Effect of litter size and maternal malnutrition to the hormone secretion, blood flow of uterine artery and nutrient uptake by the gravid uterus in late pregnant goats

摘要

The maternal plasma hormone and metabolites concentration, blood flow and net nutrient uptake by gravid uterus with different litter size were observed using 10 Saanen goats under maternal malnutrition. Surgery was done under general anesthesia at 105 days of pregnancy. The ultrasonic flow probe was surgically fitted around the uterine artery. Heparinized catheters were inserted into the uterine vein and carotid artery. Uterine blood flow was measured continuously for 24 h at 1 min interval and blood samples were collected every 3 h at an average of 119.0 (single, n=4), 113.5 (twin, n=4) and 121.5 (triplet, n=2) days of pregnancy. As percentage of requirement (maintenance + pregnancy), metabolizable energy intake was 56.4 percent (single), 59.4 percent (twin) and 71.4 percent (triplet). Retention energy in the triplet pregnant goats were lowest because the heat production was significantly (P<0.01) greater than in the single or twin pregnant goats. Plasma flow rate in the uterine artery, net glucose uptake by the gravid uterus, plasma glucose and urea nitrogen concentrations in the triplet pregnant goats were higher than in the single or twin pregnant goats. There were no clear differences in plasma free fatty acid concentration among each litter size. Molar ratio of plasma insulin and glucagon tended to be lower in the triplet pregnant goats. Our results suggest that the triplet pregnant goats could adapt to the energy deficit by increased secretion of glucagon to maintain glucose supply for fetuses. And furthermore, results showed that the techniques used in the present experiment would contribute to an accurate determination of nutrient uptake by gravid uterine tissues in ruminants.