A new perspective in perinatal lamb mortality

Abstract

Perinatal lamb mortality is one of the most important factors limiting the biological and economic efficiency of sheep production systems worldwide. The losses derive not only from the death of animals but also from the greater use of forage and less production of wool from the pregnant sheep, as well as from the lesser number of animals available for selection. In Uruguay, the average perinatal mortality figure is estimated at 20% of lambs born, with a variation from 14 to 32% depending on the years and the properties. Similar losses occur in Australia, New Zealand, South Africa and other countries with significant sheep production. It is significant that these levels of losses have not changed substantially in recent decades despite the efforts made by researchers, extensionists, and producers. Under extensive production conditions, mortality is difficult to decrease beyond 10%. For these reasons, many experts consider that perinatal mortality in sheep is a frustrating and unsolvable problem. The results suggest that to decrease perinatal mortality, greater emphasis should be placed on the ease of calving of the sheep and/or on the biotype of the lambs, either by selecting new biotypes or incorporating new genetic lines. In conclusion, the perinatal mortality of lambs is a still open problem that requires new lines of research.