Saturday, June 04, 2011

Australia's Tropical Beef Herd - Methane Emissions Lower Than Current Estimates

New CSIRO research indicates that the amount of methane emitted from cattle fed on tropical grasses in northern Australia is up to 30 per cent less than figures currently used to calculate the northern cattle industry's contribution to Australia's greenhouse gas accounts.

Speaking at a recent Lansdown Field Day near Townsville, Queensland, CSIRO research leader Dr Ed Charmley said the findings would help to refine the nation's greenhouse gas accounting."

Measurements from cattle in CSIRO's custom-built respiration chambers show that Brahman cattle fed a wide range of tropical grasses emit up to 30 per cent less methane than previously determined. "While you always have to be cautious in extending lab data to the field and across an industry, we have been able to cross-check our findings with methane detecting laser systems used in the field."

These findings, while not changing the actual emissions, could have significant implications for calculating the emission footprint of the northern cattle industry and also for Australia's greenhouse gas accounts. "Methods used to determine these national greenhouse gas accounts are regularly reviewed and if the new data are confirmed via this review process, future accounts will be adjusted to reflect the lower emissions for the northern beef herd," Dr Charmley said.

With about half of the nation's beef herd located in northern Australia, current greenhouse gas accounts indicate that methane from the northern cattle industry contributes about 4.5 per cent of Australia's greenhouse gas emissions. As a by-product of digesting plants, ruminant livestock such as sheep and cattle produce methane and, of those, beef cattle produce the most - about 200 grams a day, or about 1.5 tonnes of CO2 equivalents per animal every year."

CSIRO research also shows that northern cattle fed on a diet of predominantly Leucaena, a legume tree, emit less methane than cattle grazing on tropical grasses," Dr Charmley said. "What this nutrition research is showing is that there can be win-win scenarios for the industry and the environment if we can redirect the breakdown of plant material in a way that reduces the amount of methane produced while improving the amount of energy or weight gain that animals get from their feed. "We are addressing cattle methane emissions from several angles - from examining the gut microbes that produce methane from ingested pasture and alternative diets, to a landscape focus on northern Australia's extensive grazing systems using state-of-the-art technologies, such as lasers and wireless sensor networks, to measure and model cattle methane emissions under tropical conditions."

The Lansdown Research Station is a key part of CSIRO's broader research programs on livestock production and emissions reduction in agriculture.

Lansdown Research Station is funded by the Australian Government's Climate Change Research Program, Meat & Livestock Australia and CSIRO and is one of five national research hubs and demonstration sites for practical methane management on-farm.

While this CSIRO press release is encouraging news for the northern beef producers, it is still to be verified in other research.

It seems to also confirm that using higher digestibility forages - in this case leucaena, a legume, it is possible to further lower methane emissions. This is similar to broad results from research work in temperate regions on dairy cows where lowered methane emissions were also corelated strongly with use of higher quality [ digestibility] feed.

There has been a trend in the past 20 years to push for more grass in beef pastures as compared to earlier periods of northern development when pasture legumes were seen as more important - then related to higher protein levels in the diet. Unfortunately, most grass now eaten by stock is on the dry side, with quite low digestibility, especially in more extensive pastoral regions. Changing digestibility can be done through plant breeding, but that is unlikely to happen any time soon. Tropical grasses also tend to be of lower digestibility intrinsically than temperate pasture species.

Leucaena is a viable option in many areas, although getting pasture areas established is time consuming and costly. It does have well proven performance in growing and finishing stock across many regions of north Australia. Superb results were achieved about 25 years ago in the Ord Valley at kununurra, but not too many producers are using the system - why would you, when live export has been the normal practice and there is little bonus for good quality finished cattle, with high carcase quality, in the north of Australia.

Lowered estimated methane emissions might quell some of the wild statements made about how awful the beef herd is environmentally though!

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