Impact of inmediate postnatal sucking on mortality and growth of sucklings in field condition.

Abstract

Viability and growth of 191 kits born alive from 33 does from a local population was studied in tropical conditions (Benin) in relation to achieving the initial sucking. After observing the state of the kit?s belly at the first control, each kit was weighed and classified as suckled (S) or non suckled (NS), and returned to it?s mother?s nest box. On average 34% of kits were considered to be in the NS group. The proportion ranged from 15% in very small litters (2-3 born alive) to 42% in the largest litters observed (8-9 born alive). Apparent live weight of NS kits was significantly lower than that of S kits: 40.4 vs. 53.6 g. The weight difference was not related to litter size. Birth to weaning mortality (0-35 d.) was significantly higher for NS kits than for S kits: 36.9% vs. 13.5%. But of those kits which died during the lactation period, the proportion of deaths during the first week of life was almost identical for NS and S kits: 66.7% and 64.7%. Birth weight of non suckled kits which died before weaning was significantly smaller than that of non suckled kits alive at weaning time: 37.6 vs. 42.0 ± 7.9 g without any significant interaction with litter size. However, for suckled kits, the corresponding difference was smaller and non significant: 51.4 vs 53.9 ± 8.0g again without interaction with litter size. The average 0-35 days growth rate was not affected by the initial sucking (NS 12.23 and S 12.21 g/d). Nevertheless an interaction with litter size was observed (P=0.091): in small litters (2-5 kits born alive) NS kits had a lower growth rate than those of the S group (12.8 vs. 14.2 g/day), while in larger litters (6-9 kits) the reverse was observed (12.1 vs. 11.1 g/day). Careful observation of newborn kits would allow stockbreeder to reduce mortality among young rabbits in a critical situation.