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ANIMAL HEALTH AND RESEARCH
The hidden losses of pasture utilisation
Pastures underpin the competitive advantage of Australian key livestock production systems like beef, sheep and dairy. Are farmers getting the most from them?
By Professor Sergio (Yani) Garcia
and water are the most important drivers of pasture growth. In fact, water alone explains most of the above-mentioned difference between yield of dryland and irrigated dairy pastures. Managing these key inputs (water obviously more limited for extensive systems), puts the farmer in the driver seat for increasing pasture growth and utilisation -and from this, profitability. But growing more is not the whole story. For a given level of inputs and potential growth, a large part of that potential can be lost, either by not growing it in the first place; or by growing it and not utilising it properly. Or worse, both! An example of missing growth potential is in overgrazing or ‘grazing too hard’. On perennial ryegrass pastures we have measured a reduction of 25 per cent in the rate of pasture regrowth when the residual pasture cover (biomass above the ground) was less than 1,500-1,300 kilograms of dry matter per hectare (measured to the ground level). Many farmers like to graze a lot harder (i.e. leave lower residual) than that! The result of this is simply a much slower regrowth: the lower the residual the
I have always been intrigued about the gap between potential and actual pasture productivity of Australian livestock systems. I will use dairy as example, but the principles behind pasture utilisation are the same for beef, sheep, or other livestock production systems. In pasture-based dairying, the average amount of pasture converted into milk (i.e., pasture utilisation) is only about 6 to 7 tonnes of dry matter per hectare and per year. Yet, the potential shown by our previous research (www.futuredairy.com.au) was consistently greater than 12 (dryland) and over 20 (irrigation) tonnes of dry matter per hectare and per year with adequate pasture monitoring and management. Why? Where is the gap? The answer is not difficult to understand; it is just difficult to find on farm! The gap is what we call the ‘hidden losses’ of pasture utilisation: neither the pasture that wasn’t grown due to nutrients or water limitations, nor the pasture what was lost (or not grown) due to inadequate grazing management, is readily detectable in practice. Logically, key nutrients (particularly nitrogen)
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