Abstract
The purpose of this study was to investigate oestrus synchronization efficiency and ram maturity effect on fertility of ewes of MIS sheep population during summer season. Research was performed on the experimental sheep farm of the Institute for Animal Husbandry in Belgrade, Serbia. The study included 70 crossbred ewes of MIS sheep population (Pirot Pramenka, Merinolandschaf and Ile de France breed) and 3 Ile de France rams (2 young, sexually unexperienced rams and 1 mature ram). Oestrus was synchronized in all 70 ewes using progestagen impregnated vaginal sponges (30 mg fluorogestone acetate) in combination with 500 IU PMSG. Ewes were mated with rams 48 h later. Obtained fertility and productivity results were as follows: lambing rate 57.14% (40/70), gestation length 147.11, litter size 1.82, stillborn rate 15.07%, birth weight of lambs 4.29 kg and body weight of lambs at 30 days of age 13.07 kg on average. Based on the results obtained in this study it was concluded that presented oestrus synchronization and mating protocol yielded lower than expected lambing rate. The effect of ram maturity on lambing rate was significant (P<0.05), as ewes mated to mature ram had higher lambing rate compared to those mated to two young unexperienced rams. Mature ram also had bigger litter size and higher stillborn rate, as well as lower birth weight of lambs.
Highlights
The use of exogenous hormones for oestrus synchronization is a common practice in intensive sheep farming
The effect of ram maturity on lambing rate was significant (P
Location and animals Research was performed on the experimental sheep farm of the Institute for Animal Husbandry in Belgrade, Serbia at the end of July and the beginning of Oestrus synchronization efficiency in ewes and ram
Summary
The use of exogenous hormones for oestrus synchronization is a common practice in intensive sheep farming. Progestagens are widely used to synchronize oestrus in sheep and usually result in greater than 90% of ewes in heat in a 24-hour period and conception rate of 70–. Fertility results achieved after hormone induced/synchronized oestrus vary depending on a number of factors, such as season, dose of PMSG used, fertilization method, body condition and physiology status of ewes. These are mostly female factors, but male factors, such as sperm fertility and libido, are important. It is difficult to determine exactly which factors, female or male, contribute to fertility results and in what amount, but both must be taken into consideration
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