The influence of vaccination with Fecundin and supplementation with lupin grain on the reproductive performance of Merino ewes in Western Australia

The reproductive performances of groups of 4-6-year-old medium wool Merino ewes that were vaccinated with Fecundin and/or fed sweet lupin grain prior to and during the early part of the joining period were compared with untreated ewes over 2 years. The rams were joined with the ewes in early January of each year. In both years the Fecundin and lupin treatments increased ovulation rates (between 0.13 and 0.56) and the incidence of multiple pregnancies (between 1 and 36%). The proportions of lambs born following treatment with Fecundin were larger than those from the ewes fed only lupins. When the treatments were combined, there were no increases in lambs born above that of Fecundin alone. Pregnancy significantly depressed wool production from individual ewes, while those with more than 1 lamb produced less wool than those with only 1 lamb. However, the average quantity (4.6 kg greasy) and quality of wool produced by the ewes each year was similar for all groups, indicating that the variation in the incidence of multiple pregnancies had not affected flock wool production. The average rate of growth of the progeny from marking to weaning was also similar for each group (191 and 238 g/head.day for years 1 and 2, respectively) even though there were more multiple-born lambs in the Fecundin-treated groups. On a flock basis, it would appear that the nutritional conditions experienced during this study were adequate to avoid significant penalties associated with multiple pregnancies.