Effects of dietary biotin supplementation on performance and hoof quality of Chinese Holstein dairy cows

The objective of study was to determine the effects of supplemental biotin on lactation performance and hoof quality in dairy cows. Forty-five multiparous Chinese Holstein dairy cows (4076 d in milk) were randomly divided in three groups according to parity, previous lactation milk yield and days in milk. The experimental diets were identical for three treatments except for the level of biotin: 0, 20 and 40 mg/d, respectively. The experiment lasted for 70 d including the first 10 d for adaptation. Milk was sampled weekly and blood samples were taken from coccygeal vein biweekly. Hoof quality was assessed by hardness test, moisture content and light-microscopic examination of hoof structure. Dry matter intake was not different significantly across treatment groups. Milk yield was increased by supplementation of 20 or 40 g biotin per day to 35.3 kg/d from 32.7 kg/d in non-supplementation group. There were no significant differences in milk fat percentage and yield, lactose, total solid in milk, and concentrations of glucose, triglyceride, nonesterified fatty acid in plasma among three groups. Concentrations of milk protein and milk urea nitrogen in 40 mg/d group were higher than those in control, with no significant difference between 20 and 40 mg/d or control groups. However, protein yield was increased linearly by supplementation of biotin with the highest value at 40 mg/d group, mainly attributed to the increased milk protein content. Biotin concentration in plasma was higher in biotin-added groups than in the control. Biotin supplementation did not have effect on moisture content and hardness of hoof, but made hoof more compact than control group. In summary, supplemental biotin increased milk and milk protein yields, with no significant difference in milk performance and hoof quality between supplemental levels of 20 and 40 mg biotin per day. & 2012 Elsevier B.V. All rights reserved.