Identifying feed supply throughout the year

The amount of forage available determines feed availability and stocking rates. Seasonal conditions govern regrowth, which also impacts the stocking rate and grazing period. A solid understanding of how long current forage will last is needed to make informed grazing management decisions. 

Estimates are made by calculating the amount of dry matter per hectare (kg DM/ha). This can be done by measuring forage directly or using the Photo standards tool (12.11). More photo standards can be found on the Feed On Offer website.  

Estimating the available feed of a pastoral property is no easy task due to scale and the variability in land and vegetation types. However, with practice and regular checking of estimates, accuracy will improve quite quickly. 

When estimating the amount of feed available, bear in mind the following factors: 

• Do not include feed stock will not eat (i.e. non-palatable plants). 
• Aim to leave 70% of the available feed to ensure the plants can grow again, rather than letting animals graze all of the plant/pasture. 
• Determine a realistic grazing radius from each water point to calculate the area grazed, as the distances sheep range depends on their water requirements. For example, lactating ewes won’t graze as far out from water as dry stock and high temperatures limit the grazing radius. 
• Consider how long the pasture will last. For example, is it made up of perennial grasses rather than annual forbs, which will shrivel up and blow away on the first hot day? 

Be mindful when making calculations that the total dry matter present in a paddock is not all made available to sheep. In the pastoral areas, a conservative utilisation rate of dry matter is adopted to ensure there is sufficient biomass remaining after grazing. This is often set at 20–30%. 

This residual biomass is useful for ensuring adequate groundcover remains to: 

• protect soils from wind and water erosion. 
• allow water to infiltrate when rain falls, which facilitates rapid pasture growth in response to rainfall received. 
• ensure efficient nutrient cycling — adequate soil cover means more soil water and nutrients available for pasture growth.