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Sheep adapted to consume tannins rich feeds such as oak leaf (OL) appear to develop defensive mechanisms by their ruminal bacteria against these polyphenols. The capabilities of ruminal isolated tannins resistant bacteria from these animals to ferment a tanniniferous feed (i.e., pistachio hulls, (PH) which were incubated with rumen fluid from Holstein dairy cows was assessed. Six g positive cocci were isolated from the rumen of sheep and the 16s rRNA gene sequences showed them to be closely related to Streptococcus gallolyticus. In three runs of in vitro gas production (GP), the effect of two of the isolates incubated with buffered-ruminal fluid of Holstein cow and PH was evaluated. The GP was recorded from 1 to 96 h of incubation. Incubating either of the isolates with PH caused a significantly higher in vitro gas production, estimated parameters, in vitro organic matter disappearance, metabolisable energy and volatile fatty acids than those without any isolate. The improvement in the ruminal parameters when either of the isolates was used suggested the possible presence of isolated tannins-resistant bacteria (Streptococcus gallolyticus sp.), however, in vivo studies must be conducted to confirm the in vitro results. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the effect of several doses of spearmint essential oil (SEO; 0, 250, 500, 750 or 1,000 μg ml-1 buffered rumen fluid) on the fermentation kinetic and digestibility using in vitro gas production technique. A total mixed ration (30% roughage: 70% concentrate) was incubated with buffered rumen fluid. In vitro gas production, asymptotic gas production (A), rate of gas production (μ), partitioning factor (PF), microbial biomass (MB), ammonia concentration and digestibility were determined. Increasing the dose of SEO decreased the parameters A and μ. Adding SEO, however, increased PF, ammonia concentration, apparent in vitro dry matter digestibility and true in vitro organic matter digestibility at the lower levels of SEO (250 and 500 μg ml-1). But, at the level of 1,000 μg ml-1, a decrease was observed for these parameters. The increment in PF and digestibility illustrate that SEO has a potential to modulate the rumen fermentation, which may be beneficial (at low doses) for improving nutrient utilization. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the effect of several doses of spearmint essential oil (SEO; 0, 250, 500, 750 or 1,000 μg ml-1 buffered rumen fluid) on the fermentation kinetic and digestibility using in vitro gas production technique. A total mixed ration (30% roughage: 70% concentrate) was incubated with buffered rumen fluid. In vitro gas production, asymptotic gas production (A), rate of gas production (μ), partitioning factor (PF), microbial biomass (MB), ammonia concentration and digestibility were determined. Increasing the dose of SEO decreased the parameters A and μ. Adding SEO, however, increased PF, ammonia concentration, apparent in vitro dry matter digestibility and true in vitro organic matter digestibility at the lower levels of SEO (250 and 500 μg ml-1). But, at the level of 1,000 μg ml-1, a decrease was observed for these parameters. The increment in PF and digestibility illustrate that SEO has a potential to modulate the rumen fermentation, which may be beneficial (at low doses) for improving nutrient utilization. [ABSTRACT FROM AUTHOR]

Abstract: Grape pomace (GP) is a high tannin feed by-product produced in large amounts in many parts of the world. Tannins bind to proteins to prevent their degradation in the rumen. This tannin/protein complex may be advantageous when partially protecting high quality feed proteins from excessive rumen protein degradation. The objective of this experiment was to use a GP tannin extract to slow down rumen degradation of soybean meal (SBM) protein. After extracting the tannin compounds, SBM was treated with the extract to obtain mixtures with 0, 15, 30, 40 and 60g/kg dry matter (DM) of tannin extract. In vitro gas production (IVGP), organic matter digestibility (OMD) and ammonia concentrations were measured, and three rumen-cannulated sheep were used to determine in sacco rumen disappearance of N. A three-step in vitro procedure was used to determine intestinal digestibility. Treating SBM with tannin extract decreased IVGP (linear and quadratic; P <0.01) by 4.5–11%, and the in sacco digestibility of soluble N fraction (linear and quadratic effects, P <0.01) by 15–274%. It also delayed gas production (T/2) and increased in vitro intestinal digestibility of protein (linear and quadratic; P <0.01) by 8.9–17.8. Tannins in GP slow down SBM protein degradation in the rumen. [Copyright &y& Elsevier]

Abstract: Due to a shortage of ruminant feeds, co-products such as grape pomace (GP) which contain tannins, represent alternative ruminant feed resources. The aim of the current study was to assess effects of ensiling and addition of polyethylene glycol (PEG) on deactivation of tannins in the grape pomace by changes in the chemical composition and phenolics levels of fresh and ensiled GP for 5, 10 or 30 days. In vitro gas production (IVGP), estimated organic matter digestibility (OMD), ammonia concentration and microbial biomass yield (MB) of each treatment, with or without PEG addition were measured. Increasing the duration of ensilage decreased the content of WSC and pH (P<0.01). Ensiling decreased (P<0.01) total phenolics (TP), total tannin (TT), soluble condensed tannins (SCT), protein precipitable phenolics (PPP), and IVGP, OMD and MB. Adding PEG to ensiled GP, however, increased (P<0.01) IVGP, OMD, ammonia and MB. The increment in gas production at 24h for fresh and ensiled GP due to addition of PEG illustrates the positive influence of PEG addition, but not ensiling, on inactivation of tannins. [Copyright &y& Elsevier]