title: Effect of maternal heat stress during the dry period on growth and metabolism of calves.
abstract: Preliminary studies suggest that maternal heat stress (HS) during late gestation exerts carryover effects on a calf's insulin response after weaning, but a comprehensive evaluation of how maternal HS affects calf intake, growth, and metabolic response from birth to weaning is lacking. Our objective was to evaluate the effects of maternal HS during the dry period on dry matter intake, growth, and metabolism from birth to weaning. After birth, 20 heifers born to either HS (n=10) or cooled (CL, n=10) dry cows were immediately separated from their dams and fed 3.8 L of colostrum from a common pool within 4h of birth. All heifers were managed identically and weaned at 49 d of age (DOA). Calf starter intake was recorded daily, and body weight was assessed at birth and every 2 wk from birth to 56 DOA. Blood samples were collected twice a week until 56 DOA to assess hematocrit and concentrations of insulin and metabolites. To evaluate metabolic responses to maternal HS, a glucose tolerance test, insulin, and epinephrine challenge were performed on 3 consecutive days for all heifers at 8, 29, and 57 DOA. Maternal HS during the dry period did not affect heifer birth weight. Compared with HS, CL calves consumed more starter (0.53 vs. 0.34kg/d) from birth to 56 DOA and were heavier (71.7 vs. 61.4kg) at 56 DOA. Relative to HS calves, CL calves tended to have higher hematocrit (27.4 vs. 24.7%). No differences were found between treatments in plasma concentrations of insulin and glucose, but HS calves had higher nonesterified fatty acids and β-hydroxybutyrate concentrations after 32 DOA. Compared with CL, HS calves had a faster glucose clearance after a glucose tolerance test and a slower insulin clearance after an insulin challenge. In conclusion, maternal HS during late gestation reduces calf starter intake and growth, alters blood metabolite profile, and increases noninsulin-dependent glucose uptake.
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Tifton 31793.
authors.forename: A P A
authors.initials: APA
authors.lastname: Monteiro
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Tifton 31793; College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, China 163319.
authors.forename: J-R
authors.initials: JR
authors.lastname: Guo
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Tifton 31793.
authors.forename: X-S
authors.initials: XS
authors.lastname: Weng
authors.affiliation: Department of Animal Sciences, University of Florida, Gainesville 32611.
authors.forename: B M
authors.initials: BM
authors.lastname: Ahmed
authors.affiliation: Department of Animal Sciences, University of Florida, Gainesville 32611.
authors.forename: M J
authors.initials: MJ
authors.lastname: Hayen
authors.affiliation: Department of Animal Sciences, University of Florida, Gainesville 32611.
authors.forename: G E
authors.initials: GE
authors.lastname: Dahl
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Tifton 31793.
authors.forename: J K
authors.initials: JK
authors.lastname: Bernard
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Tifton 31793. Electronic address: stao@uga.edu.
authors.forename: S
authors.initials: S
authors.lastname: Tao
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000821:Animal Feed; D000818:Animals; D002417:Cattle; D003126:Colostrum; D004032:Diet / Q000662:veterinary; D005260:Female; D018882:Heat Stress Disorders / Q000662:veterinary*; D006358:Hot Temperature; D014886:Weaning
chemical_list: D020155:3-Hydroxybutyric Acid
keywords: dairy calves; glucose metabolism; heat stress