Changes in body composition relative to weight and maturity of Australian Dorset Horn rams and wethers 4. Adipocyte volume and number in dissected fat partitions

Abstract

ABSTRACTThe effect of castration on the cellular characteristics of dissected fat partitions was examined in 20 Dorset Horn rams and 20 Dorset Horn wethers. Cellular characteristics of dissected carcass (subcutaneous and intermuscular partitions) and non-carcass (kidney fat, omental and mesenteric partitions) fat partitions were examined in 13 mature animals, and the rate of change in adipocyte volume relative to the change in chemical-fat weight in that partition, examined in 27 immature animals.Mature wethers had a greater concentration of chemical fat in the subcutaneous fat partition than mature rams (917v. 885 g/kg, respectively). This, in combination with a greater weight of dissected subcutaneous fat, resulted in a greater weight of chemical fat in the subcutaneous partition of wethers compared with rams. Mature wethers had larger adipocytes than mature rams in all dissected fat partitions, with the largest increase in the subcutaneous and omental fat partitions. The increased adipocyte volume in the dissected fat partitions in mature wethers resulted in a smaller total estimated number of adipocytes in all carcass and non-carcass fat partitions compared with mature rams.Standardized allometric coefficients for adipocyte volume relative to chemical-fat weight in that partition showed that increases in chemical-fat weight were due to a combination of hypertrophy and hyperplasia. In the omental and kidney fat partitions, hypertrophy contributed more to the increase in chemical-fat weight in wethers compared with rams.