A gas production technique as a tool to predict organic matter digestibility of grass and maize silage

Dose- and substrate-dependent reduction of enteric methane and ammonia by natural additives in vitro

Ruminants contribute to global warming by emitting greenhouse gasses, particularly methane (CH4) which is a product of rumen fermentation. The use of feed additives able to modulate rumen fermentation is a promising strategy to reduce enteric CH4 and ammonia (NH3) emissions. Among the various strategies investigated, plant secondary metabolites (PSMs) have attracted attention due to their apparent potential to reduce enteric CH4 and NH3 emissions, and it would be possible to use such compounds as feed additives in organic production systems. In an in vitro system simulating rumen fermentation, we have tested the impact of different classes of naturally occurring PSMs; catechin and quercetin (flavonoids), salicylic acid (phenolic acid) and tannic acid (hydrolysable tannin). The PSMs were added to two different basal feeds (maize and grass silages) at three inclusion doses 1.5, 3 and 6% of the feed dry matter (DM). CH4 production was significantly lowered upon addition of quercetin to two basal feeds at doses of 3 and 6%, and this without changes in concentrations of total volatile fatty acid (VFA) produced during fermentation. Quercetin, as the only tested additive, reduced CH4 production, and when added to maize silage and grass silage, the reduction increased linearly with increasing dose, ie., by 51 and 43%, respectively, at a dose of 3% of feed DM and by 86 and 58%, respectively, at a dose of 6% of feed DM. Moreover, quercetin significantly reduced NH3 concentration by >12% at doses of 3 and 6% in feed DM irrespective of the basal feed used as compared to when the basal feeds were incubated alone. Although none of the other additives affected CH4 formation, several additives had significant impacts on concentrations of NH3 and VFAs in the incubated fluid after fermentation. This study demonstrated a dose-dependent ability of quercetin to reduce CH4 emission from rumen fermentation, however, the magnitude of the suppression of CH4 depended on the basal feed. Furthermore, quercetin reduced NH3 concentration irrespective of the basal feed type. These findings encourage to in vivo studies to verify whether quercetin can reduce CH4 emission also in cows.

Short Communication: Prediction of in vitro dry matter digestibility with the ANKOM Daisy II system of ruminant feeds using the gas production technique

Plaizier, J. C. and Li, S. 2013. Short Communication: Prediction of in vitro dry matter digestibility with the ANKOM Daisy II system of ruminant feeds using the gas production technique. Can. J. Anim. Sci. 93: 399–402. The potential of the gas production technique to predict in vitro dry matter digestibility was determined using 50 ruminant feeds, including grass/alfalfa forages, grain crop silages, grains, high protein feeds, and feed straws. Without including the chemical composition in the prediction equation, the prediction of IVDMD based on the cumulative gas production during 48 h alone was poor (R 2=0.48). Including the crude protein and neutral detergent fibre concentrations of the feed in the prediction equation improved the accuracy of the prediction (R 2=0.87), which was higher than that of predicting IVDMD based on the chemical composition alone (R 2=0.82).

Composition, nutritional aspects and effect on serum parameters of marine algae Ulva rigida

BACKGROUND

Algae are commonly consumed in Asia and have also gained popularity in Europe. However, data on the bioavailability of their components are limited. The present study was designed to determine the composition of Ulva rigida and the effects of inclusion of 10% of the algae in a standard diet for 4 weeks on nutritive value and serum parameters in order to consider the usefulness of Ulva as a dietary supplement.

RESULTS

Ulva rigida is rich in protein, carbohydrates, fibre, vitamins and minerals and has a low lipid content. Analysis of the amino acid composition revealed good-quality protein. The algae were well accepted by experimental animals and did not significantly change nutritional parameters but reduced LDL cholesterol.

CONCLUSIONS

Ulva rigida is an excellent source of nutrients and could improve a balanced diet. Further studies are required to research the potential of the seaweed as a natural source of bioactive compounds.

Mono fermentation of grass silage by means of loop reactors

A loop reactor was operated for mono fermentation of grass silage without manure addition under mesophilic conditions (38 degrees C). An averaged specific biogas production of 0.50 m(N)(3) per kg volatile solids (VS) with a methane concentration of 52% at an organic loading rate of up to 3.5 kg(VS)/(m(3) d) was obtained. The retention time varied from 440 days at 1.0 kg(VS)/(m(3) d) to 50 days at 3.5 kg(VS)/(m(3) d). The degradation level was more than 60% based on VS and 75% based on COD. The first-order hydrolysis rate constant of the process was estimated to be 0.6 d(-1). Despite the relative high ammonium concentration of up to 4 g/l, the system worked stable for an operation period of 310 days. In particular the TS content in the fermenter was found to be a key parameter and should not exceed 12% in order to avoid instabilities.