The removal of subtherapeutic doses of antibiotics, previously used to increase body weight (BW) gain and decrease mortality, may alter fat composition. Slower growing pigs produce fat with a greater calculated iodine value (IV) compared with faster growing pigs. However, there is little information regarding the effects of antibiotic-free diets on fat composition and belly quality. The objective of this trail was to compare growth performance, belly characteristics, and bacon slicing yields of growing-finishing pigs fed a subtherapeutic dose of an antibiotic, a natural antimicrobial, or a diet containing no antibiotics or antimicrobials. Barrows and gilts (96 each) of 27.52 ± 3.98 kg of initial BW were housed in 48 pens (8 replications per treatment) in a 2 × 3 factorial randomized complete block design. Pens were assigned 1 of 3 diets: antibiotic free, oregano or tylosin phosphate. Pigs were slaughtered at an average BW of 127.31 ± 10.18 kg.
There were no differences among dietary treatments for growth performance, carcass cutability, loin quality, fresh belly dimensional characteristics, IV or bacon processing characteristics. It is possible that both the high health status of the herd used in this study and the small pen size influenced the results and the lack of differences observed may not be representative of commercial conditions and growth performance of pigs under those conditions. Given the lack of differences carcass composition, meat quality and further processed meat quality from pigs fed diets without antibiotics, the prohibition of antibiotics as growth promoters should not result in changes in pork quality for processors or consumers.
Lowell, J. E., Bohrer, B. M., Wilson, K. B., Overholt, M. F., Harsh, B. N., Stein, H. H., Dilger, A.C., and Boler, D. D. (2017). Growth performance, carcass quality, fresh belly characteristics, and commercial bacon slicing yields of growing-finishing pigs fed a subtherapeutic dose of an antibiotic, a natural antimicrobial, or not fed an antibiotic or antimicrobial. Meat Science, 136, 93-103. https://doi.org/10.1016/j.meatsci.2017.10.011