diet, ingredients were stockpiled, and the protein composition of each ingredient determined by chemical analysis. The primary protein
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indicated that a 4 pound hen should receive a daily protein intake of 17 grams in order to support egg production at a level of 72 percent. Absolute requirements of the laying hen for protein nitrogen were determined by Shapiro and Fisher (1965), and Shapiro (1968). They reported that 13-14 grams of protein per hen per day would support 70 percent egg production and a satisfactory nitrogen retention of 800 mg. of N per hen per day. On the other hand, 16-17 grams of protein were required per hen per day to bring about a maximum retention level of 1200 mg. of nitrogen per hen per day. In an attempt to clarify the situation and to pinpoint protein intake requirement more precisely, two feeding trials were designed (1) to provide graded levels of protein intake per hen per day on an ad libitum feeding basis over the first 20-weeks of the laying period, (2) to fully meet amino acid requirements through strict attention to amino acid balance pattern, and (3) to allow the layer hens to meet their protein intake requirements at both the upper and lower extremes of the graded protein intake range without being limited by energy intake. This was done by manipulating ration levels of dietary weight, dietary volume, dietary protein, and dietary energy based upon data reported by Gleaves et al. (1968).
357
PROTEIN INTAKE OF LAYERS
TABLE 1.—Percentage composition of experimental diets Feeding trial 2
Feeding trial 1 Diet 1 Diet 18 Diet 1
Ingredients
3.60 27.76 23.59 10.00 5.73 4.28
4.75 23.42 19.82 8.40 4.80 3.60
7.11 1.86 2.11 1.69 1.27 1.61 1.27
11.48 3.01 3.42 2.73 2.05 2.60 2.05
2.08 5.04 0.50 0.50
1.36 5.51 0.50 0.50
Diet 7 Diet 13 Diet 19
7.20 31.90 25.11 3.39 7.47
1.96 31.68 30.90 8.72 7.92
1.30 29.40 28.66 8.09 7.35
0.40 27.92 27.22 7.68 6.98
2.41 5.63 2.41 1.61
1.56 3.64 1.56 1.04
1.39 3.24 1.39 0.93
1.21 2.83 1.21 0.81
1.61 0.81 0.97 0.64 2.40 5.44 0.50 0.50
1.04 0.52 0.62 0.42 2.24 5.16 0.51 0.51
0.93 0.46 0.56 0.37 2.06 4.72 0.51 0.51 8.13
0.81 0.40 0.49 0.32 1.92 4.36 0.50 0.50 14.44
'Manufactured by Diamond V. Mills, Cedar Rapids, Iowa 2 Supplies per kilogram of finished ration: vitamin A, 17,600 I.U., vitamin D3, 2640 I.U.; vitamin E, 13.21.U.; Vitamin K, 6.6 mg.; vitamin B12,0.018 mg.; riboflavin, 8.8 mg.; niacin, 70.4 mg.; panthothenic acid, 17.6 mg.; choline chloride, 110 mg.; manganese, 60.94 mg.; iodine, 1.89 mg.; cobalt, 1.30 mg.; iron, 47.96 mg.; copper, 3.63 mg.; zinc, 49.94 mg. and energy containing ingredients were mixed into two separate basals, respectively, and different amounts of each basal were combined to give dietary protein levels which would provide a range of graded protein intake levels. Specific energy intake levels,
feed weight intake levels, and feed volume intake levels to be provided with each protein intake level were obtained by adding varying amounts of cerelose, tallow, and sand to given basal combinations. Chemical analyses for crude protein were made on each diet after
TABLE 2.—Experimental designs, Feeding Trials 1 and 2 Feeding trial 1 Estimated intake per pullet per day Feed consumption (gm.) 100
Energy consumption (Kcal. M.E.)
Volume consumption (ml.)
300
170
Protein consumption (gm.) (increments of 0.25 gm.) 15 16 17 18 1*,2,3,4, 5,6,7,8 9,10, 13,14, 11,12 15,16,
19 17,18
Feeding trial 2 Estimated intake per pullet per day Nutrient density
Feed consumption (gm.)
Energy consumption (Kcal. M.E.)
Volume consumption (ml.)
13
1 2 3 4
100 100 100 100
316 286 261 240
170 170 170 170
1* 7 13 19
*Experimental diet number
Protein consumption (gm.) 14 16 17 15 2 8 14 20
3 9 15 21
4 10 16 22
5 11 17 23
18 6 12 18 24
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Tallow (feed grade) Ground yellow corn Ground milo Pulverized oats Ground wheat Cerelose Soybean meal (50% protein) Fish meal (60% protein) Meat & bone scrap (50% protein) Blood meal (80% protein) Dried whole egg solids Alfalfa meal (17% protein) Distillers solubles Live yeast culture 1 Dried whey Di-calcium phosphate Calcium carbonate VMC-602 Salt Sand
*Pullets within treatment within period
Average periods 1-5
304 301 273 285 298 293 307 326 294 306 294 298 289 281 78 79 76 78 78 77 77 78 80 80 75 80 78 77 55 56 56 56 54 55 57 58 57 57 55 57 54 55
Protein 13.2 13.9 15.2 15.2 15.8 15.3 15.7 14.3 16.2 15.4 15.2 14.8
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
12.6 14.1 14.8 14.9 15.0 14.3
282 275 259 276 289 278 286 300 273 268 275 280 271 270 82 77 78 78 82 80 78 80 84 75 78 80 83 82 51 49 50 50 50 51 51 52 51 49 49 50 50 50
12.4 13.7 14.3 14.4 14.0 13.8
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
12.4 13.7 14.8 14.1 13.7 13.7
12.7 14.0 14.4 13.8 14.7 13.9
1 2 3 4 5 Average Periods 1-5
Period no.
Experimental diet number 10 11 12 13 14 consumption per pullet per day (gm.) 14.1 15.2 13.8 13.5 14.3 15.2 14.6 15.1 16.0 16.8 15.7 15.3 15.2 16.5 16.5 16.3 16.0 17.3 16.2 15.7 16.3 16.6 17.1 17.0 15.7 16.7 15.7 14.8 16.4 16.4 16.9 16.1 15.7 16.7 15.1 16.9 17.1 17.3 15.2 16.8 15.5 16.5 15.3 15.2 15.9 16.4 16.1 16.3
TABLE 3.—Data on protein consumption per pullet per day, energy consumption per pullet per day,
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PROTEIN INTAKE OF LAYERS
Feeding Trial 1. Eighteen diets were fed
(Table 2). Each diet was fed to 24 individually caged pullets. The diets were formulated to provide the pullets with estimated daily protein intakes ranging from 15 to 19.25 grams in increments of 0.25 grams. All diets were isocaloric and designed to provide an estimated daily energy intake per pullet of 300 kilocalories of metabolizable energy. Feeding Trial 2. Twenty-four diets were fed with each diet being fed to 24 individually caged pullets (Table 2). These diets contained 4 energy densities (Nutrient Densities 1,2, 3,4), and 6 protein levels in a 4 x 6 factorial arrangement of treatments. Estimated daily energy intake levels of 316, 286, 261, and 240 kilocalories of metabolizable energy were provided in the four energy densities with estimated daily feed weight intake at 100 grams per pullet. On the basis of 100 grams of feed weight intake, and 170 ml. of feed volume intake per pullet per day, estimated daily intake levels per pullet were set at 13, 14, 15, 16, 17, and 18.grams of protein. RESULTS AND DISCUSSION Feeding Trial 1. The means for the response variables of energy consumption, protein consumption, egg production, and egg weight are listed in Table 3, and body weight gain in Table 4. Protein intake per pullet per day is summarized by periods in Table 3 with the means listed for Periods 1 through 5 combined, and Periods 6 through 10 combined. Although means by period are not presented for energy consumption, egg pro-
TABLE 4.—Average body weight gain in grams per pullet by periods, Feeding Trial 1 Experimental diet number Net gain
Net gain
1
2
3
120
132
115
10
11
12
186
168
210
4
5
6
7
8
9
145
173
130
204
192
137
16
17
18
269
173
150
Experimental diet number 13 14 15 162
210
261
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it had been mixed, and these values were used to calculate actual protein intake per hen per day. Each feeding trial was divided into 10 periods with 14 days in each period. Individual feed consumption data were collected at the end of each period in both feeding trials. In Feeding Trial 1, individual body weight data were recorded at the end of each period. In Feeding Trial 2, body weight data were collected at the beginning of the first period, at the beginning of the sixth period, and again at the end of the tenth period. Egg production was recorded daily and all eggs were weighed individually. Analyses of variances were calculated on the data collected during each experimental period, and on the combined data for all 10 periods within a given feeding trial (Steel and Torrie, 1960). In Feeding Trial 1 for both the overall and the period by period analyses, data were used only from those pullets which were alive at the end of Period 10. In Feeding Trial 2, the period by period analyses were based upon the data from those pullets which were alive at the end of each period. The overall analysis, on the other hand, involved data from 14 randomly selected pullets from each treatment. The pullets were selected from those that were alive at the end of Period 10. The following response variables were involved in these analyses: protein consumption, energy consumption, body weight gain, percent egg production, and egg weight.
