This study aimed to perform a meta-analysis on the effect of 3-nitrooxypropanol (3-NOP) on enteric methane (CH 4 ) emissions from ruminants. A total of 12 in vivo studies from 10 articles were integrated into a database. Ruminant species included were dairy cows, beef cattle and sheep. Concentration of 3-NOP in diets varied from 0 to 280 mg/kg dry matter intake (DMI). Parameters included were CH 4 emissions, rumen fermentation, microbial population, nutrient digestibility and animal performance. Meta-analysis of data was performed by using mixed model methodology in which different studies were treated as random effects whereas 3-NOP addition levels in diets of ruminants were treated as fixed effects. Results showed that increasing level of 3-NOP addition in diets of ruminants decreased enteric CH 4 emissions per unit of body weight, CH 4 /DMI, CH 4 /milk produced, CH 4 /digested organic matter or CH 4 /gross energy intake (p < .05). Production of H 2 was higher with increasing level of 3-NOP addition (p < .001). Addition of 3-NOP decreased total VFA concentration (p < .01), and decreased and increased proportions of C 2 and C 3 , respectively (p < .001). Addition of 3-NOP decreased archaea population (p < .01) but it did not change total bacteria and protozoa populations. The substance had minor effect on digestibility of nutrients. Production performance of dairy cows and beef cattle was limitedly influenced by the addition of 3-NOP in the diets, and it had no negative effect on DMI of ruminants. It is concluded that 3-NOP is an effective feed additive to mitigate enteric CH 4 emissions without compromising productive performance of ruminants.

Background and Aim: Lactiplantibacillus plantarum is one of the lactic acid bacteria that is often used as probiotics. This study aimed to evaluate the effects of Lactiplantibacillus plantarum TSD10 as a probiotic on rumen fermentation and microbial population in Ongole breed cattle. Materials and Methods: This study adopted an experimental crossover design, using three-fistulated Ongole breed cattle. Treatments were as follows: T0, control without probiotic; T1, 10 mL probiotic/day; T2, 20 mL probiotic/day; and T3, 30 mL probiotic/day. The basal diet of the cattle comprised 70% concentrate: 30% elephant grass (Pennisetum purpureum). The concentration of probiotic used was 1.8 × 1010 colony-forming unit (CFU)/mL. Results: We observed significantly lower acetate production compared with control (64.12%), the lowest values being in the T3 group (55.53%). Contrarily, propionate production significantly increased from 18.67% (control) to 23.32% (T2). All treatments yielded significantly lower acetate–propionate ratios than control (3.44), with the lowest ratio in the T3 group (2.41). The protozoal number decreased on probiotic supplementation, with the lowest population recorded in the T2 group (5.65 log cells/mL). The population of specific rumen bacteria was estimated using a quantitative polymerase chain reaction. We found that the population of L. plantarum, Ruminococcus flavefaciens, and Treponema bryantii, did not change significantly on probiotic supplementation, While that of Ruminococcus albus increased significantly from 9.88 log CFU/mL in controls to 12.62 log CFU/mL in the T2 group. Conclusion: This study showed that the optimum dosage of L. plantarum TSD10 as a probiotic was 20 mL/day. The effect of L. plantarum as a probiotic on feed degradation in rumen was not evaluated in this experiment. Therefore, the effect of L. plantarum as a probiotic on feed degradation should be performed in further studies.

This study investigated the effect of phloroglucinol (1,3,5-trihydroxybenzene) supplementation alone on methane production, rumen fermentation profiles, and microbial population structure of mixed in vitro cultures. Treatments included a control group containing a substrate with no supplement, and substrates supplemented with 2, 4, 6, 8, or 10 mmol/L of phloroglucinol. The results revealed that phloroglucinol was able to decrease methane production in a dose-dependent manner. The highest decrease was observed with 8 and 10 mmol/L supplementations. The relative quantity of methanogen was not affected by phloroglucinol, whereas genus Coprococcus was increased with increasing concentrations of phloroglucinol (p<0.05). Total gas production, dry matter digestibility (DMD), and NH 3-N were significantly lowered by phloroglucinol (p<0.001). Total short-chain fatty acid (SCFA) concentration was not affected by phloroglucinol. Acetate proportion increased with the addition of phloroglucinol at the expense of propionate (p<0.001). This might indicate the redirection of [H] from methane to acetate, and might be related to methane inhibition.. Our study concluded that supplementation of phloroglucinol alone could decrease methane production by inhibiting nutrient digestibility in the rumen and by possible redirection of rumen fermentation to acetate production. Genus Coprococcus could be an important actor for phloroglucinol metabolism in the rumen.

