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The ethanolic (EE) and hydroalcoholic (HE) extracts of Urochloa brizantha concentrations were developed with the aim of evaluating their effect on rumen fermentation using an in vitro gas production technique. The EE and HE presented 3.62 and 5.38 mg protodioscin/mL, respectively. Ten treatments were evaluated in a completely randomized factorial arrangement (2 × 4 + 2), where the main effects were two extracts (EE and HE) and four levels (50, 100, 150, and 200 mL of extract/kg of DM) plus two controls: one positive (25 ppm of monensin–MON) and one (with no additives–CTL). The extract treatments (EXT, EE, and HE) reduced colonization time by 33.59% compared to the MON. IVDMD (p < 0.001) and IVOMD (p < 0.0001) were negatively affected by EXT addition when compared to CTL. Additionally, EXT reduced the proportion of propionic acid and increased the proportion of butyric acid in relation to CTL and MON treatments. Both EE and HE extracts of U. brizantha were able to alter rumen fermentation kinetic, with HE showing a higher concentration of protodioscin. Further research is needed to optimize extraction methodologies, comprehensively profile secondary compounds, and conduct trials with varying doses to effectively assess the viability of U. brizantha extract as an additive. [ABSTRACT FROM AUTHOR]

The inclusion of the coproduct dry distil- lers grains plus soluble (DDGS) in the diet of finishing cattle can lead to changes in the nutritional profile of the diets, causing an increase in protein content and a reduction in starch. It is necessary to understand how changes in rumen substrates affect rumen metabolic activity, acids, and enteric methane (CH4) production. Five treatments were used, considering levels of DDGS inclusion in the dry matter (DM) of 1) 0 g/kg of DDGS, 2) 150 g/kg of DDGS, 3) 300 g/kg of DDGS, 4) 450 g/kg DDGS, or 5) 600 g/kg DDGS in finishing diets. The metabolism experiment was conducted with rumen-cannulated Nellore bulls (n = 20) with initial body weight (BW) of 401.8 ± 27.0 kg. The production of short-chain fatty acids (SCFA) and CH4 were determined using the ex-situ ruminal fermentation technique. Rumen content was manually collected from 0, 4, 8 and 12 h post-feeding. The liquid and solid fractions of rumen content were used in four 50 mL penicillin-type flasks per animal. Of the four flasks prepared, two are called “blank” and inactivated in boiling water to stop fermentation, and the other two (microrumen) are incubated in a thermostatic bath, simulating the conditions existing in the rumen of animals (presence of microorganisms, anaerobes, temperature of 39ºC, natural animal saliva, physiological pH) for 30 min. After 30 min, incubated flasks were also inactivated in boiling water to stop fermentation. Subsequently, measurements of the final products of rumen fermentation (SCFA and CH4) were carried out in each bottle. Total rumen emptying was performed to determine the rumen pool of DM. The data will be analyzed in the SAS software, the mean of the treatments will be compared using test of mean and orthogonal contrasts. The declared significance is P ≤ 0.05. The inclusion or levels of DDGS did not affect CH4 production of gּ·kg DM-1ּ·d-1ּ and gּ·kg DM-1ּ d-1ּ (P > 0.05). There was an effect of the treatments on the production of propionate (gּ·kg DM-1ּ d-1ּ; P = 0.0448), with a decreasing linear effect (P = 0.0087) with the increase in the inclusion of DDGS in diet (0; 150; 300; 450; 600 g/kg of DDGS; means 137.20; 160.32; 117.60; 87.09; 91.52 gּ·kg DM-1ּ d-1ּ propionate, respectively). There was no effect of DDGS levels on the production of Acetate, Butyrate, or total SCFAs (gּ·kg DM-1ּ d-1ּ). In summary, DDGS inclusion affects rumen metabolic activity, decreasing propionate production, but does not affect the production of other SCFAs nor CH4 production. [ABSTRACT FROM AUTHOR]

This study was carried out to evaluate the use of tannin extract from Acacia mearnsii as a strategy to reduce methane (CH4) in two distinct cattle genotypes and its effect on intake, digestibility, microbial efficiency and ruminal fermentation. Four Nellore (Bos indicus) and four Holstein (Bos taurus) dry cows fitted with rumen cannula were assigned to two 4 × 4 Latin square design, in a 2 × 4 factorial arrangement, where each genotype represented a square receiving four tannin levels (commercial extract of A. mearnsii) in the diet (0%, 0.5%, 1.0% and 1.5% of dry matter). Tannin levels used did not cause a reduction in feed intake or rumen passage rate for both genotypes (p > 0.05), although there was a linear reduction in the degradation rate and ruminal disappearance of diet (p < 0.05). The increase in tannin levels reduced the amount of entodiniomorph protozoa in the Nellore cattle (p < 0.05). There was no change in N retention or microbial efficiency (p > 0.05), despite the linear reduction of nutrient digestibility and the synthesis of microbial nitrogen (p < 0.05). The ruminal CH4 production was reduced (p < 0.05) without reducing the short‐chain fatty acid production. The threshold of 0.72% of tannin in the diet was estimated as the starting point for the reduction of ruminal CH4 production with long‐term efficacy. Therefore, the use of low levels of tannin extract from A. mearnsii is a potential option to manipulate rumen fermentation in Nellore and Holstein cattle and needs to be further investigated. [ABSTRACT FROM AUTHOR]

Objective: Feed additives that modify rumen fermentation can be used to prevent metabolic disturbances such as acidosis and optimize beef cattle production. The study evaluated the effects of liquid and powdered forms of polyclonal antibody preparation (PAP) against Streptococcus bovis and Fusobacterium necrophorum on rumen fermentation parameters in ruminally cannulated non-lactating dairy cows that were adapted or unadapted to a high concentrate diet. Methods: A double 3×3 Latin square design was used with three PAP treatments (control, powdered, and liquid PAP) and two adaptation protocols (adapted, unadapted; applied to the square). Adapted animals were transitioned for 2 weeks from an all-forage to an 80% concentrate diet, while unadapted animals were switched abruptly. Results: Interactions between sampling time and adaptation were observed; 12 h after feeding, the adapted group had lower ruminal pH and greater total short chain fatty acid concentrations than the unadapted group, while the opposite was observed after 24 h. Acetate:propionate ratio, molar proportion of butyrate and ammonia nitrogen concentration were generally greater in adapted than unadapted cattle up to 36 h after feeding. Adaptation promoted 3.5 times the number of Entodinium protozoa but copy numbers of Streptococcus bovis and Fibrobacter succinogens genes in rumen fluid were not affected. However, neither liquid nor powdered forms of PAP altered rumen acidosis variables in adapted or unadapted animals. Conclusion: Adaptation of cattle to highly fermentable carbohydrate diets promoted a more stable ruminal environment, but PAP was not effective in this study in which no animal experienced acute or sub-acute rumen acidosis. [ABSTRACT FROM AUTHOR]