# Average daily gain

Average daily gain (ADG) is a measurement of the average daily body weight change of an animal over a specified period of time. Average daily gain is calculated as follows: ADG (average daily gain) = (Final weight – Initial weight) / Days on test

It can also be expressed as a ratio as follows: ADGR (average daily gain ratio) = (ADG / Breed-test group average ADG) x 100

Initial and final weight data can be obtained as combinations of weights from specific testing periods (such as from feed intake tests), or from combinations of birth, weaning, yearling, mature, or harvest weights.

## Genetic evaluation

Several organizations publish EPDs for average daily gain. In all cases in North America, this is the average daily gain prediction for the period from weaning to yearling. It is simply calculated as,

${\displaystyle ADG={\frac {Yearling\,Wt\,EPD-Weaning\,Wt\,EPD}{160days}}}$

It is important to note that in many North American genetic evaluations, including those of private organizations, the yearling weight EPD is calculated from a multiple-trait analysis that includes models for weaning weight and post-weaning 160-day gain. While not published as post-weaning gain EPDs, the few organizations that publish ADG EPDs produce them using the post-weaning 160-day gain EPDs from this multiple-trait analysis.