| Popis: |
Two 49-d winter pen trials using straight-run Ross x Ross broiler chickens at 0.667 ft 2 /bird (0.062 m 2 /bird) were conducted on new litter to compare the efficacy of commercial mannan oligosaccharide (MOS) as an alternative growth promoter to bacitracin methylene disalicylate (BMD) followed by virginiamycin (VM). Feed phases were 0 to 21, 21 to 42, and 42 to 49 d. In experiment 1, treatment effects were nonsignificant at 21 d. At 49 d, BMD (55, 55, or 27.5 ppm) or MOS (1,000, 500, or 500 ppm) significantly (P < 0.05) improved body weight and feed conversion ratio and increased feed expense per bird and net income (live value minus feed expense) per bird, without affecting mortality, compared with the unsupplemented negative control (nCON). In experiment 2, there were 6 dietary treatments: 1) nCON; 2) BMD (27.5, 55 ppm), VM (11 ppm); 3) MOS (1,000 ppm), BMD (55 ppm), VM (11 ppm); 4) BMD (27.5, 55 ppm), MOS (500 ppm); 5) MOS (1,000, 500, 500 ppm); and 6) BMD + MOS, VM + MOS. The BMD + MOS, VM + MOS shuttle program gave best body weight, feed conversion, and mortality at 21 and 49 d of age resulting in the lowest feed expense and highest net return per bird. It was concluded that MOS supported live performance equivalent to BMD followed by VM and had an additive effect when combined with the antibiotics. |
