Effects of exogenous enzymes on in vitro gas production kinetics and ruminal fermentation of four fibrous feeds

Abstract

a b s t r a c tThis study was conducted to investigate effects of increasing doses: 0 (control), 6 (low), 12 (medium) and 24 (high) mg/g DM of ZADO ® enzyme preparation mixture (ENZ) on in vitro gas production (GP) and some ruminal fermentation parameters of the fibrous feeds Saccharum officinarum (leaves), Andropogon gayanus (leaves), Pennisetum purpureum (leaves) and Sorghum vulgare (straw). Rumen liquor was obtained from two Brown Swiss cows fitted with permanent rumen cannulae fed a total mixed ration of a 500:500 commercial concentrate and alfalfa hay ad libitum. The GP was recorded at 2, 4, 6, 8, 10, 12, 24, 48, 72 and 96 h of incubation. After 96 h, the incubation was stopped and the pH of the mixture was determined and filtrate used to determine dry matter degradability (DMD), partitioning factor (PF 96 ), gas yield (GY 24 ), in vitro organic matter digestibility (OMD), metabolizable energy (ME), short chain fatty acids (SCFA), and microbial crude protien production (MCP). In general, the crude protein (CP) content of the fibrous feeds was low and ranged from 23 g/kg DM (S. officinarum) to 44 (A. gayanus). The fibre contents (i.e., NDFom and ADFom) were highest (P<0.05) in S. officinarum. Increasing ENZ dose linearly increased (P<0.05) GP of all fibrous feeds and had a quadratically increased (P<0.05) asymptotic gas production in P. purpureum and S. vulgare and rate of gas production in S. officinarum and S. vulgare. Addition of ENZ also quadratically increased (P<0.05) GP at all incubation times in S. officinarum and S. vulgare, and A. gayanus, but only at 72 h in A. gayanus. The parameters of ruminal fermentation of OMD, ME, GY 24 and SCFA linearly increased (P<0.05) and MCP linearly decreased (P<0.05) with the ENZ addition. Addition of enzyme affected ruminal fermentation of our feeds differently, mainly dependent on their fibre content, although dosage of enzyme was also important as impacts generally increased at higher dosages of ENZ. Crown Abbreviations: ADFom, acid detergent fibre; CP, crude protein; DM, dry matter; DMD, DM degradability; ENZ, the ZADO ® enzyme preparation mixture; GP, gas production; GY 24 , gas yield at 24 h of incubation; OM, organic matter; OMD, in vitro OM digestibility; MCP, microbial CP production; ME, metabolizable energy; NDFom, neutral detergent fibre; PF 96 , partitioning factor at 96 h of incubation; SCFA, short chain fatty acids.

Influence of the addition of exogenous xylanase with or without pre-incubation on the in vitro ruminal fermentation of three fibrous feeds

“…The addition of fibrolytic enzymes facilitates the access of microorganisms to feed components enabling a faster microbial growth. Gas production during the first hours of ruminal fermentation was increased in the present study, supporting the hypothesis that a suitable ENZ level could improve the fermentation of feeds during the initial stages of forage digestion (Elghandour et al 2013). Diaz et al (2013) observed that the addition of a fibrolytic enzyme increased the fermentation rate of maize stover, although asymptotic GP was unaffected.…”

“…Elghandour et al (2013) observed that the amount of enzyme added to different fibrous feeds has a positive effect on in vitro nutrient digestibility. Lara-Bueno et al (2013) reported a greater disappearance in situ for DM and NDF after 24 and 48 h of incubation of oat straw treated with a fibrolytic enzyme.…”

“…This may be due to greater enzymatic hydrolysis of feeds into readily fermentable substrates that depress pH when fermented. Elghandour et al (2013) recorded reduced ruminal pH values when four fibrous substrates were incubated with different levels of an exogenous enzyme. On the other hand, Diaz et al (2013) stated that enzyme treatment of maize stover had no effects on final pH values in vitro.…”

“…The application of ENZ may be a mean of overcoming the problem of low intakes and slow digestion rates of low quality forages . Elghandour et al (2013) concluded that it is necessary to determine the optimal application rate of ENZ preparation for individual feeds.…”

Effects ofSaccharomyces Cerevisiaeat Direct Addition or Pre-incubation onin VitroGas Production Kinetics and Degradability of Four Fibrous Feeds

“…These variations arise from variation in the genotype of the crops, differences between production environments, and from the interaction between environment and genotypes (Welch, 1995;Denčić et al, 2011). Environmental differences will include variation in climate, the soil and agronomic practice, together with variations raised from different harvesting conditions, and post harvesting treatments (Welch, 1995;Elghandour et al 2013). There is usually an inverse relationship between the CP and crude fibre content in a given forage species, and this has been revalidated in this study.…”