Carbon and Emissions: Livestock
There are many techniques 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 stomach called methanogens to generate energy.
These microbes produce the gas methane as an end product, which the animal then belches out. Poorer quality feeds produce 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.
Livestock waste (i.e. dung and urine) contains nitrogen. If managed effectively, wastes can be used to improve pasture or crop growth instead of losing nitrous oxide to the atmosphere as greenhouse gas emissions.
Methane is a major inefficiency in animal production systems - 6% to 10% of gross energy intake is 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, and 40 days for dairy cows.
Nitrogen levels that are optimal for plant growth can result in excess nitrogen intake for grazing animals. Consequently, 70% to 95% of nitrogen consumed by ruminants is excreted. Livestock urine and dung, fertiliser applications and nitrogen fixed by legumes are the largest sources of nitrous oxide emissions from grazing enterprises.
1. Optimise feed quality (digestibility) and use and minimise nutrient excretion:
- improve the quality of pasture or forage by optimum grazing management, growing high quality forage crops or supplementing the diets of grazing livestock when necessary with grain or other energy-rich, low fibre feeds (e.g. during summer and autumn).
- consider finishing prime stock in feedlots (see opportunity lot feeding of beef cattle) on high quality diets to reduce finishing times and meet market specifications.
- as far as possible, match the protein to energy ratio of livestock feed with animal requirements. Young, growing stock and lactating females have a higher need for protein than dry stock. The feed demand calculator can help you estimate the feed demand of your herd and/or flock across the year on a monthly basis.
- use plant variety selection to produce fodder that better matches livestock needs (e.g. high metabolisable energy, optimum protein varieties).
- use feeding systems (see Dairy Australia feeding systems) that reduce spillage and spoiling.
- manage pasture quality (e.g. maturity, legume content) through grazing strategies, such as rotational grazing, to optimise feed value (see Dairy Australia pastures, forages and crops).
- manage silage and hay quality using short lockup periods and good storage practices (see Dairy Australia pastures, forages and crops).
2. 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 (see management of beef breeding cows).
- optimise fertility through good health and body condition (see body condition scoring in dairy herds).
- minimise neo-natal losses through good husbandry and provision of adequate shelter.
- improve female fertility by minimising negative energy balance and optimising body condition at joining (see body condition at calving).
3. Implement a genetic improvement program to achieve increased reproductive rates and shorter finishing times:
- include breeding values (see Dairy Australia bull selection) for productivity traits such as fecundity, growth rate, feed conversion efficiency and disease resistance in your ram and bull selection criteria.
- identify, monitor and cull less productive stock.
4. Manage livestock waste (dung and urine) to minimise nitrous oxide emissions:
- avoid applying slurries or manure to land in wet conditions, such as wet winter soils (see Managing wet soils).
- avoid causing conditions that lead to poorly aerated soils (e.g. pasture pugging; see Managing wet soils: what are your best options?).
- consider processing livestock waste (e.g. for organic fertilizer or methane collection).
- when using manure as fertiliser (see dairy effluent and pastures or flood irrigation dairy effluent), test for its nitrogen content and apply at a rate based on crop or pasture requirements.
- manage manure stockpiles (e.g. through composting) to avoid anaerobic conditions.
- de-water storage ponds approximately every 6 months and anaerobic ponds approximately every 3 years by irrigating to crops or pastures (see applying dairy shed effluent to land or flood irrigation dairy effluent). The timing required will vary depending on rainfall.
5. Estimate the methane and nitrous oxide emissions on your farm using a greenhouse gas accounting tool.
The Carbon Toolkits in Agriculture Network provides regular e-newsletters, to keep you informed of the latest information relating to carbon and emissions in agriculture.
The following Farmers taking action case studies tell the stories of landholders having a go at calculating their emissions:
- Measuring Greenhouse Emissions on a Dairy Farm
- Measuring carbon and emissions on a mixed sheep and beef farm
- Beef farmers lead on climate challenge
Dairy Australia Animals, feed and environment webpages.