81 Effects of Hurricane-Related Stress During Gestation on Replacement Heifer (Bos Taurus) Development in a Limited-Resource Beef cow-Calf System

Abstract

Abstract In a limited resource cow-calf operation, obtaining puberty in heifers is one of the main concerns for long-term productivity. Although nutritional factors have a large role in heifer development, environmental factors are sometimes overlooked until a catastrophic event such as a hurricane occurs. For this project, two heifer groups, born in the same herd at different intervals, were compared: Group 1(experienced catastrophic hurricane event in 3rd trimester of their fetal development) and Group 2 (no adverse event during gestation). The groups were weighed four similar time points during development: at 12 months of age (Period 1, pre-pubertal), 13-14 months (Period 2, puberty), pre-breeding (Period 3), and at the end of breeding (Period 4). The blood cortisol, glucose, and progesterone concentrations were compared between the groups during their pre-pubertal period. Group comparisons were performed using mixed procedures of SAS. Data are presented as means ±SEM. Group mean differences were declared significant at P < 0.05. We observed a significant (P < 0.01) Group by Period effect on heifer body weight (655.2± 14.2 vs. 747.3 ±15.4, for Groups 1 and 2, respectively). Overall, Group 1 was lighter than Group 2 in periods 1 and 2, but there was no difference thereafter. There were significant group differences in glucose (60.5± 8.8 vs 95.3±11.5, mg/dL for groups 1 and 2 respectively, P< 0.01) and progesterone (62.2±12.6 vs 124.0± 13.8, pg./mL for groups 1 and 2, respectively, P< 0.01). However, there was no significant difference in cortisol concentrations (P< 0.48). Therefore, catastrophic weather events such as hurricanes that are common throughout the world might have a negative impact on heifer development, as observed in this project. This observation warrants further investigation. Funding agency: USDA- NIFA CBG #2021-38821-34599