Effect of Dietary Protein and Energy Levels on Pullet Development1

METABOLISM AND NUTRITION Effect of Dietary Protein and Energy Levels on Pullet Development1 A. S. HUSSEINS A. H. CANTOR,3 A. J. PESCATORE, and T. H. JOHNSON Department of Animal Sciences, University of Kentucky, Lexington, Kentucky 40546-0215 kg) energy diet. After 18 wk, half of the pullets within each rearing treatment were fed a layer diet containing 16% CP and 0.34% methionine, whereas the other half were fed a layer diet with 19% CP and 0.40% methionine. Increasing the level of protein fed during Weeks 2 through 6 significantly (P < 0.05) increased body weight and feed intake up to 14 wk of age. High dietary energy increased weight gain and decreased feed intake during Weeks 15 through 18. Mortality and days to 50% egg production, as well as egg production, feed intake, feed conversion, and egg weight during the first 16 wk following photostimulation were not affected by rearing dietary treatments. Egg weight, but not other production parameters, was significantly increased by raising CP in the layer diet from 16 to 19%.

(Key words: protein, energy, pullet growth, egg production) 1996 Poultry Science 75:973-978

INTRODUCTION For many years it has been a standard practice to feed growing egg-type pullets a series of diets generally termed starter, grower, and developer diets. These rations are characterized by decreasing levels of a number of nutrients, including protein and amino acids. Such a decrease is in agreement with the dietary requirements listed by current and previous publications of the NRC. Currently, the NRC (1994) lists the following dietary protein requirements for pullets: 18% for 0 to 6 wk, 16% for 6 to 12 wk, and 15% for 12 to 18 wk of age. In recent years, different approaches to feeding replacement pullets have been tried for a number of reasons. One is the concern that the pullets might be too heavy when brought into production. Another reason is a desire to delay sexual maturity so that the hen is larger at the initiation of egg production and will therefore lay a greater percentage of large eggs. During the last

Received for publication September 18, 1995. Accepted for publication April 5, 1996. J Paper Number 95-07-143 of the Kentucky Agricultural Experiment Station. 2 Current address: Faculty of Agricultural Sciences, United Arab Emirates University, Al Ain, United Arab Emirates. 3 To whom correspondence should be addressed.

decade, the poultry industry has been using pullets that mature earlier. With these birds, it is of even greater importance that pullets come into production at the proper weight and frame size. Several researchers have compared the growth, development, and subsequent laying performance of pullets fed conventional rearing diets with a step-up protein series in which the protein levels used were reversed. The step-up treatment resulted in lower BW at 20 wk of age. During the laying period, it resulted in equivalent egg production and smaller egg size compared to the conventional treatment (Leeson and Summers, 1979; Doran et al, 1983). Keshavarz (1984) observed lower BW at 20 wk and decreased performance during the early phase of the egg production cycle when pullets were given low-protein rearing regimens. Cantor and Johnson (1985) compared the effects of feeding diets with increasing, decreasing, and constant levels of protein to replacement pullets up to 20 wk of age. The increasing protein program resulted in lower BW from 3 to 20 wk and reduced egg production during the first 5 wk after lighting, whereas feeding a constant 16% CP did not reduce 20-wk BW or egg production, compared with the decreasing protein program. Leeson and Summers (1981) have indicated that energy intake is of greater importance than protein during the last few weeks of pullet development. 973

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ABSTRACT The effects of protein and energy levels in rearing diets and protein levels in layer diets on pullet development and subsequent layer performance were studied using 576 Single Comb White Leghorn pullets of a commercial strain. Twelve groups of 16 1-d-old chicks were assigned to each of three dietary treatments. All chicks were fed a 19% CP starter diet during Week 1. Respective protein levels in diets fed during Weeks 2 through 6, 7 through 14, and 15 through 18 were 13.5, 15.8, and 18.9% for the increasing protein treatment; 15.8, 15.8, and 15.8% for the constant protein treatment; and 18.9, 15.8, and 13.5% for the decreasing protein treatment. During Weeks 15 through 18, half of the groups in each protein treatment were assigned to a high (3.09 Meal AME n /kg) or a low (2.78 Meal AME n /

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HUSSEIN ET AL.

