Abstract
BackgroundIn recent years, nitrooxy compounds have been identified as promising inhibitors of methanogenesis in ruminants. However, when animals receive a nitrooxy compound, a high portion of the spared hydrogen is eructated as gas, which partly offsets the energy savings of CH4 mitigation. The objective of the present study was to evaluate the long-term and combined effects of supplementation with N-[2-(nitrooxy)ethyl]-3-pyridinecarboxamide (NPD), a methanogenesis inhibitor, and fumaric acid (FUM), a hydrogen sink, on enteric CH4 production, rumen fermentation, bacterial populations, apparent nutrient digestibility, and lactation performance of dairy goats.ResultsTwenty-four primiparous dairy goats were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments: supplementation without or with FUM (32 g/d) or NPD (0.5 g/d). All samples were collected every 3 weeks during a 12-week feeding experiment. Both FUM and NPD supplementation persistently inhibited CH4 yield (L/kg DMI, by 18.8% and 18.1%, respectively) without negative influence on DMI or apparent nutrient digestibility. When supplemented in combination, no additive CH4 suppression was observed. FUM showed greater responses in increasing the molar proportion of propionate when supplemented with NPD than supplemented alone (by 10.2% vs. 4.4%). The rumen microbiota structure in the animals receiving FUM was different from that of the other animals, particularly changed the structure of phylum Firmicutes. Daily milk production and serum total antioxidant capacity were improved by NPD, but the contents of milk fat and protein were decreased, probably due to the bioactivity of absorbed NPD on body metabolism.ConclusionsSupplementing NPD and FUM in combination is a promising way to persistently inhibit CH4 emissions with a higher rumen propionate proportion. However, the side effects of this nitrooxy compound on animals and its residues in animal products need further evaluation before it can be used as an animal feed additive.
Highlights
Methane (CH4) emissions from ruminants contribute to anthropogenic greenhouse gas emissions and enlarge the carbon footprint of dairy or beef production [1] and drain dietary energy (2% to 12% of gross energy (GE)) [2]
Methane production and lactation performance The persistent and combined effects of fumaric acid (FUM) and NPD supplementation on CH4 production and milk parameters are shown in Table 2 and Fig. 1
The NPD supplementation increased (P < 0.05) the daily milk production (DMP), improved feed conversion efficiency expressed as DMP/Dry matter intake (DMI), and tended to increase the daily Fat corrected milk (FCM) production and FCM/ DMI, but it decreased (P < 0.05) the fat and protein content of the milk without changing milk fat and protein yields
Summary
Methane (CH4) emissions from ruminants contribute to anthropogenic greenhouse gas emissions and enlarge the carbon footprint of dairy or beef production [1] and drain dietary energy (2% to 12% of gross energy (GE)) [2]. When the methanogenesis pathway is inhibited, hydrogen production increased and is eructated as gas (increased by 48- to 100-fold) [6, 8,9,10], and hydrogen is a greenhouse gas with high energy [11, 12]. Nitrooxy compounds have been identified as promising inhibitors of methanogenesis in ruminants. When animals receive a nitrooxy compound, a high portion of the spared hydrogen is eructated as gas, which partly offsets the energy savings of CH4 mitigation. The objective of the present study was to evaluate the long-term and combined effects of supplementation with N-[2-(nitrooxy)ethyl]-3pyridinecarboxamide (NPD), a methanogenesis inhibitor, and fumaric acid (FUM), a hydrogen sink, on enteric CH4 production, rumen fermentation, bacterial populations, apparent nutrient digestibility, and lactation performance of dairy goats
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