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THAYER, HUBBELL, KASBOHM, MORRISON AND NELSON
There was a statistically significant difference (P < .01) in protein intake per pullet per day among the pullets fed the 18 diets both on a period to period basis and overall. Thus, the feeding procedure which was followed accomplished the objective of providing graded protein intake levels ranging from approximately 15 grams to 29 grams per pullet per day. The following rational was used to establish specific values by diet for protein intake per pullet per day for use in data interpretation. Data on protein intake per pullet per day, when compared period by period, fall into a rather definite pattern for each diet during the 20-week laying period. Protein intake in Period 1 started below the estimated level upon which each diet was calculated (Table 2) and then progressively increased during
a part of all of the first 5 periods until a definite plateau was reached. At the higher protein intake levels, this plateau was reached within a period or two and seemed to be established more quickly than for the lower intake levels. During these first 5 periods the pullets were in the process of adjusting to the diets primarily from an energy intake standpoint. Apparently the specific level of this plateau in terms of grams of protein intake per pullet per day was directly related to calorie-protein ratio and energy intake requirement. As has previously been pointed out, the pullets all consumed energy to a level of approximately 295 kilocalories per day. Therefore, for purposes of interpretation in this study, the mean for protein intake at this plateau level during Periods 6 through 10 has been selected for each diet as the best estimate of actual protein intake per pullet per day. On this basis, the following values for actual protein intake per pullet per day were established for each diet: 14 grams, Diet 3; 15 grams, Diets 1 and 2; 16 grams, Diets 4, 5 and 6; 17 grams, Diets 7, 9, 10, 11, 12, 13, and 14; 18 grams, Diets 8, 15, 16, and 17; and 19 grams, Diet 18. There were no statistically significant differences in egg production among the pullets fed the different diets either within any given 2-week period or on the basis of overall means for the ten 2-week periods combined. The pullets peaked at an egg production level of 84 percent, and the mean for the entire feeding trial for all pullets was 78 percent. In addition, there were no statistically significant differences in egg weight or body weight change. Mean egg weight for the entire 20-week laying period ranged from 52 to 55 grams among the pullets fed the 18 diets. These overall means for egg weight reflect the initial low egg weight which was obtained during the early weeks of egg production. The means for Periods 6 through 10 combined show that egg weight among the pullets, regardless of the diet fed, plateaued at a mean
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duction, and egg weight, the means for combined Periods 1 through 5, and 6 through 10 are given. In formulating the experimental diets to provide an estimated energy intake of 300 kilocalories of metabolizable energy per hen per day, the assumption was made that the pullets would consume approximately this amount of energy to meet energy intake requirements, and in so doing, consume protein in graded increments. The means listed in Table 3 indicate that average energy consumption ranged from 259 to 300 kilocalories of metabolizable energy per pullet per day during Periods 1-5, and 273 to 326 kilocalories of metabolizable energy per pullet per day during Period 6-10 with averages of 275 and 295 kilocalories, respectively. The differences in energy intake among the pullets on the 18 diets were statistically significant (P < .01). A critical examination of the means for energy intake, however, shows that differences among these means are relatively small in magnitude, and energy intake, for all practical purposes, was essentially equivalent among the pullets fed all 18 experimental diets.
PROTEIN INTAKE OF LAYERS
361
marginal to need or in the others to free the pullets to consume protein as dictated by requirements for egg production or body weight gain. When the experiment was designed, it was anticipated that Nutrient Density 1 would impose the greatest control through energy intake, Nutrient Density 2 would serve somewhat as a positive control, and Nutrient Densities 3 and 4 would loosen restrictions imposed by energy intake. This proved to be the case in so far as Nutrient Densities 1 and 2 were concerned. However, the inclusion of sand in the diets in Nutrient Densities 3 and 4, and the fact that the actual protein content of the diets as determined by chemical analysis was lower than calculated, held protein intake down to 14 grams per hen per day for Diets 13 and 19. Nevertheless, the ultimate objectives were accomplished to control protein intake at a level marginal to need, and to create a situation in which the hens could consume protein in line with need.
Feeding Trial 2. The means for the response variables of energy consumption, protein consumption, egg production, and egg weight are listed in Table 5, and body weight change in Table 6. The data in Table 5 have been summarized and presented in the same format as previously described for comparable data in Feeding Trial 1 (Table 3). By following the same rational as used in Feeding Trial 1, actual grams of protein intake per pullet per day were established for each diet at: 14 grams, Diets 13 and 19; 15 grams, Diets 1, 2, 7, 8, 14, 15, 20, and 21; 16 grams, Diet 9; 17 grams, Diets 3, 4, 10, 16, and 22; 18 grams, Diets 6, 11, 12, 17, 23, and 24; and 19 grams, Diets 5 and 18.
Energy consumption per pullet per day was equivalent for all diets regardless of dietary energy level (nutrient density). The points at which statistically significant differences (P < .01) in energy consumption were observed due to dietary energy level were only in Periods 1, 8, and 10. However, dietary protein level was responsible for statistically significant differences (P < .01) in energy consumption in Periods 3 through 10. These differences indicate that the need for additional protein at estimated protein intake levels of 13 and 14 grams per pullet per day was exerting considerable pressure for the pullets to increase actual protein intake above these levels. This is most apparent in a comparison of energy consumption data from the pullets fed Diets 1 and 7, and to a lesser degree with the pullets fed Diets 13, 19, and 20. In the case of Diets 1 and 7, actual protein intake per pullet per day was 15 grams when estimated intake had been set at 13 grams.
