A COMPARISON OF PERFORMANCE AND ENERGY INTAKE OF COMMERCIAL LAYERS BASED ON BODY WEIGHT OR EGG WEIGHT^ R H. HARMS2, V. OLlVERO, and G. B. RUSSELL Depment of Daily and Poulby Sciences, University of Florida, Gainesville, FL 32611 Phone: (352) 392-1932 FAX: (352) 392-3047 E-mail: russell@dps.ufl.edu Primary Audience: Nutritionists, Egg Producers, Extension Workers DESCRIPTION OF PROBLEM The National Research Council [ 1 J in 1971 calculated the nutrient requirement of the commercial laying hen as a percentage of the diet. In the next edition [2], the requirement was again expressed as a percentage of the diet, but also included a suggested daily intake per hen based on feed consumption (FC) of 110 @day. Harms et d. [3] designed a feeding program for commercial layers in which the nutrient content of the diet was changed as feed intake changed. The basis of the requirements was again modified by NRC [4] when the requirement was expressed as a percentage of the diet and as a daily requirement per hen, assuming an average daily feed intake of 110 g. In the latest NRC [5] revision, the 1 Florida Agricultural Experiment Station, Journal Series No. R06978. 2 To whom correspondence should be addressed requirement was expressed as a percentage of the diet when the hen consumes 80, 100, or l.20&day. It has previouslybeen suggested [6,7,8,9] that pullets should be housed based on body weight (BW). This practice resulted in segregating pullets as to age at sexual maturity. Therefore, it has been questioned whether one feed wiu furnish the requirement for all hens in a flock. It has been reported [lo] that daily egg production (EP) did not differ significantly between light, medium, and heavy hens. Egg weight (EW) increased significantly as BW increased, accompanied by an increase in FC and energy intake. Harms and Russell [ll] also assigned hens into three groups based on EW at 42 wk of age. They found that BW was positively related to egg output.
180 ENERGY FOR LAYING HENS Feed intake increased as egg output increased, resulting in essentially the same amount of energy and Met consumed per g of egg content (EC) for all three groups. The Met intake of hens increased with each increase in EC; however, the MeVg EC did not differ for the three groups. Recently, Harms [ 121 suggested that the ratio of energy to Met should be considered when formulating feed for commercial layers. Therefore, the present experiment was conducted to study the relationship of EW or BW to energy intake, as well as to energylg EC, and to determine whether EW or BW would be affected in any of the three groups when fed the same feed. M~TERTALS AND METHODS The experiment employed 150 Hy-Line W-36 [D] pullets 22 wk of age placed in individual cages in awindowless, tunnel-ventilated house. The first 2 wk were considered as an adjustment period and collection of experimental data was started when the hens were 24 wk of age. A corn-soybean meal diet was fed (Table 1). The feed was supplied to individual hens in two plastic cups. The data for the 25- to 27-wk age period for analysis of future performance was used to divide the pullets into three groups based on BW or EW. The comparative measurements were made for 10 wk (27 to 38 wk of age). The three groups were selected based on BW. The hens were also selected on the basis of EW. The 10 hens with the heaviest BW or EW and the hens with the lightest BW or EW were discarded before selecting the respective groups. The next 40 lightest hens constituted the light BW or EW group. The 30 hens with the average BW or EW constituted the medium group. Ten hens at the extremes of this group were eliminated. The next 40 hens were selected as the heaviest group. Daily EP for each hen was recorded and averaged for the week. One egg laid from each hen during the last 2 days of the week was welghed. These eggs were broken out. Researchers washed the shells, allowed them to dry, and weighed them. EC was calculated by multiplying the percentage of EP by EW minus shell welght. FC was measured at the end of each week, and fresh feed was placed in the cups. The kcal of energy consumed per dav was calculated bv multidvine the dailvfc TABLE 1. Composition of layer diet INGREDIENT % OF DIET Yellow corn I 68.40 CALCULATED VALUES (%)D Protein Calcium Methionine Methionine + Cvstine 0.66 Lvsine I 0.78 Tqptophan Cvstine Threonine Arginine Valine Isoleucine Leucine Histidine Phenyialanine Energy (kcal MEVkg) 0.18 0.28 058 0.97 0.70 059 0.39 0.41 0.76 2810 by the energy content of the feed. The kcal energy per/g EC was calculated by dividing daily energy intake by daily EC. The hens were individually weighed on the last day of each week. The data for each measurement were analyzed using a one-way ANOVA [14]. Duncan s multiple range test [15] was used to determine differences amone treatments.
