Effects of Prepartum L-Tryptophan Supplementation on the Postpartum Performance of Holstein Cows.

Simple Summary: The peripartum period is a challenging phase in the production of dairy cattle. Tryptophan is an essential amino acid in animals and has a variety of physiological functions. This study examined the effects of L-tryptophan supplemented to Holstein cows during the prepartum period on the postpartum performance. We found that L-tryptophan supplementation in the prepartum period significantly improved the reproductive, antioxidative and anti-inflammatory performance of cows compared to the controls. All these lead to the improved quality of colostrum and milk yield, indicating a healthy transition of the cows from their prepartum to postpartum status. The negative energy balance occurring in the periparturient period of cows will impede their health and postpartum performance. To target this issue, L-tryptophan was supplied to the prepartum cows. The results showed that L-tryptophan supplementation significantly increased the serum melatonin level and was accompanied with increases in SOD activity, IL-10 and colostrum IgA levels as well as decreases in MDA and IL-6 levels compared to the control cows. The incidence of postpartum diseases was significantly lower and the pregnancy rate was significantly higher in cows fed L-tryptophan than in the control group. A striking observation was that prepartum L-tryptophan supplementation not only improved the milk production but also the quality compared to the control cows. In general, supplementation with L-tryptophan in the prepartum period can improve the postpartum reproduction and lactation performance of cows to some extent. [ABSTRACT FROM AUTHOR]