Influence of sex on cellularity and lipogenic enzymes of Spanish lamb breeds (Lacha and Rasa Aragonesa)

Abstract

AbstractThe effect of sex on the size and number of adipocytes and on the lipogenic enzyme activity in different fat depots in Lacha (L) and Rasa Aragonesa (RA) lambs was studied. Male and female L lambs were fed on ewe milk and were slaughtered at 25 and 24 days of age corresponding to 11·4 and 10·9 kg live weight (UN), respectively. Male and female RA lambs were weaned at 58 days (16·0 kg LW) and were then given concentrates and barley straw until slaughtered at 89 and 91 days of age corresponding to 24·5 and 23·1 kg LW, respectively. A number of parameters were studied in omental (OM), mesenteric (MES) and kidney knob and channel fat (KKCF) depots including the amount of fat, the number and size of adipocytes and the activity of the following enzymes: glycerol 3-phosphate dehydrogenase (G3PDH), fatty acid synthetase (FAS), glucose 6-phosphate dehydrogenase (G6PDH) and NADPmalate dehydrogenase (MD). In subcutaneous (SC) and intermuscular (IM) depots, all the former parameters except the adipocyte number were studied. Females of both breeds had higher amounts of adipose tissue than males in the internal fat depots(P < 0·05)as well as larger adipocytes, mainly in the KKCF(P < 0·05andP< 0·001for L and RA lambs, respectively) and OM(P < 0·05in the RA lambs) depots. There were no differences between sexes in the number of adipocytes. The activity of the G3PDH enzyme was higher in females than in males in OM and SC depots(P < 0·01)in L lambs, and in KKCF, IM(P < 0·05),OM and MES(P < 0·001)depots in RA lambs. Thus, the sex effect on adiposity in both breeds studied involved a greater fattening of the females which was consistent with a greater hypertrophy and a higher G3PDH activity.