APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
PROTEASE SUPPLEMENTATION ENHANCES APPARENT DIGESTIBILITY OF
AMINO ACIDS AT FOUR SMALL INTESTINAL SITES IN BROILER CHICKENS
OFFERED SORGHUM-BASED DIETS
S.Y. LIU 1 , P.H. SELLE 1 , S.G. COURT 2 and A.J. COWIESON 1
Summary
A feeding study with a 4×2 factorial array of dietary treatments was conducted to determine
apparent amino acid digestibilities in the proximal jejunum, distal jejunum, proximal ileum
and distal ileum of broilers fed sorghum-based diets without or with exogenous protease.
Interactions between intestinal site and protease supplementation were not observed.
Intestinal site significantly influenced apparent digestibility coefficients of all amino acids
which increased from an average of 0.466 in the proximal jejunum to 0.803 in the distal
ileum. Protease improved apparent digestibility of amino acids by an average of 9.16% with
significant responses in 14 ex 16 amino acids. The more pronounced responses to protease
were recorded for proline (14.6%), alanine (12.8%), and leucine (12.7%). The present study
indicates that the Bacillus lichenformis-derived protease has the capacity to improve amino
acid digestibility coefficients in sorghum-based diets.
I. INTRODUCTION
The effects of protease supplementation on nitrogen (N) and starch digestibility in four small
intestinal sites of broilers offered sorghum-based diets were determined in an earlier study
(Selle et al., 2012). Protease significantly increased N digestibility in the distal jejunum
(0.538 vs. 0.627), proximal ileum (0.727 vs. 0.770) and distal ileum (0.719 vs. 0.770).
Moreover, protease significantly improved starch digestibility in the distal jejunum (0.678 vs.
0.770) and proximal ileum (0.812 vs. 0.851). Thus, the intention of the present study was to
determine the effect of protease on apparent amino acids digestibility throughout the small
intestine given the observed improvement in crude protein (N) digestibility generated by this
protease.
II. MATERIALS AND METHODS
The methodology used in this experiment has been previously outlined (Selle et al., 2012).
Briefly, a red sorghum (Buster) was hammer-milled (3.2 mm) and incorporated into broiler
diets that were steam-pelleted at 80 ˚C and offered to male Ross 308 chicks (seven replicate
cages of six birds per treatment) without and with protease from 7 days to 28 days post-hatch.
Dietary composition, nutrient specification and analysed amino acid concentrations of the
experimental diets are shown in Table 1. Dependent on treatment, the exogenous protease
was incorporated into the sorghum-based diet prior to steam-pelleting at 80°C. The enzyme
was a serine endopeptidase from Bacillus lichenformis (Cibenza TM DP100; Novus
International Inc.) with a protease activity of 600,000 units/g and a recommended inclusion
rate 300 units/g of feed. The analysed protease activity in the relevant experimental diet was
257 units/g of feed or 86% of the recommended activity-and protease activity was not
detected in the corresponding control diet. At day 28, digesta samples were collected in their
entirety from the proximal jejunum, distal jejunum, proximal ileum and distal ileum, which
were demarcated by the end of the duodenal loop, Meckel’s diverticulum and the ileo-caecal
1 Poultry Research Foundation, The University of Sydney. sonia.liu@sydney.edu.au
2 Novus International Inc., St. Charles, MO 63304 USA.
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