The four nutrient densities (Table 2) were designed to both tighten (Nutrient Density 1), and loosen (Nutrient Density 3 and 4) the nutrient intake control imposed on protein intake by energy intake. It was anticipated that this would force the pullets in the one case to consume a protein level somewhat
The estimated protein intake levels as pro-
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egg weight of approximately 56 grams. Average body weight gain seemed to fluctuate from 2-week period to 2-week period no matter what diet was fed (Table 4). Periods in which body weight was lost were followed by periods of compensatory gain. No definite pattern was apparent and weight fluctuation took place regardless of protein intake. Overall change was a net gain. From a practical standpoint under commercial production conditions, net weight gains of from 0.3 to 0.6 pounds per pullet would seem to be satisfactory. These data lead to the conclusion that protein intakes per pullet per day over the range from 14 to 19 grams supported an equivalent level of egg production during the first 20 weeks of the laying period. In addition, all protein intake levels were sufficient to maintain egg weight and permitted the pullets to make satisfactory overall gains in body weight.
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THAYER, HUBBELL, KASBOHM, MORRISON AND N E L S O N
TABLE 5.—Data on protein consumption per pullet per day, energy consumption per pullet per day, egg production, and egg weight in Feeding Trial 2 Nutrient density 2 Experimental diet number
Nutrient density 1 Experimental diet number Period
8 9 10 11 12 Protein consumption per pullet per day (gm.)
Protein consumption per pullet per day (gm.) 11.4 12.7 13.2 13.3 14.7 13.1
11.2 12.8 13.2 12.5 14.7 12.9
12.3 13.5 14.3 15.0 14.8 14.0
13.6 15.7 16.0 15.7 15.4 15.3
14.4 16.1 10.3 15.4 16.0 12.2 16.7 14.8 12.6 17.2 16.4 13.2 18.2 18.5 14.1 16.4 16.4 12.5 Average periods
11.3 12.7 13.7 14.1 14.6 13.3 1-5
12.5 13.8 13.7 14.0 15.0 13.8
12.2 13.7 13.6 13.9 15.0 13.7
12.9 14.8 15.8 16.6 17.6 15.5
13.5 16.8 16.6 17.0 17.0 16.2
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.) 6 7 8 9 10 Average Periods 6-10
301 72 42 14.3 14.9 15.4 15.8 15.6 15.2
272 66 43 15.0 15.3 15.8 15.8 14.9 15.4
278 65 42 16.4 17.0 16.4 17.5 16.8 16.8
289 76 44 15.0 17.8 16.9 18.4 18.4 17.3
286 276 287 285 81 69 78 71 48 42 47 46 18.4 18.0 14.2 14.6 18.3 18.3 15.0 15.0 19.5 18.0 15.7 15.7 18.9 19.1 15.8 15.6 20.2 18.5 15.9 15.6 19.1 18.4 15.3 15.3 Average periods 6-10
277 71 44 15.9 16.2 16.7 16.9 16.0 16.3
257 72 43 16.2 17.1 17.0 17.0 18.7 17.2
274 77 46 16.0 19.8 17.3 18.5 19.2 18.2
270 73 44 18.6 19.3 16.5 18.9 18.0 18.3
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
351 77 55
328 76 52
336 81 53
324 83 53
338 83 56
266 79 53
322 82 54
320 82 55
304 77 51
Period
353 82 56
328 79 52
Nutrient density 3 Nutrient density 4 Experimental diet number Experimental diet number 13 14 15 16 17 18 19 20 21 22 23 24 X MS1* df Protein consumption Protein consumption per pullet per pullet per day (gm.) per day (gm.) 10.6 10i.7 11.9 12.5 13.2 14.7 9.9 11.1 10.3 12.0 13.0 13.7 12.29 6.02 543 12.2 12.5 13.4 13.8
Average Periods 1-5
306 83 56
11.3 11.9 12.3 14.0
12.8 13.4 13.6 14.9
14.6 14.6 15.5 16.3
16.0 15.6 15.0 17.6
15.9 16.6 17.0 18.8
11.2 12.1 11.3 13.3
12.7 13.6 14.1 14.5
12.3 12.3 13.6 14.5
14.2 15.3 15.2 16.7
15.1 15.2 15.5 16.9
15.5 13.8910.61 13.0 14.2014.70 14.914.6010.25 17.3 15.70 8.69
526 523 503 486
12.5 12.0 13.3 14.7 15.5 16.6 11.6 13.2 12.6 14.7 15.1 14.9 Average periods 1-5
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.) 6 7 8 9 10 Average Periods 6-10 Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
288 72 44 13.8 13.6 14.1 14.1 14.2
258 67 40 14.6 14.4 15.2 15.2 14.9
266 69 43 14.5 15.1 15.6 15.5 15.4
276 73 44 16.2 17.1 16.6 17.2 17.5
273 77 45 18.0 17.8 17.8 18.2 18.1
277 77 47 18.9 19.8 19.6 19.4 19.4
267 68 41 13.8 14.3 13.6 14.5 13.8
283 79 47 15.0 15.1 14.9 16.1 15.1
252 66 41 15.5 15.8 14.3 15.0 15.5
276 74 46 17.0 17.3 16.5 17.6 16.3
267 76 46 17.3 17.8 17.2 18.5 17.6
248 69 43 17.615.99 18.416.65 18.0 16.40 18.7 16.95 18.1 16.78
14.0 14.9 15.2 16.9 18.0 19.4 14.0 15.2 15.2 16.9 17.7 18.2 Average periods 6-10 322 318 304 317 317 304 320 326 304 317 312 303 73 79 74 78 78 76 80 76 73 82 82 83 51 53 50 52 52 53 52 53 52 57 55 57 *Pullets within treatment within period
11.18 11.87 12.44 10.30 8.67
475 468 463 450 444
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1 2 3 4 5 Average Periods 1-5
PROTEIN INTAKE OF LAYERS
363
TABLE 6.—Average body weight change in grams per pullet in Feeding Trial 2 Nutrient density Experimental diet number Overall gain in grams Nutrient density Experimental diet number Overall gain in grams
1 1
2
3
246
311
339
2 4
5
6
7
8
9
297
272
322
233
207
235
3
10
11
12
255
312
269
4
13
14
15
16
17
18
19
20
21
22
23
24
149
244
214
335
243
262
159
188
232
217
208
211
that egg weight was maintained at a comparable level on all protein intakes from 14 to 19 grams per pullet per day. An important criteria to measure the adequacy of protein intake during the first 20 weeks of the laying period is body weight gain since the pullets are still growing during this time interval. There was a statistically significant difference (P < .05) in body weight gain due to protein intake level. This difference involved Rations 13 and 19 where actual protein intake was 14 grams per hen per day and overall weight gains were 149 to 159 grams, respectively. Even though Ration 20 supplied a protein intake of 15 grams per hen per day, weight gain was somewhat below that observed for the other pullets with a comparable protein intake. It can be concluded from these data that 14 grams of protein intake per pullet per day will not support weight gain during the first 20 weeks of egg production equivalent to that produced by protein intakes ranging from 15 to 19 grams per pullet per day. A protein intake level of 15 grams per pullet per day appeared to be entirely adequate for this purpose. Based upon these findings, it seems logical to recommend that a minimum protein intake level of 14 grams of protein per pullet per day be provided, and that this protein be well balanced from an amino acid standpoint. Even though body weight gain when 14 grams of protein is consumed, is not equivalent to the gains observed when higher levels of
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vided in the diets brought about statistically significant differences (P < .01) in actual protein intake per pullet per day in all 10 periods. Statistically significant differences (P < .01) in protein intake due to dietary energy level (nutrient density) occurred only in Periods 1, 8 and 10. This means that the actual graded protein intake levels observed were similar regardless of dietary energy level. A relatively uniform energy intake per pullet was effectively controlling protein intake. The statistical analysis of egg production data indicates that there were no differences in level of egg production among the pullets fed the 24 diets during any one of the 10 periods with one exception. In Period 1 a statistically significant difference (P < .05) in egg production was apparent. Since this difference was due to estimated protein intake level, it can be concluded that it was brought about by the extremely low levels of actual protein intake observed during Period 1 as the pullets adjusted to the diets. Once this adjustment had been made, these differences disappeared entirely. Egg production was maintained at a level of approximately 80 percent regardless of protein intake per pullet per day. A similar observation was made in connection with the egg weight data. There were no statistically significant differences in egg weight brought about by the diet which was fed during any of the 10 periods with the exception of Period 4. It can be concluded
364
THAYER, HUBBELL, KASBOHM, MORRISON AND NELSON
protein are fed, the gain is substantial and would be adequate under practical production conditions. However, since a protein intake of 15 grams per pullet per day was the level which seemed to be selected by the pullets as being minimum (Ration 1 and 7), this level might prove to be most adequate under a variety of production conditions.
