Effects of dietary methionine deficiency followed by replenishment on the growth performance and carcass characteristics of lambs

Abstract

Twelve pairs of male twin lambs were used to assess the effects of dietary methionine (Met) deficiency followed by replenishment on lamb growth performance and carcass characteristics. All lambs were weaned at 7 days of age and divided into the Control (CON) group and Met deficiency (MD) group. From 8 to 56 days of age, the lambs in the CON group were fed a milk replacer and starter feed containing 0.91% and 0.60% Met, respectively, whereas the lambs in the MD group were fed with a milk replacer and starter feed containing 0.21% and 0.20% Met, respectively. All lambs were fed a starter feed containing 0.60% Met from 57 to 84 days of age. Six twin pairs were slaughtered at 56 and 84 days of age, and their organ weights and carcass traits were measured. During 8 to 56 days of age, the Met-deficient diet decreased (P < 0.05) Met intake, average daily gain, feed conversion ratio, shrunk bodyweight, empty bodyweight, hot carcass weight, and the apparent digestibility of crude protein, ether extract and neutral detergent fibre; however, no differences were detected in dressing percentage or in the percentage of visceral organ weight to shrunk bodyweight between the groups (P > 0.05). During the follow-up Met replenishment stage, no differences in growth performance, nutrient digestibility, carcass characteristics, and percentages of visceral organs to shrunk bodyweight were found between the groups (P > 0.05). In conclusion, dietary Met deficiency in early life retarded the growth and development of lambs. Growth rate was not retarded during the 28 days of subsequent Met replenishment, but the difference in bodyweight between the groups remained.