Vol. 10, Issue 8, Part C (2025)

Author(s): Sakshi Vaishnav, Argana Ajay, Gyanendra Singh, Amit Kumar and Anuj Chauhan

Abstract: Global climate change, driven by anthropogenic greenhouse gas emissions, has led to rising temperatures and increased extreme weather events, exacerbating heat stress in livestock, particularly in tropical regions. The present study aimed to compare breed-specific responses to heat stress in Tharparkar and Vrindavani cattle, elucidating mechanisms for enhancing resilience amid climate change. Six healthy adult cattle (Three per breed, matched for age, sex, and status) were selected at ICAR-IVRI, Izatnagar, India, under uniform management. Animals underwent controlled heat exposure in a psychrometric chamber at 40 °C for 6 hours daily over 7 days, simulating high THI conditions. Thermoneutral samples were collected in November. Physiological parameters were measured. Serum was analysed for creatinine (modified Jaffe's colorimetric assay, ERBA kit) and cortisol (BT Lab ELISA kit with standard curve via GraphPad Prism) under thermoneutral and heat stress condition. THI ranged 85.24–88.12 during stress (vs. 53.6–67.5 thermoneutral). Tharparkar showed baseline RT of 100.5±0.66°F and RR of 27.3±0.58 breaths/min, rising to 103.1±0.50°F and 40.0±1.0 breaths/min under heat stress, indicating stability. Vrindavani had higher baselines (102.3±0.45°F, 36.0±1.0 breaths/min) and peaks (104.0±0.20°F, 52.3±0.58 breaths/min), reflecting reduced tolerance. Creatinine increased from 0.91±0.16 mg/dL (thermoneutral) to 1.27±0.09 mg/dL (stress) in Tharparkar, and 1.15±0.10 to 1.64±0.24 mg/dL in Vrindavani, signaling greater metabolic strain in crossbreds. Cortisol rose from 4.03±0.31 ng/mL to 6.07±0.45 ng/mL in Tharparkar, versus 5.1±0.3 to 10.33±0.71 ng/mL (102.5% surge) in Vrindavani, highlighting amplified stress responses. These findings underscore Tharparkar breed’s superior adaptation, informing breed promotion and interventions for sustainable livestock farming.