Lipogenic enzyme activities in muscles of growing Large White and Meishan pigs

Abstract

We compared the activities of acetyl-CoA-carboxylase (ACX), malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G6-PDH) in the muscles of growing Large White (LW) and Meishan (MS) pigs. In Exp. 1, adipocytes were isolated from Semimembranosus and Diaphragma muscles of six 60-kg LW pigs, and enzyme activities were compared in isolated adipocytes and in muscle homogenates. More than 80% of ACX and ME, but only half of G6-PDH, activities in muscle could be ascribed to adipocytes. In Exp. 2, lipogenic enzyme activities were measured in LW and MS pigs at 20, 60 and 100 kg live weight ( n=18/breed×weight group). Although the lipogenic enzyme activities were low, the intramuscular adipose tissue seemed to possess adequate levels of lipogenic enzymes for in situ lipid synthesis. All three lipogenic enzyme activities were generally higher in MS than in LW pigs, the largest difference being found for ME activity. G6-PDH activity was much lower than that of ME in both breeds, irrespective of animal weight. We observed a close relationship between intramuscular fat content and ME activity in the two breeds, both within and between weight groups. We conclude that ME activity may be an important factor affecting intramuscular fat content in pigs.