Abstract
Agriculture is responsible for 5% to 10% of the global anthropogenic greenhouse gas (GHG) emissions. Livestock contribute about 65% of agricultural GHG and enteric fermentation accounts for 90% of this. The global warming potential of CH4 is known to be 23 times more than that of carbon dioxide, resulting in it being a significant role player in the greenhouse gas family. The laser methane detector (LMD) is an instrument that has the potential to measure enteric CH4 emission from livestock under normal husbandry activities. This study was aimed at evaluating the efficiency and results, when using the LMD to measure CH4 production under normal production conditions. Twelve heifers, four each from the Bonsmara, Nguni and Jersey breeds, were subjected to grazing natural veld, forage sorghum under irrigation, oats pasture under irrigation or a total mixed ration. Measurements were taken late afternoon (18:00) when the animals were ruminating. Four repeated measurements, lasting 60 seconds each, were taken on 10 consecutive days on each of the production systems. The animals were adapted for a period of 14 days on the specific feed, before the measurements were taken. The Jersey heifers produced significantly less CH4 than the Bonsmara and Nguni on natural veld, with no significant differences between breeds on the forage sorghum. On natural veld the heifers generated 48% more CH4. These results thus indicate that the LMD produce sensible and repeatable measurements that can be interpreted in respect of CH4 production by cattle. The next step will be to increase the number of breeds, numbers per breed, and feeding strategies over all seasons in order to validate and build up a baseline data set on the use of the LMD to measure CH4 emissions from cattle under different grazing conditions.
Generated Summary
This research investigates the potential of a Laser Methane Detector (LMD) to measure methane (CH4) production in cattle under various grazing and feeding conditions. The study aimed to evaluate the effectiveness of the LMD in measuring CH4 emissions from different breeds of cattle (Bonsmara, Nguni, and Jersey) under different diets, including natural veld, forage sorghum, oats pasture, and a total mixed ration (TMR). Measurements were taken in the late afternoon when the animals were ruminating, with repeated measurements over several days. The core approach involved using the LMD to assess methane production, with the goal of establishing a reliable method for measuring enteric CH4 emissions under normal husbandry activities. The study contributes to the broader understanding of greenhouse gas emissions from livestock, particularly in relation to the use of a less invasive and more practical method for assessing CH4 production in cattle.
Key Findings & Statistics
- Agriculture is responsible for 5% to 10% of global anthropogenic greenhouse gas emissions, with livestock contributing about 65% of agricultural GHG. Enteric fermentation accounts for 90% of these livestock emissions.
- The global warming potential of methane is 23 times more than that of carbon dioxide (CO2).
- The study involved twelve heifers, four each from the Bonsmara, Nguni, and Jersey breeds.
- Measurements were taken on natural veld, forage sorghum, oats pasture, and a total mixed ration (TMR).
- Measurements were taken in the late afternoon (18:00) when animals were ruminating.
- Four repeated measurements (60 seconds each) were taken over 10 consecutive days.
- Animals were adapted for 14 days on the specific feed before measurements.
- Jersey heifers produced significantly less CH4 than Bonsmara and Nguni on natural veld.
- No significant differences in CH4 production were found between breeds on forage sorghum.
- Heifers generated 48% more CH4 on natural veld compared to forage sorghum.
- Methane production was measured in parts per million-meter (ppm-m).
- The mean methane production values (± SD) for each breed and feed source were as follows:
- Bonsmara on Natural veld: 32.7 ± 5.3 ppm-m
- Bonsmara on Total mixed ration: 31.3 ± 9.8 ppm-m
- Bonsmara on Oats grazing: 26.3 ± 7.3 ppm-m
- Bonsmara on Forage sorghum: 15.3 ± 1.6 ppm-m
- Jersey on Natural veld: 25.8 ± 1.1 ppm-m
- Jersey on Total mixed ration: 36.6 ± 3.4 ppm-m
- Jersey on Oats grazing: 30.7 ± 7.0 ppm-m
- Jersey on Forage sorghum: 14.5 ± 1.7 ppm-m
- Nguni on Natural veld: 30.6 ± 1.4 ppm-m
- Nguni on Total mixed ration: 26.4 ± 4.0 ppm-m
- Nguni on Oats grazing: 24.6 ± 3.0 ppm-m
- Nguni on Forage sorghum: 16.5 ± 2.8 ppm-m
- Statistical analysis revealed significant differences in methane production among the different feed sources (P < 0.0001).
- Significant differences were also found between breeds (P < 0.05).
- The feeding of a total mixed ration (TMR) produced more methane than heifers grazing on natural veld, oats, or forage sorghum.
Other Important Findings
- The Laser Methane Detector (LMD) is a promising instrument for measuring enteric CH4 emissions from livestock under normal husbandry conditions.
- The Jersey heifers produced significantly less methane on natural veld compared to the Bonsmara and Nguni.
- The LMD measurements provide sensible and repeatable results for CH4 production in cattle.
- The study suggests that dairy cattle might react differently than beef cattle on different feed sources due to selective grazing behavior.
- Variations in enteric methane production can occur based on the digestive system, feed intake, diet composition, feed processing, and the addition of specific feed additives.
- The need for accurate estimates of enteric methane production in ruminants is crucial.
- The study highlights the importance of addressing environmental factors that can affect LMD measurements.
- Individual animals showed a tendency to emit higher or lower quantities of methane, regardless of the feed source, which can indicate potential genetic differences.
Limitations Noted in the Document
- The study focuses on a limited number of breeds (Bonsmara, Nguni, and Jersey).
- The sample size, with only four heifers per breed, is relatively small.
- The study did not cover all seasons, which could influence the results.
- The study focused on measurements taken at a specific time of the day (late afternoon).
- The study acknowledges that the tendency of individual animals to emit higher or lower quantities of methane, regardless of the feed source.
Conclusion
The study successfully employed a Laser Methane Detector (LMD) to measure methane production in different breeds of cattle under various feeding and grazing conditions. The LMD’s ability to produce recordable and interpretable measurements in respect to enteric methane emissions in cattle was confirmed, validating its use for evaluating CH4 production. The Jersey heifers produced significantly less methane on natural veld compared to the Bonsmara and Nguni breeds, while no significant differences were observed in forage sorghum grazing. The study highlights the importance of considering feed sources’ impact on methane emissions and demonstrates the LMD’s potential for monitoring methane production in cattle. These findings support the use of LMD as a practical tool. The authors recommend further research. In the face of climate change and the need for sustainable livestock practices, tools like the LMD will contribute significantly to the ability to measure and potentially mitigate methane emissions in cattle. The ability to measure methane production accurately and efficiently is critical for developing effective strategies to reduce the environmental impact of livestock farming. Further research involving a larger number of breeds, animals, and feeding strategies is recommended, along with an investigation into the genetic differences between animals.