MATERIALS AND METHODS A total of 576 DeKalb XL pullets, 1 d of age, were housed in pullet cages (51 cm wide x 61 cm long x 36 cm high) at a density of 16 birds per cage during Weeks 1 through 6 and at 8 birds per cage during Weeks 7 through 18. During Week 1, the chicks were given 23 h of light/d. Subsequent light was provided at 8 h/d. All

birds received a starter diet containing 19% CP and 2.92 Meal AME n /kg for the 1st wk. Feed and water were provided on an ad libitum basis. After the 1st wk six replicate groups of 16 pullets were randomly allocated to each of six dietary treatments. The experimental design consisted of a 3 x 2 factorial arrangement of dietary treatments, using three protein sequences and two energy levels. The increasing protein sequence consisted of feeding diets containing 13.5, 15.8, and 18.9% protein (hereafter referenced as 13, 16, and 19%, respectively) diets during Weeks 2 through 6, 7 through 14, and 15 through 18, respectively. The constant sequence consisted of feeding 16% protein during Weeks 2 through 18. The decreasing sequence consisted of feeding 19, 16, and 13% protein diets during the three periods. During Weeks 15 through 18, half of the groups in each of the three protein treatments were given high dietary energy (3.09 Meal AME n /kg) and the other half were given the same lower energy level (2.78 Meal AMEn/kg) as previously used. The calculated nutrient composition of the diets, based on ingredient composition tables (Scott et ah, 1982), is shown in Table 1. Only three of these diets (13L, 16L, and 19L) were used up to the end of 14 wk. During Weeks 15 through 18, all six diets were used. These contained high or low energy levels at each of the three protein levels. Energy and protein were adjusted by varying the amounts of ground yellow corn, soybean meal, alfalfa meal, wheat middlings, and blended fat. Methionine was maintained proportional to the protein level. Other nutrients were maintained approximately the same in all diets.

TABLE 1. Composition of the experimental rearing diets Ingredients and composition

13H1

13L2

16H

16L

19H

19L

62.04 15.71 7.78 10.00

61.49 27.30 3.00

57.78 24.63 3.00 10.00

•O / S Ground yellow corn Soybean meal (48% CP) Dehydrated alfalfa meal Wheat middlings Blended fat Salt Ground limestone Dicalcium phosphate Vitamin-mineral premix 3 DL-methionine (99%) Calculated nutrient composition Energy (AMEn), Mcal/kg Protein Methionine Methionine + cystine Lysine Calcium Phosphorus, available

78.43 13.01 3.00 0.% 0.38 1.11 2.11 1.00 3.09 13.50 0.24 0.49 0.58 1.00 0.50

65.07 9.06 11.49 10.00

71.20 19.10 3.00

.">)

0.35 1.02 2.00 1.00 0.01

2.13 0.39 1.10 2.07 1.00 0.01

0.36 1.11 1.98 1.00 0.02

3.71 0.39 1.08 2.00 1.00 0.03

0.38 1.24 1.93 1.00 0.04

2.78 13.50 0.24 0.48 0.55 1.05 0.50

3.09 15.80 0.28 0.56 0.75 1.00 0.50

2.78 15.80 0.28 0.55 0.72 1.05 0.50

3.09 18.90 0.34 0.66 0.99 1.00 0.50

2.78 18.90 0.34 0.66 0.96 1.05 0.50

!High energy diet (3.09 Mcal/kg). 2 Low energy diet (2.78 Mcal/kg). 3 Provided the following per kilogram of diet: vitamin A (retinyl acetate), 6,000 IU; cholecalciferol, 1,100 IU; vitamin E (all-rac-a-tocopheryl acetate), 10 IU; menadione dimethylpyrimidinol bisulfite, 4.4 mg; riboflavin, 2.2 mg; pantothenic acid, 5 mg; niacin, 10 mg; biotin, 0.10 mg; choline, 200 mg; ethoxyquin, 125 mg; selenium, 0.2 mg; copper, 6 mg; iodine, 0.53 mg; iron, 120 mg; manganese, 83 mg; zinc, 60 mg; and cobalt, 5 mg.

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In addition to the production rate, egg weight is an extremely important economic parameter in laying flocks. Body size, which is influenced by nutritional and other factors during rearing, can affect egg size, especially during the early phase of production. The levels of protein and essential amino acids, especially methionine, in the layer diet are among the most important nutritional factors affecting egg weight (Scott et ah, 1982). Keshavarz (1984) noted decreased egg production and egg weight in hens fed low-protein (14.5% CP) layer diets. In contrast, Summers and Leeson (1983) observed that adding extra methionine to 17% CP layer diets or increasing protein to 22% did not increase egg weight in early-maturing pullets. The first objective of the present study was to evaluate the effect of protein sequence, namely diets with increasing, constant, or decreasing levels during Weeks 2 through 18, in combination with the use of high or low energy levels during Weeks 15 through 18, upon pullet development. The second objective was to determine the response of pullets subjected to these rearing treatments to different levels of protein in the layer diet.

