A comparison of the reproductive performance of ewe lambs and mature ewes

Abstract

This work compared the reproductive performance of ewe lambs and mature ewes and the growth of their lambs from birth to weaning under conditions in which they had been managed as a single group. Two studies were conducted; the first study, conducted in 2007, included 307 multiparous mature ewes and 297 primiparous ewe lambs and the second study, conducted in 2009, included 399 multiparous mature ewes and 400 primiparous ewe lambs. Physical measures of ewes and lambs were recorded as was their behaviour within 12h of birth in study one. Ewe lambs were lighter (P<0.05) than mature ewes throughout pregnancy and lactation. However, the total live weight gained during pregnancy was similar (P>0.05). Lambs born to ewe lambs were smaller (P<0.05) and lighter (P<0.05) than their birth rank contemporaries born to mature ewes. However, single lambs born to ewe lambs and twin lambs born to mature ewes had similar birth weights and growth to weaning. Lamb survival rates were lowest (P<0.05) for lambs born to ewe lambs although in study two, singleton lambs born to ewe lambs had similar survival rates to both singleton and twin lambs born to mature ewes. This study identified that the limitations to ewe lamb breeding were that they produced smaller, lighter lambs with lower survival rates to weaning and maternal behaviour indicating a lack of experience compared to mature ewes. Therefore future research should be directed at alleviating these constraints.