Components of reproductive wastage in different systems of sheep production with particular reference to lamb mortality
1982
Omowumi, Olatunji Ajao. | Miller, Keith | Blewett, David
The literature on sources of loss in the reproductive cycle of sheep is reviewed in order to obtain data on the reported levels of losses throughout the world. The various factors that influence the level of reproductive performance and the causes of loss at every stage of the reproductive cycle are considered. Infertility as indicated by the incidence of barreness in the flock, was most commonly reported to be in the range of five to ten percent, whereas lamb mortality rates commonly ranged between ten and fifteen percent. Abortion and adult mortality were usually insignificant sources of loss. The House O’Muir flock belonging to the East of Scotland College of Agriculture was chosen for particular study and the production records over the period 1973—1982 were critically analysed. The flock consists of half-bred ewes crossed with Suffolk rams, over-wintered indoors and maintained at pasture for the rest of the year. The levels of reproductive loss were compared with those reported in the literature. It was concluded that lamb mortality is usually the main component of reproductive loss and that faulty management, especially poor nutrition of the ewes and lambs is as important as any other factor as a cause of poor lamb survival. Certain aspects of on-farm flock recording of factors related to reproductive losses are discussed and attention is drawn to the problems of reproductive losses in sheep in the humid and arid tropics.
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