What question did this study set out to answer?

This research aims to examine how age and climate affect stress and metabolic hormone levels in different goat breeds.

May 18, 2026Open Access

The Age and Climate Related Changes in Stress and Metabolic Hormones of Goat Bucks Raised Under Tropical Conditions

Key Points

This research aims to examine how age and climate affect stress and metabolic hormone levels in different goat breeds.
Evaluated 63 goat bucks from Kalahari Red, West African dwarf, and Kalawad breeds across three age groups over one year.
Collected bimonthly blood samples to analyze stress and metabolic hormones across four seasons.
Applied three-way ANOVA using SAS (1999) for data analysis.
Cortisol levels were highest in the 37-48 month age group (13.91±0.04 ng/mL) during the early dry season (14.43±0.03 ng/mL).
Thyroxine peaked at 7.45±0.04 ng/dL and triiodothyronine at 1.76±0.04 ng/mL during the early rainy season.
The lowest cortisol value was recorded in the West African dwarf breed (9.42±0.03 ng/mL).

Abstract

This study determined the stress and metabolic potentials of 63 goat bucks of different breeds - Kalahari Red (KR), West African dwarf (WAD) and Kalawad (KW) with 21 animals each. They were assigned to three age groups – 11 - 24, 25 - 36 and 37 - 48 months and evaluated across four seasons (early/late rainy and early/late dry) in a 3 × 3 × 4 factorial design. Animals were managed under same conditions for one year. Bimonthly blood samples were collected to analyze hormonal profile on stress and metabolic indices. Three-way ANOVA was used for data analysis using SAS (1999). All determined hormones were significantly (p <0.05) influenced by breed, age and season. The cortisol level was highest (13.91±0.04 ng/mL) in the animals at age 37 – 48 months (p <0.05) and during early dry season (14.43±0.03 ng/mL) while thyroxine and triiodothyronine concentrations had least values (5.79±0.05 ng/dL and 1.75±0.04 ng/mL) but peaked (7.45±0.04 ng/dL and 1.76±0.04 ng/mL) respectively during early rainy season. The least cortisol value (9.42±0.03 ng/mL) was recorded in WAD. Breed, age and season exert influences on hormones considered in goats bucks. This information provides reference values for selection of these breeds in heat-stressed environments.

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