Effect of age, retinol, and cholecalciferol on carcass fat and adipocyte number and size in growing lambs

Abstract

To determine whether hyperplasia occurs in young growing meat lambs when fat is laid down we measured the changes in fat parameters with age in Coopworth × Dorset lambs and, in parallel, ran groups treated with retinol and cholecalciferol (reported inhibitors of adipocyte differentiation in vitro), which were slaughtered at 33–34 weeks of age. The lambs were fed a pelleted ration at 30 g/kg body weight from 16 weeks of age and serially slaughtered for age effects in groups of 4, whereas the treatment groups contained 6 lambs. Some lambs developed urethral blockage from pellet feeding so the experiment was terminated early at 33–34 weeks. The lambs showed a steady growth rate and an increase in the proportion of fat in the carcass, total carcass fat, and subcutaneous adipocyte diameter at 25–29 weeks of age. The total number of adipocytes in the carcass derived from diameter measurements on subcutaneous adipocytes and the total carcass fat showed no significant changes. Retinol and cholecalciferol caused significant reductions in cell diameter and increases in total adipocytes but little change in total fat.