EFFECT OF EXTRACT OF CHESTNUT WOOD INCLUSION (ENC®) IN NORMAL AND LOW PROTEIN AMMINOACID SUPPLEMENTED DIETS ON HEAVY BROILER RABBITS

A chestnut (Castanea sativa) extract (ENC), rich in hydrolysable tannins, was evaluated in rabbit diets without antibiotics. A total of 72 five week-weaned rabbits were fed as follows: 1) control diet (C); 2) Aminoacid supplemented low protein diet (A); 3) diet A+0.45 % ENC (TA); 4) diet C+0.45 % ENC (TC). Feeding was modulated in two phases characterised by different levels of CP (DM basis): diet C first period 175 g/kg, second period 197 g/kg vs. diet A first period 145 g/kg, second period 159 g/kg. The ENC was extracted from chestnut wood by a heat and low-pressure treatment, and only the water-soluble fraction was kept and subsequently dehydrated. The product is commercially available as fine brown powder (92 to 95 % dry matter) with a pure tannin content of 77 % on a DM basis. The trial was carried out in full summer conditions. The productive traits were recorded each 14 days. ENC inclusion did not have any negative effects on the productive parameters, while low protein AA supplemented diets enhanced significantly (P<0.01) protein utilization. Over the whole period, ENC inclusion did not influence the daily feed intake, daily weight gain, feed conversion ratio and protein efficiency ratio, but reduced significantly (P<0.01) the mortality from 44 % to 11 % in group C and group TC fed high protein diets; while mortality was exactly the same (11%) in groups A and TA. The high level of protein can be suspected as being the cause of mortality