High ambient temperature represents an increasingly frequent challenge for animal farming, especially for those animal species more susceptible to heat stress (HS), like the rabbit. The present research studied the impact of different ambient temperatures (T: 20 °C—Control vs. 28 °C—High) on the meat quality of two rabbit lines (L: Fat line, Lean line) obtained after 5 generations of divergent selection for total body fat content. After slaughter, the ground meat of 60 carcases (15 rabbits/treatment) was used for physicochemical and sensory quality evaluation. Overall, high T affected hind leg weight (p < 0.001), pHu (p = 0.001), and oxidative status (p = 0.004) during a shelf-life trial. High T increased meat haem-iron (p < 0.001), decreased lipids (p < 0.001), MUFA (p < 0.001), and PUFA classes (p < 0.001), and consequently, increased water content (p < 0.001). Regarding L effect, Fat line was richer in lipids (p < 0.001) and ash (p = 0.008), but less rich in water (p < 0.001) than Lean line. The content of all fatty acid (FA) classes was therefore significantly higher in Fat line meat (p < 0.001). It can be concluded that the two genotypes differed for proximate composition, haem-iron, FA, and amino acid profiles of carcase meat. High T increased meat pHu, water, haem-iron, and reduced polyunsaturated FA (PUFA) amount. At high T the meat of the Fat line showed higher TBARS, whereas Lean line had higher lysine content. Sensory analysis revealed that high T improved tenderness and extinguished onion off-flavour.

The effects of heat stress and feed restriction were evaluated on a total of 180 weaned rabbits divided into three experimental groups (60 animals/group): 2 groups were fed ad libitum and reared under different temperatures (20 °C – 20AD and 30 °C – 30AD), while a third group was housed under controlled temperature (20 °C) but pair-fed to 30AD rabbits, thus feed restricted (20FR). During the trial, both 30AD and 20FR groups exhibited reduced growth performance, including body weight and daily weight gain (both, P < 0.001), although feed conversion ratio improved (P = 0.016). The reference carcasses of 20FR and 30AD rabbits were lighter and leaner (both, P < 0.001) than that of 20AD rabbits, while the slaughter yield decreased only in 20FR rabbits (P = 0.001). Regarding meat physical traits, 20FR rabbits exhibited the highest pHu (P < 0.001) and the lowest total losses (P < 0.001), whereas the meat-to-bone ratio decreased in both 20FR and 30AD groups (P = 0.007). As for meat proximate composition, protein and lipid contents were lower (P = 0.008 and P = 0.0002, respectively) in 20FR and 30AD rabbits, while water content was greater (P < 0.001) compared to 20AD rabbits. At the lipid level, higher TBARS (P = 0.001) were found in both 20FR and 30AD groups. The 20FR and 30AD groups showed some differences in their carcass and meat quality traits, however the majority of changes induced by chronic heat stress were mostly attributed to the reduced feed intake.