Remember everyone.... birth weight is not the only factor to consider when selecting a bull to use on heifers. I have witnessed c-sections done on heifers who had 78 lb Red Angus calves, and my vet says he has seen many of them.The calves were wide skulled and shouldered, and impossible for the heifer to calve by herself. ( I am not bashing the Red Angus breed, as there are many outstanding R Angus sires. My experience with R Angus sired calves is very limited, but I had three calves, a couple of years ago, that were from a well known RAngus sire, and they were all over 110 lb. ) Birth weight is one factor to consider, however, it is only one. The other thing to remember is that selection for low birth weight for generations, will lead to females with smaller pelvic measurements. I am not opposed to low BW bulls, in fact I am in constant search for one that has a low BW without sacrificing performance. I just think we have to know what we want as an end product ...and be a little careful what we wish for.
There appears to be some differences between breeds when it comes to birth weight and performance. Where we hold our bull test for our Shorthorn bulls, there is also an Angus bull test , so it has been interesting to watch the two breeds develop. As I have mentioned here several times before, we have never had a Shorthorn bull in the bottom 50% of BW end the test in the top 50% ( ie: index over 100) for growth. That is in two years of tests and 120 bulls. This leads me to think that where we want and need to be is somewhere in the middle.... or optimum BW and optimum growth. In the Angus test, the same trend is seen, however, it is not as significant as in the Shorthorn pen. This is probably due to breed differences, along with generations of selection on a much larger gene pool.
EXACTLY!
