Formosan sambar deer (Rusa unicolor swinhoei) are of great economic significance in Taiwan, resulting in a substantial increase in deer farming to meet the high demand for velvet antlers. Inbreeding depression and reduced genetic variability can lead to the deterioration of captive populations. In this study, 239 Formosan sambar deer were genotyped using 13 microsatellites to analyze their genetic diversity and population genetic structure. Our results indicate a high-resolution power of these microsatellites in individual discrimination and parentage analysis. However, captive populations exhibit a low level of genetic diversity, likely because of inbreeding and bottleneck effects. Both principal coordinate analysis (PCoA) and STRUCTURE analyses revealed two distinct and segregated genetic groups within the captive populations and indicated no clear population genetic structure among the captive populations. Introducing new genetic material from the wild through translocation offers a potential solution for mitigating the impact of inbreeding and enhancing genetic diversity. The comprehensive information obtained from these genetic analyses is crucial for the development of effective breeding strategies aimed at preserving and enhancing Formosan sambar deer populations.

Taiwan’s subtropical climate poses substantial heat stress challenges to poultry production. This study compared four red-feathered rooster lines (n = 10 per line, BB homozygous HSP70 genotype)—three commercially bred lines (F, T, K) selected for maximum body weight, and one native trial line (TLRI-09) developed through marker-assisted selection targeting the HSP70 BB genotype—during a one-hour acute heat challenge at 42 °C. A pre-specified statistical decision tree was applied: normality was assessed by the Shapiro–Wilk test for each group’s change score (Δ = post − pre); one-way ANOVA with Tukey’s HSD was used when all groups were normally distributed; Kruskal–Wallis with Dunn’s post hoc test (Bonferroni correction) was used otherwise. Within-group pre-to-post changes were assessed by paired t-test. TLRI-09 showed a substantially lower body weight (909 ± 102 g vs. 2039–2226 g) and zero mortality, whereas each commercial line experienced one death (10%). Cloacal temperatures in F, T, and K groups exceeded the thermometer’s upper limit (>44 °C) within one hour; TLRI-09 reached only 42.8 ± 0.1 °C. Respiratory rate increment was highest in TLRI-09 (Δ = 82.0 ± 8.4 breaths/min) and differed significantly among lines (p < 0.001). Plasma T₃ change differed among lines (p = 0.006); post hoc analysis identified a significant K vs. T contrast only (p = 0.019). These results indicate that, despite sharing the same HSP70 genotype, breeding objective is an important determinant of acute thermal resilience—an observation that warrants further validation under chronic and commercial production conditions.