Dose-response effect of 3-nitrooxypropanol on enteric methane emissions in dairy cows

Abstract

This experiment was designed to test the effect of inclusion rate of 3-nitrooxypropanol (3-NOP), a methane inhibitor, on enteric methane emissions in dairy cows. The study was conducted with 49 multiparous Holstein cows in a randomized complete block design in 2 phases; phase 1 was with 28 cows, and phase 2 with 21 cows. Cows were fed a basal total mixed ration ad libitum and were blocked based on days in milk, milk yield, and enteric methane emissions during a 14-d covariate period. Treatments were control (no 3-NOP) and 40, 60, 80, 100, 150, and 200 mg of 3-NOP/kg of feed dry matter. Following a 14-d adaptation period, enteric gaseous emissions (methane, carbon dioxide, and hydrogen) were measured using the GreenFeed system (C-Lock Inc., Rapid City, SD) over a 3-d period. Compared with the control, inclusion rate of 3-NOP quadratically decreased daily enteric methane emissions from 22 to 40%. Maximum mitigation effect was achieved with the 3 highest 3-NOP doses (with no statistical difference among 100, 150, and 200 mg/ kg). The decrease in methane emission yield and emission intensity ranged from 16 to 36% and from 25 to 45%, respectively. Emissions of hydrogen quadratically increased 6-to 10-fold, compared with the control; the maximum increase was with 150 mg/kg 3-NOP. Treatment did not affect daily emissions of carbon dioxide, but a linear increase in carbon dioxide emission yield was observed with increasing 3-NOP doses. Dry matter intake and milk yield of the cows was not affected by 3-NOP. Milk fat concentration and yield were increased by 3-NOP due to increased concentration of de novo synthetized short-chain fatty acids in milk. Inclusion of 3-NOP also tended to increase milk urea nitrogen but had no other effects on milk components. In this shortterm experiment, 3-NOP decreased enteric methane emissions without affecting dry matter intake or milk yield and increased milk fat in dairy cows. Maximum mitigation effect was achieved at 100 to 200 mg/kg of feed dry matter.

Effects of 3-nitrooxypropanol on rumen fermentation, lactational performance, and resumption of ovarian cyclicity in dairy cows

“…The increase in MUN when 3-NOP was fed in the current experiment contrasts with earlier reports (Reynolds et al, 2014;Lopes et al, 2016;Haisan et al, 2017) but is consistent with more recent data reported by Melgar et al (2018bMelgar et al ( , 2019. In our earlier study, in which graded levels of 3-NOP (from 0 to 80 mg/kg of feed DM) were fed, MUN was not statistically different among treatment, although compared with the control, a numerical increase in MUN occurred with the 3-NOP treatments (10.9, 11.3, 12.0, and 11.3 mg/dL, respectively; SEM = 0.52; P = 0.51; unpublished data from Hristov et al, 2015b).…”

“…These results agree with previous reports from long-term production studies (Hristov et al, 2015b;Van Wesemael et al, 2019) and short-term experiments (Haisan et al, 2014(Haisan et al, , 2017Reynolds et al, 2014;Lopes et al, 2016) in which 3-NOP did not affect lactational performance of dairy cows. Exceptions are the reported increased milk fat yield with 3-NOP by Lopes et al (2016) and the linear increase in milk fat concentration in a dose-response study by Melgar et al (2018b). In a recent study by Melgar et al (2019) with mid-lactation cows, 3-NOP increased milk fat concentration and tended to increase fat yield compared with a control diet.…”

“…Supplementation with 3-NOP has been demonstrated as a highly effective strategy for inhibiting rumen methanogenesis with no negative effects on intake and lactation performance in dairy cows (Haisan et al, 2014(Haisan et al, , 2017Hristov et al, 2015b;Melgar et al, 2018bMelgar et al, , 2019. In this experiment cows were not blocked according to BW; thus, the lower DMI among 3-NOP cows observed in the current study can be partially explained by the lower overall BW of the 3-NOP cows throughout the course of the experiment, which is supported by the Main effect of treatment.…”

“…A recently discovered substance under investigation, 3-nitrooxypropanol (3-NOP; Duval and Kindermann, 2012), has been shown to inhibit methanogenesis through targeting methyl-coenzyme M reductase in the last step of CH 4 formation by rumen archaea (Duin et al, 2016). Several studies have investigated the effects of 3-NOP on CH 4 emission in dairy cattle (Hristov et al, 2015a;Melgar et al, 2018bMelgar et al, , 2019Van Wesemael et al, 2019). Although 3-NOP consistently decreased enteric CH 4 emission, inclusion rate, application technique, diet composition, and timing of application appear to affect the extent of CH 4 reduction.…”

Application of 3-nitrooxypropanol and canola oil to mitigate enteric methane emissions of beef cattle results in distinctly different effects on the rumen microbial community

“…Hristov et al (2015) reported a 25 to 32% decrease in CH 4 production in lactating dairy cows that persisted over a 12-week study when 3-NOP was included in the ration at 40 to 80 mg/kg dry matter (DM) [9]. A dose response study identi ed a quadratic decrease in enteric CH 4 emissions in dairy cattle with maximum reduction of CH 4 yield with 3-NOP included at 100 to 200 mg/kg DM [10]. In a study with growing beef cattle, a 37 to 42% decrease in enteric CH 4 emissions occurred over 238-days when 3-NOP was supplemented at 125 to 200 mg/kg DM [11].…”