Effects of particle size of processed barley grain, enzyme addition and microwave treatment on in vitro disappearance and gas production for feedlot cattle.

Shin-Ichi Tagawa,Wen Zhu Yang,Lucia Holtshausen,Tim A Mcallister,Karen Ann Beauchemin

doi:10.5713/ajas.16.0351

Abstract

ObjectiveThe effects of particle size of processed barley grain, enzyme addition and microwave treatment on in vitro dry matter (DM) disappearance (DMD), gas production and fermentation pH were investigated for feedlot cattle.MethodsRumen fluid from four fistulated feedlot cattle fed a diet of 860 dry-rolled barley grain, 90 maize silage and 50 supplement g/kg DM was used as inoculum in 3 batch culture in vitro studies. In Experiment 1, dry-rolled barley and barley ground through a 1-, 2-, or 4-mm screen were used to obtain four substrates differing in particle size. In Experiment 2, cellulase enzyme (ENZ) from Acremonium cellulolyticus Y-94 was added to dry-rolled and ground barley (2-mm) at 0, 0.1, 0.5, 1, and 2 mg/g, while Experiment 3 examined the interactions between microwaving (0, 30, and 60 s microwaving) and ENZ addition (0, 1, and 2 mg/g) using dry-rolled barley and 2-mm ground barley.ResultsIn Experiment 1, decreasing particle size increased DMD and gas production, and decreased fermentation pH (p<0.01). The DMD (g/kg DM) of the dry-rolled barley after 24 h incubation was considerably lower (p<0.05) than that of the ground barley (119.1 dry-rolled barley versus 284.8 for 4-mm, 341.7 for 2-mm; and 358.6 for 1-mm). In Experiment 2, addition of ENZ to dry-rolled barley increased DMD (p<0.01) and tended to increase (p = 0.09) gas production and decreased (p<0.01) fermentation pH, but these variables were not affected by ENZ addition to ground barley. In Experiment 3, there were no interactions between microwaving and ENZ addition after microwaving for any of the variables. Microwaving had minimal effects (except decreased fermentation pH), but consistent with Experiment 2, ENZ addition increased (p<0.01) DMD and gas production, and decreased (p<0.05) fermentation pH of dry-rolled barley, but not ground barley.ConclusionWe conclude that cellulase enzymes can be used to increase the rumen disappearance of barley grain when it is coarsely processed as in the case of dry-rolled barley. However, microwaving of barley grain offered no further improvements in ruminal fermentation of barley grain.

Highlights

In 2014, global production of cereal grains included 990 million metric tonnes of corn, 717 million mt of wheat, 478 million mt of rice, and 145 million mt of barley [1]
We hypothesized that microwave treatment would improve in vitro disappearance of barley grain, especially when subjected to fibrolytic enzyme additives, and that this combination of treatments would reduce the degree of particle size reduction needed to optimize rumen availability of barley
The fermentation pH only differed among barleys after 24 h of incubation (p

Summary

Introduction

In 2014, global production of cereal grains included 990 million metric tonnes (mt) of corn, 717 million mt of wheat, 478 million mt of rice, and 145 million mt of barley [1]. Extensive processing can be costly and can increase the incidence of rumen acidosis in cattle [10] Alternative technologies such as enzymes and heat-treatment may help optimize the efficiency of barley grain utilization by ruminants. Krause et al [11] showed that exogenous fibrolytic enzymes improved nutrient digestion by feedlot cattle fed high-concentrate diets that contained barley grain. Processing using methods such as steam-rolling and steamflaking, in which heat and moisture are applied to grain, can help gelatinize starch and may increase degradation by microorganisms in the rumen [2]. We hypothesized that microwave treatment would improve in vitro disappearance of barley grain, especially when subjected to fibrolytic enzyme additives, and that this combination of treatments would reduce the degree of particle size reduction needed to optimize rumen availability of barley

Methods

Results

Conclusion