REFERENCES
JANUARY 27-30.
FEBRUARY 4-8.
SOUTHEASTERN-INTER CIVIC CENTER,
^ POULTRY TRADE SHOW, ATLANTA ,GEORGIA
AUSTRALASIAN POULTRY SCIENCE CONVENTION, HOBART, TASMANIA, AUSTRALIA
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Berg, L. R., and G. E. Bearse, 1957. The effect of protein and energy content of the diet on the performance of laying hens. Poultry Sci. 36: 1105. Blaylock, L. G., L. A. Neagle, G. E. Poley and J. H. Goihl, 1967. Studies on the daily protein requirement of laying hens. Poultry Sci. 46: 1235. Bray, D. J., R. C. Jennings and T. R. Morris, 1965. The effects of early and late maturity on the protein requirements of pullets. British Poultry Sci. 6: 311-319. Britzman, D. C , and C. W. Carlson, 1965. Limiting amino acids in corn-soybean meal diets for laying hens. Feedstuffs, 37: (43) 20-21. Gleaves, E. W., L. V. Tonkinson, J. D. Wolf, M. H. Henley, C. K. Harman and R. H. Thayer, 1963. Poultry Nutrition Manual, Miscellaneous Publication, Department of Poultry Science, Oklahoma State University (195 pages). Gleaves, E. W., L. V. Tonkinson, J. D. Wolf, C. K. Harman, R. H. Thayer and R. D. Morrison, 1968. The action and interaction of physiological food intake regulations in the laying hen. 1. Effects of dietary factors upon feed consumption and production responses. Poultry Sci. 47: 38-67. Heywang, B. W., H. R. Bird and M. G. Vavich, 1955. The level of protein in the diet of laying White Leghorns during hot weather. Poultry Sci. 34: 148152. Hochreich, H. J., C. R. Douglas and R. H. Harms, 1957. The effect of dietary energy and protein levels upon production of Single Comb White Leghorn hens. Poultry Sci. 36: 1127. Lillie, R. J., and C. A. Denton, 1967. Evaluation of dietary protein levels for White Leghorns in the
grower and subsequent layer periods. Poultry Sci. 46: 1550-1557. Manoukas, A. G., and R. J. Young, 1969. The performance of laying hens fed various levels of protein and a non-essential amino acid mixture. Poultry Sci. 48: 2037-2044. Miller, E. C , M. L. Sunde and C. A. Elvehjem, 1957. Minimum protein requirement of laying pullets at different energy levels. Poultry Sci. 36: 681-690. Nivas, S. C , and M. L. Sunde, 1969. Protein requirements of layers per day and phase feeding. Poultry Sci. 48: 1672-1678. Novacek, E. J., andC. W. Carlson, 1969. Low protein cage-layer diets and amino acids. Poultry Sci. 48: 1490-1497. Quisenberry, J. H., and J. W. Bradley, 1962. Effects of dietary protein and changes in energy levels on the laying house performance of egg production stocks. Poultry Sci. 41: 717-724. Reid, B. L., A. A. Kurnick and B. J. Hulett, 1963. Effect of dietary protein level on laying hen performance. Poultry Sci. 42: 1302-1303. Shapiro, R., and H. Fisher, 1965. The amino acid requirement of laying hens. 6. The absolute daily protein requirement for peak production. Poultry Sci. 44: 198-205. Shapiro, R., 1968. Protein requirement, nitrogen retention and egg production of the laying hen. Fed. Proc. 27 (3): 923-926. Smith, R. E., 1967. The utilization of poultry diets containing high, low and intermediate levels of protein of identical amino acid pattern. Poultry Sci. 46: 730-735. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York, New York. Thornton, P. A., L. G. Blaylock and R. E. Moreng, 1957. Protein level as a factor in egg production. Poultry Sci. 36: 552-557. Tonkinson, L. V., E. W. Gleaves, R. H. Thayer, J. L. Folks and R. D. Morrison, 1968. Production responses as affected by nutrient intake of laying hens. Poultry Sci. 47: 32-38. Touchburn, S. P., and E. C. Naber, 1962. Effect of nutrient density and protein energy interrelationships on reproductive performance of the hen. Poultry Sci. 41: 1481-1488.
P. G. JOHNSON AND J. A. BOWERS
1954. Flavor studies. Origin of chicken flavor. J. Ag. Food Chem. 2: 364-367. Schermerhorn, E. P., and W. J. Stadelman, 1964. Treating hen carcasses with polyphosphates to control hydration and cooking losses. Food Technol. 18: 101-102. Tallan, H. H., S. Moore and W. H. Stein, 1954. Studies on the free amino acids and related compounds in the tissues of the cat. J. Biol. Chem. 211:927-939.
Tarladgis, B. G., B. M. Watts, M. T. Younathan and L. Dungan, 1960. A distillation method for the quantitative determination of malonaldehyde in rancid foods. J. Am. Oil Chem. Soc. 37: 403-406. Tims, M. J., and B. M. Watts, 1958. Protection of cooked meats with phosphates. Food Technol. 12: 240-243. Yemm, E. W., and E. C. Cocking, 1955. The determination of amino acids with ninhydrin. Analyst, 80: 209-213.
ROLLIN H . THAYER, G. E . HUBBELL, J. A. KASBOHM, R. D . MORRISON AND E . C . NELSON
Departments of Animal Sciences and Industry, Mathematics and Statistics, and Oklahoma State University, Stillwater, Oklahoma 74074
Biochemistry,
(Received for publication May 25, 1973)
ABSTRACT Two feeding trials were conducted with commercial hybrid pullets housed in individual cages. In these feeding trials (1) graded levels of protein intakes ranging from 14 to 19 grams per pullet per day were provided on an ad libitum feeding basis over the first 20-weeks of the laying period, (2) amino acid requirements were fully met through strict attention to amino acid balance pattern, and (3) the pullets were allowed to meet protein intake requirements without being limited by energy intake. This was accomplished by manipulating ration levels of dietary weight, dietary volume, dietary protein, and dietary energy. Comparisons were made on egg production, egg weight, and body weight gain among the pullets fed the different protein intake levels. There were no differences in egg production or egg weight regardless of protein intake. A protein intake level of 14 grams per pullet per day was adequate to support egg production, and egg weight, but did not produce body weight gains comparable to the body weight gains produced by protein intakes of 15 to 19 grams per pullet per day. Even so, body weight gain with the 14 gram protein intake level was substantial, and this protein intake level could be recommended for use under practical feeding conditions. However, the pullets seemed to consume 15 grams of protein per pullet per day as a minimum, and this protein intake level might be more satisfactory under marginal management conditions. POULTRY SCIENCE 53: 354-364, 1974
INTRODUCTION
UMEROUS studies have been conducted to determine the protein requirement of layer hens for egg production both from the standpoint of the percentage of protein in the layer ration, and grams of protein intake per hen per day. A comparison of the data from the different studies leads to the conclusion that the results obtained are not in full agreement. In general, these studies indicate that a satisfactory level of egg production
