Birth Weight Update for the Approaching Calving Season

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Birth Weight Update for the Approaching Calving Season

By Jackie Atkins, Ph.D.

Research study finds hoof tape correlates highly to scale weights but exhibits less variation.

There has long been a stigma against using hoof circumference for estimating birth weight; however, there are pragmatic reasons why hoof tape is a sound alternative. Collecting scale weights at birth can be difficult for breeders due to labor constraints. It is known that some breeders are using hoof tape to estimate birth weight. Recently, IGS and consulting scientists, Drs. Bruce Golden and Matt Spangler, delved into a number of potential improvements to the genetic evaluation of growth traits including how to handle hoof tape records as a measure of birth weight in genetic evaluation.

Dr. Golden started looking at large numbers of records from herds known to use hoof tape or known to use scale weights. Golden used over 7,000 hoof tape records and 15,000 scale weight records and found hoof tape and scale weights have a high genetic correlation (0.92). As expected, hoof tape estimates for birth weight had less variation in the records resulting in hoof tape measurements with fewer extremely light or heavy birth weight estimates compared to scale weights (see graph).

What does this mean for seedstock breeders? Scale weights remain a gold standard for birth weight measurements. However, hoof tape measurements look like a very reasonable alternative. The Beef Improvement Federation recently came out with the following statement. “BIF recommends that organizations responsible for recording performance data require breeders who use a hoof tape to record birth weight to indicate that they have done so.”

Remember, with both measurements, the economically relevant trait is Calving Ease. The genetic correlation between hoof tape measurements and calving ease is not yet known but given the high correlation to scale weights, it is likely to be similar to the correlation between birth weight and calving ease.

As a reminder, for ALL phenotypic records, if animal measurements are missed for any reason, it is far better to leave the records blank than to fill in the blanks with guesses.  Inaccurate records introduce noise to the genetic prediction that reduces the ability to assess the genetic merit of these and related animals.       Stay tuned for more updates on other improvements in the growth traits predictions in the IGS Multi-breed Genetic Evaluation.

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