Slow-release amylase increases in vitro ruminal digestion of maize and sorghum grain

M Crosby,Gd Mendoza,I Bonola,Lm Melgoza,Fx Plata,H Sandoval

doi:10.4314/sajas.v42i1.4

Abstract

The objective of this study was to evaluate the effects of slow-release α-amylase in ruminal in vitro digestion of maize and sorghum grains. Digestibility was measured using an in vitro procedure with 40 mL of buffer and 10 mL of ruminal fluid, flushed with CO 2 and incubated at 39 °C. The digestibility of sorghum and maize grain was measured after 6 and 12 hours of fermentation with or without exogenous α-amylase in powder form or dispersed in a matrix system for slow release by a diffusional mechanism. Tablets were used as the drug release matrix system, and were formulated with barium sulphate and ethylcellulose as the core of the final tablet. Treatments consisted of incubation of sorghum or maize grains with four doses of enzyme, using α-amylase in powder or in the press-coated tablet (16 treatments). The results showed that with a higher dose of exogenous enzyme, the digestibility of the grains was improved. Sorghum and maize digestion with tablets were improved compared with α-amylase in powder form. Releasing α-amylase from matrix tablets represents a potential technology to improve grain digestion in ruminants. Keywords: Enzymes, slow-release, grains, digestibility, rumen

Highlights

The finishing of sheep can be carried out on high grain diets (Mendoza et al, 2007), where sorghum and maize are commonly used in the diet
In vitro and in situ studies using these grains as substrates have shown that the addition of the enzyme, α-amylase from Bacillus licheniformis, or glucoamylase from Aspergillus niger in liquid form, increases grain digestion as a function of dose (Gutierrez et al, 2005; Rojo et al, 2007)
Even when amylolytic enzymes have been shown to increase ruminal starch digestion, performance is not always improved (Rojo et al, 2005), because the addition of these enzymes increases the rate of starch digestion, causing subacute acidosis

Summary

Introduction

The finishing of sheep can be carried out on high grain diets (Mendoza et al, 2007), where sorghum and maize are commonly used in the diet. Both grains are usually processed to increase their digestibility (Ortega & Mendoza, 2003). In vitro and in situ studies using these grains as substrates have shown that the addition of the enzyme, α-amylase from Bacillus licheniformis, or glucoamylase from Aspergillus niger in liquid form, increases grain digestion as a function of dose (Gutierrez et al, 2005; Rojo et al, 2007). Modulation of the rate of starch digestion may be needed in systems based on grains to improve animal performance

Objectives

Methods

Results