***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The objective was to evaluate whether long-term addition of 3-nitrooxypropanol ( NOP ) to a beef cattle diet results in a sustained reduction in enteric CH4 emissions in beef cattle . Eight ruminally cannulated heifers ( 637 ± 16.2 kg BW ) were used in a completely r and omized design with 2 treatments : Control ( 0 g/d of NOP ) and NOP ( 2 g/d of NOP ) . Treatments were mixed by h and into the total mixed ration ( 60 % forage , DM basis ) at feeding time . Feed offered was restricted to 65 % of ad libitum DMI ( slightly over maintenance energy intake ) and provided once per day . The duration of the experiment was 146 d , including an initial 18-d covariate period without NOP use ; a 112-d treatment period with NOP addition to the diet , divided into four 28-d time intervals ( d 1 to 28 , 29 to 56 , 57 to 84 , and 85 to 112 ) ; and a final 16-d recovery period without NOP use . During the covariate period and at the end of each interval and the end of the recovery period , CH4 was measured for 3 d using whole animal metabolic chambers . The concentration of VFA was measured in rumen fluid sample s collected 0 , 3 , and 6 h after feeding , and the microbial population was evaluated using rumen sample s collected 3 h after feeding on d 12 of the covariate period , d 22 of each interval within the treatment period , and d 8 of the recovery period . Average DMI for the experiment was 7.04 ± 0.27 kg . Methane emissions were reduced by 59.2 % when NOP was used ( 9.16 vs. 22.46 g/kg DMI ; P < 0.01 ) . Total VFA concentrations were not affected ( P = 0.12 ) ; however , molar proportion of acetate was reduced and that for propionate increased when NOP was added ( P < 0.01 ) , which reduced the acetate to propionate ratio ( 3.0 vs. 4.0 ; P < 0.01 ) . The total copy number of the 16S rRNA gene of total bacteria was not affected ( P = 0.50 ) by NOP , but the copy number of the 16S rRNA gene of methanogens was reduced ( P < 0.01 ) and the copy number of the 18S rRNA gene of protozoa was increased ( P = 0.03 ) . The residual effect of NOP for most of the variables studied was not observed or was minimal during the recovery period . These results demonstrated that the addition of NOP to a diet for beef cattle caused a sustained decrease of methanogenesis , with no sign of adaptation , and that these effects were reversed once NOP addition was Significance Methane from enteric fermentation in the ruminant digestive system is a major contributor to anthropogenic greenhouse gas emissions in the United States and worldwide . Methane is also a net loss of feed energy to the animal . This study was undertaken to investigate the effect of a methane inhibitor on enteric methane emissions from lactating dairy cows . The experiment demonstrated that , under industry-relevant conditions , the inhibitor persistently decreased by 30 % enteric methane emissions , without negatively affecting animal productivity . The spared methane energy was partially used for tissue synthesis , which led to a greater body weight gain by the inhibitor-treated cows . If adopted , this mitigation practice could lead to a substantial reduction of greenhouse gas emissions from the ruminant livestock sector . A quarter of all anthropogenic methane emissions in the United States are from enteric fermentation , primarily from ruminant livestock . This study was undertaken to test the effect of a methane inhibitor , 3-nitrooxypropanol ( 3NOP ) , on enteric methane emission in lactating Holstein cows . An experiment was conducted using 48 cows in a r and omized block design with a 2-wk covariate period and a 12-wk data collection period . Feed intake , milk production , and fiber digestibility were not affected by the inhibitor . Milk protein and lactose yields were increased by 3NOP . Rumen methane emission was linearly decreased by 3NOP , averaging about 30 % lower than the control . Methane emission per unit of feed dry matter intake or per unit of energy-corrected milk were also about 30 % less for the 3NOP-treated cows . On average , the body weight gain of 3NOP-treated cows was 80 % greater than control cows during the 12-wk experiment . The experiment demonstrated that the methane inhibitor 3NOP , applied at 40 to 80 mg/kg feed dry