[Lipogenesis in adipose tissues of kids weaned at 4, 6, and 8 weeks]

Adipose deposits and their lipogenic enzymes were studied on 27 young Alpine male kids. They were weaned either at 28, 42 or 56 days of age and for each age at weaning, 3 animals were slaughtered unweaned (P 0), or 14 (P + 14) or 56 (P +56) days after weaning. They received milk replacer ad libitum from day 5 after birth to weaning and concentrate, hay and water from a week before weaning to slaughter. The adipose tissues were very developed in the abdomen in P 0 and P + 56 animals. Subcutaneous tissues were scarce. All adipose tissues in the P + 14 were lighter. The older the animals, the greater was the reduction in adipose tissue weight between P 0 and P + 14. But this loss was proportionally higher in younger animals. In all P + 14 animals the perirenal tissues showed higher loss. Lipoprotein lipase (LPL) activity was high in abdominal adipose tissues of P 0 and P + 56 kids, particularly in the omental tissue, but was very low in sternal adipose tissue. LPL activity had a low value 14 days after weaning but its specific activity roughly reached the unweaned LPL value 56 days after weaning. By contrast, acetyl CoA carboxylase (ACX) activity was very low in omental adipose tissue but existed even in unweaned kids. Fifty-six days after weaning, this activity was high in 28-day weaned kids. The activity of both glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme (EM) was high in unweaned kids, particularly at 42 days. Surprisingly, EM activity was higher than G6PDH activity in kids weaned for 56 days. Thus, in ad libitum concentrate-fed kids, the ATP-citrate lyase EM pathway seemed to be active and important for lipogenesis.