The effects of a product of the solid-state fermentation of Aspergillus niger on in sacco degradation of feeds and rumen volatile fatty acid production in dairy cattle.

Abstract

This Research Paper addresses the hypothesis that the dietary inclusion of an Aspergillus niger fermentation product will alter the degradation kinetics and rumen fermentation patterns of feeds in dairy cattle. Fungal fermentation products often contain a suite of bioactive compounds and secondary metabolites, which can influence the microbial environment in the rumen and act as digestibility enhancers. As the cattle sector is under increasing pressure to enhance its sustainability, the investigation of dietary interventions that could improve the efficiency of production is warranted. In a previous experiment, Synergen®, a product of the solid-state fermentation of Aspergillus niger (ANP) containing residual enzyme activities, significantly increased the in vitro digestibility of a grass silage-based dairy total mixed ration (TMR), suggesting that in vivo studies would be valuable. Hence the present study aimed to quantify the effects of this ANP on rumen fermentation measures in cattle. Using a 4 × 4 Latin square design, the effect of four doses of ANP (0, 5, 10, 15 g/day) in four cannulated Jersey heifers was measured on the in sacco degradation of dry matter (DM), organic matter, crude protein and neutral detergent fibre in steam-flaked barley, grass silage and a grass silage-based TMR formulated for dairy cattle. Treatments had no significant effect on the rate, or extent, of degradation of any component in any feed investigated. Rumen volatile fatty acid concentrations and proportions, and rumen pH, were quantified at seven timepoints during each 48-h sampling period and were unaffected by treatment, as was the apparent total tract digestibility of DM. Under the conditions of this trial, ANP did not influence rumen fermentation kinetics; indicating that supplementing mature, non-lactating Jersey cattle with this fungal fermentation product is not an advantageous strategy to enhance feed digestibility.