A PRISMA-guided systematic review and random-effects meta-analysis (k = 35 studies; 2000–2025) quantified adaptability of major Southern African meat goat genotypes across agro-ecological zones (AEZs) using physiological, morphological, behavioral, and production traits, with risk of bias assessed via ROBIS and heterogeneity evaluated using I2. Significant genotype-by-environment interactions were detected (p < 0.01), with high between-study heterogeneity for physiological traits (I2 = 81–92%; τ2 = 92.32), justifying random-effects modelling and subgroup analyses by breed and AEZ. Indigenous Veld Goats (IVGs; Mashona, Tswana, Matebele) demonstrated superior thermoregulatory stability, with lower heart rate (74.6 ± 2.8 bpm) compared to Boer goats (84.4 ± 3.1 bpm) and significantly reduced (p < 0.05) respiration rates under heat stress (48.2 ± 4.5 vs 61.7 ± 5.2 breaths/min). Rectal temperatures remained comparatively stable in IVGs (38.7 ± 0.2 °C) relative to Boer (39.3 ± 0.3 °C). Morphologically, IVGs exhibited higher hair density (Mashona: 215.7 ± 12.4 vs Boer: 142.0 ± 10.8 n/cm2) (p < 0.01), supporting enhanced heat dissipation. Behavioral meta-estimates showed significantly higher browsing allocation in IVGs (565 ± 35 min/day) compared to improved breeds (420 ± 28 min/day), reflecting adaptive foraging plasticity. Kalahari Red goats displayed intermediate but stable responses across arid AEZs, with low physiological variability (CV < 10%) and high survival (> 85%), indicating robust resilience. In contrast, Boer and Savannah goats exhibited higher growth rates (Boer: + 18–25% ADG relative to IVGs) but significantly elevated stress indices and mortality risk under arid conditions (p < 0.05). Crossbreeding improved productivity (heterosis estimates: + 12–18% for growth traits) but increased physiological variability and reduced stability (I2 > 85%). Funnel plot symmetry and ROBIS assessments indicated moderate risk of bias, primarily due to inconsistent trait reporting and small sample sizes in some studies. Integrated evidence from multi-trait visualization confirms that adaptability is a composite, multi-dimensional phenotype shaped by physiological regulation, morphological traits, and behavioral plasticity. These findings establish IVGs as climate-resilient genetic resources and support AEZ-specific breeding strategies that balance productivity with resilience, with implications for sustainable intensification and climate-smart livestock systems.

A systematic review of adaptability measures in selected meat goat genotypes from Southern Africa across agro-ecological zones

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2026年7月20日

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Celokuhle Faith Mashaba,
Obert Tada,
Busisiwe Gunya

摘要

A PRISMA-guided systematic review and random-effects meta-analysis (k = 35 studies; 2000–2025) quantified adaptability of major Southern African meat goat genotypes across agro-ecological zones (AEZs) using physiological, morphological, behavioral, and production traits, with risk of bias assessed via ROBIS and heterogeneity evaluated using I². Significant genotype-by-environment interactions were detected (p < 0.01), with high between-study heterogeneity for physiological traits (I² = 81–92%; τ² = 92.32), justifying random-effects modelling and subgroup analyses by breed and AEZ. Indigenous Veld Goats (IVGs; Mashona, Tswana, Matebele) demonstrated superior thermoregulatory stability, with lower heart rate (74.6 ± 2.8 bpm) compared to Boer goats (84.4 ± 3.1 bpm) and significantly reduced (p < 0.05) respiration rates under heat stress (48.2 ± 4.5 vs 61.7 ± 5.2 breaths/min). Rectal temperatures remained comparatively stable in IVGs (38.7 ± 0.2 °C) relative to Boer (39.3 ± 0.3 °C). Morphologically, IVGs exhibited higher hair density (Mashona: 215.7 ± 12.4 vs Boer: 142.0 ± 10.8 n/cm²) (p < 0.01), supporting enhanced heat dissipation. Behavioral meta-estimates showed significantly higher browsing allocation in IVGs (565 ± 35 min/day) compared to improved breeds (420 ± 28 min/day), reflecting adaptive foraging plasticity. Kalahari Red goats displayed intermediate but stable responses across arid AEZs, with low physiological variability (CV < 10%) and high survival (> 85%), indicating robust resilience. In contrast, Boer and Savannah goats exhibited higher growth rates (Boer: + 18–25% ADG relative to IVGs) but significantly elevated stress indices and mortality risk under arid conditions (p < 0.05). Crossbreeding improved productivity (heterosis estimates: + 12–18% for growth traits) but increased physiological variability and reduced stability (I² > 85%). Funnel plot symmetry and ROBIS assessments indicated moderate risk of bias, primarily due to inconsistent trait reporting and small sample sizes in some studies. Integrated evidence from multi-trait visualization confirms that adaptability is a composite, multi-dimensional phenotype shaped by physiological regulation, morphological traits, and behavioral plasticity. These findings establish IVGs as climate-resilient genetic resources and support AEZ-specific breeding strategies that balance productivity with resilience, with implications for sustainable intensification and climate-smart livestock systems.