Preslaughter feed withdrawal and sex influences on rabbit physiological response and meat quality

Abstract

Although preslaughter feed withdrawal is commonly used in the livestock industry to reduce the risk of viscera puncture during evisceration, the optimal feed withdrawal time (FWT) appears to be species dependent and is not yet well defined in rabbits. This study aimed to evaluate the impact of three preslaughter FWTs while considering the effect of sex on physiological response and meat quality of rabbits. Three FWTs (4, 11 and 18 h) were tested using 144 recently weaned Grimaud rabbits fed until they reached an average commercial slaughter live body weight of 2.5±0.2 kg. Rabbits were allocated into 24 cages, with six animals in each cage. Eight cages (four cages for females and four cages for males) were assigned to each of the three FWTs. Blood lactate concentrations measured at exsanguination did not raise concerns related to stress. Female rabbits subjected to 4 h FWT had a higher gastrointestinal tract weight compared to male rabbits and to other females subjected to 11 and 18 h FWT (P=0.04). Stomach content weights were lower after 18 h FWT compared to 4 and 11 h (P=0.002) for both sexes, while caecum weights were not affected by FWT. Caecum pH was higher after 11 and 18 h FWT compared to 4 h (P=0.02). Technological meat quality was not particularly affected by FWT, except for Longissimus lumborum drip loss which was lower for rabbits after 18 h FWT compared to 4 h FWT (P=0.005). With respect to microbiological meat quality, the end of shelf life was reached after 10 days for vacuum-packed hind legs from rabbits after 11 h FWT, as Escherichia coli cell counts for four out of the eight hind legs analysed were higher than 3 Log10 colony-forming units (CFU)/10 g. For the other two FWT groups, the end of shelf life was reached after 15 d, at which point the cell counts for all hind legs were ≥3 Log10 CFU/10 g for E. coli and ≥7 Log10 CFU/g for total aerobic mesophilic and presumptive lactic acid bacteria (the maximum threshold concentrations according to current regulations). Our results demonstrate that when transport (30 min) and lairage (30 min) times are short (1 h in total), an 18-h preslaughter feed withdrawal for both male and female rabbits can allow the gut to empty properly with limited effect on meat quality.