Effect of adding cofactors to exogenous fibrolytic enzymes on preingestive hydrolysis, in vitro digestibility, and fermentation of bermudagrass haylage

Abstract

Our objectives were to examine if adding metal ion cofactors (COF) to exogenous fibrolytic enzymes (EFE) would increase the beneficial effects of the EFE on the preingestive hydrolysis and in vitro digestibility and fermentation of bermudagrass haylage. In experiment 1, 5 COF (Mn(2+), Co(2+), Fe(2+), Ca(2+), and Mg(2+)) were screened to select the best candidates for synergistically enhancing release of water-soluble carbohydrates (WSC) from bermudagrass haylage by 5 EFE. The 5 EFE (1A, 2A, 11C, 13D, and 15D) were sourced from Trichoderma reesei and Aspergillus oryzae and they were the most effective of 12 EFE at increasing the neutral detergent fiber digestibility of bermudagrass haylage in a previous trial. Adding 1mM of each of the COF to EFE 2A or 11C synergistically increased release of WSC from bermudagrass haylage, as did adding (1mM) Fe(2+) to 1A, Mn(2+), Co(2+), or Fe(2+) to 13D, or Co(2+)or Fe(2+) to 15D. The greatest release of WSC responses were obtained by adding Mn(2+) to 11C (38%) or by adding Fe(2+) to 2A or 13D (10 and 21.9%, respectively). In experiment 2, the effect of increasing the COF dose on in vitro digestibility and fermentation of bermudagrass haylage was examined using the best EFE-COF combinations from experiment 1. Effects of adding increasing doses of these COF on EFE-mediated changes in vitro digestibility depended on the COF-EFE combination. Adding 10mM Mn(2+) alone to bermudagrass haylage increased DMD and NDFD by 2.7 and 6.3% and adding 11C alone increased these measures by 6.6 and 15.5%, respectively. However, adding 10mM Mn(2+) with 11C resulted in 3.5 and 8.1% increases in DMD and NDFD, respectively, beyond the increases caused by adding 11C alone. Adding Fe(2+) to 2A had no effects on EFE-mediated digestibility responses, but 2A prevented adverse effects of adding Fe(2+) alone on DMD and NDFD. In contrast, adding Fe(2+) to 13D reduced the increases in DMD and NDFD caused by adding the EFE alone. This study shows that adding COF to EFE can synergistically increase, decrease, or not affect the hydrolytic effects of EFE on bermudagrass haylage cell walls. The outcome depends on the specific EFE-COF combination and the COF dose. More research is required to understand the mechanisms resulting in these outcomes to exploit beneficial effects of COF on EFE.

Improving the performance of dairy cattle with a xylanase-rich exogenous enzyme preparation

“…This could be because 3A provided only 85% of the xylanase in 2A when applied to the TMR, as well as the substantial difference in the ratio of xylanase to endoglucanase plus exoglucanase activities in both EFE. Previous in vitro experiments with bermudagrass (Romero et al, 2015c) showed that 3A was effective at improving NDFD, but each of the component enzymes of 3A (1A and 2A) was more effective at increasing the in vitro NDFD of bermudagrass haylage than 3A, with 2A being the most effective component. Eun and Beauchemin (2007) found that an earlier batch of 3A (called FF+FT) improved the in vitro NDFD of corn silage and alfalfa hay when applied at 1 g/kg of DM.…”

“…Such batch-tobatch variations in enzyme activity may be due to variations in Trichoderma reesei culture conditions and crude extract processing (Considine and Coughlan, 1989;Paloheimo et al, 2010). Although such variations should be minimized, it should be noted that enzymatic activities are unreliable descriptors or predictors of the capacity of an enzyme product to improve the in vitro digestibility of forages (Eun and Beauchemin, 2008;Romero et al, 2015c).…”

“…Protein concentration was measured using the Bio-Rad Protein Assay with BSA as the standard (Bio-Rad Laboratories, Hercules, CA). Because of batch-to-batch variations, the endoglucanase, xylanase, and exoglucanase activities, and protein concentration of 2A were 75, 92, 144, and 83% and those of 3A were 79, 86, 65, and 110% of the respective values in the corresponding enzyme preparations evaluated by Romero et al (2015c).…”

“…The aims were to determine the most promising EFE for increasing the NDFD of bermudagrass haylage and its optimal dose, and to examine whether its efficacy would be improved by metal ion cofactors. These experiments (1) identified 5 of 12 EFE that increased the NDFD of bermudagrass haylage by at least 8% (Romero et al, 2015c), (2) determined the lowest doses of each of the 5 selected EFE that maximized the NDFD of bermudagrass haylage (Romero et al, 2015b), and (3) showed that metal ion cofactors such as manganese synergistically increased the effects some EFE on the NDFD of bermudagrass haylage but did not affect those of others (Romero et al, 2015a). These studies revealed that the most promising EFE for increasing the NDFD of bermudagrass haylage was EFE 2A (Xylanase Plus, Dyadic International, Jupiter, FL), and unlike others, its efficacy was not synergistically improved by adding cofactors.…”

Symposium review: Technologies for improving fiber utilization

“…The effects of EFE in ruminant diets can be classified as pre-ingestive, ruminal, and postruminal (McAllister et al, 2001). When EFE are applied to fibrous substrates before feeding, fiber hydrolysis can be observed as partial solubilization of NDF and ADF and release of sugars and free or monomeric hydroxycinnamic acids (Krueger et al, 2008b;Romero et al, 2015c), which may contribute to improvements in in vitro fiber digestibility (Romero et al, 2015a) and microbial growth (Forsberg et al, 2000). Furthermore, pre-ingestive hydrolysis seems to cause structural changes ("digestive pits") that make the feed more amenable to further degradation, even when substrates were autoclaved and washed before treatment (Nsereko et al, 2000).…”