M ethane (CH 4) emission from ruminants is widely known as a threat to the environment and an economic loss. CH 4 is the second most abundant greenhouse gas in the atmosphere and among the most potent greenhouse gases. CH 4 also represents inefficiency of ruminant digestion as it represents a 2-12% loss of dietary energy depending on the feed (Johnson and Johnson, 1995). McAllister and Newbold (2008) proposed a dietary strategy to mitigate CH 4 emission from ruminants by redirecting the H 2 utilization to short-chain fatty acid (SCFA) production. The strategy is to create competition for H 2 utilization by adding a substrate that may act as an alternative H 2 sink, such as fumarate or aspartate. Those compounds are precursors of propionate that naturally occurs in the rumen from carbohydrate digestion. Phloroglucinol (PHLO) is a phenolic compound that naturally occurs in the rumen as a product of rumen metabolism of tannins. Several rumen bacteria can degrade PHLO by using formate or H 2 for acetate production. This finding showed an opportunity to use PHLO as an alternative H 2 sink agent. Previous in vivo studies showed that PHLO could redirect research Article Abstract | This study was conducted to investigate the effects of phloroglucinol (PHLO) and the forage: concentrate ratio (F:C) on methane (CH 4) production, rumen fermentation profiles, and the microbial population in vitro. Rumen fluid was collected from male Friesland sheep using a stomach tube before the morning feeding. The treatments comprised two different diets: a low F:C diet (20:80) and high F:C diet (80:20), and three PHLO doses (0, 6, and 10 mmol/L PHLO). The results showed that PHLO lowered CH 4 production in both diets, whereas F:C did not have any effect on CH 4 production. The CH 4 decrease due to PHLO was accompanied by a simultaneous decrease in the relative quantity of methanogens and dry matter digestibility (DMD). This indicated that PHLO might decrease CH 4 by directly inhibiting methanogen growth and by indirect effects through the retardation of digestibility. PHLO lowered total short-chain fatty acid (SCFA) production with the low F:C diet but increased total SCFA production with the high F:C diet. PHLO increased acetate production in high F:C diet but lowered acetate production of low F:C diet. This finding showed that PHLO might redirect rumen fermentation from CH 4 production to acetate production. PHLO lowered the relative quantity of Ruminococcus albus, which might explain the retardation of digestibility by PHLO.

Extracts of Acacia and Quebracho have been used as a feed additive in ruminant diets; the effects, however, have been varied. This study used a meta-analysis approach to evaluate the use of those extracts on nutrient utilization, performance, and methane production of ruminants. A database was developed from 37 published papers comprising 152 dietary treatments. The result showed that a higher concentration of tannins was associated with a decrease (p < 0.05) in nutrient intake and digestibility. An increasing tannin concentration was negatively correlated with ammonia, acetic acid, and the ratio of acetic to propionic acid. Methane production decreased (p < 0.01) with the increasing tannin concentration. Nitrogen (N) balance parameters were not affected by the tannin concentrations, but fecal N excretion increased (p < 0.01) as the tannin concentration increased. The relationships between the Acacia and Quebracho and the changes in organic matter intake, milk fat concentration, butyric acid, valeric acid, and methane production were significantly different. In conclusion, it is possible to use both condensed tannins (CT) extracts as a methane emission mitigation without impairing the ruminant performance. Furthermore, the Quebracho showed more pronounced to decrease ruminal protein degradation and lower methane emission than the Acacia.