Adult equivalent

Adult equivalents in Breedcow+

Another key concept underpinning Breedcow+analyses is that of adult equivalents. The calculation of the total adult equivalents for each modelled herd structure indicates the relative grazing pressure exerted by the herd structure and, if herds have similar total adult equivalents, a meaningful comparison of relative profitability can be made.

The main calculation of adult equivalents is based on the total number of cattle carried for the whole year in all classes. The number carried is calculated as the opening number plus purchases less sales less spays. Cattle recorded as sold or spayed are no longer in the “number carried” and have an adult equivalent rating attributed to them separately.

What are adult equivalents? Most planning in grazing livestock enterprises requires that track be kept of how much feed is used or at least of the “stocking rate”. Thus the comparison of herd structures, turnoff strategies or gross margins is undertaken whilst observing self-imposed limits on how much stock the property can carry.

An immediate problem encountered in herd modelling is that all cattle are not the same size and do not eat the same amount of feed, e.g. weaners eat less than bullocks. Likewise a herd of 2,000 cattle comprising breeders turning off weaners will most likely not eat the same amount as a herd of 2,000 comprising fewer cows but turning off older steers.

To ensure that herds are compared on the basis of consuming the same amount of feed when making predictions of relative profitability, feed requirements are estimated for each class of cattle relative to an adult equivalent.

For the Breedcowplus program an adult equivalent is taken as a non-pregnant, non-lactating beast of average weight 455 kilograms (1,000 lbs) carried for 12 months.