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DIETARY PROTEIN AND ENERGY AND PULLET DEVELOPMENT TABLE 2. Composition of the experimental laying diets Ingredients and composition

16% CP

19% CP C'u\

56.81 29.40 2.30 0.40 8.30 1.70 1.00 0.09

65.93 21.50 1.00 0.40 8.30 1.80 1.00 0.07

2.82 19.00 0.40 0.72 1.03 3.62 0.45

2.83 16.00 0.34 0.62 0.80 3.62 0.45

JProvided the following per kilogram of diet: vitamin A (retinyl acetate), 6,000 IU; cholecalciferol, 1,100 IU; vitamin E (all-rac-atocopheryl acetate), 10 IU; menadione dimethylpyrimidinol bisulfite, 4.4 mg; riboflavin, 2.2 mg; pantothenic acid, 5 mg; niacin, 10 mg; biotin, 0.10 mg; choline, 200 mg; ethoxyquin, 125 mg; selenium, 0.2 mg; copper, 6 mg; iodine, 0.53 mg; iron, 120 mg; manganese, 83 mg; zinc, 60 mg; and cobalt, 5 mg.

At 18 wk of age, 12 representative pullets were selected from each group and transferred to laying cages (25 x 41 cm). Excessively heavy or light birds were not included. During the laying period, each replicate group consisted of six cages housing two pullets per cage. Hens were photostimulated at 18 wk of age using an intermittent lighting program of five cycles of 1 h of light (L) plus 2 h of dark (D) followed by 1L:8D [5 x (IL: 2D) + 1L:8D]. Hens were fed corn-soybean meal layer diets containing 3.6% Ca and 0.45% available P (Table 2). Within each rearing dietary treatment, half (three replicate groups) was fed the layer diet containing 16% CP and 0.34% methionine, and the other half was fed the layer diet with 19% CP and 0.40% methionine. This created a 3 x 2 x 2 factorial arrangement of treatments. The effect of the treatments on layer performance was monitored for 16 wk following photostimulation. Data collected through 14 wk of the rearing period were subjected to a one-way ANOVA. An ANOVA based on a 3 x 2 factorial design and one based on a 3 x 2 x 2 factorial design were used for results from Weeks 15 through 18 and from the laying period, respectively. Statistical analyses were performed using a linear model program for microcomputers. 4 The test of least significant difference was used to separate means only when a significant value of F was obtained in the ANOVA (Snedecor and Cochran, 1980). A probability of P < 0.05 was required for significance in all statistical analyses.

4

Statistix Version 3.0, Analytical Software, Tallahassee, FL 32317.

There were no significant interactive effects of protein sequence by energy levels fed during pullet rearing on any of the parameters observed during the rearing and laying periods; therefore, only the main effects of diets will be presented. The effect of feeding the three protein sequences upon the growth performance of pullets is shown in Table 3. Body weight significantly increased as the level of protein increased during the first 6 wk. With each increase in protein level, there was a significant increase in feed intake. The effect of dietary treatments on mortality rate was not significant. At the end of 14 wk, all three treatment groups had been fed the 16% protein diet for 8 wk; thus, there was less of a difference between treatment groups. Pullets initially fed the 13% protein diet had significantly lower BW and cumulative feed intake at 14 wk than those fed the 19% protein diet during Weeks 2 to 6. The birds fed the constant 16% protein diets did not differ significantly from the other two treatment groups with respect to these parameters. Again, no effect of dietary treatments on mortality was observed. The main effects of dietary protein sequence on growth performance and mortality of pullets during Weeks 15 through 18 are shown in Table 4. By the end of the 18-wk growing period there were no significant differences in feed intake, weight gain, BW, and mortality of pullets among the three protein sequences. Also, during this period, there were no significant differences in mortality among protein sequences. The main effects of dietary energy used during Weeks 15 through 18 on growth performance are shown in Table 4. Body weight at 18 wk and mortality were not significantly affected by the energy level used during the final 4 wk. However, the higher energy level resulted in significantly lower feed intake and higher weight gain. There were no significant effects on layer performance due to the interaction of protein sequence by dietary energy used during pullet rearing or due to the interaction of the pullet rearing treatments by layer

