The Role of Bovaer® (3-NOP) in Mitigating Methane Emissions from Dairy and Beef Cattle

Introduction

Methane (CH₄) is a major greenhouse gas (GHG), much stronger than carbon dioxide (CO2) in trapping heat (Tian et al., 2016). Livestock, especially dairy and beef cattle, produce CH₄ as a by-product of digestion, contributing to global warming and representing a significant loss of gross energy (2-12%) for the animals (Johnson & Johnson, 1995). Reducing CH₄ emissions from livestock is important for two main reasons. First, it helps protect the environment by lowering GHGs that contribute to climate change. Second, it improves energy efficiency because less CH₄ means more energy is available for the animals to use for growth and production. Scientists have tried various feed additives to reduce CH₄ emissions from ruminants (Anderson et al., 2010; Grawert et al., 2014; Gadzama, 2024). One effective additive is Bovaer®, formerly known as 3-nitrooxypropanol (3-NOP; Jayanegara et al., 2018; Kebreab et al., 2023; van Gastelen et al., 2024). This synthetic, non-toxic compound works by inhibiting an enzyme called methyl-coenzyme M reductase, which is responsible for the final step of CH₄ production in the stomach of ruminants (Díaz, 2023). 

What is Bovaer®   

Bovaer® is a feed additive designed to reduce livestock CH₄ emissions. It works by safely suppressing the enzyme responsible for CH₄ production in the stomachs of cows and beef cattle (Figure 1).

How Bovaer® Works

In a cow's stomach, microbes help break down food, releasing hydrogen (H₂) and CO₂. Normally, an enzyme combines these gases to form CH₄. Bovaer® works by inhibiting this enzyme, so less CH₄ is produced (Figure 1). It has been shown that 3-NOP was more effective against certain methane-producing microbes (Methanobrevibacter) than others (Methanosphaera) in a cow's stomach (Pitta et al., 2022). Recent trials have shown promising results for Bovaer® in reducing CH₄ emissions in dairy and beef cattle (Almeida et al., 2023; van Gastelen et al., 2024). However, the challenge remains in finding effective delivery mechanisms for pasture-based dairy farming systems (Marmont et al., 2024). This paper aims to review current findings on the impact of Bovaer® as a feed additive and its potential to reduce CH₄ emissions in both dairy and beef cattle.

Impact of Bovaer® on Methane Emissions in Dairy Cows

Several short-term studies have shown that feeding Bovaer® to dairy cows for up to 4 weeks effectively reduces CH₄ emissions (Haisan et al., 2014; van Gastelen et al., 2022).

• Holstein cows (both first-time and experienced mothers) fed with Bovaer® at 60 mg/kg of feed dry matter reduced CH₄ emissions by 26% per day, 27% per kg of feed, and 29% per kg of milk produced (Melgar et al., 2021). 
• Danish Holstein cows (24 first-time mothers and 24 experienced mothers) fed Bovaer® at up to 80 mg/kg DM to reduce CH₄ emissions by 18-23%. Combining Bovaer® with fat and nitrate did not further reduce methane emissions compared to using Bovaer® alone (Maigaard et al., 2024).
• Holstein Friesian and Brown Swiss cows fed with Bovaer® at 60 mg per kg of their total mixed ration (dry matter) reduced CH₄ emissions by about 13-14% (Ma et al., 2024).

Recently, van Gastelen et al. (2024) studied the long-term effects of 3-NOP on CH₄ emissions and milk production in dairy cows. The researchers found that:

69.8 mg/kg DM supplementation led to:

• 21% reduction in total CH₄ production (g/day)
• 20% reduction in CH₄ yield (g/kg DMI or Dry Matter Intake)
• 27% reduction in CH₄ intensity (g/kg fat- and protein-corrected milk).

The study indicated that the effectiveness of 3-NOP varied with diet composition (e.g., grass and corn silage) and lactation stage, showing CH₄ reductions of:

• 16% during the dry period
• 20% in early lactation
• 16% in mid-lactation
• 26% in late lactation.

