191 The effect of high and low doses of follicle-stimulating hormone on embryo collection in Romanov sheep

Abstract

The use of embryo transfer in small ruminants has served as a way of increasing superior female genetics. This technique, although not new, has been adopted by an increasing number of breeders over the past few years. The Romanov sheep breed is considered a natural litter-bearing breed compared with other small ruminant species, which generally have only 1 or 2 offspring during a natural parturition. This experiment was designed to evaluate the effect of FSH dosage on embryo production and collection in Romanov sheep. Sheep donors (n = 12), with an average age of 2 ± 1.4 years and an average body weight of 43 ± 6.7 kg, were randomly assigned to either a high (175 mg) or low (140 mg) dosage treatment of FSH during the breeding season. Hormone injections were given in a decreasing dosage twice daily over a period of 5 days. Donors were naturally cycling before being subjected to a CIDR-G protocol for a period of 15 days, with hormone injections beginning on Day 11. Donors were mated with rams (n = 2) of known fertility for a total of 3 hand matings. After the third hand mating, the ram was turned into the breeding pen with the ewes. Embryos were collected 7 days after breeding and evaluated for transfer. A one-way ANOVA was utilised to analyse statistical differences between groups with significance set at (0.05). Results are given as mean ± s.e.m. Only embryos of quality grades 1 and 2 were transferred during this study. No differences were detected between the 2 groups for total embryos collected between both high (7.6 ± 6) and low (6.6 ± 5) FSH groups. Furthermore, no differences were detected between both high and low FSH groups for the number of embryos transferred (5.6 ± 5 and 6.3 ± 4, respectively). The results of this study suggest that a lower total dosage (140 mg) of FSH can be used in superovulation programs of Romanov ewes without affecting the total number of embryos collected and transferred. However, further investigation should be performed with various levels of FSH to determine the most accurate dosage for Romanov sheep.