TABLE 3. Effect of dietary protein on body weight, cumulative feed intake, and cumulative mortality of pullets1 Weeks of age

Dietary protein 2

Body weight

Feed intake fe/hirdl

6 Pooled SEM 14

Pooled SEM

13 16 19 13-16 16-16 19-16

363" 406t> 450^ 7 1,115" 1,141* 1,152b 10

-

Mortality

(%)

1,078" 1,124>> 1,158c 9

4.1 1.0 0.5 1.5

4,446" 4,527* 4,584* 31

5.2 2.1 3.1 2.1

"-'Means within a column with no common superscript differ significantly (P < 0.05). iEach level is the mean of 12 replicate groups of 16 chicks. ^Levels of protein diets fed pullets during Weeks 2 to 6 and 7 to 14.

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Ground yellow corn Soybean meal (48% CP) Blended fat Salt Ground limestone Dicalcium phosphate Vitamin-mineral premix 3 DL-methionine (99%) Calculated nutrient composition Energy (AME n ), Mcal/kg Protein Methionine Methionine + cystine Lysine Calcium Phosphorus, available

RESULTS

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HUSSEIN ET AL. TABLE 4. The main effects of dietary protein sequence and energy levels on growth performance and mortality of pullets during Weeks 15 to 181 Treatment Dietary protein2 13-16-19% 16-16-16% 19-16-13% Pooled SEM Dietary energy3 High Low Pooled SEM

Feed intake

Weight gain

18-wk BW

1,865 1,852 1,898

256.3 246.8 252.2

1,371 1,388 1,405

20

5.0

13

1,822b 1,922"

264.1' 239.5b

16

Mortality

0.56 0.00 0.49 0.43 0.37 0.33 0.35

1,400 1,376

4.0

10

a b

DISCUSSION

dietary protein. Therefore, only the main effects of the rearing diets and of the layer diets are reported. The main effects of dietary protein sequence used during rearing on layer performance during the first 16 wk following photostimulation are shown in Table 5. Dietary protein sequence did not significantly affect age at 50% egg production, hen-day egg production, feed intake, feed conversion, final BW, and egg weights during the 8th, 12th, and 16th wk of the production period. The only variably that approached significance was hen-day egg production (P < 0.07). Similarly, these parameters were unaffected by dietary energy level used during Weeks 15 through 18 (Table 6). The level of protein in the layer diets failed to affect age at 50% production, hen-day production, feed intake, feed conversion, or BW at 34 wk of age (Table 7). However, egg weight measured at the 8th, 12th, and 16th wk of production was significantly decreased by feeding the lower level of protein.

There is considerable variation in the levels of protein and, to a lesser extent, the ME recommended by various commercial breeders of pullets. Most recommendations for pullets generally include a starter diet, a grower diet, and a developer diet. In addition to the differences from strain to strain, there is considerable variation in the levels of protein and energy that are actually fed by pullet growers. The actual levels fed are determined by many factors in addition to the genetic strain of the bird used. The results of this study indicated that BW at 6 wk of age was higher for pullets given 19% CP as part of the decreasing protein sequence during Weeks 2 through 6 than for pullets given 16% CP (Table 3). Body weight for the latter group was significantly higher than for pullets given the increasing protein sequence (13% CP during Weeks 2 through 6). Average feed intake showed the

TABLE 5. The main effect of dietary protein sequence used for pullet rearing on layer performance during Weeks 19 through 341 Dietary protein sequence2

Pooled SEM

Variable

13-16-19%

16-16-16%

19-16-13%

Age at 50% egg production, d Hen-day production, % Feed intake, g/hen/d Feed conversion, kg feed:dozen eggs BW at 34 wk, kg Egg weight, g 8th wk 12th wk 16th wk

142.9 72.4 92.0 1.54 1.64

142.0 73.6 91.4 1.49 1.60

141.5 76.9 92.8 1.45 1.64

0.9

54.1 56.1 56.5

53.4 56.1 56.4

54.2 56.5 56.5

0.4 0.5 0.4

1.43

0.9 0.03 0.02

1 Pullets were transferred to layer cages and photostimulated at 18 wk of age. Each value is the mean of 12 replicate groups of 12 pullets. 2 Protein levels of diets fed during Weeks 2 to 6, 7 to 14, and 15 to 18. 3 P < 0.07 for main effect of protein sequence from ANOVA F test.

