Tuesday, February 20, 2018

‘Secrets’ about birth weight and weaning weight

Calving ease equals sleep and money at this time of the year. There are extensive studies that quantify the negative impact of calving difficulties (on the calf, the cow, and the producer). So, we select for genetics that we think will ensure peaceful slumber and easy calving. 

Traditionally, producers have done this by choosing to use low birth weight bulls, thinking that low birth weight mean high calving ease. The two traits are associated but they are not the same. The estimated genetic correlation between birth weight and calving ease is -0.65. So, low birth weight contributes to calving ease, but it is not the complete answer. After a certain threshold, low birth weight is also correlated with calf mortality and morbidity. 

The other trait that birth weight is correlated with is weaning weight. The estimated genetic correlation between birth weight and weaning weight is 0.29. This means selection for lower birth weight results in lower weaning weight. The same is true for yearling weight. Animals with the genetic potential for low birth weight will also have the genetic potential for low performance at every other stage in its life. Its genetic potential for growth is correlated from birth to weaning to yearling and through to mature weight. 

Canadian Angus members often tell me that the only performance information bull buyers ask for is birth weights. Let’s start talking about the traits that they really want, what really makes them money – calving ease and weaning weight. If you need some ‘talking points’, an explanation of traits or EPDs, or anything else for your bull sale catalogue, please don’t hesitate to contact your Angus Association. We have created several ¼ page inserts for your sale catalogues. These are a great way to share information with your bull customers.

The key to profitability for cattle producers is a live calf that grows well. We wish you the best through this calving season and bull sale season.