title: Climatic conditions, twining and frequency of milking as factors affecting the risk of fetal losses in high-yielding Holstein cows in a hot environment.
abstract: An epidemiological study of risk factors for fetal losses was carried out on 62,403 high-yielding Holstein cows in 29 large highly technified dairy herds in northern Mexico (25° N; 23.5 °C mean annual temperature). Multivariate multiple-group response model indicated that fetal losses between 43 and 260 days of pregnancy were 23 %. Heat-stressed cows at conception (temperature-humidity index, THI >82) were 14 times more likely (P < 0.01) to present fetal losses than not heat-stressed cows (27 vs. 18 %). Heat-stressed cows at 60 days of pregnancy (THI >82) were 4.5 times more likely (P < 0.01) to present fetal losses than cows suffering heat stress in early gestation (29.1 vs. 17.7 %). The proportion of cows experiencing fetal loss was lower for multiparous than primiparous cows (odds ratio; OR = 0.7). Cows with twin pregnancies had significantly increased chances of losing their fetuses than cows with a single fetus (33.6 vs. 20.7 %; P < 0.01). Cows with three milkings per day were 30 % more likely (P < 0.01) to lose their fetuses than cows milked twice daily. Cows calving in winter and spring had significantly increased chances of losing their fetuses than cows calving in summer and fall (30-35 vs. 4-5 %; P < 0.01). It was concluded that, in this particular environment, heat stress exert a great influence on fetal losses in high producing Holstein cows.
authors.affiliation: Department of Animal Nutrition, Autonomous Agrarian University Antonio Narro, Saltillo, Coah, 25315, Mexico.
authors.forename: Miguel
authors.initials: M
authors.lastname: Mellado
authors.affiliation: Department of Veterinary Science, Autonomous Agrarian University Antonio Narro, Torreon, Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: López
authors.affiliation: Department of Veterinary Science, Autonomous Agrarian University Antonio Narro, Torreon, Mexico.
authors.forename: Ángeles
authors.initials: Á
authors.lastname: de Santiago
authors.affiliation: Department of Veterinary Science, Autonomous Agrarian University Antonio Narro, Torreon, Mexico.
authors.forename: Francisco G
authors.initials: FG
authors.lastname: Veliz
authors.affiliation: Institute of Agricultural Sciences, Autonomous University of Baja California, Mexicali, Mexico.
authors.forename: Ulises
authors.initials: U
authors.lastname: Macías-Cruz
authors.affiliation: Institute of Agricultural Sciences, Autonomous University of Baja California, Mexicali, Mexico.
authors.forename: Leonel
authors.initials: L
authors.lastname: Avendaño-Reyes
authors.affiliation: Department of Animal Nutrition, Autonomous Agrarian University Antonio Narro, Saltillo, Coah, 25315, Mexico. egarcia@uaaan.mx.
authors.forename: José Eduardo
authors.initials: JE
authors.lastname: García
mesh_terms: D000034:Abortion, Veterinary / Q000453:epidemiology; D000822:Animal Husbandry; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000503:physiopathology; D003612:Dairying; D020964:Embryo Loss / Q000209:etiology / Q000662:veterinary; D005260:Female; D018882:Heat Stress Disorders / Q000453:epidemiology / Q000662:veterinary*; D007774:Lactation / Q000502:physiology; D008800:Mexico / Q000453:epidemiology; D008892:Milk / Q000378:metabolism; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology / Q000662:veterinary*; D011272:Pregnancy, Multiple; D055703:Reproductive Physiological Phenomena; D012307:Risk Factors; D012621:Seasons; D014329:Tropical Climate
keywords: Frequency of milking; Gestation; Heat stress; Season of calving; Twinning