Feeding supplemental niacin for milk production in six dairy herds

Six dairy farms representing 300 lactating dairy cows were used to assess effects of feeding 6 g of supplemental niacin during the first 10 wk of lactation. Means for niacin and control cows for 10 wk postpartum were 31.2 and 31.1 kg/day milk, 3.7 and 3.6% milk fat, and 30.3 and 30.2 kg/day 4% fat-corrected milk. A scoring system with 1 to 5 scale was utilized to measure body condition of dairy cows at parturition. Average body condition score for niacin and control cows at calving was 3.1. High producing heifers in first lactation receiving niacin (greater than 28 kg/day of milk) produced more milk than controls (31.8 compared to 30.2 kg/day). Thin cows (body condition score 2) receiving niacin produced less milk than controls with a body condition score of 2 (27.0 compared to 30.7 kg/day). Analyzing body condition scores 3 and 4 revealed no difference of milk production for niacin and control groups; however, milk production increased as scores for body condition increased.