N
1. This research was supported in part by a grantin-aid from Farmland Industries, Inc., Kansas City, Missouri.
can be supported by dietary protein levels ranging from 11 to 19 percent, although results differ in some respects from study to study in terms of egg production, egg weight, and body weight change. Smith (1967) found no differences in egg production when rations were fed which contained protein levels of 11, 15 and 19 percent. However, Britzman and Carlson (1965) concluded that a layer ration with a protein content of 11 percent would support egg production for a period of 5 or 6 months, but at a level 10 percent below that obtained with a protein level of 16 percent. Miller et al. (1957) observed that laying hens main-
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Daily Protein Intake Requirement of Laying Hens
PROTEIN INTAKE OF LAYERS
Egg weight and body weight data also differed among the several studies which were reported. Some research workers concluded that egg weight increased with increases in the dietary protein level (Smith, 1967; Quisenberry and Bradley, 1962; Reid et al, 1963; Bray et al, 1965). However, Berg and Bearse (1957) observed that egg weight increased with an increase in dietary protein (above 14 percent) at a dietary energy level of 1450 kilocalories of metabolizable energy per pound, but was depressed when the 14 percent dietary protein level was fed in combination with a dietary energy level
of 1100 kilocalories. In addition, Lillie and Denton (1967) found that a 14 percent protein level was adequate for egg production, but not for the maintenance of egg weight or body weight, and that a 16 to 18 percent protein level was required to support these two responses. In contrast to these finding, Hochreich et al (1957) reported that there were no differences in egg weight among eggs laid by hens fed dietary protein levels of 15.7, 17.0, and 18.3 percent; and Thornton et al. (1957) found no effect on body weight when dietary levels of 11, 13, 15 and 17 percent were fed. Other research workers have approached the problem of determining the protein requirement of layer hens from the standpoint of grams of protein intake per hen per day. Novacek and Carlson (1969) stated that the protein requirement of layer hens was not more than 11.3 grams per day for a 4.4 pound hen at a level of 60 percent egg production. Manoukas and Young (1969) reported that a total intake of 14.4 to 15 grams of protein per hen per day supported optimum egg production. Blaylock et al. (1967) concluded that no more than 14 grams of protein intake per hen per day were required to support egg production up to a level of 80 percent. Nivas and Sunde (1969) provided layer hens with protein intakes of 14, 16, and 18 grams per day. They reported that egg production was lower when protein intake was 14 to 16 grams per hen per day as compared to an intake of 18 to 20 grams; egg weight increased as protein intake increased above a 14 to 16 gram intake; and body weight increased as protein intake increased above 14 grams per hen per day. Gleaves et al (1968) indicated that more than 16 grams of protein per hen per day is required for optimum egg production. Data published by Tonkinson et al. (1968) sets the protein intake requirement at 17.5 grams of protein per hen per day with a daily energy intake of 343 kilocalories. Touchburn and Naber (1962)
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tained in batteries laid at a rate of approximately 70 percent when the layer ration contained a protein level of 12.5 percent and energy levels of either 640 or 785 kilocalories of productive energy per pound. However, when a dietary energy level of 930 kilocalories was fed, it was found that egg production dropped to 55 percent. Heywang et al. (1955) reported the optimum dietary protein level for layers to be 15 percent. Lillie and Denton (1967) compared dietary protein levels of 12, 14 and 16 percent. They found that when the 12 percent protein level was fed egg production was significantly lower than that obtained with the 14 percent protein level, but was equivalent to that obtained with the 16 percent protein level. Berg and Bearse (1957) designed a study in which two dietary energy levels (1100 and 1450 kilocalories of metabolizable energy per lb.) were combined with dietary protein levels of 14, 16 and 18 percent. It was apparent from the data obtained that a dietary protein level of 14 percent depressed egg production at a dietary energy level of 1450 kilocalories. Dietary protein levels of 16 and 18 percent produced essentially the same rate of lay, although there was a slight advantage in favor of the 18 percent protein level. With a dietary energy level of 1100 kilocalories per pound, rate of lay was equivalent for both the 14 and 18 percent dietary protein levels.
355
356
THAYER, HUBBELL, KASBOHM, MORRISON AND NELSON
EXPERIMENTAL PROCEDURE General. Two feeding trials were conducted in a windowless caged layer laboratory which contained 576 individual wire cages arranged in twenty-four blocks with twenty-four cages per block. Each cage was equipped with an automatic waterer, a feeder, and a feed storage container. The individual feed storage containers made it possible to weigh the feed separately for each pullet, and permitted an individual pullet to be considered as an experimental unit. Artificial light was supplied by incandes-
cent lights which were controlled by automatic time clocks. In both feeding trials the pullets received 14 hours of continuous light and 10 hours of continuous darkness until egg production reached 50 percent. At this point, the length of daily light was increased by 15 minutes each week until the pullets were receiving 17 hours of continuous light and 7 hours of darkness each day. The pullets remained on this lighting schedule until the end of the experiment. Environmental temperature during the two feeding trials varied from a high of 32° C. (90° F.) in the late summer and early fall to a low of 15° C. (60° F.) in the winter months. The two feeding trials were conducted over a span of two years with each feeding trial being initiated in September of one year and terminated in January or February of the following year. The hybrid pullets used in the first feeding trial were DeKalb 131 while those used in the second were H&N Nick Chicks. The age of the pullets at the beginning of the feeding trials was 22 weeks for Feeding Trial 1, and 20 weeks for Feeding Trial 2. The pullets used in both feeding trials were grown in floor pens on litter, and fed a series of pullet replacement grower rations developed through research at Oklahoma State University. The experimental diets as listed in Table 1 for the two feeding trials were selected to illustrate typical diet composition within each feeding trial. Estimated intakes of feed weight, energy, protein, and feed volume per hen per day for each diet are listed in Table 2. The formulation procedures followed, and the amino acid ratio standard used for all diets were those described in detail by Gleaves et al. (1963). In order to keep the amino acid pattern as uniform as possible from diet to diet, ingredients were stockpiled, and the protein composition of each ingredient determined by chemical analysis. The primary protein
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indicated that a 4 pound hen should receive a daily protein intake of 17 grams in order to support egg production at a level of 72 percent. Absolute requirements of the laying hen for protein nitrogen were determined by Shapiro and Fisher (1965), and Shapiro (1968). They reported that 13-14 grams of protein per hen per day would support 70 percent egg production and a satisfactory nitrogen retention of 800 mg. of N per hen per day. On the other hand, 16-17 grams of protein were required per hen per day to bring about a maximum retention level of 1200 mg. of nitrogen per hen per day. In an attempt to clarify the situation and to pinpoint protein intake requirement more precisely, two feeding trials were designed (1) to provide graded levels of protein intake per hen per day on an ad libitum feeding basis over the first 20-weeks of the laying period, (2) to fully meet amino acid requirements through strict attention to amino acid balance pattern, and (3) to allow the layer hens to meet their protein intake requirements at both the upper and lower extremes of the graded protein intake range without being limited by energy intake. This was done by manipulating ration levels of dietary weight, dietary volume, dietary protein, and dietary energy based upon data reported by Gleaves et al. (1968).
