Effect of biotin supplementation on milk yield of Girolando cows reared in a tropical climate.

The objective of this study was to evaluate the effect of biotin supplementation on milk yield and the reproductive efficiency in Girolando cows. The study was conducted on a dairy farm located in central Brazil, between April 2012 and December 2016. Thirty-six Girolando cows in their first lactation were used. The cows were distributed in two treatment groups, each with equivalent weight distributions. Control treatment (CT) cows (n = 18) received a diet without any supplemental biotin, whereas biotin treatment (BT) cows (n = 18) received a diet supplemented with 20 mg/day of biotin during lactation. Biotin supplementation caused a significant increase (p = 0.001) in milk yield in the second lactation, and a trend (p = 0.09) toward higher average production during the three lactations was evaluated. There was no statistically significant difference between the treatments in terms of reproductive efficiency. In conclusion, biotin supplementation (20 mg/day) during lactation for Girolando cows reared in a tropical climate is able to increase milk yield, but does not improve reproductive efficiency.