From the Gate Post
Bruce Holmquist General Manager - Canadian Simmental Association
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What is an Optimal Birth Weight?
he 2017 bull sale season is quickly approaching, and with it comes the onslaught of bull sale catalogues that are delivered to us daily. In those catalogues there is often a large amount of information that will assist producers in selecting that new herd-bull including pictures, pedigree, birth information; EPDs in many cases, and occasionally carcass data. Of this information, birthweight is often the first number that is considered and in recent years has become a focus for some producers who believe that it is an assurance of calving ease and that lower is better. For some producers it has even taken precedent over performance, specifically weaning weight. The belief that a lower birthweight is the simplest way to ensure calving ease has caused some producers to ignore some very good bulls with slightly larger birthweights. These bulls will most likely calve just fine on mature cows and will add additional performance to their calves with heavier sale weights in the fall. That means dollars in a producer’s pocket and was especially evident during the fall 2016 calf run where lighter calves were often several hundred dollars lower than the price per head received for heavier calves. The American Angus Association recently held their Annual Convention and one of the featured speakers was Dr. Dan Shike, who is an animal scientist at the University of Illinois. During his presentation Dr. Shike stated that in his opinion, there is no “one size fits all” in the cattle business. That phrase applies to many things including calving ease and birth weight. As many of us have learned, cow size and body condition, along with calf shape and presentation of the calf, all figure into calving season success. What works for some producers may not work for others. To gauge what breeders at the convention thought was ideal for birthweight, Dr. Shike polled those in the room with approximately half of the attendees answering a series of questions via text message. One question was; what birth weight do you consider excessive for cows? The majority, fifty-six percent, indicated greater than 90 pounds, while thirty-three percent said greater than 100 pounds, and six percent said more than one hundred
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and ten pounds. Only six percent indicated that they felt that greater than 80 pounds was excessive until the question changed to what the attendees felt was the maximum birth weight acceptable to their commercial customers. Then, twenty-nine percent of the crowd said that greater than 80 pounds was too big, indicating that selection pressure can be based on customer preference. Fifty-three percent, the majority, still said greater than 90 pounds. Another question was, what is too small of a birthweight and can we make it too small? The answer to this was a range from 40 pounds to 70 pounds being too light, with about half of respondents saying that less than 50 pounds was most definitely too light. Dr. Shike summed his presentation up by stating, that he was not sure that all producers need to target the same degree of calving ease, noting many herds have generations stacked with a high degree of maternal calving ease. The take-home message for breeders was that if environmental factors are favorable and there aren’t already calving problems, they probably don’t need to focus on double-digit EPD calving-ease bulls; and should also focus on other variables that affect calving ease, not solely targeting birth weight and to not keep driving birth weight down. Many of us who have been around this business for some time remember the old adage that a cow should be able to give birth to a calf that is six to seven percent of her body weight. Therefore, a 1450 pound cow should be able to deliver a hundred pound calf unassisted. If you are using 75 to 80 pound birthweight bulls on mature cows of that size you are likely not realizing the true production potential that cow can provide. While some producers may purchase several bulls each year, there are others who may only go through that process every three to four years. In each scenario, buying a new herd-sire is one of the most important decision making processes that a cattle producer undertakes. If you are in the market for bulls this year be sure to factor in all the variables and don’t overlook a bull that may suit your program simply because he might have been a couple of pounds heavier than what you feel is your ideal birthweight.