Resilience of three indigenous goat breeds to heat stress based on phenotypic traits and PBMC HSP70 expression

The objective of this experiment was to evaluate the influence of summer heat stress on physiological and behavioral responses of Osmanabadi, Salem Black, and Malabari goats. The study also evaluated the differences in heat shock protein 70 (HSP70) expression pattern between these breeds. The study was conducted over 45 days during summer (April-May) using 36 1-year-old female goats by randomly allocating them into six groups with six animals in each group: Osmanabadi control (Osmanabadi CON), Osmanabadi heat stress (Osmanabadi HS), Malabari control (Malabari CON), Malabari heat stress (Malabari HS), Salem Black control (Salem Black CON), and Salem Black heat stress (Salem Black HS). The Osmanabadi CON, Malabari CON, and Salem Black CON animals were housed in a shed while the Osmanabadi HS, Malabari HS, and Salem Black HS groups were subjected to heat stress by exposing them to outside environment between 1000 and 1600 h during the experimental period. All 36 animals were provided with ad libitum feed and water. The data generated were analyzed by general linear model (GLM) repeated measurement analysis of variance. Results indicated that the drinking frequency (DF) was higher (p < 0.01) in heat stress groups (12.58, 12.25, and 10.75 times for the Osmanabadi HS, Malabari HS, and Salem Black HS, respectively) as compared to their respective control groups (5.67, 6.25, 5.58 times for the Osmanabadi CON, Malabari CON, and Salem Black CON, respectively). Water intake (WI) also showed similar trend to DF. The urinating frequency also (UF) differed between breeds with lower value (p < 0.05) recorded in the Salem Black HS (1.5 times) compared to the Malabari HS (2.92 times). The highest (p < 0.05) rumination time (RuT) was recorded in the Malabari HS (48.00 min) than both the Osmanabadi HS (20.91 min) and Salem Black HS (23.67 min). The heat stress increased (p < 0.05) all physiological variables at 1400 h. The findings of this study suggest RR, RT, and PBMC HSP70 are reliable biological markers for evaluating thermo-tolerance capacity of indigenous goat breeds.