The effects of stocking density on behavior and biological functioning of penned sheep under continuous heat load conditions.

This article investigates the welfare implications of three allometric stocking densities (k = 0.030, 0.033, 0.042) for Merino wethers housed under continuous hot and humid conditions simulating live export voyages from Australia to the Middle East. The study found that higher stocking densities restricted some lying positions, with more space allowing sheep to lie with outstretched legs and in physical isolation, behaviors potentially facilitating heat dissipation. While increased wet-bulb temperature (TWB) elevated respiration rates and rumen temperatures, stocking density had minimal effects on physiological stress indicators—including fecal glucocorticoid metabolites, adrenal gland weights, liveweights, and blood parameters—suggesting sheep coped with the imposed conditions regardless of space allowance. The authors note individual variation in heat tolerance and emphasize that other voyage-related stressors (e.g., motion, ammonia buildup) were not present, so conclusions apply within the controlled experimental context. Further research is recommended to assess cumulative stressors affecting sheep welfare during live export under hot conditions.