A short note: lack of effect of post-AI hCG or GnRH treatment on embryonicmortality in dairy cattle

The aim of the present trial was to test the effects of two treatments in d airy cows, in an attempt to sustain the circulating progesterone levels and hence possibly reduce the embryonic mortality rates. Treatment 1 consisted of a 3000 IU hCG i.m. injection at day 4 (D4) after artificial inseminatio n (AI) and treatment 2 of a GnRH i.m. injection (Buserelin, 10 mug) on day 12 after AI (D12). A set of 156 Holstein females from the same herd were as signed to one of the four treatments: hCG D4 (n = 52), placebo D4 (n = 25), GnRH D12 (n = 52), placebo D12 (n = 27). They were served for the first. s econd or third time or more and monitored regularly via a herd fertility su rvey. Pregnancy status was assessed by rectal palpation at day 45 after Al. The overall mean pregnancy rate (PR) was 42% and there was no significant difference between treatment groups or between ranks of Al (P > 0.05). Thes e data show that stimulation of luteal function following ovulation and Al did not result in any reduction of the embryonic mortality rates. (C) 2001 Elsevier Science BY. All rights reserved.