HARMS et al. Research Report 181 RESULTS AND DISCUSSION SELECTION BASED ON BODY WEIGHT There were no significant differences in EP (Table 2) among the three groups. In contrast, there were significant differences among the three groups for EW at 28 wk (Table 3). The differences in BW remained consistent and sigtllficant for the 10-wk experiment. The medium group was 103 g heavier than the light group at 28 wk, up to 111 g heavier at 38 wk. The heavy group was 125 g heavier than the medium group at 28 wk, up to 166 g heavier at 38 wk. EW differed significantly for each group at 28 wk of age (Table 4). The medium hens laid eggs that were 1.3 g heavier than eggs laid by the light group; the heavy hens laid eggs 2.9 g heavier than those of the medium hens. The difference in EW for the three groups was consistent for the 10-wk period. FC was higher for the medium hens than for the light hens (Table Z), and the FC was higher for the heavy groups than for the medium group. The medium hens consumed 8.6 kcavday more energy than did the light hens during Week 28 (Table 5). The heavy hens consumed 36.6 kcal more energy than did the light hens at this age. This trend for consumption of energy was consistent for the 10 wk. The medium hens consumed 17.6 k4day more energy than did the light hens during Week 37, and the heavy hens consumed 16.5 kdday more than did the medium hens at this age. The energy consumed/g EC was essentially the same for both the light and medium hens (Table 6). Although the difference was not significant, the heavy hens consistently consumed higher energy/g EC than did the medium and light hens. There were signifcant differences among the three groups for BW at 28 wk (Table 7). The medium group weighed 52 g more than the light group. The heavy group weighed 99 g more than the medium group. These differences existed throughout the 10-wk experiment. At 38 wk the medium group weighed 38 g more than the light group, and the heavy group weighed 44 g more than the medium group. SELECTION BASED ON EGG WEIGHT Egg production did not differ sigolfcantly among the three groups (Table 2). However, EW was significantly different for the three groups at 28 wk (Table 8). Eggs from the medium group weighed 3.0 g more than those from the light group. Eggs from the heavy group weighed 4.0 g more than the eggs from the light group. Significant differences between groups existed for the 10-wk experi- x-zmeans within a row (egg weight) with different superscripts differ significantly (Pe.05). I
182 ENERGY FOR LAYING HENS BODY WEIGHT GROUP Light I Medium I Heavy beueamwithin rowswith the same superscripts do not I I differ significantlv (P <.OS). TABLE 5. Energy intake of hens grouped according to body weight wk BODY WEIGHT GROUP Light I Medium I Heavy kcayheddav 28 I 24Sb I 254.1b I 282.1' 29 253.2b 262.Ob 284.1' 30 252.OC 264.6b 281.0' 31 276.3' 289.2b 303.8' 32 279.9b 296.1' 307.6' 275.1' 289.1b 311.8' 274.8' 294.Ob 313.6' 270.2' 36 274.0b 293.6' 305.8' 37 2735' 291.1b 307.9' weamwithin a rowwith the same superscript do not I I differ significantly (P <.OS). TABLE 6. Energy intakelg egg content from hens BODY WEIGHT GROUP Light 1 Medium Heavy weanswithin a rowwith the same superscript do not differ significantly (P <.OS). ment. At 37 wk there was 3.6 g difference between the medium and light groups in the weight of eggs. Also, there was a difference between the medium and heavy groups of 4.1 g in the weight of the eggs. FC was significantly different among the three groups (Table 2). The light group had a FC of %.6 g/hen/day as compared to 102.0 and 105.6 g for the medium and heavy groups, respectively. I I 5: I 558' 5.878 1 I 6.02' 5.74a weamwithin a rowwith the same superscript do not differ significantly (P e.os). Energy intake/hen/day (Table 9) was always higher, but not always significant, based on weight. There was a difference of 12 kdday between the light and medium groups at 28 days. This gap increased to 17 kcal at 37 wk. There was 15 kcal difference between the medium and heavy groups at 37 wk of age. Hens in the heavy group consumed si&- icantly less energy/g EC than did the other two
HARMS et al. Research Report - 183 TABLE 7. Body weights of hens grouped according to egg weight EGG WEIGHT GROUP weamwithin mwswith the same superscriptsdo not differ si@icantly (P <.OS). wk 32 33 34 35 EGG WEIGHT GROUP Light Medium Heavy kcal/hen/dav 28 I 252' 1 ma I 2aa 29 I 250' I 2Mib I %la 30 I 256b I 272" I 282' I 31 I 278b I 290b I 306a 283' 296b 315' 2rSb 299a 301' 282b 294b ma 276b 298a 297a 36 I 281' I 2wa I 297a 37 I 276' I 293b I ma weamwithin rowswith the same superscriptsdo not differ significantly (P <.OS). TABLE 8. Egg weight of hens grouped according to egg weight EGG WEIGHT GROUP TABLE 10. Energy intake/g egg content from hens I 28 I 51.6' I 54.6b I 58.6' I I 29 I 53.3' I 56.10 I 59.9 I I 30 I 53.4' I 56.9b I 60.2' I I 31 53.T 57Sb I 61.1' I 32 I 54.4' I I 58.2b I 61.9 1 33 545' 58.0b 62.2" 34 55.3' 59.1b 625' 55.9" 63.6' 63.1' 56.1' 63.8' weamwithin rowswith thesamesuperscriptsdo not differ significantly (P <.OS). 7 groups at 28 wk and at 35 wk (Table 10). However, for the remainder of the experiment there was no difference among the three groups. The value of 5.23 g for the heavy group at 28 wk did not appear to be correct. If a missing value were calculated for the heavy group, it would be 5.82. This figure would agree with values for the light and medium groups. Hens selected based either on BW or EW at 25 wk remained in their respective groups to 38 wk of age (Tables 3 and 7). This finding 6.043' 5.975' 5.712' 5.802' 37 5.824' weanswithm rowswith thesamesuperscriptsdonot I I differ sienificantlv (P <.OS). agrees with previous reports [6,7,8,9]. At the end of the experiment, the BW of the heavy hens was 277 g heavier than the BW of the light hens (Table 7) as compared to 83 g difference when selected on EW. The average EP for the 10 wk was not significantly different when hens were selected based on BW or EW (Table 2). However, the average difference in EW between the light and heavy groups was 4.4 g when selected for BW as compared to 7.3 g when selected on the basis of EW (Table 2).
