I truely disagree with the late calvers coming up dry or late the following year. I keep track and totally untrue. The last 10% of calvers are NEVER the last in following year. Sometimes they are in the first 25% of calves on the ground. Perhaps your study groups don't have access to adequate nutrition. I am at a loss to where or why this has been a general concept in the beef cow calf operation. I have found more conisistent is that cows that have for whatever reason have lost calves and have calves fostered onto them... they will be the ones dry in the fall or late calvers the next year.
Michelle, thanks for sharing your experiences. This has become a generally accepted concept because of the published data. There is a strong association between date of calving and failure to conceive in the following breeding season, particularly when the length of the calving season is long in general. The slide referred to around the 13:00 of this video shows that relationship. That said, this is about averages rather than individuals. Certainly, some individual cows would (and do) “move up” in terms of their date of conception, and a portion of these later-calving cows will conceive earlier next year. We tend to remember those individuals. Importantly though, later-calving cows will not do this on the average. These cows will also wean younger and therefore lighter weight calves. That makes the fundamental return-on-investment projections for later-conceiving cows poorer than for keeping earlier conceiving cows. The argument presented here is that, when seeking to identify cows to cull, consideration should be given to when cows conceived during the breeding season because of their lower profit potential on average.
I truely disagree with the late calvers coming up dry or late the following year. I keep track and totally untrue. The last 10% of calvers are NEVER the last in following year. Sometimes they are in the first 25% of calves on the ground. Perhaps your study groups don't have access to adequate nutrition. I am at a loss to where or why this has been a general concept in the beef cow calf operation. I have found more conisistent is that cows that have for whatever reason have lost calves and have calves fostered onto them... they will be the ones dry in the fall or late calvers the next year.
Michelle, thanks for sharing your experiences. This has become a generally accepted concept because of the published data. There is a strong association between date of calving and failure to conceive in the following breeding season, particularly when the length of the calving season is long in general. The slide referred to around the 13:00 of this video shows that relationship. That said, this is about averages rather than individuals. Certainly, some individual cows would (and do) “move up” in terms of their date of conception, and a portion of these later-calving cows will conceive earlier next year. We tend to remember those individuals. Importantly though, later-calving cows will not do this on the average. These cows will also wean younger and therefore lighter weight calves. That makes the fundamental return-on-investment projections for later-conceiving cows poorer than for keeping earlier conceiving cows. The argument presented here is that, when seeking to identify cows to cull, consideration should be given to when cows conceived during the breeding season because of their lower profit potential on average.