APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
ENZYME COMPLEX IMPROVES PERFORMANCE OF BROILERS FED WHEAT- AND
SOYBEAN-BASED DIETS WITH GRADED DENSITY: OPTIMUM DEFINITION
P. COZANNET 1 , M. LE MEUR 1 , H. BATUT 1 A. PREYNAT 1 Y.G. LIU 2 and
P. DALIBARD 3
Summary
An experiment was carried out to measure regulation of feed intake by broiler chickens fed
on graded density diets and possible interaction with enzyme supplementation. Male broilers
were randomly assigned to four wheat and soybean meal-based diets providing 10.03, 11.15,
12.26 and 13.38 MJ AMEn/kg with or without NSP enzyme (Rovabio Excel). Each treatment
was tested with 12 replicates of 15 birds grown to 35 d of age, to evaluate growth parameters:
daily feed intake (DFI), daily weight gain (DWG) and feed conversion ratio (FCR). The
results showed that increasing dietary energy density without enzyme addition significantly
improved performance. Final body weight and FCR were positively correlated to dietary
AMEn content according to a quadratic plateau (R² = 0.97, 0.99 and RSD = 43g and 0.03,
respectively). Feed intake was significantly correlated to AMEn content for a standardized
body weight (R² = 0.83, RSD = 80g). Over the entire period, the addition of the NSP enzyme
improved DWG and FCR by 3% on average. The enzyme effect on FCR was clearly related
to dietary energy density (P < 0.01), with improvement ranging from +1.4 % for the 13.38
MJ AMEn/kg diet to -6.8 % for the 11.15 MJ AMEn/kg diet. In contrast, no consistent
enzyme effect on DFI was observed (P = 0.79), in relation to body weight. It is concluded
that broilers still possess the ability to control DFI based on desire to regulate energy intake,
implying a need for precise formulation tools. The enzyme effect was highly related to
dietary density but this relationship was not linear.
I. INTRODUCTION
Feed normally accounts for up to 70% of the total broiler production cost. Chickens have
been traditionally fed with relatively high-energy diets, because, in addition to better feed
utilization, it is also assumed that this type of diet maximizes growth rate (Leeson and
Summers, 1991). As energy remains the most expensive nutrient, it is now suggested that diet
density may be reduced while striving to maintain overall performance. The use of
carbohydrases, hydrolyzing insoluble as well as soluble non-starch polysaccharides (NSP), is
widely and successfully implemented when viscous cereals (wheat, barley, rye, oats, or
triticale) are used (Bedford and Classen, 1992). By breaking down the cell wall matrix,
enzymes may facilitate release of nutrients encapsulated in the cell walls, resulting in an
easier access of digestive enzymes to their target nutrients (Cowieson et al., 2006) thus
improving the nutritional value of the diet. The aim of the present study was to investigate the
effect of carbohydrases and diet density on growth performance.
II. MATERIALS AND METHODS
The study was conducted in a 4 × 2 factorial arrangement of treatments with 4 levels of
AMEn (10.03, 11.15, 12.26 and 13.38 MJ AMEn/kg), with or without carbohydrase
(Rovabio ® Excel, Adisseo France SAS, Antony, France) supplementation. All nutrient
1 Adisseo France S.A.S. CERN, Commentry. Aurelie.Preynat@adisseo.com
2 Adisseo Asia Pacific P/L, Singapore.
3 Adisseo France S.A.S., Antony, France.
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