(P-274) Effect of short and long-term oestrus synchronisation protocols in Merino ewes during non-breeding season

Abstract Authors: Fhulufhelo V. Ramukhithi¹; Khoboso C. Lehloenya²; Nhlakanipho S. Zulu²

1. Agricultural Research Council, Germplasm Conservation and Reproductive Biotechnologies, South Africa

2. University of Zululand, Department of Agriculture, South Africa

Abstract Text: The aim of the study was to compare the effect of short and long-term oestrus synchronisation protocols and their combination with or without equine chorionic gonadotropin (eCG) on hormonal levels, oestrous response, onset and duration of South African Merino ewes during non-breeding season. Seventy-six (76) South African Merino ewes aged between 2–5 years were divided into 2 groups (36 for short-term and 40 for long-term oestrus synchronisation protocols). In the short and long-term progesterone treatment groups, controlled internal drug release devices (CIDR) were inserted for 11 and 14 days, respectively. At withdrawal of CIDR, half of each group were injected intramuscularly with 300 IU of eCG. Blood samples were collected to measure the levels of progesterone and oestradiol. Ewes treated with both short or long-term progesterone combined with or without eCG resulted in the same oestrus response, onset and duration. The levels of progesterone hormone were the same at CIDR insertion, removal and 48 hours post CIDR removal. However, oestradiol hormone was significantly higher at CIDR removal and 48 hours post CIDR removal than at insertion in all treated groups. Therefore, it can be concluded that oestrous synchronisation protocols of both short and long-term progesterone combined with or without eCG during non-breeding season can be used to synchronise oestrus of South African Merino ewes during non-breeding season.