Abstract: One hundred and sixty crossbred (Duroc-Jersey×Landrace·Meishan) pigs weighing approximately 27 kg were allocated randomly into treatment and control groups. The treatment group was fed with the basal diet supplemented with 75mg/kg oral type antibody against adipocyte plasma membrane (OAAb). Following a 104-day trial, the pigs were slaughtered, the carcass composition was measured and the weights of internal fat depots were recorded, Blood and tissue samples were taken for further analysis. Serum concentrations of insulin and leptin were determined with RIA. Diameters of adipocytes from different fat depots were measured by using histological methods, DNA/RNA concentrations and NADP-MDH, lipoprotein lipase (LPL) activity were analyzed. Dietary supplementation of OAAb increased lean mass by 10.3% (P < 0.01) with unaffected dressing percentage. Backfat thickness at 6th~7th rib was reduced by 24.14% (P<0.01), the perirenal,mesenteric and subcutaneous fat depots were reduced by 27.27%(P<0.05),20.42%(P<0.01) and 29.21%(P<0.01),respectively, However, the intramuscular fat content of the longissimus muscle remained unaffected. Serum concentrations of insulin and leptin were reduced by 26.19%(P<0.05) and 26.53%(P<0.05), respectively. Dietary supplementation of OAAb reduced adipocyte size in all the three different adipose pads (P<0.05), LPL activity in adipose tissue and the ratio of LPL activity between adipose tissue and skeletal muscle were reduced significantly (P<0.05) whereas NADP-MDH activity was unaffected. We first demonstrated the oral effect of OAAb on carcass composition in the pig and the changes of serum insulin and leptin levels as well as the tissue LPL activity may be involved in the acting mechanism.

Key words: Pigs, Antibody, Adipocyte plasma membrane, Carcass composition, LPL activity