Cellular and Enzymatic Changes with Animal Growth in Porcine Intramuscular Adipose Tissue

Abstract

This study was conducted to determine the cellular and metabolic changes occurring during the development of intramuscular adipose tissue during animal growth as an attempt to determine the major contributing factors to the accumulation of intramuscular fat in the pig. The major increase in intramuscular fat began after 16 weeks of age and this dramatic deposition was not only due to increase in cell size but also due to increase in cell number. Unlike the subcutaneous fat tissue, the adipose cell number did not reach a plateau even at 24 weeks but continued to increase. An increase in the activities of malic and citric cleavage enzymes expressed on a cellular basis accompanied the rapid deposition of marbling fat. Unlike the subcutaneous fat depot where the enzyme activities reached maximum at 16 weeks of age and decreased gradually thereafter, the enzyme activities in the intramuscular adipose tissue did not decrease at any sampling period until 24 weeks, but continued to increase even after 16 weeks, at a diminishing rate. The lipoprotein lipase activity in muscle was initially high during the suckling period and remained unchanged until 24 weeks of age. Its possible role in fat deposition was discussed. It was concluded that the intramuscular adipose tissue is a later developing tissue and behaves differently from the subcutaneous adipose tissue in development of cellularity and metabolic capacity. Copyright © 1974. American Society of Animal Science . Copyright 1974 by American Society of Animal Science