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.