Comparative Evaluation of Organ Weights and Breast Meat Yield of Commercially Reared Broiler Chickens on Conventional and Alternative Feeding Programs

There are concerns that antibiotics used in human medicine are no longer as effective in the treatment of disease due to the perception of overuse in animal agriculture. Consequently, the agricultural industry must identify alternative feeding strategies that do not rely on antibiotics. Overall health and performance in response to elimination of antibiotics has been reported but the physiological response to elimination as a component of commercial feeding programs remains unclear. The objective of this study was to evaluate the impact of different antibiotic regimes on organ weight and breast meat yield in commercially reared broilers. Parameters were compared between barns allocated to conventional, antibiotic-reduced or antibiotic-free (RWA) programs across Ontario. At 28 days of age, 288 clinically normal broilers were euthanized over 4 consecutive quota periods and body weight, organ weights and breast yield evaluated. Data was analyzed to ensure residuals were normally distributed and an analysis of variance was conducted on the effects of treatments over time (Proc Glimmix, SAS 9.4). Feeding program did not (P>0.05) impact body or organ weights (gizzard, proventriculus, spleen, small intestine, and bursa). Breast yield (P=0.006) was significantly lower (-13%) for RWA birds compared to the other programs. Crop (P=0.03) and liver weight (P=0.03) were significantly larger in birds on the RWA program. In conclusion, reduction of breast yield in RWA birds may be due to reduced amino acid availability, moreover, RWA birds may be exposed to higher levels of antinutritional factors and pathological conditions leading to changes in organ structure and function. Additional investigations are required to quantify the differences throughout a broiler’s life cycle to determine the impact on overall growth performance and economics. 

Key words: broiler, antibiotics, organ weights, breast yield.

Published in the proceedings of the Animal Nutrition Conference of Canada 2020. For information on the event, past and future editions, check out https://animalnutritionconference.ca/.