Treatment of tropical forages with exogenous fibrolytic enzymes: effects on chemical composition and in vitro rumen fermentation

Abstract

The effects of three treatments of fibrolytic enzymes (cellulase from Trichoderma longibrachiatum (CEL), xylanase from rumen micro-organisms (XYL) and a 1:1 mixture of CEL and XYL (MIX) on the in vitro fermentation of two samples of Pennisetum clandestinum (P1 and P2), two samples of Dichanthium aristatum (D1 and D2) and one sample of each Acacia decurrens and Acacia mangium (A1 and A2) were investigated. The first experiment compared the effects of two methods of applying the enzymes to forages, either at the time of incubation or 24 h before, on the in vitro gas production. In general, the 24 h pre-treatment resulted in higher values of gas production rate, and this application method was chosen for a second study investigating the effects of enzymes on chemical composition and in vitro fermentation of forages. The pre-treatment with CEL for 24 h reduced (p < 0.05) the content of neutral detergent fibre (NDF) of P1, P2, D1 and D2, and that of MIX reduced the NDF content of P1 and D1, but XYL had no effect on any forage. The CEL treatment increased (p < 0.05) total volatile fatty acid (VFA) production for all forages (ranging from 8.6% to 22.7%), but in general, no effects of MIX and XYL were observed. For both P. clandestinum samples, CEL treatment reduced (p < 0.05) the molar proportion of acetate and increased (p < 0.05) that of butyrate, but only subtle changes in VFA profile were observed for the rest of forages. Under the conditions of the present experiment, the treatment of tropical forages with CEL stimulated their in vitro ruminal fermentation, but XYL did not produce any positive effect. These results showed clearly that effectiveness of enzymes varied with the incubated forage and further study is warranted to investigate specific, optimal enzyme-substrate combinations.

Fibrolytic enzymes improving in vitro rumen degradability of tropical forages

“…5,000 µl) of FEE, which was certainly due to the higher TDOM and DNDF observed for these samples, in accordance with the findings of Soltan et al (2013) and Dineshkumar et al (2014). Previous studies suggested that fibrolytic enzymes may weaken and/or degrade the plant cell wall constituents thus facilitating the microbial attachment and enhancing ruminal fermentation (Díaz et al, 2015;Elghandour et al, 2016). Our study showed that the most elevated dose levels of FEE improved TDOM and DNDF of different tropical forages and this could be a result of the higher substrate hydrolysis and synergism with other ruminal enzymes (Beauchemin et al, 2003;Elghandour et al, 2016;Eun & Beauchemin, 2008;López et al, 2016).…”

“…Elghandour et al (2016) observed some changes in SCFA profile with the addition of fibrolytic enzymes, but this variation was roughage dependent. The increase in propionate production suggests a change in the fermentation pattern, which affected C2:C3 ratio and this could be attributed to fermentation of soluble carbohydrates arising from cell wall degradation (Díaz et al, 2015;Romero et al, 2015) and also from the FEE (soluble carbohydrates). The improvement of C2:C3 ratio is an indication of better efficiency of energy utilisation in the rumen (Arriola et al, 2011).…”

“…In this context, several studies demonstrated that exogenous fibrolytic enzymes can enhance in vitro (Díaz et al, 2015;Dineshkumar et al, 2014;Pech-Cervantes et al, 2019;Romero et al, 2015;Soltan et al, 2013) and in vivo (Alsersy et al, 2015;Arriola, Kim, Staples, & Adesogan, 2011;Beauchemin, Rode, & Sewalt, 1995;He, Walker, McAllister, & Yang, 2015;Kholif et al, 2018;Kondratovich et al, 2019;Salem et al, 2015;Valdes et al, 2015) degradability of forage for ruminant. According to the authors, with the use of exogenous fibrolytic enzymes, it is possible to improve forage utilisation (Dineshkumar et al, 2014;Kholif, Elghandour, Rodríguez, Olafadehan, & Salem, 2017) and reduce energy losses as enteric CH 4 (Hristov et al, 2015).…”

“…According to the authors, with the use of exogenous fibrolytic enzymes, it is possible to improve forage utilisation (Dineshkumar et al, 2014;Kholif, Elghandour, Rodríguez, Olafadehan, & Salem, 2017) and reduce energy losses as enteric CH 4 (Hristov et al, 2015). The increase in the fibre degradability can be explain by the fact that fibrolytic enzymes may weaken and/or degrade the plant cell wall constituents, thus facilitating microbial attachment on the substrate, enabling greater use of nutrients and a faster growth of micro-organisms populations (Díaz et al, 2015;Elghandour et al, 2016).…”

Nutritive value of elephant grass hay ammoniated by urea

“…is a forage plant of important use in livestock feeding, both for its great dry mass production and for its longevity and nutritive value (DIEHL et al, 2013). However, like most tropical forages, it has low nutritional value when harvested at an advanced stage of maturity, and as forage is the main component of ruminant diets in Brazil, the low-quality forage might result in low animal productivity (DÍAZ et al, 2015).…”