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The present study aimed to assess the dynamics of rumen methane (CH4) production following the addition of NaNO3. This was done using an in vitro rumen fermentation system that ensures continuous gas and methane assessments. Four different levels of NaNO3 were used to get the final nitrate concentrations of 0.5, 1.0, 1.5, and 2.0 mg/ml of rumen fluid. For each dose, corresponding controls contained sodium chloride and urea were realised to ensure comparable levels of sodium and nitrogen. The addition of nitrates had slight effect on the intensity of fermentation because the total gas produced minus CH4 (total methane-free gas) only went down at the highest dose (2.0 mg/ml), and the final concentrations of SCFA were the same at all doses. The most evident effect was a modification of the SCFA profile (low concentrations of propionate and valerate, progressive increments of acetate, and decreases of butyrate) and a reduction in overall CH4 production. The CH4 yield for the 0.5 mg/ml dose was not different from control in the entire fermentation. Yield of the 1.0 mg/ml dose was significantly lower than the control group (p < 0.05) only within the initial 24-h period, and higher dosages (1.5 and 2.0 mg/ml) were lower during the entire fermentation (p < 0.01). Methane yields were well fitted with the Gompertz model, but only the highest level of nitrate inclusion had a significant impact on the majority of model parameters (p < 0.01). The linear regressions between CH4 yields (y) and the amounts of nitrates (x) at progressive fermentation durations (e.g. 6, 12, 24, and 48 h) produced equations with increasing absolute slopes (from −0.069 to −0.517 ml/mg of nitrate). Therefore, nitrate reduced rumen CH4 yield in a dose-dependent manner: the impact of low doses was primarily observed at the initial stages of fermentation, whereas high doses exhibited effectiveness throughout the entire fermentation process. In conclusion, in batch fermentation systems, the dose effect of nitrates on methane yield was time dependent. [ABSTRACT FROM AUTHOR]

A new rumen batch fermentation system that allows continuous measures of total gas (GP) and methane production (MP) was tested. The fermentation system is composed of glass bottles connected to gas counters (Ritter Apparatebau GmbH & Co. KG) and an infrared gas analyser that measures the methane concentration. The system allows direct and continuous measurement of GP and MP for accurate kinetic studies. The aim of the work was to test the rumen fermentation system and compare the GP and MP kinetics obtained. Barley meal (BM), alfalfa hay (AH), corn silage (CS), and soya bean hulls (SH) were used as substrates in four consecutive fermentation runs. Cumulative volumes of GP and MP and the percentage of methane on total GP were recorded continuously until 48 h and average values at 1 h intervals were fitted with an exponential model with a lag phase reaching a good fit (R2 > 0.992). GP and MP reached the highest plateau levels for SH (1836 and 370 ml, respectively; p < 0.01) and the lowest for AH (1000 and 233 ml, respectively). The remaining substrates showed intermediate values. MP kinetics showed a discrete lag phase (from 0.09 to 1.12 h), whereas it was equal to zero for the total GP (except for SH). The methane concentration in gas flowing increased rapidly at the beginning of fermentation (from 0.35 to 0.95 h−1) and reached a plateau after approximately 8–12 h. In conclusion, the rumen fermentation system evaluated generates methane data comparable to those reported in the literature and allows simple continuous measurement of methane release throughout fermentation. [ABSTRACT FROM AUTHOR]

The aim of the trial was to evaluate the effect of dietary additions of Stevia rebaudiana Bertoni extract (SB) and Chestnut wood tannin (CWT) on the in vitro rumen fermentability, protozoal population and methane yield. Both plant products were tested at 3 different levels of inclusion (0.75, 1.50 and 3.00% of incubated dry matter, DM) in a total mixed ration (TMR) for ruminants by using rumen batch culture systems and a rumen inoculum collected from sheep. Total volatile fatty acid concentration, their proportions and gas production were not modified by the plant extracts inclusion, except a significant linear increment of gas production at 24 hr for SB (p =.049). Ammonia concentration decreased (p <.05) of about 17% when 1.50 or 3.00% of CWT were included into TMR. Rumen protozoa population was depressed by the SB inclusion (p =.002) with a maximum reduction of 40% at the highest SB dosage, whereas CWT negatively affected total protozoa counts (−19%) only at the dose of 3.00%. In vitro DM and NDF degradability were not affected by the supplementation of SB and CWT, as well as the methane yield. Thus, the addition of SB and CWT decreases the in vitro protozoa population of the rumen with different intensity and without effects on fermentation parameters, apart from a reduction of nitrogen degradability caused by CWT. Despite the effect on protozoa, no decreasing effect on methane production was detected. [ABSTRACT FROM AUTHOR]

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Two experiments were conducted to investigate the inclusion of high cut whole plant corn silage (HCCS) in diets for finishing heavy pigs on digestibility, metabolic utilisation, growth performance and slaughter traits. A control diet (CTR, containing maize meal, barley meal, extracted soybean meal and wheat bran, 550, 250, 90 and 80 g/kg DM, respectively) was compared with diet (CS) containing 200 g/kg DM of HCCS. The HCCS replaced wheat bran and part of maize meal in the CTR diet. In the first experiment, eight barrows were used in a two periods cross over design with periods of 21 d, included 7 d of total collection and three cycles of 24 h each in a respiratory chamber. In the second experiment, 28 barrows were divided into pairs on the basis of BW, kept in 14 pens and fed with the experimental diets until slaughter. Lower DM, OM, CP and energy total tract apparent digestibility was measured for the CS diet. Overall P retention as percentage of P intake was higher for CS diet, while N retention was similar for the two diets. Pigs fed CS tended to have a lower retained energy and the estimated NE of maize silage was 8.47 MJ/kg DM. Pigs fed the CS diets had a lower daily gain, a lower BW at slaughter and a reduction in the weight of back fat. The inclusion of HCCS increased the size of the stomach, the aNDFom concentration of stomach content and reduced the incidence of follicular gastritis. [ABSTRACT FROM PUBLISHER]