In another study, Holstein cows were given 3-NOP at 0,  48.4, and 51.2 mg/kg DM from 28 days before calving to 120 days after. Results showed:

• 23% reduction in CH₄ emissions with low concentrate feed proportions (CFP)
• 33% reduction with high CFP, indicating a synergistic effect when combining 3-NOP with high CFP, outperforming high CFP alone (12% reduction) or 3-NOP alone (22% reduction) (Schilde et al., 2021).

Holstein-Friesian dairy cows fed 3-NOP at 60 or 80 mg/kg DM in different diets had the following CH₄ reductions:

• Grass silage-based diet: 26.2% (60 mg) and 28.4% (80 mg)
• Mixed grass and corn silage diet: 35.1% (60 mg) and 37.9% (80 mg)
• Corn silage-based diet: 34.8% (60 mg) and 41.6% (80 mg).

These results demonstrate greater reductions in CH₄ emissions with mixed and corn silage diets than with grass silage diets (van Gastelen et al., 2022).

Summary

• Feeding dairy cows 3-NOP reduces CH₄ emissions, with reductions of up to 29% per kg of milk in short-term studies (Melgar et al., 2021).
• Long-term studies show a 27% reduction in CH₄ intensity with 69.8 mg/kg DM (van Gastelen et al., 2024).
• Combining 3-NOP with high-concentrate feed can enhance reductions, achieving up to 33% (Schilde et al., 2021), while the highest reduction of 41.6% was seen with 80 mg/kg DM in a corn silage diet (van Gastelen et al., 2022).

Impact of Bovaer® on Methane Emissions in Beef Cattle 

Feeding cattle with Bovaer® is an effective way to lower CH₄ emissions. Here's a simplified overview of the research:

1. Feedlot bulls (starting weight: 360 kg ± 37.3 kg) fed 0, 100, and 150 mg/kg of 3-NOP for 96 days reduced their CH₄ emissions by about 49.3%, CH₄ yield by 40.7%, and CH₄ intensity by 38.6% (Araújo et al., 2023).
2. Angus steers (weighing 356 kg) on a barley and canola oil diet, given 0-125 mg/kg of 3-NOP, reduced their CH₄ emissions drop by 65.5% to 87.6% (Almeida et al., 2023).
3. Beef cattle (average weight: 407 kg) fed 0, 75, and 100 mg/kg of 3-NOP experienced a 38.2% methane reduction (Pedrini et al., 2024).
4. Young beef calves (under 6 months) on a diet of 50% forage and 50% concentrate with 150 mg/kg of 3-NOP reduced their CH₄ emissions by 30% over 12 weeks (Kirwan et al., 2024).
5. Grazing beef cattle, fed pellets containing 51% 3-NOP (510 mg/kg) up to 4 times a day for 56 days (with 2 kg of pelletsdaily providing 150 mg of 3-NOP per kg DMI) resulted in significant reductions in CH₄ emissions by 15.9% per day, 24.8% per kg of weight gain compared to energy pellets, and 31.5% per kg of weight gain compared to control pellets (Meale et al., 2024).

In summary, these studies revealed that 3-NOP can significantly reduce CH₄ emissions, with the highest reduction being 87.6% in Angus steers.

Benefits of Using Bovaer®

• Environmental Impact: Bovaer® reduces GHG emissions from livestock, contributing to climate change mitigation (Almeida et al., 2023).
• Feed Efficiency: Reducing CH₄ emissions allows more energy from the feed to be used for milk fat production, which can potentially improve overall productivity.

Conclusion

Incorporating Bovaer® in animal feed can effectively reduce CH₄ emissions by inhibiting the key enzyme responsible for CH₄ production in ruminants. The effectiveness of Bovaer® depends on the dose, diet composition, and cattle breed. Higher doses are more effective, but excessive dietary fiber can reduce its impact. Additionally, the effectiveness of Bovaer® varies by region and livestock production systems. The reduction in CH₄ emissions is most pronounced immediately after feeding. Ongoing research aims to maximize the benefits of Bovaer® in pastoral systems.   Keywords: Methane (CH₄), Greenhouse gas, Livestock, Feed additives, Bovaer®, 3-nitrooxypropanol (3-NOP), Climate change, Methane emissions, Ruminants, Dairy cows, Beef cattle, Feedlot, Energy efficiency, Sustainable farming

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