Effects of dietary crude protein on slaughter yield of selected broiler stocks
Languages of publication
The objective of this paper was to determine the differences in yield and body composition between a commercial strain (COM) and a weakly selected strain (FR) of broilers at two slaughter ages on diets differing in protein content. There were 306 males reared on litter floor pens, fed ad libitum, and randomly assigned to 16 pens in a 2 x 2 factorial design with 4 repetitions. The diets were HP (high protein): 20.5% protein to 6 weeks of age and 16.9% from then on; LP (low protein): 16.9% protein all the time. At 50 and 71 days, four broilers from each pen were taken at random, fasted, killed, slaughtered and the following weights were recorded: live weight, eviscerated carcass, abdominal fat, feathers, blood, small intestine, large intestine, gizzard, proventriculus, liver, breast, thighs and heart. Analyses of variance for traits and for their proportions to live weight were done. The model included genotype, diet, genotype x diet and replicate. The genotypes differed in live weight and growth patterns, COM showing a higher proportion of commercial cut weight and FR a higher digestive organ and relative feather weight at older ages. The low protein diet affected COM genotypes more than FR genotypes, probably because there was a difference in protein requirements.
Publication order reference
J.E. Melo, Animal Production Department, Faculty of Veterinary Sciences, University of Buenos Aires, Chorroarin 280 (1427) CF, Argentina.