The impacts on broiler performance and yield by removing antibiotic growth promoters and an evaluation of potential alternatives

摘要

Three experiments were conducted to evaluate the impacts of removing antibioticgrowth promoters (AGP) on broiler performance and yield and to evaluate alternativeproducts as potential replacements. In experiment one, approximately 552,000 broilerswere reared in four solid-wall, tunnel ventilated houses that were divided into twopaired-house facilities, each assigned one of two dietary treatments. The treated groupreceived basal diets containing salinomycin (SAL), roxarsone (ROX) and AGP, whilethe control group received the same diets without ROX and AGP. Removal of ROX andAGP had no affect on average body weight and feed efficiency, while livability wassignificantly affected negatively by the removal of ROX and AGP. Tender, wing, drumand percentage of total white meat showed significant improvements in yield during thestudy, while all other parts were not affected by removal of ROX and AGP.In experiment two, an investigation was conducted to evaluate the effects onperformance 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 dietssupplemented with B. subtilis spores, while the control group was fed the same basaldiets containing an AGP. Feed conversion ratio was significantly lower for the treatmentgroup, while average body weight, coccidiosis lesion scores, and footpad scores were notaffected by the treatments.In experiment three, 6,000 broiler chickens were equally divided among fourtreatment groups and reared to 49 d to determine the effectiveness mannanoligosaccharides (MOS, Bio-Mos?, Alltech, Nicholasville, Kentucky, USA) as analternative for an AGP program and MOS plus Natustat? (NAT, Alltech, Nicholasville,Kentucky, USA) as an alternative to an enteric health program (AGP+anticoccidialdrug). Average body weight for the control (CON) and antibiotic (ANT) groups wassignificantly different from the MOS+NAT group, but not the MOS group. Carcass fronthalf, carcass hind half, frame and skin yields were improved for all treatments whencompared to the MOS+NAT group. Conversely, percent total white meat yield wasimproved 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 ofcommercial broiler chickens does not affect the performance and yield of the birds overa one year production period. Furthermore, B. subtilis spores and mannanoligosaccharides provide acceptable alternatives to an AGP program.