Impact of space allowance on performance traits, brain neurotransmitters and blood antioxidant activity of New Zealand White rabbits

The objective of this trial was to investigate the effect of space allowance on performance, welfare-related parameters and the levels of brain neurotransmitters in growing male rabbits. In a cage housing system, a total of 96 weaned rabbits were accommodated on three space allowance conditions (S₁ = 1425 cm²/rabbit; S₂ = 850 cm²/rabbit; S₃ = 625 cm²/rabbit), with 8 replicate cages per each group. Rabbits in the S₁ and S₂ groups showed better daily feed intake and feed conversion ratio compared with the high stocking density group (p = 0.004 and 0.018, respectively). Compared to the highest stocking density group (S₃), rabbits in the S₁ and S₂ groups showed significantly lower serum cortisol, MDA and GSSH level (p = 0.026, 0.018 and 0.009, respectively). The concentration of dopamine in brain tissues was significantly decreased in the S₃ group compared with other experimental groups (P = 0.001). However, there was no significant effect of space allowance on the brain AChE level (P = 0.277). Brain serotonin and GABA levels showed a significant decrease in rabbits reared with a limited space allowance (S₃) compared with S₁ and S₂ groups (P = 0.001 and 0.038, respectively). The level of brain MDA was significantly increased in the S₃ group compared with the S₁ group (P = 0.006). However, there were no detectable differences in the brain ATP level in rabbits reared with different space allowance (P = 0.693). In conclusion, the current study indicates that the 850 cm²/rabbit stocking density has resulted in a better feed intake, and welfare-related conditions compared with the 625 cm²/rabbit. Furthermore, the limited space allowance may impair the most important brain neurotransmitters in male rabbits.