357
PROTEIN INTAKE OF LAYERS
TABLE 1.—Percentage composition of experimental diets Feeding trial 2
Feeding trial 1 Diet 1 Diet 18 Diet 1
Ingredients
3.60 27.76 23.59 10.00 5.73 4.28
4.75 23.42 19.82 8.40 4.80 3.60
7.11 1.86 2.11 1.69 1.27 1.61 1.27
11.48 3.01 3.42 2.73 2.05 2.60 2.05
2.08 5.04 0.50 0.50
1.36 5.51 0.50 0.50
Diet 7 Diet 13 Diet 19
7.20 31.90 25.11 3.39 7.47
1.96 31.68 30.90 8.72 7.92
1.30 29.40 28.66 8.09 7.35
0.40 27.92 27.22 7.68 6.98
2.41 5.63 2.41 1.61
1.56 3.64 1.56 1.04
1.39 3.24 1.39 0.93
1.21 2.83 1.21 0.81
1.61 0.81 0.97 0.64 2.40 5.44 0.50 0.50
1.04 0.52 0.62 0.42 2.24 5.16 0.51 0.51
0.93 0.46 0.56 0.37 2.06 4.72 0.51 0.51 8.13
0.81 0.40 0.49 0.32 1.92 4.36 0.50 0.50 14.44
'Manufactured by Diamond V. Mills, Cedar Rapids, Iowa 2 Supplies per kilogram of finished ration: vitamin A, 17,600 I.U., vitamin D3, 2640 I.U.; vitamin E, 13.21.U.; Vitamin K, 6.6 mg.; vitamin B12,0.018 mg.; riboflavin, 8.8 mg.; niacin, 70.4 mg.; panthothenic acid, 17.6 mg.; choline chloride, 110 mg.; manganese, 60.94 mg.; iodine, 1.89 mg.; cobalt, 1.30 mg.; iron, 47.96 mg.; copper, 3.63 mg.; zinc, 49.94 mg. and energy containing ingredients were mixed into two separate basals, respectively, and different amounts of each basal were combined to give dietary protein levels which would provide a range of graded protein intake levels. Specific energy intake levels,
feed weight intake levels, and feed volume intake levels to be provided with each protein intake level were obtained by adding varying amounts of cerelose, tallow, and sand to given basal combinations. Chemical analyses for crude protein were made on each diet after
TABLE 2.—Experimental designs, Feeding Trials 1 and 2 Feeding trial 1 Estimated intake per pullet per day Feed consumption (gm.) 100
Energy consumption (Kcal. M.E.)
Volume consumption (ml.)
300
170
Protein consumption (gm.) (increments of 0.25 gm.) 15 16 17 18 1*,2,3,4, 5,6,7,8 9,10, 13,14, 11,12 15,16,
19 17,18
Feeding trial 2 Estimated intake per pullet per day Nutrient density
Feed consumption (gm.)
Energy consumption (Kcal. M.E.)
Volume consumption (ml.)
13
1 2 3 4
100 100 100 100
316 286 261 240
170 170 170 170
1* 7 13 19
*Experimental diet number
Protein consumption (gm.) 14 16 17 15 2 8 14 20
3 9 15 21
4 10 16 22
5 11 17 23
18 6 12 18 24
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Tallow (feed grade) Ground yellow corn Ground milo Pulverized oats Ground wheat Cerelose Soybean meal (50% protein) Fish meal (60% protein) Meat & bone scrap (50% protein) Blood meal (80% protein) Dried whole egg solids Alfalfa meal (17% protein) Distillers solubles Live yeast culture 1 Dried whey Di-calcium phosphate Calcium carbonate VMC-602 Salt Sand
*Pullets within treatment within period
Average periods 1-5
304 301 273 285 298 293 307 326 294 306 294 298 289 281 78 79 76 78 78 77 77 78 80 80 75 80 78 77 55 56 56 56 54 55 57 58 57 57 55 57 54 55
Protein 13.2 13.9 15.2 15.2 15.8 15.3 15.7 14.3 16.2 15.4 15.2 14.8
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
12.6 14.1 14.8 14.9 15.0 14.3
282 275 259 276 289 278 286 300 273 268 275 280 271 270 82 77 78 78 82 80 78 80 84 75 78 80 83 82 51 49 50 50 50 51 51 52 51 49 49 50 50 50
12.4 13.7 14.3 14.4 14.0 13.8
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
12.4 13.7 14.8 14.1 13.7 13.7
12.7 14.0 14.4 13.8 14.7 13.9
1 2 3 4 5 Average Periods 1-5
Period no.
Experimental diet number 10 11 12 13 14 consumption per pullet per day (gm.) 14.1 15.2 13.8 13.5 14.3 15.2 14.6 15.1 16.0 16.8 15.7 15.3 15.2 16.5 16.5 16.3 16.0 17.3 16.2 15.7 16.3 16.6 17.1 17.0 15.7 16.7 15.7 14.8 16.4 16.4 16.9 16.1 15.7 16.7 15.1 16.9 17.1 17.3 15.2 16.8 15.5 16.5 15.3 15.2 15.9 16.4 16.1 16.3
TABLE 3.—Data on protein consumption per pullet per day, energy consumption per pullet per day,
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PROTEIN INTAKE OF LAYERS
Feeding Trial 1. Eighteen diets were fed
(Table 2). Each diet was fed to 24 individually caged pullets. The diets were formulated to provide the pullets with estimated daily protein intakes ranging from 15 to 19.25 grams in increments of 0.25 grams. All diets were isocaloric and designed to provide an estimated daily energy intake per pullet of 300 kilocalories of metabolizable energy. Feeding Trial 2. Twenty-four diets were fed with each diet being fed to 24 individually caged pullets (Table 2). These diets contained 4 energy densities (Nutrient Densities 1,2, 3,4), and 6 protein levels in a 4 x 6 factorial arrangement of treatments. Estimated daily energy intake levels of 316, 286, 261, and 240 kilocalories of metabolizable energy were provided in the four energy densities with estimated daily feed weight intake at 100 grams per pullet. On the basis of 100 grams of feed weight intake, and 170 ml. of feed volume intake per pullet per day, estimated daily intake levels per pullet were set at 13, 14, 15, 16, 17, and 18.grams of protein. RESULTS AND DISCUSSION Feeding Trial 1. The means for the response variables of energy consumption, protein consumption, egg production, and egg weight are listed in Table 3, and body weight gain in Table 4. Protein intake per pullet per day is summarized by periods in Table 3 with the means listed for Periods 1 through 5 combined, and Periods 6 through 10 combined. Although means by period are not presented for energy consumption, egg pro-
TABLE 4.—Average body weight gain in grams per pullet by periods, Feeding Trial 1 Experimental diet number Net gain
Net gain
1
2
3
120
132
115
10
11
12
186
168
210
4
5
6
7
8
9
145
173
130
204
192
137
16
17
18
269
173
150
Experimental diet number 13 14 15 162
210
261
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it had been mixed, and these values were used to calculate actual protein intake per hen per day. Each feeding trial was divided into 10 periods with 14 days in each period. Individual feed consumption data were collected at the end of each period in both feeding trials. In Feeding Trial 1, individual body weight data were recorded at the end of each period. In Feeding Trial 2, body weight data were collected at the beginning of the first period, at the beginning of the sixth period, and again at the end of the tenth period. Egg production was recorded daily and all eggs were weighed individually. Analyses of variances were calculated on the data collected during each experimental period, and on the combined data for all 10 periods within a given feeding trial (Steel and Torrie, 1960). In Feeding Trial 1 for both the overall and the period by period analyses, data were used only from those pullets which were alive at the end of Period 10. In Feeding Trial 2, the period by period analyses were based upon the data from those pullets which were alive at the end of each period. The overall analysis, on the other hand, involved data from 14 randomly selected pullets from each treatment. The pullets were selected from those that were alive at the end of Period 10. The following response variables were involved in these analyses: protein consumption, energy consumption, body weight gain, percent egg production, and egg weight.
