Effect of early feed restriction on performance and health status in growing rabbits slaughtered at 2 kg live-weight

Abstract

The effect of a time-limited access to the feeders (8 h per d from 9:30 to 17:30) on fattening performance and health status was studied in rabbits reared until 2 kg live-weight as typical in the Spanish market. For this purpose, the same diet (10.5 MJ digestible energy/kg, 38.9% neutral detergent fibre and 18.4% crude protein on dry matter basis) was used over two consecutive trials. A total of 192 growing rabbits (96 in each trial) were weaned at 35 d and assigned to 2 different feeding treatments (continuously fed ad libitum or restricted from 35 until 49 d). In the first trial, feed restriction reduced daily feed intake (94.3 vs. 74.2 g; P<0.001), daily weight gain (43.6 vs. 27.1 g; P<0.001) and impaired feed conversion rate (FCR) (2.28 vs. 2.92, P<0.001) in the first 14 d after weaning. Later on, no feed restriction was applied and a compensatory growth was observed in previously restricted rabbits (44.8 vs. 54.8 g/d; P<0.001). Early restricted rabbits did not reach the Spanish commercial weight (2 kg) at 63 d of age and weighed less than full-fed rabbits (1989 vs. 1888 g; P=0.001). Moreover, feed restriction did not improve FCR in the whole fattening period (2.56 on average). The second trial was extended until 70 d to permit restricted rabbits to attain market weight. However, at that age, live weight of restricted rabbits was also lower than that of rabbits always fed ad libitum (2285 vs. 2101 g; P=0.001). In the first trial, no health problem was recorded (average mortality 1.04%) whereas in the second trial feed restriction allowed both mortality (25.6 vs. 6.34%, P=0.017) and morbidity (41.4 vs. 12.7%, P=0.004) to decrease. The higher number of losses in the second trial made economic FCR differ from scientific FCR (3.63 vs. 2.89, on average) in the 35–70 d period. Moreover, morbidity increased heterogeneity of fattening performance. In conclusion, the interest of feed restriction in Spanish fattening rabbit farms is mitigated by the conventional market weight. Nevertheless, in a context with high rates of digestive troubles, a time-limited access to the feeder enhances health status on the farm and could justify the short delay necessary to reach slaughter weight.