Effect of outdoor grazing area size and genotype on space and pasture use, behaviour, health, and growth traits of weaned rabbits

Providing rabbits with outdoor access allows them to express a large repertoire of behaviours and addresses societal expectations surrounding animal welfare in livestock systems. The aim of this work was to study rabbit growth, health, and behaviour according to genetic type and pasture area size. We distributed 192 weaned rabbits into two groups with different pasture sizes, i.e., a large pasture (LP): 60 m² (n = 4 × 24) and a small pasture (SP): 30 m² (n = 4 × 24). Each group contained half Californian 1001 × New Zealand 1777 rabbits (1001) and half PS119 × New Zealand 1777 rabbits (PS119). Rabbits were reared from 31 to 73 days of age. Rabbit growth and morbidity were measured individually weekly for 36 days (from 31 to 67 days of age). The rabbits’ behaviours were assessed three times a day on days 44, 58, and 70 by a direct visual scan, and the use of space was evaluated six times a week based on the rabbits’ spatial distributions. The available biomass was evaluated on days 35, 50, and 73. Finally, the amount of corticosterone was measured in hair samples from 18 rabbits of each genotype in LP and SP on day 72. PS119 rabbits were heavier than 1001 rabbits on day 67 (2 444 vs 2 113 g, respectively; P < 0.05) but we observed no effect of genotype on mortality or morbidity. The animals expressed a large variety of specific behaviours on pastures, with grazing and resting being predominant. We found a lower level of corticosterone in PS119 rabbits than in 1001 rabbits (2.19 vs 6.34 pg per mg of hair, respectively; P < 0.05). LP pastures offered herbage until the end of the fattening period, enabling the rabbits to express grazing behaviour until the end of the experiment, and grazing behaviour was more frequent in LP-group rabbits (25.4 vs 21.5% of occurrences in LP vs SP; P < 0.05). This study found that a pasture of 60 m² for 24 rabbits enables the animals to express grazing for the entire fattening period. The rabbit genotype was found to influence some of their behaviour.