Effects of immunisation with polyandroalbumin (Fecundin), pasture allowance, post-mating shearing, and method of synchronisation on reproductive performance of Romney and Marshall Romney ewes

Abstract

Abstract Mature Marshall Romney (MR) and control Romney (CR) ewes were used in a factorial experiment to determine the effects of immunisation with polyandroalbumin (Fecundin; Glaxo N.Z. Ltd) on reproductive performance of ewes on low or moderate pre-joining pasture allowances (0.8 and 3.0 kg green DM per ewe per day respectively). Comparisons were also made of the effects of shearing 10 days post-mating on reproductive performance and the effects of using CIDRs (controlled internal drug release dispensers) compared wlth sponges for the synchronisation of oestrus. Age and strain of ewes had no effect on the increase in ovulation rate or multiple births following immunisation. Immunisation with Fecundin increased ovulation rate by the same amount for ewes on the two pasture allowances (34–35%), and there was a 16–19% increase in ewes lambing multiples. The increase in pasture allowance from 0.8 to 3.0 kg green DM per ewe per day was associated with a 20% increase in ovulation rate and an 18% increase in ewes lambing multiples. Sheanng post-mating had no effect on the reproductive performance of the ewes. Ewes treated with the CIDRs had an earlier onset of oestrus than ewes treated with sponges. Over the first 10 days, fewer of the ewes treated with CIDRs were mated (87 v. 94%) as a result of a higher loss rate of the CIDRs (6.3%) compared with sponges (0.8%).