Two trials were carried out to investigate the need for supplemental biotin in the diet of weanling pigs when high dietary copper is used as growth promoter. Wheat - soybean meal based feeds, containing marginal levels of biotin (.10 ppm) were supplemented or not with .4 ppm biotin (BIO) and 250 ppm copper (COP). The diets were fed to 168 piglets weaned at 4 weeks of age with an average weight of 7.8 kg. The trials were conducted for 5 weeks. In trial 1 there was a BIO x COP interaction (P < .05) for weight gain; BIO resulted in a 10% improvement in gain in absence of COP, but not when COP was present; COP resulted in a 16% improvement in absence of BIO and no improvement when BIO was present. There was also a main effect of COP on feed efficiency (P < .05), resulting in a 7% improvement. A similar tendency was observed in trial 2, but the differences were not significant (P > .05). The combination of supplemental BIO and COP did not result in further improvement in performance compared to the individual supplementation.
copper; biotin; weanling pigs
