Comparison of techniques for synchronisation of oestrus and subsequent fertility in beef cattle

Abstract

One hundred and seventy-eight heifers and 275 suckling cows were allocated to either a control (untreated) group or to one of three groups treated to synchronise oestrus. The treatments were eitheraprogestagen ear implant (SMB),aprogesterone intravaginal device (pRIO + PMSG), or two injections ofaprostaglandin analogue (pG). Progestagen treatments effectively synchronised oestrus with similar numbers ofanimals exhibiting oestrus within 2 days of treatment, as were observed over 21 days in the control group. The prostaglandin treatment was much less effective (control 79%, 5MB 72%, PRID + PMSG 71%, andPG 45%). Conception to timed insemination in the 5MB-and PGsynchronised heifers was lower than that obtained in the other treatments (control 33%, 5MB 17%,PRID + PMSG 33%, and PG 25%). In the suckling cows the conception rates of the progestagen-treated groups (48 and 50%) were better than that following PG (20%) with the controls (37%) intermediate. Plasma progesterone levels indicated that anoestrus was not the majorreason for the poor performance of the PGtreated cows. An additional group of 36 cows treated with progestagen and PMSG before Day 30 postpartum indicated some advantage from this procedure in reducing the interval from calving to A90039 Received 26 March 1990; accepted 20 June 1990 conception. Techniques based on the administration ofprogestagens appear to offer a practical means of synchronisingoestrus for artificial insemination (AI) in suckling beef cows.

Recent Developments in Oestrous Synchronization of Postpartum Dairy Cows with and without Ovarian Disorders

“…One of the major limitations of the use of prostaglandins to synchronize oestrus in dairy cows is the failure of the drug in anoestrous or non‐cyclic cows (Stevenson and Pursley 1994). Progestogens have the advantage that, besides improving oestrous synchronization, they also induce oestrus and ovulation in an acceptable percentage of anoestrous cows (Smith and Kaltenbach 1990; Fike et al. 1997).…”