Search

Urea dilution technique (130 mg/kg live weight) was used to estimate total body water (BW) in 12 goats. Empty body water (EBW) determined by lyophilization was more closely related to urea space (US) than total BW. EBW was estimated with a better precision (CV = 4.7%) from the prediction equation including US measured 20 min after urea infusion and body weight. This urea technique was considered convenient.

Four adult goats were given lucerne hay ad libitum and had access to water, salt stone and the litter straw. They were housed in a box and were completely free to move. Their meals consisted of the main behavioural activity of hay intake and other activities such as salt-stone licking, water drinking and straw intake. Ingestion was relatively slow because the goats took a long time to choose what they ingested. They chose the hay with more leaves and less stems which had a higher nutritive value.

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.

Mammary metabolism was studied in 4 normal lactating goats (group N) and in 4 non-pregnant goats induced to lactate by hormonal treatment (group 1). Tissue was sampled by biopsy after 3, 9 and 18 weeks of lactation. Although milk potential was the same in both groups, group 1 produced 45% less milk than group N. The RNA-DNA ratio, activities of lipoprotein lipase (LPL), glucose-6-phosphate dehydrogenase and acetyl-CoA carboxylase, and the beta-casein % of in vitro protein synthesis were not significantly lower in the 1 than in the N goat mammary tissue. This suggests that differences in mammary cell hyperplasia during hormonal treatment, and not potential metabolic activities, partially accounted for the difference in milk yield levels. Milk composition was comparable in the two groups. However, milk fat in group N had a higher long-chain fatty acid content (stearic and oleic acids) during the first month of lactation due to the higher mobilization of body lipids in high-yielding animals. Another qualitative difference was the delayed increase in milk LPL secretion during the first 3 months of lactation in induced goats.