Feed composition at the onset of feeding behaviour influences slaughter weight in rabbits

• Suckling rabbits do not regulate their feed intake on energy content of the diet.
• Feeding strategy before weaning has an impact on rabbit live weight at slaughter.
• Lighter rabbits at weaning have better feed conversion ratio during fattening.

This study aimed to assess the influence of feed composition at the onset of solid feed intake, at 18 to 28 d of age, on growth performance and health in young rabbits until slaughter age (70 d). 796 rabbit kits, issued from 64 does followed during two successive reproduction cycles, were divided into 2 experimental groups differing in the diet that the suckling rabbits received from 18 to 28 d of age. From 18–28 d, young rabbits in the RF group were fed a diet that met the needs of reproductive does (R; 10.57 MJ DE/Kg, 128 g DP/kg, 199 g DF/kg), while young rabbits in the FF group were fed a diet that met the needs of growing rabbits (F; 9.35 MJ DE/kg, 98 g DP/kg, 258 g DF/kg). From 28 to 70 d rabbits of both groups were fed the F diet. Does received the R diet throughout the experiment thanks to experimental cages that allow separate feeding between mothers and their litters. In both groups, feed was offered ad libitum before weaning (35 d) and from 63 to 70 d of age but was restricted from weaning to 63 d. Feed intake, animal weights and health status were recorded weekly. Mortality was recorded daily. Feed intake was higher in the RF group than in the FF group from 18 to 21 d (+ 27%, P<0.001) and 21–28 d (+14.7%, P<0.01). Feed intake was similar in both groups from 28 to 35 d (34 g/d/kit, NS). This resulted in a higher average daily gain from 18 to 28 d (+13.9%, P<0.001) and a higher weight at weaning (+7.7%, P<0.001) in the RF group compared to the FF group. This difference in live weight between the two groups was reduced at 70 d (+2.4%, P<0.05) due to a lower feed conversion rate in the FF group at 42–49 d and 63–70 d (P<0.05). Mortality was low before (1.2%) and after weaning (0.4%), and no differences were seen between the groups concerning mortality and morbidity (NS). This did not support the hypothesis that suckling rabbits regulate feed intake based on energy content of the diet at the onset of solid feed intake, but suggests that the moment of distribution of fattening feed before weaning has an impact on weight at weaning and kit health during the fattening period.