Effect of type and quantity of concentrates on superovulation and embryo yield in beef heifers.

摘要

Heifers received grass silage as the basal diet plus barley (3 kg daily or ad lib; 20 and 19 animals respectively), or citrus/beet pulp (3 kg daily or ad lib; 18 and 19 animals). In heifers given the 3 kg supplements, silage was given ad lib, but inthose given ad lib supplements, silage was restricted to 1 kg (dry matter basis) daily. After 100 days, the heifers were given an intravaginal progesterone-releasing device for 7 days, and superovulation was carried out 60 h before removal of the device. The superovulation treatment comprised 265 mg FSH given as 12 injections at 12-h intervals, the last 2 injections being given 12 and 24 h after removal of the intravaginal device. Insemination was carried out 56 and 72 h after device removal. The heifers were slaughtered 6, 7 or 8 days after the 1st insemination for recovery of embryos. Superovulatory responses were significantly greater in heifers given 3 kg supplements than in those given ad lib supplements, but there was no significant difference between the barley and citrus/beet pulp supplements. The number of transferable embryos produced was significantly greater in heifers given 3 kg supplements than in those given ad lib supplements. Heifers given citrus/beet pulp produced significantly moretransferable embryos than heifers given barley.