matter , decreased methane emissions from high-producing dairy cows by 30 % and increased body weight gain without negatively affecting feed intake or milk production and composition . The inhibitory effect persisted over 12 wk of treatment , thus offering an effective methane mitigation practice for the livestock industries This study evaluated if 3-nitrooxypropanol reduces enteric methane ( CH4 ) emissions when added to the diet of beef cattle . The effects of 3-nitrooxypropanol on related variables including diet digestibility , ruminal fermentation , and ruminal microorganisms were also investigated . Eight ruminally cannulated Angus heifers ( 549 ± 64.3 kg [ mean BW ± SD ] ) were fed a high forage diet ( background ing diet ) supplemented with 4 levels of 3-nitrooxypropanol ( 0 , 0.75 , 2.25 and 4.50 mg/kg BW ) . The experiment was design ed as a duplicated 4 × 4 Latin square with 2 groups of heifers and four 28-d periods . Methane emissions were measured during 3 consecutive days using metabolic chambers . Up to a 5.8 % reduction in ad libitum DMI was observed when 2.5 mg/kg BW of 3-nitrooxypropanol was fed ( P = 0.03 ) . Increasing level of 3-nitrooxypropanol linearly ( P < 0.001 ) reduced CH4 , with 33 % less CH4 ( corrected for DMI ) at the highest level of supplementation compared with the control . Feed energy lost as CH4 was also reduced when 3-nitrooxypropanol was supplemented ( P < 0.001 ) . Molar proportion of acetate was reduced ( P < 0.001 ) and that for propionate increased ( P < 0.001 ) with increasing dose of 3-nitrooxypropanol , which in turn led to a reduction in the acetate to propionate ratio ( P < 0.001 ) . Total copy numbers of 16S ribosomal RNA ( rRNA ) genes for bacteria , methanogens , and 18S rRNA genes for protozoa in ruminal contents were not affected by 3-nitrooxypropanol supplementation ( P ≥ 0.31 ) . There was no effect of 3-nitrooxypropanol on DM ( P = 0.1 ) digestibility in the total tract . The use of 4.5 mg/kg BW of 3-nitrooxypropanol in beef cattle consuming a background ing diet was effective in reducing enteric CH4 emissions without negatively affecting diet digestibility It has been suggested that the rumen microbiome and rumen function might be disrupted if methane production in the rumen is decreased . Furthermore concerns have been voiced that geography and management might influence the underlying microbial population and hence the response of the rumen to mitigation strategies . Here we report the effect of the dietary additives : linseed oil and nitrate on methane emissions , rumen fermentation , and the rumen microbiome in two experiments from New Zeal and ( Dairy 1 ) and the UK ( Dairy 2 ) . Dairy 1 was a r and omized block design with 18 multiparous lactating cows . Dairy 2 was a complete replicated 3 x 3 Latin Square using 6 rumen cannulated , lactating dairy cows . Treatments consisted of a control total mixed ration ( TMR ) , supplementation with linseed oil ( 4 % of feed DM ) and supplementation with nitrate ( 2 % of feed DM ) in both experiments . Methane emissions were measured in open circuit respiration chambers and rumen sample s were analyzed for rumen fermentation parameters and microbial population structure using qPCR and next generation sequencing ( NGS ) . Supplementation with nitrate , but not linseed oil , decreased methane yield ( g/kg DMI ; P<0.02 ) and increased hydrogen ( P<0.03 ) emissions in both experiments . Furthermore , the effect of nitrate on gaseous emissions was accompanied by an increased rumen acetate to propionate ratio and consistent changes in the rumen microbial population s including a decreased abundance of the main genus Prevotella and a decrease in archaeal mcrA ( log10 copies/ g rumen DM content ) . These results demonstrate that methane emissions can be significantly decreased with nitrate supplementation with only minor , but consistent , effects on the rumen microbial population and its function , with no evidence that the response to dietary additives differed due to geography and different underlying microbial population The study objective was to evaluate the effects of sustained reduction of enteric methane ( CH ) emissions with dietary supplementation of the inhibitor 3-nitrooxypropanol ( NOP ) on growth rate and feed conversion efficiency of growing