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- Means within a treatment effect with no common superscript differ significantly (P < 0.05). !Each value is the mean of 12 or 18 replicate groups of 16 chicks for protein or energy treatments, respectively. 2 Levels of protein diets fed pullets during 2 to 6 and 7 to 14, and 15 to 18 wk. 3 High energy diet = 3.09 Meal AMEn/kg, low energy diet = 2.78 Meal AMEn/kg, fed during Weeks 15 to 18.

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DIETARY PROTEIN AND ENERGY AND PULLET DEVELOPMENT TABLE 6. The main effect of dietary energy used during Weeks 15 to 18 of pullet rearing on layer performance during Weeks 19 through 341 Dietary energy level2 Variable

High

Low

Pooled SEM

Age at 50% egg production, d Hen-day production, % Feed intake, g/hen/d Feed conversion, kg feed:dozen eggs BW at 34 wk, kg Egg weight, g 8th wk 12th wk 16th wk

143.0 75.1 92.3 1.48 1.63

.41.3 73.5 91.9 1.50 1.62

0.7 1.1 0.8 0.02 0.01

54.2 56.3 56.7

53.6 56.2 56.3

0.3 0.4 0.3

same trend seen in BW. Body weight and cumulative feed intake at 14 wk of age were significantly higher for pullets given the decreasing protein sequence man for those given the increasing sequence. The respective values for the pullets given the constant 16% protein diets were intermediate between and not significantly different from those of two other treatments. Similar results were previously reported by Cantor and Johnson (1985), who conducted a trial having the same conditions as the present study. Summers and Leeson (1978) reported that the protein intake of pullets was positively correlated with their age. These authors (Leeson and Summers, 1979) reported that, at 20 wk of age, pullets reared on step-up protein diets (12, 16, and 19% CP) were significantly smaller than those given step-down protein diets (18, 15, and 13% CP). Birds in the step-up treatment also consumed 100 g less protein and 200 kcal less ME than pullets given the step-down treatment from 0 through 20 wk. Leeson and Summers (1981) found that when pullets were reared on a reverse protein program (12, 16, and 19% CP) they were smaller than conventionally restricted pullets at 8 wk of age, after which time the converse was true. In addition, Doran et al. (1983) reported that pullets given the stepup protein feeding program were 82 g lighter in average BW, had higher mortality, and consumed less feed than birds on the step-down protein treatment at 20 wk of age. In this present study, no effect on mortality was observed. Pullet BW for the increasing protein sequence was 37 g less (P < 0.05) than that for the decreasing sequence at 14 wk. The numerical difference between these groups (34 g) at 18 wk was approximately the same as at 14 wk, but was no longer significant. Increasing dietary energy during the last 4 wk of the rearing period resulted in decreased feed intake and increased weight gain. This result is different from the observation of Cunningham and Morrison (1977) that dietary energy levels did not significantly affect BW gain of pullets during the growing period. Also, Doran et al. (1983) found that dietary energy levels had no signifi-

cant effect on BW, feed consumption, or mortality up to 20 wk of age. However, it was reported that voluntary energy intake was a limiting factor to growth in rearing young pullets (Leeson and Summers, 1981). In addition, Lilburn et al. (1987) stated that above some minimal level of protein intake, caloric intake has the greatest control over BW gain in restricted broiler breeder pullets, particularly when every-other-day feeding is used during part of the growing period. In the present study, it would appear that protein requirements were met by all diets during Weeks 15 through 18. Therefore, BW was affected by dietary energy, but not protein. Neither protein nor energy levels during rearing affected the onset of egg production, as indicated by days to 50% production. Leeson and Summers (1979) found in their pullet study that birds reared on the stepup protein regimen consumed significantly less feed than the conventionally reared birds, while producing a comparable number of eggs of smaller size and greater shell deformation during the subsequent 40-wk laying period. They also observed that step-up birds were

TABLE 7. The main effect of protein level in the layer diets on layer performance during Weeks 19 through 341 Layer prot ein level Variable

16% CP

19% CP

Pooled SEM

Age at 50% egg production, d Hen-day production, % Feed intake, g/hen/d Feed conversion, kg feed/dozen eggs BW at 34 wk, kg Egg weight, g 8th wk 12th wk 16th wk

142.7 73.7 92.7

141.6 74.9 91.5

0.7 1.1 0.8

1.52 1.61

1.47 1.64

0.02 0.01

53.4bb 55.5 55.8b

54.4" 57.0* 57.1*

0.3 0.4 0.3

a-bMeans within a row with no common superscript differ significantly (P < 0.05). bullets were transferred to layer cages and photostimulated at 18 wk of age. Each value is the mean of 18 replicate groups of 12 pullets.

