Effects of a rumen protected B vitamin blend substituted for biotin upon milk production and component yield in lactating dairy cows

Abstract

Results from 4 switchback field trials involving 608 cows were combined to assess the effects of a protected B vitamin blend (BVB) vs 10 mg of unprotected biotin upon milk yield (kg), fat %, protein %, fat yield (kg) and protein yield (kg) in primiparous and multiparous cows. Trials consisted of 3 DHIA periods executed in the order control-test-control. Cows from 45 to 300 days in milk (DIM) at the start of the experiment that were available for all 3 periods were included in the analysis. No diet changes other than the substitution of 3 grams/cow/day of the BVB for 10 mg of biotin during the test period occurred. Results from the two control periods were compared to results obtained during the test period by individual cow using a paired T test. Results for all cows showed that the provision of the BVB resulted in increased (P<0.05) milk, fat percentage (%), protein %, fat yield and protein yield. Analysis by age revealed that milk production and milk protein yield were only improved in mature cows. Milk production had a negative effect upon the magnitude of the increase in milk components. The change in milk yield was greatest in early lactation and declined with DIM. Protein % and fat % increased with DIM in mature cows, but not in first lactation cows. Differences in fat yields between test and control feeding periods did not change with DIM, but the improvement in protein yield in mature cows declined with DIM. These results indicate that the BVB provided economically important advantages throughout lactation beyond those witnessed with biotin, but expected results would vary with cow age and stage of lactation.