Effect of Lactation Yield on First Follicular Wave Surge After Calving of Crossbred Dairy Cattle

Abstract

Abstract: This study aimed to evaluate the effect of lactation on first follicular wave surge of crossbred (Gir x Holstein) dairy cattle. Nine multiparous crossbred dairy cattle were divided according to daily milk production (Group 1 = milk production higher than average, n = 5; Group 2 = milk production lower than average, n = 4). From calving (Day 0) until divergence of first follicular wave, ovaries was monitored daily by ultrasound exams to observed the follicular emergence, growth rate, maximum follicular diameter, day of follicular divergence and ovulation. The mean of milk production was 17.4 + 6.4 L/day (n= 9). Group 1 had higher daily milk production than Group 2 (21.8 + 3.8 L/day vs. 11.9 + 3.9 L/day, P< 0.001). Data of follicular emergence were similar in both groups (P >0.05). The growth rate of first follicular surge was higher in Group 2 than Group 1 (2.0 + 0.0 mm/day vs 1.2 + 0.6 mm/day, P< 0.05). The maximum follicular diameter was 11.6 + 0.9 mm (Group 1) and 13.5 + 1.7 mm (Group 2); P< 0.05. The follicular divergence occurred earlier in Group 1 than Group 2 (12.2 + 0.8 days vs 13.7 + 0.6 days; P< 0.05). One animal of Group 2 ovulated. In conclusion, data suggested that milk production had influence on ovarian follicular dynamic after calving.Keywords: Follicle, post-partum, lactation, dairy cattle