Our birth weights ranged from 64 to 109 pounds from a bull with CE of 15, BW of -1.2 and $CEZ of 50.33. Another bull with CE of 5, BW of +5.1 and $CEZ of 15.21 had birth weights between 76 and 122. Four were CE = 3 with one of those a mal-presentation (76 pounds). Two ET calves were born from first calf heifers, who calved at a week under two years of age, at 92 and 105 pounds. The 92 pound calf took less than an hour from start to finish. The 105 pound calf required assistance mostly because the heifer did not get serious about her job. The delivery was not that difficult. Their sire had CE of 7, BW of +3.4 and $CEZ of 19.03.
As far as the weight tape, if you are using the fetlock tape on newborns, it is plus or minus 7 pounds for bull calves and plus or minus 6.4 pounds for heifer calves. That is too much variation in my opinion. Another area that impacts calving ease is heifers with their first calves at older than 30 months. As the heifer ages the ligaments around the pelvis become less elastic and will not expand readily during the birth process. Finally, mal-presentations are heritable. I don't know at what percentage but those genetics need to be removed as well. That cow that had the light weight CE3 calf, was an idiot and her calf got his mother's mental capacity. The calf has to be smart enough to get in proper position for birth.
As far as the weight tape, if you are using the fetlock tape on newborns, it is plus or minus 7 pounds for bull calves and plus or minus 6.4 pounds for heifer calves. That is too much variation in my opinion. Another area that impacts calving ease is heifers with their first calves at older than 30 months. As the heifer ages the ligaments around the pelvis become less elastic and will not expand readily during the birth process. Finally, mal-presentations are heritable. I don't know at what percentage but those genetics need to be removed as well. That cow that had the light weight CE3 calf, was an idiot and her calf got his mother's mental capacity. The calf has to be smart enough to get in proper position for birth.
