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.

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.

Introduction – Heat stress (HS) represents a major challenge for rabbit production, particularly in regions characterized by high environmental temperatures. The present study investigated the impact of hair shearing on the meat quality traits of growing rabbits exposed to chronic HS conditions. Methods – A total of 150 weaned Pannon Ka rabbits were equally divided into three experimental groups (50 animals/group) and allocated into two rooms. In the first room, a temperature of 20 °C was applied and the control group (unsheared, CON) was housed. In the second room, a temperature of 28 °C was applied and two groups of rabbits were housed: an unsheared heat-stressed group (HET) and a sheared group (SHR). At slaughter (12 weeks of age), both hind legs (HL) and longissimus thoracis et lumborum (LTL) muscles from 15 carcasses per treatment were collected for physicochemical analyses, sensory evaluation, and heat-shock protein (HSP) expression analysis. Results – Heat stress affected rabbit bone development by decreasing both femur length (P<0.05) and weight (P<0.01). HS also reduced redness and yellowness of the biceps femoris muscle (P<0.01) and increased LTL lightness (P<0.05). Moreover, HS increased LTL meat protein (P<0.05) and ash (P<0.01) contents while reducing lipid content (P<0.05). In contrast, sensory traits of rabbit meat were not affected by HS. Hair shearing partially mitigated most of the observed changes, with sheared rabbits generally showing intermediate values for most traits, except for LTL moisture content, which was the lowest (P<0.05). Gene expression analysis revealed a higher induction of HSP70_1b (P<0.05) and HSP70_8 (P<0.05) in the HET group compared with the CON group, whereas no significant differences were observed in the SHR group compared with either of the other groups. No significant differences were detected in the expression of HSP90 family members. Discussion – Overall, the study confirmed that HS impacts carcass and meat quality of rabbits and that hair shearing can be considered an effective low-cost strategy to alleviate part of the negative effects caused by chronic HS conditions. Hair shearing is particularly applicable in rural production rather than in industrial contexts where this practice would represent a significant labor cost.