Abstract
Effects of the investigational methane (CH4) inhibitor 3-nitrooxypropanol (3-NOP) on animal performance, health and enteric CH4 production of beef cattle were evaluated in a commercial feedlot. Two concurrent studies were conducted: a large pen study (4,048 cattle, eight pen replicates per experimental group) to measure animal performance and health and a small pen study (a subset of 50 cattle from the large pen study, n = 25 per experimental group) to measure enteric CH4 emissions. Within the study, animals (body weight ± SD, 282±8 kg) were assigned in a completely randomized design to one of two groups: control, fed a backgrounding diet (70% corn or barley silage, 30% steam-flaked barley grain concentrate; dry matter (DM) basis) and 3-NOP, fed the backgrounding diet containing 3-NOP. The treatment group in the large pen study was adapted to 3-NOP (12 ± 3 d) before receiving the final target level of 200 mg/kg of DM, which was fed for 108 ± 8 d. Animals in the small pen CH4 emissions study received a basal diet or a basal diet with 3-NOP, with the dose increased every 28 d: low (150 mg/kg DM; 1.27 g/d), medium (175 mg/kg DM; 2.25 g/d), and high (200 mg/kg DM; 2.75 g/d). Intake in the small pens was monitored by electronic feeding bunks and CH4 was measured using the GreenFeed system. In the large pen study, total weight gained, average daily gain, and animal health variables were not affected by 3-NOP, but DM intake (DMI) tended to decrease (P = 0.06) by 2.6% relative to control (8.07 kg/d), while gain:feed ratio tended to be improved (P = 0.06) by 2.5% relative to control (0.161 kg weight gain/kg DMI). In the small pen study, average daily consumption of 3-NOP increased with inclusion rate whereas average DMI was decreased by 5.4% (P = 0.02) compared with control (10.4 kg/d). On average, addition of 3-NOP decreased (P = 0.001) CH4 emissions (g/d) by 25.7% and yield (g CH4/kg DMI) by 21.7%. In conclusion, supplementing a backgrounding diet with 3-NOP decreased CH4 yield and tended to improve feed efficiency of beef cattle fed in a commercial feedlot with no negative impacts on animal health.
Generated Summary
The study investigated the effects of 3-nitrooxypropanol (3-NOP), a methane (CH4) inhibitor, on the performance, health, and enteric CH4 production of beef cattle in a commercial feedlot. Two concurrent studies were conducted: a large pen study to assess animal performance and health, and a small pen study to measure CH4 emissions. Animals were assigned to either a control group (fed a backgrounding diet) or a 3-NOP group (fed the backgrounding diet with 3-NOP). The large pen study included 4,048 cattle, while the small pen study utilized a subset of 50 cattle from the large pen study. The animal performance study evaluated dry matter intake (DMI), average daily gain (ADG), feed conversion efficiency (gain:feed ratio, G:F), and health. The CH4 production study measured enteric CH4 emissions. In the large pen study, total weight gained, ADG, and animal health variables were not affected by 3-NOP, but DMI tended to decrease, and G:F tended to improve. In the small pen study, average daily consumption of 3-NOP increased with inclusion rate, while average DMI decreased. The study aimed to evaluate the impact of 3-NOP on feed consumption, animal performance, animal health, and enteric CH4 production in a commercial feedlot environment, providing insights into sustainable beef cattle production.
Key Findings & Statistics
- In the large pen study, DMI tended to decrease by 2.6% relative to control.
- G:F ratio tended to be improved by 2.5% relative to control.
- In the small pen study, DMI was decreased by 5.4% (P = 0.02) compared with control.
- Addition of 3-NOP decreased CH4 emissions (g/d) by 25.7% (P = 0.001).
- CH4 yield (g CH4/kg DMI) decreased by 21.7%.
- Initial individual animal live weight for control and 3-NOP groups: 283 ± 9 kg and 282 ± 8 kg, respectively.
- In the large pen study, animals were fed the backgrounding diet containing 70% whole crop barley silage and 30% barley-based concentrate.
