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[EN] This study aims to determine the digestibility of milk by the young rabbit (21-25 d old), taking into account the increment of digesta content and urine excretion. Nineteen litters of 9 young rabbits 21 to 25 d old were used: 12 litters (S group) fed exclusively with milk using controlled suckling, and 7 litters (Control group) with free suckling and access to the pelleted feed of the doe. The faecal digestibility of milk dry matter (DM) was measured between 21 and 25 d of age, for S litters housed from 15 d of age in a metabolism cage separately from their mother. Between 21 and 25 d, the milk intake, faeces and urine excretion were controlled daily, and the mean increment in digesta content was measured by comparing digesta weight of the whole tract at 21 and 25 d of age (one kit per litter). The increment in digesta content from 21 to 25 d averaged 77% (+8.5 g), sourcing mainly from stomach and caecum contents increase (+57 and +120% respectively). The mean increase for the dry content of the gut (from 21 to 25 d) was 1.75 g DM/kit, and was considered as non-digested to calculate the digestibility coefficient of the milk. The milk intake averaged 30 g/d/kit (7.9 g DM/d kit). No faecal excretion was recorded between 21 and 25 d. From the milk intake and increment in digesta content, the corrected digestibility of the milk dry matter reached 94% (minimum=92.9%, maximum=95.6%). The daily urine excretion averaged 5.1 mL/kit, corresponding to 1.2 g DM/kit. Therefore, the corrected DM retention coefficient of the milk was 79.5%. The quantity of nitrogen excreted in urine was low (0.06 g/d kits), thus the corrected nitrogen retention coefficient for milk reached 82% and the nitrogen retained (corrected) reached 0.44 g/d kit. Accordingly, the amount in metabolisable protein for the milk was 90 g/kg (fresh). The corrected energy retention coefficient was estimated to 95.8%, for a crude energy concentration estimated at 28.14 MJ/kg DM for the milk. Thus, the energy retained (corrected) reached 223 kJ/d kit and the content in metabolisable energy for the milk was 26.94 MJ/kg DM., The authors thank INRA PHASE division for the financial support. The authors would also like to thank the technicians involved in the experiment at the INRA UE PECTOUL (Patrick Aymard, Jacques De Dapper & Jean De Dapper) and in the GenPhySE laboratory (Véronique Tartié).

The purpose of this experiment was to evaluate the accuracy of a total body electrical conductivity technique (TOBEC; EM-SCAN Inc., Springfield, IL, USA) to estimate in vivo body composition of steady state rabbit females. Eighty-four female rabbits (New Zealand×Californian, weight range: 3126–5465 g) at different physiological states were used in the experiment. After TOBEC assessment (five passages through a SA-3203 type chamber), animals were weighed, slaughtered and stored at −20 °C until chemical analyses (dry matter, lipids, proteins, ash and energy). A multiple regression analysis was employed to develop appropriate prediction equations for chemical composition using TOBEC assessment (E-value) and weight of the animals as independent variables. The mean variability of the E-value for an animal (CV) was 1.21%. Very weak correlations were obtained with the prediction equations of proteins and ash (R2