Effect of rebreeding on lamb production

Abstract

SUMMARYThis experiment was carried out in a newly reclaimed desert area south-west of Alexandria. The purpose was to study the effect of breeding Barki ewes more than once per year on body weights and mortality rates of their lambs. Lambs were weighed 24 h after birth and at the ages of 1, 2, 2·5 (weaning age), 3, 4, 5, 6, 9 and 12 months.The experiment comprised three groups of single-born lambs of both sexes. The first group included 385 lambs born (in October–November) to ewes lambing once per year; tho second group comprised 155 lambs born (in January–February) to ewes lambing twice in twelve months and the third comprised 102 lambs also born in January–February to ewes lambing thrice in two consecutive years.Lambs born to ewes lambing once were heavier from the age of 1 month to the age of 5 months than lambs born to ewes lambing twice in the same year or three times in two consecutive years. However, the three groups of lambs did not significantly differ in their body weights from 5 to 12 months of age.Rebreedi ng did not significantly affect the mortality rate of lambs at the three studied ago periods, i.e. from birth to 1 month of age, from 1 month to weaning and from weaning to the age of 12 months.Sex had a significant effect on body weights of lambs but did not affect their mortality rates.