Investigating the Impact of Quebracho Tannins Supplementation on Productive and Reproductive Efficiency of Dairy Cows

This study was conducted to investigate effects of supplementing two doses of que-bracho tannins
(QT; 100 or 200 g/cow/d; QT100 or QT200) pre and post parturition to thirty Holstein dairy cows on Dry
Matter Intake (DMI), milk yield and composition, blood metabolites and reproductive performance for
12 weeks. There were no significant changes in DMI due to QT at transition period of dairy cows. QT
supplementation at either level decreased (P < 0.004) milk yield, Fat Corrected Milk (FCM) and Feed
Efficiency (FE; P < 0.016) compared to untreated dairy cows. The supplementation of QT had no
significant effect on milk fat, lactose percentage and protein and solid nonfat (SNF) yield, while protein
percentage increased significantly in treated compared to control cows. Treatment time had significant
effects on milk composition. The only time × treatment interactions were found on milk fat and protein
percentages. Supplementation with QT tended to decrease (P > 0.05) the total number of ovarian
follicles, number of large follicles, diameter of largest follicle, number of small follicles, number and
diameter of corpus luteum, and progesterone concentration. The inclusion of QT increased days open
and number of services per conception, which consequently decreased conception rate, compared to
the control cows. QT100 decreased (P < 0.05) serum total protein, globulin, glucose and triglycerides
concentrations as compared with their values in control cows. Thus, the supplementation of
commercial QT to dairy cows at their transition period had negative impacts on productive and
reproductive performance. More experiments using different proportions of RDP and RUP for specific
judgment on the impacts of commercial QT in ruminant diets are warranted to be done.