Energy and protein utilization and partition in rabbit does concurrently pregnant and lactating

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AbstractChanges in body composition during lactation in 40 primiparous rabbits were studied by comparative slaughter. The results were used to determine the utilization of digestible energy (DE) and digestible protein (DP) and their partitioning between maternal body, milk and foetal tissues.Twelve does were slaughtered immediately after their first parturition (first slaughter group) to estimate initial body composition. The 28 remaining does were remated 1 to 3 days after parturition and divided into two groups offered a pelleted diet at different levels: group L, fed ad libitum and group R, fed 0·75 of ad libitum. The 19 does that were pregnant (10 of L group, 9 of R group) were kept in individual metabolism cages until their second parturition. They were then slaughtered with their litters.Milk yield was higher (147·0 v. 117·2 g/day, P < 0·02) and live-weight loss was lower (–42 v. –294 g) in group L than in group R. The food intakes were 304·7 and 234·4 g/day, respectively. Body composition of the does changed substantially between the first and second parturition, with a considerable loss of fat and some loss of protein. A large decrease in empty body (digesta-free body) weight was observed in both groups. The loss of energy corresponded to proportionately 0·32 and 0·41 of the initial body energy, in L and R groups respectively.The DE requirement for maintenance was estimated to be 468 kj/day per kg M0·75 and the efficiencies of utilization of DE and body energy for milk production were 0·63 and 0·76, respectively. The efficiency of utilization of DE for foetal tissue synthesis was estimated to be 0·27 throughout pregnancy. The DP requirement for maintenance was 3·80 g/day per kg M0·75 and the efficiency of utilization of DP for milk protein production was 0·76 and of body protein 0·61. The efficiency of utilization of DP for foetal protein synthesis was 0·46.