THE IMPORTANCE OF DIGESTIVE DYNAMICS IN BROILER CHICKEN NUTRITION
Sonia Liu (1,2), Shemil Macelline (1,2), Mehdi Toghyani (1,2) and Peter Selle (2,3)
1- School of Life and Environmental Sciences, The University of Sydney, Australia
2- Poultry Research Foundation, Faculty of Science, The University of Sydney, Australia
3- Sydney School of Veterinary Science, The University of Sydney, Australia
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DIGESTIVE DYNAMICS MATTER
In typical broiler diets, protein and amino acids are primarily the building blocks of protein and starch and glucose are the principal source of energy. Both are required for optimal growth performance and an appropriate balance of amino acids and glucose should be made available at sites of protein synthesis to generate efficient protein accretion and growth. The various body proteins require a specific profile of amino acids and each gram of protein synthesised demands an energy input of 5.35 kJ for in broiler chickens (Aoyagi et al., 1988). This is the fundamental construct of digestive dynamics.
Conventionally, nutrient utilisation in chickens is determined from total tract nutrient digestion and retention or apparent digestibility coefficients based on digesta taken from the terminal ileum. While the later eliminates the confounding effects of hindgut fermentation it overlooks the fact that digestion of protein and starch, absorption of amino acids and glucose principally occurs in duodenum and jejunum (Hurwitz et al., 1972, Riesenfeld et al., 1980). Moreover, the digestion of starch is more rapid than protein. Sorghum is considered to be a slowly digestible source of starch (Giuberti et al., 2012); however, starch digestion rates were nearly 40% faster than protein (3.38 versus 2.46 ×10-2 min-1, Figure 1) in birds offered conventional, sorghum-based diets in Liu et al. (2013c). Digestive dynamics consider the extent, rate and site of nutrient digestion along the small intestine and the bilateral, post-enteral bioavailability of amino acids and glucose. The fundamental premise is that balanced quantities of amino acids and glucose should be made available at the sites of protein synthesis to drive efficient protein deposition and growth performance (Liu and Selle, 2017).
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