86 Effects of Hurricane-Related Prenatal Stress on Postnatal Growth and Development of Steers and Heifers in a Limited Resource Beef cow-Calf System

Abstract

Abstract Cost effective growth in beef calves is necessary for productivity of limited-resource pasture-based cow-calf operations. However, pasture-based production systems are often plagued by environmental stressors such as droughts, high ambient temperatures and adverse weather events that might impede calf growth and development. Our study evaluated the effects of prenatal stressors such as hurricanes on postnatal calf growth and development. Crossbred beef calves born from the same lineage in two different years were compared: Group 1, dams experienced effects of a category 5 hurricane in their late gestation. Group 2, dams experienced no adverse environmental effects their late gestation. Body weights and condition scores were collected at weaning, yearling age, 14 -15 months age and, and 20 months of age. Blood samples were collected periodically to evaluate metabolite and hormone profiles. Data were evaluated by mixed procedures of SAS, and significance determined at P< 0.05. Calf body weights during the juvenile periods were less (P< 0.05) in both steers and heifers born to dams that experienced hurricane-related stress during late gestation compared with their normal contemporaries. However, this weight difference was not evident during adult stages. Further, although blood cortisol was not different in yearling heifers, glucose and progesterone concentrations were decreased (P< 0.05; P< 0.01, respectively) in Group 1 heifers compared with the control group. In adult steers, serum cortisol differed (P< 0.001) between groups (965±38 vs 1282±40.5, pg/mL for Groups 1 and 2 respectively). Indeed, Group 1 steers exhibited decreased serum cortisol concentrations at both summer and fall periods when ambient temperatures were expected to present varied stressful challenges to the animals. Thus, detrimental effects of a natural disaster such as a hurricane may impede postnatal growth and development of heifers and steers as seen in this project. Further investigation is on this phenomenon is warranted. Funded by NIFA CBG # 2021-38821-34599.