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

Abstract

This study examined the effect of 3-nitrooxypropanol (3-NOP), a substance under investigation, on enteric methane (CH 4 ) emission, rumen fermentation, lactational performance, sensory properties of milk, and the resumption of ovarian cyclicity in early-lactation dairy cows. Fifty-six multi-and primiparous Holstein cows, including 8 that were rumen cannulated, were used in a 15-wk randomized complete block design experiment. Cows were blocked based on parity and previous lactation milk yield (MY) or predicted MY, and within each block were randomly assigned to one of 2 treatments: (1) control (CON), administered no 3-NOP, or (2) 3-NOP applied at 60 mg/kg of feed dry matter (3-NOP). Enteric CH 4 emission was measured during experimental wk 2, 6, 9, and 15, using the GreenFeed system. Dry matter intake (DMI) and MY data were collected daily throughout the experiment, and milk composition samples were collected 7 times during the experiment. Milk samples were collected from 14 to 60 (±2) d after calving, 3 d per week, and assayed for progesterone concentration to determine resumption of ovarian activity. Compared with CON, 3-NOP decreased daily CH 4 emission by 26%, CH 4 yield (CH 4 per kg of DMI) by 21%, and CH 4 emission intensity [CH 4 per kg of MY or energy-corrected milk (ECM)] by 25%. Enteric emission of carbon dioxide was decreased by 5%, and hydrogen emission was increased 48-fold by 3-NOP. Inclusion of 3-NOP decreased concentration of total volatile fatty acids (by 9.3%) and acetate but increased butyrate molar proportion, ethanol, and formate concentrations in ruminal fluid. Dry matter intake was lower for 3-NOP compared with CON, but DMI expressed as a percentage of body weight was not different between treatments. Treatment had no effect on milk and ECM, body weight change, or body condition score. Milk composition and milk fat and protein yields were not affected by treatment, except that concentrations of short-chain fatty acids in milk were increased by 3-NOP. Nutrient digestibility and blood metabolites and hormones were not affected by 3-NOP, except that insulin was decreased by 3-NOP. There was no effect of 3-NOP on postpartum resumption of ovarian activity, including days to first and second luteal phases, length of first and second luteal phases, and interval from first to second luteal phase. Sensory properties of milk from cows fed 3-NOP and cheese made from that milk were not affected by treatment. In this experiment, 3-NOP decreased daily enteric CH 4 emission, emission yield, and emission intensity, improved feed efficiency, and did not affect lactational performance or onset of ovarian activity in early-lactation dairy cows.

Effects of 3-nitrooxypropanol and varying concentrate feed proportions in the ration on methane emission, rumen fermentation and performance of periparturient dairy cows

“…This was explained by the decreased acetate to propionate ratio reflecting a shift from H 2 liberating to H 2 consuming fermentation pathways and the potential redirection of excessive H 2 from inhibited methanogenesis to alternative sinks. The present experiment confirmed that both 3-NOP and the readily degradable carbohydrates in HC diets decreased the molar proportions of acetate (Van Kessel and Russell 1996;Lopes et al 2016) but increased that of propionate, butyrate and valerate (Haisan et al 2014;Lopes et al 2016;Melgar et al 2020) which are thermodynamically favourable for H 2 disposal (Morgavi et al 2010). Additionally, the deamination of branched-chain amino acids could have been affected as iso-valerate increased due to 3-NOP supplementation.…”

“…In contrast, in our trial, antimethanogenic effects of 3-NOP were identified to be transient in NOP LC group (70% forages). This could be related to the notably higher dietary aNDFom content of approximately 400 g/kg in NOP LC and 340 g in NOP HC group, respectively, ( Table 2) when compared to 276 g of NDF/kg DM (Hristov et al 2015b) and 318 g of NDF/kg DM (Melgar et al 2020). In a meta-analytical approach, Dijkstra et al (2018) identified that the 3-NOP effect on CH 4 yield decline was impaired by 1.52 ± 0.41% per 10 g/kg DM increase of dietary NDF content in dairy cattle.…”

“…With regard to NOP HC group, our results of approximately 33% lower CH 4 emissions [g/d; g/kg DMI; g/kg ECM] verified the recently postulated 30%-reduction potential of 3-NOP. To investigate this, both Hristov et al (2015b) and Melgar et al (2020) supplemented 60 mg of 3-NOP/kg DM mixed into a forage-based diet (60% forages) for 48 and 56 lactating cows and reported a persistent CH 4 inhibition by 31% and 26% over a 12-and 15-week trial period, respectively. In contrast, in our trial, antimethanogenic effects of 3-NOP were identified to be transient in NOP LC group (70% forages).…”

Metabolic Hydrogen Flows in Rumen Fermentation: Principles and Possibilities of Interventions

“…The same calculation conducted with NADH oxidation occurring through electron confurcation would yield a considerable higher range of dissolved H 2 concentration between 6 and 100 µM, again assuming equilibrium between gaseous and aqueous H 2 . Therefore, with electron confurcation, the range of dissolved H 2 concentration at which NADH oxidation becomes thermodynamically controlled coincides or is even higher than previously reported peaks of dissolved H 2 concentration after feed ingestion, or the dissolved H 2 concentration reported by Melgar et al (2019) for methanogenesis inhibition (Table 1). This agrees with the findings by Greening et al (2019) regarding the importance of confurcating hydrogenases in H 2 formation in the rumen.…”

“…Pathways of [H] flow alternative to H 2 formation can result in the production of other intercellular e − carriers, such as lactate, ethanol, and formate, or final fermentation products such as propionate, all of which also help NADH oxidation (Van Lingen et al, 2016). Formate, succinate or ethanol have been shown to accumulate along with H 2 when methanogenesis was inhibited in vitro (Slyter, 1979;Asanuma et al, 1998;Ungerfeld et al, 2003) and in vivo (Martinez-Fernandez et al, 2016, 2017Melgar et al, 2019), so it is important to understand if the accumulation of those metabolites could potentially inhibit cofactors re-oxidation and fermentation. The effects of lactate, ethanol, formate and propionate on fermentation and digestion are best studied in experiments in which those metabolites are externally added to rumen fermentation as pure compounds.…”