title: Acute brief heat stress in late gestation alters neonatal calf innate immune functions.
abstract: Heat stress, as one of the environmental stressors affecting the dairy industry, compromises the cow milk production, immune function, and reproductive system. However, few studies have looked at how prenatal heat stress (HS) affects the offspring. The objective of this study was to evaluate the effect of HS during late gestation on calf immunity. Calves were born to cows exposed to evaporative cooling (CT) or HS (cyclic 23-35°C) for 1 wk at 3 wk before calving. Both bull and heifer calves (CT, n=10; HS, n=10) were housed in similar environmental temperatures after birth. Both CT and HS calves received 3.78 L of pooled colostrum within 12 h after birth and were fed the same diet throughout the study. In addition to tumor necrosis factor α, IL-1β, IL-1 receptor antagonist (IL-1RA), and toll-like receptor (TLR)2, and TLR4 mRNA expression, the expression of CD14(+) and CD18(+) cells, and DEC205(+) dendritic cells were determined in whole blood samples at d 0, 3, 7, 14, 21, and 28. The neutrophil to lymphocyte ratio, differential cell counts, and the hematocrit were also determined. During late gestation, the HS cows had greater respiration rates, rectal temperatures, and tended to spend more time standing compared with the CT cows. The HS calves had less expression of tumor necrosis factor-α and TLR2 and greater levels of IL-1β, IL-1RA, and TLR4 compared with CT calves. The HS calves also had a greater percentage of CD18(+) cells compared with the CT calves. Additionally, a greater percentage of neutrophils and lesser percentage of lymphocytes were in the HS calves compared with the CT calves. The results indicate that biomarkers of calves' immunity are affected in the first several weeks after birth by HS in the dam during late gestation.
authors: Department of Animal Sciences, Purdue University, West Lafayette, IN 47907.
authors: R A
authors: RA
authors: Strong
authors: Livestock Behavior Research Unit, USDA-Agricultural Research Service, West Lafayette, IN 47907.
authors: E B
authors: EB
authors: Silva
authors: Livestock Behavior Research Unit, USDA-Agricultural Research Service, West Lafayette, IN 47907.
authors: H W
authors: HW
authors: Cheng
authors: Livestock Behavior Research Unit, USDA-Agricultural Research Service, West Lafayette, IN 47907. Electronic address: Susan.Eicher@ars.usda.gov.
authors: S D
authors: SD
authors: Eicher
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology*; D003126:Colostrum / Q000276:immunology; D004032:Diet / Q000662:veterinary; D005260:Female; D015870:Gene Expression; D005865:Gestational Age; D018882:Heat Stress Disorders / Q000150:complications / Q000276:immunology / Q000662:veterinary*; D006358:Hot Temperature; D007958:Leukocyte Count / Q000662:veterinary; D018655:Lymphocyte Count; D008297:Male; D008892:Milk; D009504:Neutrophils; D011247:Pregnancy; D011248:Pregnancy Complications / Q000276:immunology*; D011297:Prenatal Exposure Delayed Effects / Q000662:veterinary; D051195:Toll-Like Receptor 2 / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
chemical_list: D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha
keywords: calf; dairy cattle; heat stress; innate immunity