360
THAYER, HUBBELL, KASBOHM, MORRISON AND NELSON
There was a statistically significant difference (P < .01) in protein intake per pullet per day among the pullets fed the 18 diets both on a period to period basis and overall. Thus, the feeding procedure which was followed accomplished the objective of providing graded protein intake levels ranging from approximately 15 grams to 29 grams per pullet per day. The following rational was used to establish specific values by diet for protein intake per pullet per day for use in data interpretation. Data on protein intake per pullet per day, when compared period by period, fall into a rather definite pattern for each diet during the 20-week laying period. Protein intake in Period 1 started below the estimated level upon which each diet was calculated (Table 2) and then progressively increased during
a part of all of the first 5 periods until a definite plateau was reached. At the higher protein intake levels, this plateau was reached within a period or two and seemed to be established more quickly than for the lower intake levels. During these first 5 periods the pullets were in the process of adjusting to the diets primarily from an energy intake standpoint. Apparently the specific level of this plateau in terms of grams of protein intake per pullet per day was directly related to calorie-protein ratio and energy intake requirement. As has previously been pointed out, the pullets all consumed energy to a level of approximately 295 kilocalories per day. Therefore, for purposes of interpretation in this study, the mean for protein intake at this plateau level during Periods 6 through 10 has been selected for each diet as the best estimate of actual protein intake per pullet per day. On this basis, the following values for actual protein intake per pullet per day were established for each diet: 14 grams, Diet 3; 15 grams, Diets 1 and 2; 16 grams, Diets 4, 5 and 6; 17 grams, Diets 7, 9, 10, 11, 12, 13, and 14; 18 grams, Diets 8, 15, 16, and 17; and 19 grams, Diet 18. There were no statistically significant differences in egg production among the pullets fed the different diets either within any given 2-week period or on the basis of overall means for the ten 2-week periods combined. The pullets peaked at an egg production level of 84 percent, and the mean for the entire feeding trial for all pullets was 78 percent. In addition, there were no statistically significant differences in egg weight or body weight change. Mean egg weight for the entire 20-week laying period ranged from 52 to 55 grams among the pullets fed the 18 diets. These overall means for egg weight reflect the initial low egg weight which was obtained during the early weeks of egg production. The means for Periods 6 through 10 combined show that egg weight among the pullets, regardless of the diet fed, plateaued at a mean
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duction, and egg weight, the means for combined Periods 1 through 5, and 6 through 10 are given. In formulating the experimental diets to provide an estimated energy intake of 300 kilocalories of metabolizable energy per hen per day, the assumption was made that the pullets would consume approximately this amount of energy to meet energy intake requirements, and in so doing, consume protein in graded increments. The means listed in Table 3 indicate that average energy consumption ranged from 259 to 300 kilocalories of metabolizable energy per pullet per day during Periods 1-5, and 273 to 326 kilocalories of metabolizable energy per pullet per day during Period 6-10 with averages of 275 and 295 kilocalories, respectively. The differences in energy intake among the pullets on the 18 diets were statistically significant (P < .01). A critical examination of the means for energy intake, however, shows that differences among these means are relatively small in magnitude, and energy intake, for all practical purposes, was essentially equivalent among the pullets fed all 18 experimental diets.
PROTEIN INTAKE OF LAYERS
361
marginal to need or in the others to free the pullets to consume protein as dictated by requirements for egg production or body weight gain. When the experiment was designed, it was anticipated that Nutrient Density 1 would impose the greatest control through energy intake, Nutrient Density 2 would serve somewhat as a positive control, and Nutrient Densities 3 and 4 would loosen restrictions imposed by energy intake. This proved to be the case in so far as Nutrient Densities 1 and 2 were concerned. However, the inclusion of sand in the diets in Nutrient Densities 3 and 4, and the fact that the actual protein content of the diets as determined by chemical analysis was lower than calculated, held protein intake down to 14 grams per hen per day for Diets 13 and 19. Nevertheless, the ultimate objectives were accomplished to control protein intake at a level marginal to need, and to create a situation in which the hens could consume protein in line with need.
Feeding Trial 2. The means for the response variables of energy consumption, protein consumption, egg production, and egg weight are listed in Table 5, and body weight change in Table 6. The data in Table 5 have been summarized and presented in the same format as previously described for comparable data in Feeding Trial 1 (Table 3). By following the same rational as used in Feeding Trial 1, actual grams of protein intake per pullet per day were established for each diet at: 14 grams, Diets 13 and 19; 15 grams, Diets 1, 2, 7, 8, 14, 15, 20, and 21; 16 grams, Diet 9; 17 grams, Diets 3, 4, 10, 16, and 22; 18 grams, Diets 6, 11, 12, 17, 23, and 24; and 19 grams, Diets 5 and 18.
Energy consumption per pullet per day was equivalent for all diets regardless of dietary energy level (nutrient density). The points at which statistically significant differences (P < .01) in energy consumption were observed due to dietary energy level were only in Periods 1, 8, and 10. However, dietary protein level was responsible for statistically significant differences (P < .01) in energy consumption in Periods 3 through 10. These differences indicate that the need for additional protein at estimated protein intake levels of 13 and 14 grams per pullet per day was exerting considerable pressure for the pullets to increase actual protein intake above these levels. This is most apparent in a comparison of energy consumption data from the pullets fed Diets 1 and 7, and to a lesser degree with the pullets fed Diets 13, 19, and 20. In the case of Diets 1 and 7, actual protein intake per pullet per day was 15 grams when estimated intake had been set at 13 grams.
The four nutrient densities (Table 2) were designed to both tighten (Nutrient Density 1), and loosen (Nutrient Density 3 and 4) the nutrient intake control imposed on protein intake by energy intake. It was anticipated that this would force the pullets in the one case to consume a protein level somewhat
The estimated protein intake levels as pro-
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egg weight of approximately 56 grams. Average body weight gain seemed to fluctuate from 2-week period to 2-week period no matter what diet was fed (Table 4). Periods in which body weight was lost were followed by periods of compensatory gain. No definite pattern was apparent and weight fluctuation took place regardless of protein intake. Overall change was a net gain. From a practical standpoint under commercial production conditions, net weight gains of from 0.3 to 0.6 pounds per pullet would seem to be satisfactory. These data lead to the conclusion that protein intakes per pullet per day over the range from 14 to 19 grams supported an equivalent level of egg production during the first 20 weeks of the laying period. In addition, all protein intake levels were sufficient to maintain egg weight and permitted the pullets to make satisfactory overall gains in body weight.
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TABLE 5.—Data on protein consumption per pullet per day, energy consumption per pullet per day, egg production, and egg weight in Feeding Trial 2 Nutrient density 2 Experimental diet number
Nutrient density 1 Experimental diet number Period
8 9 10 11 12 Protein consumption per pullet per day (gm.)
