Effects of Aspergillus oryzae fermentation extract on in vitro equine cecal fermentation

Abstract

The objective of this study was to examine the effects of Aspergillus oryzae fermentation extract on the in vitro equine cecal fermentation of soluble starch, amino acids/peptides, coastal bermudagrass hay, and alfalfa hay. Cecal contents were obtained from a cecally fistulated Quarter Horse gelding fed coastal bermudagrass and grain (70:30) either unadapted or adapted to dietary A. oryzae supplementation (2 g/d). Mixed cecal microorganisms were incubated in anaerobic media for either 24 h (soluble starch, amino acids) or 48 h (bermudagrass hay, alfalfa hay). A. oryzae was added to the incubation bottles (n = 4) at concentrations of 0, .07, or .7 g/L. Fermentation of soluble starch in the presence of .7 g/L of A. oryzae resulted in increased concentrations of acetate, propionate, NH3, and L-lactate and decreased final pH. Addition of .7 g/L of A. oryzae to amino acid/peptide fermentations decreased final pH and increased concentrations of H2, acetate, propionate, butyrate, and total VFA. When alfalfa hay or bermudagrass hay was fermented with .7 g/L of A. oryzae, CH4, IVDMD, and digestion of NDF and ADF decreased. When adapted mixed cecal microorganisms were used, .7 g/L of A. oryzae did not inhibit methanogenesis or fiber digestion and L-lactate concentrations were not increased with soluble starch as the substrate. These results suggest that cecal microorganisms exposed to A. oryzae via the diet may adapt to the product. Incorporation of A. oryzae into in vitro incubations at concentrations similar to current recommended usage levels resulted in little change in final pH and fermentation products.

In vitro fermentation profiles of palm kernel meal (PKM)-based diet supplemented with xylanase or cellulase using caecal digesta of broiler chickens as inoculums

“…The iso-valerate was produced in a trace amount in xylanase and cellulase supplemented groups, whereas no iso-butyrate and valerate production was found in all feed ration. The finding of the present study was in agreement with a data recorded by [29] and [27] where the fermentation of high fiber diets incubated with caecal inocula from broiler chickens and equine recorded with higher acetate level followed by Rate of gas production c …”

Influence of Confinement Housing on the Cecal Environment of the Horse

“…Previous research has concluded that when cattle and horses are fed a grain diet methane production is decreased (McDaniel et al, 1993;Lana et al, 1998). There is limited research on the production of fermentative gases from the cecum; however, available studies suggest that methane producing bacteria are significantly lower in horses compared to ruminants (Spring, 2000).…”

“…In previous studies, methane production has been reported as 0.16 L/d/kg BW (Crutzen et al, 1986). McDaniel et al (1993) observed in vitro fermentation with soluble starch to be 0.26 mM of methane. Although these values are higher than current values, methane production was not affected by housing which could be related to the minimal changes observed in the bacterial populations.…”

“…When high-starch diets are fed to cattle, methane production is decreased from 48 to 7 nmol mg/protein/min compared to high-fiber diets that decreased from 14 to 2 nmol mg/protein/min when in vitro pH decreased (Lana et al, 1988). McDaniel et al (1993) demonstrated a decrease in methane production measured by in vitro fermentation of equine cecal fluid with bermudagrass hay and soluble starch resulting in 1.49 mmols and 0.26 mmols, respectively. The decrease in methane production could be caused by the increased number of amylolytic bacteria producing higher amounts of lactic acid then decreasing the pH below 6.2, no longer being optimal for cellulolytic bacteria (Jouany, 2008).…”

“…Feeding concentrate decreases ammonia accumulation. McDaniel et al (1993) reported that in vitro fermentation of bermudagrass hay accumulated 373.7 mg/L of ammonia compared to in vitro fermentation of soluble starch that only accumulated 8.8 mg/L of ammonia when equine cecal fluid was utilized. The decrease in ammonia accumulation was believed to be due to an assimilation of ammonia into amino acids and ultimately microbial protein synthesis.…”