Effect of fish oil supplementation and forage source on Holstein bulls performance, carcass characteristics and fatty acids profile

AbstractThirty-six Holstein bulls (initial body weight, 345 ± 61 kg) were randomly assigned to six dietary treatments with a 2 × 3 factorial arrangement, with two levels of AH (alfalfa hay) (10 and 20% of AH) combining with three levels of FO (fish oil) (0, 1 and 2.1% of DM) to investigate the effects of AH proportion and FO supplementation on performance, carcase characteristics, and meat fatty acids profile. DMI (dry matter intake) (kg/day) was lower (p < .01) for high (8.0) than for low (8.7) AH. Highest level of FO reduced DMI (p < .01) regardless of AH level. Dietary inclusion of FO increased the concentration of VA (p < .01), CLA (p < .01) and n-3 (p < .01) fatty acids which subsequently reduced n-6: n-3 (p < .01). The results indicate that AH can be replaced by corn (zea mays) silage to mitigate the detrimental effect of supplemented fat on dry matter intake. Moreover, FO can be supplemented to feedlot diet to enrich ruminant products without deleterious effects on carcase characteristics.