The Impacts on Broiler Performance and Yield by Removing Antibiotic Growth Promoters and an Evaluation of Potential Alternatives

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Three experiments were conducted to evaluate the impacts of removing antibiotic growth promoters (AGP) on broiler performance and yield and to evaluate alternative products as potential replacements. In experiment one, approximately 552,000 broilers were reared in four solid-wall, tunnel ventilated houses that were divided into two paired-house facilities, each assigned one of two dietary treatments. The treated group received basal diets containing salinomycin (SAL), roxarsone (ROX) and AGP, while the control group received the same diets without ROX and AGP. Removal of ROX and AGP had no affect on average body weight and feed efficiency, while livability was significantly affected negatively by the removal of ROX and AGP. Tender, wing, drum and percentage of total white meat showed significant improvements in yield during the study, while all other parts were not affected by removal of ROX and AGP. In experiment two, an investigation was conducted to evaluate the effects on performance from feeding Bacillus subtilis spores (Gallipro®, Chr Hansen A/S, Denmark), as a direct-fed microbial additive, to commercial broiler chickens. Birds were divided among two paired-house facilities. The treatment group received basal diets supplemented with B. subtilis spores, while the control group was fed the same basal diets containing an AGP. Feed conversion ratio was significantly lower for the treatment group, while average body weight, coccidiosis lesion scores, and footpad scores were not affected by the treatments. In experiment three, 6,000 broiler chickens were equally divided among four treatment groups and reared to 49 d to determine the effectiveness mannan oligosaccharides (MOS, Bio-Mos®, Alltech, Nicholasville, Kentucky, USA) as an alternative for an AGP program and MOS plus Natustat™ (NAT, Alltech, Nicholasville, Kentucky, USA) as an alternative to an enteric health program (AGP+anticoccidial drug). Average body weight for the control (CON) and antibiotic (ANT) groups was significantly different from the MOS+NAT group, but not the MOS group. Carcass front half, carcass hind half, frame and skin yields were improved for all treatments when compared to the MOS+NAT group. Conversely, percent total white meat yield was improved with the inclusion of MOS when compared to the ANT group. The findings of this research suggest that the removal of AGP from the diets of commercial broiler chickens does not affect the performance and yield of the birds over a one year production period. Furthermore, B. subtilis spores and mannan oligosaccharides provide acceptable alternatives to an AGP program.


Bray, Joey L. The impacts on broiler performance and yield by removing antibiotic growth promoters and an evaluation of potential alternatives. PhD diss., Texas A&M University, 2008.



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