Livestock methane and nitrogen emissions
There are management strategies that can improve livestock performance and efficiency while reducing emissions produced on-farm.
Methane is the main greenhouse gas produced in grazing systems. Ruminant livestock (cattle, sheep, and goats) have microbes in their rumen called methanogens. These microbes produce methane (from the fermentation of feed) that is then belched out. Feed with lower digestibility produces more methane than higher quality feeds. Belched methane represents energy lost from your production system that might otherwise be converted to the milk, meat or fibre that generates income.
Methane is a major inefficiency in animal production systems with 6 per cent to 10 per cent of gross energy intake lost as methane. This energy loss has been calculated as the equivalent of up to:
- 55 to 60 days grazing intake for ewes and steers
- 40 days for dairy cows.
Livestock urine and dung deposition, nitrogen fertiliser applications and atmospheric nitrogen fixed by legumes are the largest inputs of reactive nitrogen to soil for grazing enterprises.
Livestock manure (dung and urine) contains a high concentration of nitrogen. Around 80 per cent of all nitrogen consumed by ruminants is excreted in dung and urine. Both directly deposited animal manure and collected manure, which is land applied, should be used efficiently to improve pasture or crop growth.
Improve the quality of the feed that livestock eat to reduce methane emissions:
- improve the quality of pasture or forage by optimum grazing management, growing high quality forage crops (e.g. legume forages which contain tannins, reduce methane and urinary nitrogen losses) or supplementing the diets of grazing livestock when necessary with grain or other high oil, energy-rich, low fibre feeds (for example, during summer and autumn) while optimising protein intake
- finish prime stock in feedlots on high quality optimum diets to reduce finishing times and meet market specifications.
- use feeding systems that reduce spillage and spoiling to maximise feed usage
- optimise silage and hay quality by harvesting when appropriate and when quality is high using short lockup periods and good storage practices
- use feed testing to assess the feed value of grain, hay or silage
- stay tuned to industry research as methane reducing feed additives become more widely available.
Manage the flock or herd to optimise reproductive efficiency:
- maximise the proportion of young, growing or lactating stock
- ensure that breeding stock are managed according to their nutritional requirements
- optimise fertility through good health and body condition
- minimise young stock losses through good husbandry and provision of adequate shelter.
- cull unproductive reproducing stock.
Consider ram/bull selection and breeding to achieve increased reproductive rates and shorter finishing times:
- utilise Australian Sheep Breeding Values (ASBV’s) when selecting rams, Estimated Breeding Values (EBVs) for beef cattle and Australian Breeding Values (ABV’s) for dairy cattle
- include breeding values for productivity traits such as fecundity, growth rate, reproduction, feed conversion efficiency, feed intake and disease resistance in your ram and bull selection criteria
- identify, and cull less productive stock.
Reduce the loss of nitrogen from animal manure (dung and urine) to minimise nitrous oxide emissions:
- avoid applying slurries or manure to land in wet conditions, such as wet winter soils
- avoid causing conditions that lead to poorly aerated soils (such as, pasture pugging and compaction)
- when using manure as fertiliser, test for its nitrogen content and apply at a rate based on crop or pasture requirements
- manage manure stockpiles to avoid anaerobic conditions
- de-water storage ponds (approximately every six months) and anaerobic ponds (approximately every three years) by irrigating to crops or pastures. Where possible manage the timing of application to replace the need for nitrogen fertiliser.
Estimate the methane and nitrous oxide emissions on your farm using a greenhouse gas accounting tool (select the link to appropriate tools for your type of enterprise).
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