and finishing beef cattle . Eighty-four crossbred steers were used in a 238-d feeding study and fed a background ing diet for the first 105 d ( background ing phase ) and transition diets for 28 d followed by a finishing diet for 105 d ( finishing phase ) with 3 doses of NOP ( 0 , 100 , and 200 mg/kg DM ) . The experiment was a completely r and omized design using 21 pens ( 4 cattle/pen ) with 7 pens per treatment . When cattle were fed the background ing diet , pen DMI was reduced ( < 0.01 ) whereas G : F tended to improve ( = 0.06 ) with increasing dose of NOP supplementation . During the finishing phase , DMI ( = 0.06 ) and ADG ( = 0.07 ) tended to decrease with increasing dose of NOP supplementation . Although both levels of NOP were effective in reducing CH emissions from the background ing diet ( < 0.01 ) , only NOP supplemented at the highest dose was effective in reducing total CH emissions from the finishing diet ( < 0.01 ) . Methane yield ( g/kg DMI ) was reduced whereas hydrogen emissions were increased at the highest dose of NOP supplementation with both background ing and finishing diets ( < 0.01 ) . Overall , these results demonstrate efficacy of NOP in reducing enteric CH emissions from cattle fed background ing and finishing diets , and these effects were negated once NOP supplementation was discontinued Strategies to manage metabolic hydrogen ( [ H ] ) in the rumen should be considered when reducing ruminant methane ( CH4 ) emissions . However , little is known about the use of dietary treatments to stimulate rumen microorganisms capable of capturing the [ H ] available when CH4 is inhibited in vivo . The effects of the phenolic compound phloroglucinol on CH4 production , [ H ] flows and subsequent responses in rumen fermentation and microbial community composition when methanogenesis is inhibited were investigated in cattle . Eight rumen fistulated Brahman steers were r and omly allocated in two groups receiving chloroform as an antimethanogenic compound for 21 days . Following that period one group received chloroform + phloroglucinol for another 16 days , whilst the other group received only chloroform during the same period . The chloroform treatment result ed in a decrease in CH4 production and an increase in H2 expelled with a shift in rumen fermentation toward higher levels of propionate and formate and lower levels of acetate at day 21 of treatment . Bacterial operational taxonomic units ( OTUs ) assigned to Prevotella were promoted whilst Archaea and Synergistetes OTUs were decreased with the chloroform treatment as expected . The shift toward formate coincided with increases in Ruminococcus flavefaciens , Butyrivibrio fibrisolvens , and Methanobrevibacter ruminantium species . The addition of chloroform + phloroglucinol in the rumen result ed in a decrease of H2 expelled ( g ) per kg of DMI and moles of H2 expelled per mol of CH4 decreased compared with the chloroform only treated animals . A shift toward acetate and a decrease in formate were observed for the chloroform + phloroglucinol-treated animals at day 37 . These changes in the rumen fermentation profile were accompanied by a relative increase of OTUs assigned to Coprococcus spp . , which could suggest this genus is a significant contributor to the metabolism of this phenolic compound in the rumen . This study demonstrates for the first time in vivo that under methanogenesis inhibition , H2 gas accumulation can be decreased by redirecting [ H ] toward alternative sinks through the nutritional stimulation of specific microbial groups . This results in the generation of metabolites of value for the host while also helping to maintain a low H2 partial pressure in the methane-inhibited rumen Volatile fatty acid concentrations ( [ VFA ] , mM ) have long been used to assess the effect of dietary treatments on ruminal fermentation in vivo 
    Output:
    
Inhibiting rumen methanogenesis tended to associate positively with milk production efficiency , although the relationship was influenced by individual experiments .
Likewise , a positive relationship between methanogenesis inhibition and growth and fattening efficiency depended on the inclusion and weighting of individual experiments .
Inhibiting rumen methanogenesis negatively associated with dry matter intake .