- In the small pen study, initial diet formulation contained barley silage, but corn silage was used mid-way through the study.
- The dose of 3-NOP was based on previous studies, with a final concentration of 200 mg/kg DM.
- DMI for animals in the large pen study was 8.07 kg/d for control.
- DMI for animals in the small pen study was 10.4 kg/d for control.
- Average daily consumption of 3-NOP increased with inclusion rate whereas average DMI was decreased by 5.4%.
- Average daily consumption of 3-NOP increased with inclusion rate.
- DMI for the low, medium, and high doses of 3-NOP was reported in Table 5.
- Total DMI was lower (P = 0.02) by 5.3% for 3-NOP compared to the control treatment (10.43 kg/d).
- Intake was not affected by the low dose but was 5.8% less for the medium dose compared with control (11.55 kg/d) and 5.9% lower for the high dose compared with control (12.06 kg/d).
- On average, each visit to the GEM system lasted slightly more than 4 min and did not differ (P > 0.48) between treatment groups.
- In the large pen study, the cattle were fed a backgrounding diet containing 70% whole crop barley silage and 30% barley-based concentrate.
- Overall, 3-NOP reduced CH4 production by an average of 25.7% (P = 0.001).
- Methane yield (g/kg DMI) decreased by 17.2, 25.7, and 21.3% for low, medium, and high doses of 3-NOP, respectively, with a 21.7% decrease overall (P = 0.001).
Other Important Findings
- In the large pen study, total weight gained, ADG, and animal health variables were not affected by 3-NOP.
- In the small pen study, average daily consumption of 3-NOP increased with inclusion rate.
- The decrease in CH4 production due to 3-NOP showed a concomitant increase in H2 production.
- The average diurnal pattern of CH4 emissions during the study by treatment is presented in Figure 4A.
- The average diurnal pattern of H2 production during the study by treatment is presented in Figure 4B.
- There were no differences in morbidity or mortality detected between the experimental groups.
- There was a tendency for animals fed 3-NOP to have a slightly greater percentage (P = 0.07) of treatment of animals for relapse without a fever.
Limitations Noted in the Document
- The study design evaluated the effects of 3-NOP sequentially, rather than simultaneously, potentially affecting the comparability of animal responses across doses.
- The smaller decline in DMI observed in the animal production study compared to small pen studies may be related to differences in competition at the feed bunk caused by the type of feeder, feed bunk management, and frequency of feed allocation.
- Animal health data did not reveal any increased risk of mortality or morbidity in cattle fed 3-NOP, but the tendency for animals with relapse without a fever requires further investigation.
Conclusion
The study’s findings suggest that supplementing a backgrounding diet with 3-NOP in a commercial feedlot setting can effectively decrease CH4 yield, while also tending to improve feed efficiency in beef cattle, without causing negative health impacts. This is consistent with previous studies on CH4 mitigation, and is of great value for the beef industry. The authors note that the present study is the first to show the effects of feeding 3-NOP on feed consumption, animal performance, animal health and enteric CH4 production of beef cattle fed a backgrounding diet in a commercial feedlot. The study indicates that the 3-NOP, if approved, could significantly reduce GHG emissions from the beef industry, particularly the feedlot sector. The research highlighted the potential of 3-NOP to reduce enteric CH4 emissions, with a sustained reduction in enteric CH4 yield of 22%, on average (ranging from 20 to 26% depending upon dose). It is suggested that achieving carbon neutral beef production will likely increase the cost of production, as well as the retail price of meat. However, the observed tendency in feed conversion efficiency improvement (2.5%) in the present study would be economically significant to the cattle industry. Furthermore, improvements in animal performance would lead to greater revenues per animal sold. The study concludes with a need for further studies to validate the efficacy of 3-NOP for CH4 mitigation and determine its effects on animal performance when used in commercial beef production systems with varying animal types, diets, and management conditions. The authors underscore the significance of this study by noting that before beef producers use 3-NOP to mitigate CH4 emissions they need information on the health and performance of animals fed 3-NOP in commercial conditions, in addition to efficacy of CH4 reduction.