Lipase Activity and Lipid Deposition

Forty cross-bred western wether lambs were divided into two equal groups. During a growth period, 20 lambs received a maintenance diet, and 20 lambs were fed an adequate diet. Four Iambs from each group were slaughtered after the growth period, and extramuscular adipose tissue lipoprotein lipase activity (LPL) and intramuscular lipid content were determined. Lambs from each growth phase group were then subdivided and fed f'mishing diets ad libitum containing two levels of protein. Lambs from each of the four finishing phase treatment groups were then slaughtered in two groups to observe changes in LPL of extramuscular adipose tissues and intramuscular lipid content. Lipoprotein lipase activity was low or nondetectable in adipose tissues from lambs fed at maintenance and slaughtered at the end of the growth phase. However, when the lambs fed at maintenance were subsequently giveh finishing diets ad iibitum, the increase in carcass adipose tissue was paralleled by an increase in total LPL. This increase in total LPL was due primarily to the increase of LPL in subcutaneous adipose tissue. Total LPL increased in the early stage of the finishing period for lambs fed ad libitum during the growth phase, but LPL did not increase for these lambs in the later stage of the finishing phase. The increase in LPL in the early stage was due to increased LPL in the subcutaneous adipose tissue. Lipoprotein lipase activity of the carcass extramuscular adipose tissues was positively related to intramuscular fat deposition.