Growth Performance, Carcass and Meat Quality Traits of Three Rabbit Lines Under Heat Stress Conditions

Given the yearly challenging environmental scenario with more and more frequent and intense heat waves, the livestock sector has to find affordable and sustainable solutions to face the expected increase in meat demand by 2050. Among livestock species, rabbits are particularly sensitive to heat stress (HS) but, paradoxically, the scientific background on the response of different genetics to environmental stressors like HS is rather scarce. This is a significant gap, especially considering that most of the demographic growth, and meat demand, is expected in developing countries where rabbits play a key role in subsistence farming. Therefore, this research investigated the effects of environmental temperature (Control-20 °C; High-28 °C) on growth performance, slaughter traits and meat quality of three Hungarian rabbit genotypes (Pannon Large-PL; Pannon White-PW; Pannon Ka-PK). Animals (n = 360) were housed in wire-mesh cages (3 animals/cage) in two separate controlled-temperature rooms (60 rabbits/genotype/room), from 5 to 11 weeks of age, during which they received ad libitum feed and water. Even if the three genotypes were exposed to the same environmental challenge, they exhibited different responses. The PL line showed superior performance, with the highest carcass weight and yield (p < 0.001), and the greatest water-holding capacity (p < 0.01) in the loin muscle. The PW rabbits showed the largest reduction in overall weight gain (-24.7%; p < 0.001) and the lowest decrease in feed conversion ratio (-3.20%; p < 0.001). PK rabbits experienced the greatest reduction in total dissectible fat (-34.6%; p < 0.001) and hind leg lipid content (-20.3%; p < 0.01), with the highest proportion of polyunsaturated fatty acids (p < 0.01), which fostered meat lipid oxidation (p < 0.05). As expected, these differences in performance and meat quality traits reflected the distinct selection criteria and genetic background of these genotypes: the PL is a paternal line, the PK is a maternal line, and the PW is a productive line. Regarding the temperature effect, PK and PW genotypes were the most impacted by chronic HS: PW rabbits suffered the largest performance depression, while PK rabbits showed the worst carcass and meat quality traits. Instead, PL rabbits demonstrated the best outcomes under chronic HS, showing the greatest productive efficiency and satisfactory meat quality traits.