It is important to not under- or over-feed heifer calves from weaning until breeding as yearlings. Not only should they have reached puberty and be fertile before their first breeding starts, but they should not be overly fat because this can negatively influence fertility; calving ease (if they remain fat all the way through pregnancy); and a variety of other important production traits.
First, let's talk about under-feeding. Based on substantial research from the 1970s and '80s, the recommendation was established that yearling heifers should reach 65% of mature weight by the start of their first breeding season. This weight target increased the probability that most of the heifers would reach puberty by breeding. That has been a highly adopted goal in the beef cattle industry.
However, times and circumstances change, and it appears that we can lower this target. Research has shown that it can easily be lowered to 60%, and some evidence even suggests that it could be lowered to 50% of mature body weight.
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