Suriya Sawanon

Evidence for the possible involvement of Selenomonas ruminantium in rumen fiber digestion

Selenomonas ruminantium strains were isolated from sheep rumen, and their significance for fiber digestion was evaluated. Based on the phylogenetic classification, two clades of S. ruminantium (clades I and II) were proposed. Clade II is newly found, as it comprised only new isolates that were phylogenetically distant from the type strain, while all of the known isolates were grouped in the major clade I. More than half of clade I isolates displayed CMCase activity with no relation to the degree of bacterial adherence to fibers. Although none of the isolates digested fiber in monoculture, they stimulated fiber digestion when co-cultured with Fibrobacter succinogenes, and there was an enhancement of propionate production. The extent of such synergy depended on the clade, with higher digestion observed by co-culture of clade I isolates with F. succinogenes than by co-culture with clade II isolates. Quantitative PCR analysis showed that bacterial abundance in the rumen was higher for clade I than for clade II. These results suggest that S. ruminantium, in particular the major clade I, is involved in rumen fiber digestion by cooperating with F. succinogenes.

Effect of source of methionine in broken rice-soybean diet on production performance, blood chemistry, and fermentation characteristics in weaned pigs

This study was conducted to compare the effect of source of methionine (Met) in broken rice- soybean diet on performance, blood biochemistry, and fermentation characteristics in weaned pigs. Forty-eight male crossbreed pigs (BW 11 ± 0.1 kg) were randomly allocated to three groups with four replications in a completely randomized design. The experimental diets were: (1) basal diet without methionine (Control; total sulfur amino acids (TSAA) 0.60%); (2) basal diet supplemented with dl-methionine (DLM) (TSAA 0.76%); and (3) basal diet supplemented with dl-2-hydroxy-4-(methylthio) butanoic acid (LMA) (TSAA 0.76%). Supple - mentation with DLM and LMA improved growth performance of piglets and decreased blood urea nitrogen and increased serum albumin ( P < 0.01). The population of Lactobacillus spp. in the caecum was decreased by both DLM and LMA supplementation ( P < 0.05). Succinic acid concentration in the caecum of pigs fed the DLM diet was greater than that of LMA group ( P < 0.05). It can be concluded that LMA can be used as a good source of Met (88% bioefficacy, weight/weight) in broken rice-soybean diet, although the serum albumin and fermentation characteristics (succinic acid) in the gastrointestinal tract were different.

Methane production from napier grass by two-stage anaerobic digestion

Digestion of Napier grass was investigated in two-stage anaerobic reactors. The reactor volume was 4 and 5 litres for the acidogenic and methanogenic reactors, respectively. The acidogenic reactors were fed once daily at 100, 150, 200, 250, and 300 mL/day with a slurry of Napier grass. The organic loading rates (OLRs) were 0.60, 0.90, 1.20, 1.50 and 1.80 kg chemical oxygen demand (COD)/m3.day. Mixed ruminal microorganisms from cows were used as the inoculum. The pH was adjusted to 7.5 for all methanogenic reactors at the start-up period. The reactors were operated at 30°C. The maximum methane (CH4) yield was observed at an OLR of 1.20 kg COD/m3.day. The average pH in the acidogenic and methanogenic reactors was 5.3 and 7.4, respectively. At the maximum CH4 yield OLR, the CH4 production was 148 litres at STP/kg dry Napier grass added to the reactor, which indicated that 6.76 kg of dry Napier grass is needed to produce 1 m3 of pure CH4.

Partial characterization of phylogeny, ecology and function of the fibrolytic bacterium Ruminococcus flavefaciens OS14, newly isolated from the rumen of swamp buffalo.

