Supplementation of dairy cows with docosahexaenoic acid did not affect ovarian activity

The effect of docosahexaenoic acid (DHA) on ovarian activity of dairy cows was determined. Experimental cows (n = 25) were fed a total mixed ration supplemented daily with 100 g/cow of an algae product All-G-Rich (Alltech, Ireland) containing 10% DHA divided into 2 doses for 52 days. Determination of DHA from milk samples taken from all cows was performed before the All-G-Rich supplementation (on Day 0, D0), and on D21 and D42 of algae supplementation. Cows were synchronized to be in oestrus on D21 and D42 of the experimental period. Monitoring of ovarian activity was performed by transrectal ultrasonography. Examinations were performed at 2-3-day intervals from D0 until D52 of the experimental period. Plasma concentrations of progesterone, oestradiol, insulin, NEFA, and cholesterol were determined. Control cows (n = 25) were examined in the same way as the experimental cows. Milk DHA concentrations on D21 and D42 were significantly higher in treated cows (D21 1.38 vs 0.28, P < 0.0001; D42 1.34 vs 0.20, P < 0.0001). There were neither important effects of DHA on ovarian structures, nor on evaluated variables in plasma. Cows in the experimental group tended to have larger corpora lutea and higher cholesterol concentrations, but differences were not significant.