The effect of a wheat-fat-interaction on the efficacy of a multi-enzyme preparation in broiler chickens

The effect of different dietary combinations of wheat (0, 250 and 500 g kg−1) and fat (low, medium, high) on the efficacy of a commercial multi-enzyme preparation (Bio-feed + CT: BCT) was assessed in a balance trial with broiler chickens from 22 to 26 days of age using mash diets. Responses were measured in terms of excreta/feed(E/F)ratio, N-retention, fat digestibility and MEn-values. All balance parameters were to a variable degree influenced by the 3 dietary factors (wheat, fat and BCT). In addition, there were 2 interesting interactions, (1) the favorable effect of BCT on the balance parameters was only obvious in combination with wheat (directly proportional to the wheat level) and (2) the effect of fat supplementation on dietary MEn-content was variable and dependent on dietary wheat concentration (the curvilinearity was directly proportional to the wheat level). The MEn-content of wheat was clearly influenced by the 3 dietary factors: its inclusion level (−3.8% lower at 500 than at 250 g kg−1), dietary fat level (−2 and −4% at medium and high fat level, resp.) and BCT-supplementation (varying from +4.9 to 9.4%). The MEn-equivalence of BCT was quite variable, varying from about 110 (at 0 g kg−1 wheat) to 1020 MJ/kg (at 500 g kg−1 wheat combined with either medium or high dietary fat level). The required wheat/BCT ratio should be adapted to the dietary wheat concentration (250 versus 500 g kg−1) or not. For a constant MEn-increase of wheat (e.g. +8%) the respective ratios were 702 and 1171, but for the same target MEn-value of wheat, this ratio was about 715 and was largely unaffected by dietary wheat concentration.