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Enhanced 205-day weight adjustments

For genetic evaluation and contemporary group ratios, weaning weights are standardized to a calf age of 205 days and a mature dam equivalent. In the past, calves outside the range of 160 to 280 days of age were excluded from American Angus Association National Cattle Evaluation procedures. As a result, the calves weaned earlier than 160 days did not receive 205-day weights or contribute to genetic predictions.

Use of these records for genetic prediction requires a new approach to the traditional 205-day weight. The traditional 205-day age adjustment tended to overestimate the adjusted weights on younger calves and underestimate the values on older calves. To improve this process, breed-specific nonlinear equations were developed to adjust calf weights to a common age. This allows fair, age-equivalent comparisons among calves weaned between 120-280 days. This new adjustment formula is applied to weaning weights processed after June 8, 2003.

The enhanced 205-day adjustment procedure permits acceptance of data into the genetic evaluation that had been previously excluded by the calf age window. Lowering the minimum acceptable weaning age to 120 days provides breeders flexibility in weaning dates, along with allowing younger calves to remain in their respective contemporary groups for National Cattle Evaluation.

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