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bullets were transferred to layer cages and photostimulated at 18 wk of age. Each value is the mean of 18 replicate groups of 12 pullets. 2 High energy diet = 3.09 Meal AMEn/kg, low energy diet = 2.78 Meal AMEn/kg, fed during Weeks 15 to 18.

978

HUSSEIN ET AL. feed cost for Weeks 2 through 18 was lowered by $0,008 and $0,011 per bird by using the increasing and constant protein sequences, respectively. However, feed costs can vary substantially, depending on the selection and cost of ingredients.

REFERENCES Cantor, A. H., and T. H. Johnson, 1985. Influence of dietary protein sequence and selenium upon development of pullets. Poultry Sci. 64:(Suppl. 1):75. (Abstr.) Cunningham, D. G, and W. D. Morrison, 1977. Dietary energy and fat content as factors in the nutrition of developing egg strain pullets and young hens. 2. Effects on subsequent productive performance and body chemical composition of present day egg strain layers at the termination of lay. Poultry Sci. 56:1405-1416. Doran, B. H., W. F. Krueger, and J. W. Bradley, 1983. Effect of step-down and step-up protein-energy feeding systems on egg-type pullet growth and laying performance. Poultry Sci. 62:255-262. Keshavarz, K., 1984. The effect of different dietary protein levels in the rearing and laying periods on performance of White Leghorn chickens. Poultry Sci. 63:2229-2240. Leeson, S., and J. D. Summers, 1979. Step-up protein diets for growing pullets. Poultry Sci. 58:681-686. Leeson, S., and J. D. Summers, 1981. Dietary self-selection and use of reverse-protein diets for developing broiler breeder pullets. Poultry Sci. 60:168-171. Lilburn, M. S., K. Ngiam-Rilling, and J. H. Smith, 1987. Relationships between dietary protein, dietary energy, rearing environment, and nutrient utilization of broiler breeder pullets. Poultry Sci. 66:1111-1118. National Research Council, 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. Scott, M. L., M. G Nesheim, and R. J. Young, 1982. Nutrition of the Chicken. 3rd ed. M. L. Scott and Associates, Ithaca, NY. Snedecor, G. W., and W. G. Cochran, 1980. Statistical Methods. 7th ed. Iowa State University Press, Ames, IA. Summers, J. D., and S. Leeson, 1978. Dietary selection of protein and energy by pullets and broilers. Br. Poult. Sci. 19:425-130. Summers, J. D., and S. Leeson, 1983. Factors influencing early egg size. Poultry Sci. 62:1155-1159.

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significantly smaller at the end of the laying period. In addition, they concluded that protein per se during rearing had no effect on egg production and that mortality was not influenced by either rearing treatment. In the present study, hen-day production for the 16-wk laying period was approximately 71 and 77% for pullets given step-up and step-down protein sequences, respectively. However, due to the variability experienced in this study, this difference was not significant (P < 0.07). The lack of effect of rearing diets on performance during the early laying period was likely due to the fact that the pullets from the different treatments had similar BW at the time of photostimulation. In contrast, the protein level in the layer diet significantly affected egg weight. This result is in agreement with the findings of Keshavarz (1984), who compared feeding 14.5% CP with feeding 16.5% CP. However, the observed effect on egg weight is in contrast to findings of Summers and Leeson (1983). In their study, hens fed a 17% CP layer diet had an average daily protein consumption of 17.7 g. The respective value for hens fed the 16% CP diet in the present study was 14.8 g. In summary, lowering the protein level in the starter diet fed during Weeks 2 through 6 decreased both BW and feed intake. The effect on feed intake was significant throughout the 18-wk growing period, whereas the effect on BW was significant to 14 wk of age. Increasing dietary energy during the last 4 wk of the growing period significantly increased weight gain and decreased feed intake. Mortality and days to 50% egg production were unaffected by dietary treatments. Moreover, the egg production rate through 34 wk of age was not significantly affected by the rearing dietary treatments. These data indicate that adequate performance can be obtained from pullets given a wide range of protein and energy during rearing, provided that BW is not compromised. Egg weight, but not other production parameters, was significantly improved by increasing protein in the layer diet from 16 to 19%. Feed cost is an important factor that needs to be considered before implementing different feeding programs. Compared with feeding the conventional decreasing protein sequence in the present study, total