184 ENERGY FOR LAYING HENS Hens selected for the respective weight groups continued to produce significantly different amounts of EC regardless of whether they were selected on the basis of BW or EW (data not shown). When hens were selected on EW, the shell we+t (SW) of the medium hens was heavier than the SW of the hght hens (Table 2), and the SW was significantly heavier from the heavy hens than the SW from the medium hens. When the hens were selected for BW, the SW from the light group was significantly lower than SW from the other two groups. However, there was no difference in SW for the medium and heavy groups. FC was sigolficantly different among the three groups for hens selected on BW or hens selected for EW (Table 2). This difference was significant each week regardless of themethod of selection (not shown). The difference in FC resulted in increased energy intake (Tables 5 and 9) since all groups received the same feed. The major cause for the increased energy intake as the hens became heavier was result of the increased production of EC (Table 2) with increased BW. However, the heavy hens consumed more energy/g EC when selected on the basis of BW than was consumed by the light and medium groups (Table 6). There was no significant difference in the energy consumed/g EC when the hens were selected on the basis of EW (Table 10). This finding agrees with a previous report [ll]. Energy intake increased as EC increased. This consistency allowed all three groups to produce 1 g EC on approximately the same energy (Table 2), indicating that individual hens consume the feed to meet their individual energy needs. CONCLUSIONS AND APPLICATIONS 1. Egg production was not affected by selection of hens based on body or egg weight. 2. Egg weights were greater as body weight increased. 3. Feed and energy intakes were greater with each increase in egg content. 4. The energy required to produce 1 g of egg content was approximately the same for medium and heavy groups when selected for egg weight. The energy required to produce 1 g of egg content was always lower for the light group regardless of the basis of selection. 1. National Research Council, 1971. Nutrient Requirements of Poultry. 6th Rev. Edition. Natl. Acad. 2. National Research Council, 1977. Nutrient Requirements of Poultry. 7th Rev. Edition. Natl. Acad. 3. Harms, RE, C.R Douglas, RB. Christmas, B.L Damron, and RD. Miles, 1978. Feeding commercial layers for maximum performance. Feedstuffs 50(8):23-24. 4. National Research Councll, 1984. Nutrient Requirements of Poultry. 8th Rev. Edition. Natl. Acad. 5. National Research Council, 1994. Nutrient Requirements of Poultry. 9th Rev. Edition. Natl. Acad. 6. Quisenbcrry, J.H., J.W. Bradley, J.R Cathey, F.D. Thornberry, and SA Nag& 1967. J3cd wei t and laying Grformance. Pages 302-303 in: Proc. Lex 968 n. S. Agric. orkers (Abs). 7. Thornberry, F.D. and J.H. Quisenberry, 1968. The effects of pullet body we1 t at housing on laying hen performance. Poultry Si. z 71727 (Abs). REFERENCES AND Noms 8. Bell, D.D., 1968. Eighteen-week b weight and performance in caged layers. Poultry Sci.21655 (Abs). 9. Leeson, S. and J.D. Summers, 1987. Effect of immature body weight on laying performance. Poultry Sci. 66:1924-1928. 10. Harms, RH., P.T. Costa, and RD. Mil- 1982. Daily feed intake and rformance of laying hens according to their bzweight. Poultry Sci. 61:1O8?yg 11. Hams, RH. and G.B. Rnssell, 1996. Ability of commercial laying hens producing different egg outputs to meet their methionine and ene requirements when fed the same diets. Poultry Sci. 75%9-521. 12. Harms, RH., 1999. Modified laying hen feeding specifications takin into account energy:amino acid ratio. Feedstuffs 71(fl):l, 20-22. 13. Hy-Line International, West Des Moines, IA 50265. 14. SAS Institute, 1990. SAS User's Guide, Statistics. SAS Institute, Inc., Cary, NC. 15. Duncan, D.B., 1955. Multiple range and multiple P tests. Biometrics 111-42.