Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/1998
Publication Date: N/A
Citation: N/A Interpretive Summary: Fat supplementation for the last 53 d of gestation but not for the last 28 d improved thermogenesis and increased plasma glucose concentrations in newborn calves. Premature calves had lower rectal temperature and glucose concentrations than term calves, suggesting that premature calves may be more sensitive to cold temperatures. Since glucose contributed to the formation of fatty acids synthesis and fatty acids are an important fuel for brown adipose tissue thermogenesis, we hypothesize that fat supplementation for the last 53 d of gestation improves non-shivering thermogenesis by increasing blood glucose concentrations and fatty acid content at the brown adipose tissue level as well as the quantity of this tissue.
Technical Abstract: Two studies were conducted to evaluate prepartum fat supplementation and norepinephrine (NE) effects on thermogenesis and blood cortisol, glucose and cholesterol concentrations of newborn (NB) premature and term (T) calves. Exp. I, primiparous cows gestating F2 Line 1 Hereford calves (n=22)received 1.7% or 4.9% dietary fat for the last 53 d of gestation. Calves were exposed to 0 deg C for 140 min, received 0 or 20 micrograms/ kg of NE and rectal temperature and blood samples taken. Exp. II, NB F1 Murray Grey sired calves (n=23) whose dams received 1.5% or 3.4% dietary fat for the last 28 d of gestation, and at d 260 of gestation 0 or 2 kg of pine needles (induce premature delivery) were used. Calves were exposed to 9 deg C for 200 min and rectal temperature and blood samples taken. Safflower (37% oil with 80% linoleic acid) was the fat source. In Exp. I, rectal temperature was affected by time, time x treatment, and time x sex x treatment (P<.01) and in Exp. II by time, calf maturity (term: 39.4 vs premature calves: 38.6 deg C) and calf maturity x time (P<.03). Cortisol was affected by time, and treatment x time x NE (P<.01) in Exp. I and in Exp. II by time, sex, and sex x time (P<.05). Cholesterol in Exp. I was affected by NE x sex x time, and NE x treat- ment x sex (P<.02) and in Exp. II by time and sex x time (P<.04). Glucose in Exp. I was affected by treatment (HF: 97.4 vs LF: 66.4 mg/ dL), and treatment x time (P<.02) and in Exp. II by calf maturity, calf maturity x time, and treatment x sex (P<.01). In conclusion, fat supple mentation for the last 53 d of gestation improved thermogenesis and increased plasma glucose concentrations in NB calves. Premature calves had lower rectal temperature and glucose concentrations than T calves.