The effect of cell wall degrading enzymes on the preservation of grass and on the silage intake and digestibility in sheep

Abstract

Two experiments were carried out to study the effects of cell wall degrading enzymes as silage additive. A primary growth of timothy was cut with a mower and picked up with a precision-chop forage harvester in Exp. I (early cut), and harvested as direct-cut with a precision-chop harvester in Exp. II (late cut). The additive treatments were in Exp. I: 1) unwilted formic acid (FA) applied as AIV II (4.5 l/t), 2) wilted untreated, 3) wilted FA (4 l/t), 4) wilted enzyme A (glucose oxidase (GO) + hemicellulase (HC) 150 ml/t + cellulase (C) 200 ml/t), 5) wilted enzyme B (HC 150 ml/t + C 200 ml/t); and in Exp. II: 1) untreated, 2) FA (4 l/t), 3) E200 (C 200 ml/t + GO), 4) E400 (C 400 ml/t + GO), 5) E800 (C 800 ml/t + GO). The rate of application of GO was 50 000 IU/t. The silages were ensiled in pilot scale silos (3 m3) and the voluntary intake and digestibility in sheep were determined in two experiments designed as a 5 x 5 Latin square. The use of enzymes decreased the fibre content of silages, mainly the cellulose fraction, as compared with FA and untreated silages. Enzyme silages were well preserved with a low pH (3.93—4.15), moderate ammonia N (72—119 g/kg total N) and no butyric acid. As compared with untreated silages (mean pH 4.6, ammonia N 131) the preservation was improved. The FA silages were also well preserved (pH 4.0, ammonia N 57) with more restricted fermentation than enzyme silages. FA and especially higher levels of enzymes increased the amount of effluent. In Exp. I, the digestibilities of dry matter (DM), organic matter (OM) and crude fibre were not significantly (P>0.05) affected by the silage treatment. In Exp. II, the digestibility of DM and OM decreased linearly (P

The effect of enzyme treatment on the nutritive value of lucerne for equids

“…In the present study, enzyme treatment resulted in a significant reduction in the apparent digestibility of OM, NDFom and TNSP digestibility in diets DE1 and DE2 relative to the control diet and DE3. Reduced digestibility of enzyme-treated diets has been observed by others in sheep (Jaakola, 1990; and cattle . In these studies, the ADF and NDF contents were lower in the enzyme-treated silages compared to the untreated control; therefore, these authors postulated that the use of enzymes resulted in the breakdown of the more readily degradable fibrous fraction during ensilage, resulting in silage with lower, but less degradable ADF and NDF residues.…”

Cellulase and Bacterial Inoculant Effects on Cocksfoot and Lucerne Ensiled at High Dry Matter Levels

“…Previous research has reported the e †ects of enzyme application rates, with or without additional LAB, on silage composition (Jaakkola 1990 ;Kung et al 1991 ;Tengerdy et al 1991 ;Selmer-Olsen et al 1993). There is, however, only limited information available on the interaction between enzyme application rates and plant species and their impact on the quality of forages ensiled at high DM levels.…”

Ensiling characteristics and ruminal degradation of Italian ryegrass and lucerne silages treated with cell wall-degrading enzymes

“…Increases in digestibility 4±9 might indicate that the breakdown of cell wall components could facilitate microbial digestion, while claims have been made that enzymes would principally hydrolyse easily degradable components and leave less digestible organic matter in the treated silages. 10,11 If forages were ef®ciently hydrolysed by cell walldegrading enzymes, then the kinetics of organic matter digestion would be altered. Although several workers examined the effect of enzymes on the in situ degradation of silages, the results were variable and did not reach agreement.…”