Protein consumption per pullet per day (gm.) 11.4 12.7 13.2 13.3 14.7 13.1
11.2 12.8 13.2 12.5 14.7 12.9
12.3 13.5 14.3 15.0 14.8 14.0
13.6 15.7 16.0 15.7 15.4 15.3
14.4 16.1 10.3 15.4 16.0 12.2 16.7 14.8 12.6 17.2 16.4 13.2 18.2 18.5 14.1 16.4 16.4 12.5 Average periods
11.3 12.7 13.7 14.1 14.6 13.3 1-5
12.5 13.8 13.7 14.0 15.0 13.8
12.2 13.7 13.6 13.9 15.0 13.7
12.9 14.8 15.8 16.6 17.6 15.5
13.5 16.8 16.6 17.0 17.0 16.2
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.) 6 7 8 9 10 Average Periods 6-10
301 72 42 14.3 14.9 15.4 15.8 15.6 15.2
272 66 43 15.0 15.3 15.8 15.8 14.9 15.4
278 65 42 16.4 17.0 16.4 17.5 16.8 16.8
289 76 44 15.0 17.8 16.9 18.4 18.4 17.3
286 276 287 285 81 69 78 71 48 42 47 46 18.4 18.0 14.2 14.6 18.3 18.3 15.0 15.0 19.5 18.0 15.7 15.7 18.9 19.1 15.8 15.6 20.2 18.5 15.9 15.6 19.1 18.4 15.3 15.3 Average periods 6-10
277 71 44 15.9 16.2 16.7 16.9 16.0 16.3
257 72 43 16.2 17.1 17.0 17.0 18.7 17.2
274 77 46 16.0 19.8 17.3 18.5 19.2 18.2
270 73 44 18.6 19.3 16.5 18.9 18.0 18.3
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
351 77 55
328 76 52
336 81 53
324 83 53
338 83 56
266 79 53
322 82 54
320 82 55
304 77 51
Period
353 82 56
328 79 52
Nutrient density 3 Nutrient density 4 Experimental diet number Experimental diet number 13 14 15 16 17 18 19 20 21 22 23 24 X MS1* df Protein consumption Protein consumption per pullet per pullet per day (gm.) per day (gm.) 10.6 10i.7 11.9 12.5 13.2 14.7 9.9 11.1 10.3 12.0 13.0 13.7 12.29 6.02 543 12.2 12.5 13.4 13.8
Average Periods 1-5
306 83 56
11.3 11.9 12.3 14.0
12.8 13.4 13.6 14.9
14.6 14.6 15.5 16.3
16.0 15.6 15.0 17.6
15.9 16.6 17.0 18.8
11.2 12.1 11.3 13.3
12.7 13.6 14.1 14.5
12.3 12.3 13.6 14.5
14.2 15.3 15.2 16.7
15.1 15.2 15.5 16.9
15.5 13.8910.61 13.0 14.2014.70 14.914.6010.25 17.3 15.70 8.69
526 523 503 486
12.5 12.0 13.3 14.7 15.5 16.6 11.6 13.2 12.6 14.7 15.1 14.9 Average periods 1-5
Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.) 6 7 8 9 10 Average Periods 6-10 Energy per pullet per day (Kcal. M.E.) Egg production (%) Egg weight (gm.)
288 72 44 13.8 13.6 14.1 14.1 14.2
258 67 40 14.6 14.4 15.2 15.2 14.9
266 69 43 14.5 15.1 15.6 15.5 15.4
276 73 44 16.2 17.1 16.6 17.2 17.5
273 77 45 18.0 17.8 17.8 18.2 18.1
277 77 47 18.9 19.8 19.6 19.4 19.4
267 68 41 13.8 14.3 13.6 14.5 13.8
283 79 47 15.0 15.1 14.9 16.1 15.1
252 66 41 15.5 15.8 14.3 15.0 15.5
276 74 46 17.0 17.3 16.5 17.6 16.3
267 76 46 17.3 17.8 17.2 18.5 17.6
248 69 43 17.615.99 18.416.65 18.0 16.40 18.7 16.95 18.1 16.78
14.0 14.9 15.2 16.9 18.0 19.4 14.0 15.2 15.2 16.9 17.7 18.2 Average periods 6-10 322 318 304 317 317 304 320 326 304 317 312 303 73 79 74 78 78 76 80 76 73 82 82 83 51 53 50 52 52 53 52 53 52 57 55 57 *Pullets within treatment within period
11.18 11.87 12.44 10.30 8.67
475 468 463 450 444
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1 2 3 4 5 Average Periods 1-5
PROTEIN INTAKE OF LAYERS
363
TABLE 6.—Average body weight change in grams per pullet in Feeding Trial 2 Nutrient density Experimental diet number Overall gain in grams Nutrient density Experimental diet number Overall gain in grams
1 1
2
3
246
311
339
2 4
5
6
7
8
9
297
272
322
233
207
235
3
10
11
12
255
312
269
4
13
14
15
16
17
18
19
20
21
22
23
24
149
244
214
335
243
262
159
188
232
217
208
211
that egg weight was maintained at a comparable level on all protein intakes from 14 to 19 grams per pullet per day. An important criteria to measure the adequacy of protein intake during the first 20 weeks of the laying period is body weight gain since the pullets are still growing during this time interval. There was a statistically significant difference (P < .05) in body weight gain due to protein intake level. This difference involved Rations 13 and 19 where actual protein intake was 14 grams per hen per day and overall weight gains were 149 to 159 grams, respectively. Even though Ration 20 supplied a protein intake of 15 grams per hen per day, weight gain was somewhat below that observed for the other pullets with a comparable protein intake. It can be concluded from these data that 14 grams of protein intake per pullet per day will not support weight gain during the first 20 weeks of egg production equivalent to that produced by protein intakes ranging from 15 to 19 grams per pullet per day. A protein intake level of 15 grams per pullet per day appeared to be entirely adequate for this purpose. Based upon these findings, it seems logical to recommend that a minimum protein intake level of 14 grams of protein per pullet per day be provided, and that this protein be well balanced from an amino acid standpoint. Even though body weight gain when 14 grams of protein is consumed, is not equivalent to the gains observed when higher levels of
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vided in the diets brought about statistically significant differences (P < .01) in actual protein intake per pullet per day in all 10 periods. Statistically significant differences (P < .01) in protein intake due to dietary energy level (nutrient density) occurred only in Periods 1, 8 and 10. This means that the actual graded protein intake levels observed were similar regardless of dietary energy level. A relatively uniform energy intake per pullet was effectively controlling protein intake. The statistical analysis of egg production data indicates that there were no differences in level of egg production among the pullets fed the 24 diets during any one of the 10 periods with one exception. In Period 1 a statistically significant difference (P < .05) in egg production was apparent. Since this difference was due to estimated protein intake level, it can be concluded that it was brought about by the extremely low levels of actual protein intake observed during Period 1 as the pullets adjusted to the diets. Once this adjustment had been made, these differences disappeared entirely. Egg production was maintained at a level of approximately 80 percent regardless of protein intake per pullet per day. A similar observation was made in connection with the egg weight data. There were no statistically significant differences in egg weight brought about by the diet which was fed during any of the 10 periods with the exception of Period 4. It can be concluded
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THAYER, HUBBELL, KASBOHM, MORRISON AND NELSON
protein are fed, the gain is substantial and would be adequate under practical production conditions. However, since a protein intake of 15 grams per pullet per day was the level which seemed to be selected by the pullets as being minimum (Ration 1 and 7), this level might prove to be most adequate under a variety of production conditions.
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