Pathology / Environment and Management IV

Broiler trials, using feeds with varying WE-AX and WU-AX levels (wheat and/or corn based) showed that the AME-uplift obtained by Nutrase Xyla is correlated with the level and type of AX. AX-dependant enzyme energy factors were calculated and put in the prediction model : AMENX (kcal/kg) = AME + 100*WE-AX (%) + 25*WU-AX (%) To validate the model, diets with very low and high AX levels were made, using respectively sorghum or rye as main cereal sources. Four treatments were tested : sorghum control, sorghum +Nutrase Xyla, rye control and rye +Nutrase Xyla. Each treatment had 12 floor pens of 15 Ross 308 broilers (6 males and 6 females). Feed intake, body weight (BW) and mortality were measured at d42, weight adjusted feed conversion (WAFC) was calculated. In the sorghum diet (0.1 % WE-AX, 2.5 % WU-AX) an enzyme effect on AME of 73 kcal/kg is predicted. Adding Nutrase Xyla improved BW gain by 6.7 % and WAFC by 2.4 % (P<0.05). This equals an energy liberation of 74 kcal/kg and confirms the estimation based on the prediction model. In the rye diet (1.4% WE-AX, 3.2% WU-AX levels) an enzyme AME increase of 220 kcal/kg is expected. Zootechnical results improved by 19.6 % for BW gain and by 9.7 % for WAFC (P<0.05) . Energy liberation corresponding to these zootechnical data is 301 kcal/kg. These results demonstrate that the energy uplift, calculated according to the prediction model, even underestimated the actual energy release by Nutrase Xyla. One may conclude that the model established mainly from wheat and corn trials was also valid for estimating energy upgrading in diets with extreme AX levels.