Nutritive value of sun-dried common reed (Phragmites australis) leaves and its effect on performance and carcass characteristics of the growing rabbit
Résumé
The nutritive value and potential use of sun-dried common reed (Phragmites australis) leaves (CRL), for growing rabbits was studied by comparing 3 diets (regression method) containing an increasing incorporation rate of CRL: 0% (control, CRL0), 15% (CRL15) and 30% (CRL30) in substitution for the control diet (356 g neutral detergent fibre (NDF) and 197 g crude protein (CP)/kg). Three groups of 37 rabbits (individually caged) were fed the 3 diets ad libitum from weaning (35 d, mean weight: 722 142 g) to 77 d of age. The faecal digestibility of the diets was measured between 42 and 46 d of age in 10 rabbits per group. CRL can be considered high-fibre roughage, as it contained 64% of NDF (38% of ADF and 10% ADL) and 10.2% of CP. The digestible energy (DE) content of CRL calculated by regression was null (-1.8 +/- 0.29 MJ/kg as fed). CP digestibility reached 29%, corresponding to a digestible crude protein concentration of 29.0 +/- 5.6 g/kg as fed basis. The fibre digestibility was reduced with CRL incorporation. Dietary incorporation of CRL impaired the rabbit growth (34.2 vs. 31.5 g/d during the period 35-77 d without CRL or with CRL (CRL15 and CRL30), respectively; P=0.002). Consequently, feed conversion was impaired with the high incorporation rate in feed (30%). Health status or main slaughter traits were not affected by CRL incorporation rate. Thus, the sun-dried common reed leaves had a poor nutritive value for growing rabbits and it can be considered a high-fibre feedstuff, interesting to supply low digested fibres (cellulose) and lignin.