Adjusted Weights

AMERICAN ANGUS ASSOCIATION - THE BUSINESS BREED

There are numerous environmental factors that can influence the weight of a calf, including age of the calf and the age of the calf’s dam. Ensuring the environmental contributions are accounted for allows for more accurate comparisons within a contemporary group.

Birth, weaning, and yearling weights are adjusted by the Association.

Adjusted 205-day Weaning Weights

For genetic evaluation and contemporary group ratios, weaning weights are standardized to a calf age of 205 days and a mature dam equivalent. Breed-specific nonlinear equations are used to adjust calf weights to a common age.

This allows fair, age-equivalent comparisons among calves weaned between 120-280 days. The lower minimum acceptable weaning age of 120 days provides flexibility to breeders in weaning dates, along with allowing younger calves to remain in their respective contemporary groups for National Cattle Evaluation.

Weaning Age of Dam Adjustment Chart
If age of dam (at 205) is:	Add lbs to age adjusted weaning weight
	Male	Female
Thru 2 years 243 days	68	57
2 years 244 days thru 3 years 91 days	67	55
3 years 92 days thru 3 years 273 days	37	32
3 years 274 days thru 4 years 91 days	29	21
4 years 92 days thru 5 years 91 days	15	12
5 years 92 days thru 10 years 91 days	0	0
10 years 92 days and older	22	19

Adjusted 365-day Yearling Weight

Adjusted 365-day weights are computed to adjust an actual yearling weight taken by the breeder to a standard animal age (365-day, typically) and age of dam (this adjustment takes place through the 205-day weaning weight). Acceptable calf ages for yearling measures are 320-440 days of age.

The suggested period between weaning and yearling weight is 160 days. A common mistake is that the two weights are taken too closely together. Although the window of acceptable weaning weight ages is 120 to 280, and yearling weight age 320 to 440 days of age, it is best to allow for more postweaning gain growth time to better characterize the trait.

= ((actual yearling wt − actual weaning wt) ÷ (No. of days between measure ages)) × 160 + 205-day adj. weaning wt

Example:

Actual yearling weight 1085 lb. (measured at 363 days of age)
Actual weaning weight 660 lb. (measured at 209 days of age)
205-day weaning weight 731 lb.

Adjusted 365-day Yearling Weight	= ((1085 − 660) ÷ (363-209)) × 160 + 731
	= (425÷154) × 160 + 731
	= (2.759) × 160+731
	= 441.55 + 731
	= 1,173 lb.

Considerations

Weight per Day of Age (WDA): Weight per day of age (WDA) calculations can provide a source of confusion. In contrast to the 365-day yearling weight, the WDA is calculated as follows:

WDA = Actual weight ÷ days of age

In the above example using weaning weight as the actual weight taken, WDA= 660/209 = 3.16 lb per day of age.

AMERICAN ANGUS ASSOCIATION - THE BUSINESS BREED