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

Abstract

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 fi bre 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 fi rst 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 fi rst 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 fi rst 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 scientifi c 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.

Comparison of behaviour, performance and mortality in restricted and ad libitum-fed growing rabbits

“…However, both heavy and light rabbits were within standard ranges for being accepted by Spanish slaughterhouses. Other authors also found this reduction in final weight when animals were fed under a restricted diet in comparison with AD-fed ones (Gidenne et al, 2009a and2009b;Romero et al, 2010). It is important to state that in the present study the restricted regimen was maintained during the entire growing period, whereas in the case of Romero et al (2010) the restriction was applied only during 2 weeks just after weaning.…”

Feed intake limitation strategies for the growing rabbit: effect on feeding behaviour, welfare, performance, digestive physiology and health: a review

“…Martignon et al (2009) confirmed that the favourable impact of the restriction originated clearly from the quantity of feed offered and not from the distribution procedure. However, this favourable impact of a reduced intake seems to occur only during the restriction period, and does not continue when animals return to AL intake (Gidenne et al, 2009a;Romero et al, 2010). Similar results were also obtained by reducing the intake level through a time-limited access to drinking water (Boisot et al, 2004;Verdelhan et al, 2004;El Maghraby, 2011).…”

“…For instance, for light slaughter weights (as in Spain) the economic value of restriction strategies may be reduced (Romero et al, 2010). In conclusion, beneficial effects of an intake limitation in growing rabbits have been proved in experiments and in field conditions.…”

“…However, to reach the market weight, about 2 or 3 additional days of breeding are necessary, which reduce the economic advantage. Besides, in one recent study on a Spanish rabbit breeding system (Romero et al, 2010), a marked impairment of the growth and FC was found after a 2-week restriction (35 to 49 days, about 80% of AL), casting doubt on the economic value of such a strategy in these conditions. Organ development, slaughter yield and carcass characteristics In parallel with a post-weaning growth reduction, a restriction strategy also modifies the body composition.…”

Impact of rearing mangement on health in domestic rabbits: a review

“…This can be accomplished either using feed with low nutrient density or feed with a high structural carbohydrate content (Rodríguez- Romero et al, 2011;Martínez-Vallespín et al, 2011, by limiting the intake of pelleted all-mash feed until postnatal week 8 (Schlolaut et al, 1978;Schlolaut and Lange, 1979;Gidenne et al, 2003Gidenne et al, , 2009), or by actively restricting the feeding time (Schlolaut and Lange, 1990;Romero et al, 2010). If despite the premature developmental state of the digestive system high growth rates are to be achieved by feeding pelleted all-mash feed ad libitum starting at postnatal day 17, or if the young have access to the mother's food, it is necessary to reduce the proliferation of pathogens by adding bacteriostatic or bactericidal food supplements.…”