Bob Weaber Replacement Heifers

(Bob) Extension Specialist at K-State in Manhattan. And recently participated in our Winter Ranch Management Series. And presented some information concerning some of the genetic aspects we’d like producers to think about as they build and mate replacement heifers. One of the things that’s really important obviously in producing heifers is making breeding decisions that minimize the potential for dystocia or calving difficulty as those heifers become cows. And a couple of things that we want producers to think about are some of the selection tools that are available relating to calving and those two EPD’s are expected prodigy differences are calving ease direct and maternal calving ease or calving ease maternal. And those two different EPD’s have different sort of application points in our selection decisions. We encourage producers to think about calving ease direct and calving ease maternal when they are picking bulls to be the sires of replacement heifers. So, which bulls they’re gonna have replacement heifers out of in their production system. And it’s important to keep both of those EPD’s in mind because they have a negative genetic relationship relationship between them. So if we only select for increased calving needs direct performance or the ability of a sire’s calves to be born directly or a dame’s calves to be born directly. Over time we’ll actually decrease some of the maternal aspects of calving ease performance. So, that’s why it’s important to keep calving ease maternal as part of our selection criteria in selecting those bulls. Calving ease maternal then is the ability of a sire’s daughters to calve or their calving performance. It’s the maternal aspects. It’s kind of like the relationship between weaning weight EPD and milk EPD. Both result in calf performance, but one’s a maternal aspect and the other one’s a direct calf aspect. The other things we’d like producers to think about in making those calving ease decisions is we have the Sunflower Supreme Heifer Program has established criteria for calving ease direct and recommendations for maternal calving ease for the sires of potential replacement heifers. And those EPD’s get updated annually and will be again released here in late January. And typically those percentile ranks represent bulls that are typically somewhere in the top third to top quarter of each respective breed for calving ease performance. That helps us assure that the products that we produce in replacement females that go out into the market have adequate calving ease genetics. As we think about selecting replacement females, choosing heifers that are born early in their calving season have been shown to have better chance and better likelihood of sustained reproductive success because they have a tendency to also calve early in their subsequent calving season. So picking heifers that are born early so they’re chronologically the oldest heifers in your replacement heifer pen. They’ll have a tendency to be more reproductively successful over time. And the value of that is that heifers if you choose one that is born late in the calving season and she ends up breeding late in her calving season, or breeding season as a replacement heifer subsequently calves late, she only has maybe one or two opportunities in a conventional breeding system, so there’s a high likelihood she won’t sustain her productivity beyond a year or two as a mature cow. Another part of the genetics of replacement heifers we encourage people to think about is the value of producing and keeping cross bred heifers. We know from a extensive research, that cross bred females have longer productive lives. They exhibit what’s called maternal heterosis and that has a positive impact on a ranch’s bottom line through increasing the longevity and reproductive efficiency of those cows over their lifetime. Current numbers indicate the value of that heterosis or hybrid vigor from a maternal aspect in the production is worth somewhere between $200 and $250 dollars per cow per year. So it has a real economic consequence value in our production system.

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