The fibrolytic rumen bacterium Ruminococcus flavefaciensOS14 was isolated from swamp buffalo and its phylogenetic, ecological and digestive properties were partially characterized. Isolates from rumen contents of four swamp buffalo were screened for fibrolytic bacteria; one of the 40 isolates showed a distinctive feature of solubilizing cellulose powder in liquid culture and was identified as R. flavefaciens based on its 16S ribosomal DNA sequence. This isolate, OS14, was employed for detection and digestion studies, for which a quantitative PCR assay was developed and defined cultures were tested with representative forages in Thailand. OS14 was phylogenetically distant from other isolated and uncultured R. flavefaciens and showed limited distribution among Thai ruminants but was absent in Japanese cattle. OS14 digested rice straw and other tropical forage to a greater extent than the type strain C94 of R. flavefaciens. OS14 produced more lactate than C94, and digested para grass to produce propionate more extensively in co-culture with lactate-utilizing Selenomonas ruminantium S137 than a co-culture of C94 with S137. These results indicate that phylogenetically distinct OS14 could digest Thai local forage more efficiently than the type strain, possibly forming a symbiotic cross-feeding relationship with lactate-utilizing bacteria. This strain might be useful for future animal and other industrial applications.

Methane Production from Napier Grass by Co-digestion with Cow Dung

Methane could substitute for fossil-fuel-derived energy and reduce environmental impacts including global warming. Grass can be transformed into energy by anaerobic digestion. The objective of this study was to investigate the co-digestion of napier grass with cow dung. Digestion of napier grass at a cutting interval of 60 days was investigated in single-stage, semi-continuous anaerobic reactors. Four reactors were operated at 30 °C with 5-day feeding. The first two reactors were fed with a slurry of napier grass alone at 10 % (napier grass:water = 10:90) and 20 % (napier grass:water = 20:80) by fresh weight. The other two reactors were fed with a mixture of napier grass and cow dung at separate concentrations of 10 % (napier grass:cow dung:water = 5:5:90) and 20 % (napier grass:cow dung:water = 10:10:80), respectively. Mixed ruminal microorganisms of approximately 8.5 g mixed liquor volatile suspended solids per litre were used as the inoculum. Each reactor working volume was 5 L and the feeding rate was 625 ml per 5 days resulting in a hydraulic retention time of 40 days. The pH was initially adjusted to be neutral in all reactors and the reactors functioned without any further pH control. The results showed that co-digestion of the mixture of napier grass and cow dung gave a higher yield than that of napier grass alone. The highest methane yield was obtained from the reactor that contained the 20 % mixture of napier grass and cow dung (napier grass: cow dung:water = 10:10:80) with 143 L at STP per kg chemical oxygen demand (COD) added and 169 L at STP per kg total volatile solids (TVS) added. The pH of the reactor was just over 7.

Biogas Production from Napier Grass at Various Cutting Intervals

This work focused on a study of methane (CH4) production from Napier grass at various cutting intervals. Digestion of Napier grass at cutting intervals of 30, 45, 60, 90 days was investigated in two-stage (acidogenic and methanogenic) anaerobic reactors. Four sets of reactors were constructed with plastic bottles. The reactor working volume was 4 and 5 L for acidogenic and methanogenic reactor, respectively. Acidogenic reactors were fed once daily at a feed rate of 200 mL/day with a slurry of 1:5 Napier grass:water. Hydraulic retention times (HRT) were set at 20 days for acidogenic and 25 days for methanogenic reactor stage. Mixed ruminal microorganisms from cow of approximately 10 g mixed liquor volatile suspended solid/L were used as inoculum. The reactors were operated at ambient temperature of 30 ± 1 °C. pH was adjusted to be 7.5 for all methanogenic reactors at the start-up period. The reactors functioned without pH control. The CH4 yield obtained from Napier grass at cutting intervals of 30, 45, 60 and 90 days was 160, 127, 104 and 74 L at STP/kg of dry Napier grass added to the reactor, respectively, which indicated that 6.25, 7.87, 9.62 and 13.51 kg of dry Napier grass, respectively, is needed to produce 1 m3 of pure CH4. However, the grass yield at the cutting intervals of 30, 45, 60 and 90 days was 16.88, 37.50, 62.50 and 81.25 tons dry weight/hectare/year, respectively. When considering the grass yield of cultivation, the annual CH4 yield per area obtained from Napier grass at the cutting intervals of 30, 40, 60 and 90 days was 2700, 4763, 6500 and 6013 m3/hectare/year, respectively. Napier grass at the cutting interval of 60 days gave the highest CH4 yield of all various cutting intervals.