Body composition of broiler chickens from hatch to 35 days

Abstract

Animal Production in Australia 1998 Vol. 22 BODY COMPOSITION OF BROILER CHICKENS FROM HATCH TO 35 DAYS FOR MODEL PREDICTION S. DUAN-YAIA, B. A. YOUNGA, J. A. COUTTSB and J. B. GAUGHAN A B A Dept of Animal Production, The University of Queensland (Gatton), Lawes, Qld 4345 Rural Extension Center, The University of Queensland (Gatton), Lawes, Qld 4345 Body compositions of broiler chickens at final weight are commonly reported. However, for system simulation, there is at present a lack of data on the weekly changes from hatch. Data developed 15-20 years ago are also inappropriate for the current situation due to genetic change (Perreault and Leeson 1992). The aim of this study was to obtain data for a better understanding in body development of broilers and a more reliable basis for model prediction. The experiment was undertaken during February to March 1997. Data were observed from three strains of commercial broilers (Ingham, Cobb and Steggle). Twenty chickens of each strain were reared in each cage at the density of 0.034 m2/bird from day old. Chickens were fed a commercial starter diet for the first 21 days and a grower diet for the last 14 days. The starter and grower diets contained 26.7 and 23.8% protein and 11.7 and 12.5 MJ ME/kg respectively. Feed and water were supplied ad lib. At day old and then every seven days, two chickens from each strain were randomly selected and starved for four hours prior to killing in a CO2 chamber. Liveweight, feather, visceral organs (alimentary tract, liver and heart), eviscerated body and cut up weight were recorded. The cut up parts resulted in two drumsticks, two thighs, two wings, two feet, neck, head, and the rest as breast and back. Statistical analysis was carried out using ANOVA and Duncans Multiple Range Test. On the liveweight basis, the percentage contributions of all portions were found to change significantly with age (P<0.01) . The mean values for these characteristics are shown in Table 1. Table 1. Changes in body composition of broiler chickens from hatch to 35 days of age day 0 Liveweight starved (g) % LW starved Feather Visceral organs Eviscerated body Drumsticks Thighs Wings Neck Head Feet Breast and back Breast meat 38 2.6 30.3 67.1 8.6 15.7 4.6 6.3 13.7 5.3 11.7 1.7 a a a a a a a a a a a a day 7 170 b a day 14 371 c b day 21 710 d bc day 28 1127 c e day 35 1679 f 2.0 b 24.3 b 73.7 a 8.8 b 18.5 b 6.8 b 5.0 b 6.3 ab 4.6 b 21.8 b 7.8 3.5 c 19.6 c 76.9 b 9.1 bc 18.7 c 7.8 a 6.0 c 4.8 bc 4.8 b 23.8 c 10.2 3.7 d 17.8 cd 78.5 bc 9.8 cd 19.1 d 8.5 b 4.5 d 3.6 bc 4.5 c 27.5 d 11.3 4..3 de 16.6 d 79.1 bc 9.7 d 20.3 d 8.7 b 4.6 de 3.1 bc 4.7 c 27.2 d 11.5 5.5 e 14.9 d 79.6 c 10.1 d 21.0 d 8.5 b 4.4 e 2.8 c 4.3 c 27.6 e 13.5 d Mean within the same row with different superscripts are significantly different (P<0.01) The result from this study indicated an increase over time in the proportion of economic cut up parts (drumsticks, thighs, wings and breast meat). The proportion of other hand decreased, similar to the result reported by Iji and Tivey (1997) from work strain. It is concluded that data on body composition based on final weight could not early ages. IJI, P.A. and TIVEY, D. R. (1997). Proc. Aust. Poult. Sci. Sym. 9, 171-174. PERREAULT, N. and LEESON, S. (1992). Can. J. Anim. Sci. 72, 919-929. eviscerated body and visceral organs on the on the Steggle x Ross represent value at the 333