April 7, 2016
Over 25 years ago, I moved to Nebraska as the general manager of the Rex Ranch. I had a lot of experience calving large groups of first-calf heifers, so until the ranch became bigger and had several units, it was only natural for me to work with one other person to calve, feed and care for the heifers and their calves.
Even though we were calving groups as large as 500 head, my co-worker did most of the feeding and cattle care. I helped with sorting heavies into the calving pasture, pairing out and periodic checking for calving problems. We split the night checking in the middle of the night so that we could overlap each other in the daytime for the few jobs that required two people
The first year, we didn’t have many heifers, so the calving difficulty didn’t seem so oppressive. However, the percentage of assisted births was far too high—though that was too long ago for me to remember the exact numbers. We were trying to grow rapidly so the next year we calved a lot of heifers. This time we didn’t have to check the numbers to recognize that we were pulling too many calves.
I don’t remember if I helped calve for a third year, but about that time, we started having some senior veterinary students come to the ranch for obstetrical rotations during our heifer calving. I stayed close to the heifer calving for a number of years.
Because of the problems, we started to AI as many heifers as we could with one cycle of synchronized AI. We then followed up with cleanup bulls for about 45 days (I hadn’t yet gotten smart—remember 21-30 days is plenty). We used a bull well known for calving ease.
Many of the calves born before due date, and well over half were, came with no problem. However, calves continued to be born, from the same sire, for another 7-10 days. Guess what? The picture changed. Each successive day we pulled a higher percentage of the calves born that day. We used the same sire on enough large groups to be sure of the pattern.
With this much experience and information, we started to ask some questions:
How can calves from the same bull have so much difference in gestation length?
Were our heifers too small at calving? You know I favor minimal development of replacement heifers.
Can we find a better calving ease bull with perhaps less variation in gestation length? What are the genetics for that?
What happens when you use a calving ease bull on first-calf heifers, but the cowherd has been bred to bulls for growth with much less, if any, attention paid to calving ease or birth weight? So what if the heifer you are now assisting was born to a cow that was born to a cow and so on— do you see the pattern? If a heifer was born to a cow with no calving ease genetics, can we expect any bull to be a complete calving ease bull when the heifer provides half of the calf’s genetic makeup and the entire prenatal environment?
I’d like to tell you that we found quick answers to each of these questions and fixed the problem quickly. We didn’t--it was slow. In my 18 years there, we reduced dystocia in heifers by more than 50%. I wanted it to be faster, but we were not using Wagyu or Corriente bulls to get easy calving. We wanted a level of performance, along with calving ease, using the breeds that were in our composite. My successors have cut dystocia in half again, and now pasture calve some heifers day and night without a night check.
There are a few answers:
You can breed to Wagyu or Corriente bulls if you have a good market for the calves and you wish to let the heifers calve with little or no checking.
You can continue to “minimally” develop your heifers and get calving ease.
We moved the calving season from late February and March to April. My successors have moved it to May. They seem to calve easier in a later calving season.
We also shortened the heifer breeding season to 30 days. When the gestational due date arrived for the last day of the breeding season, we induced all remaining heifers to get heifer calving season over and to let the calf do its growing on the outside of the cow.
We began to cull every cow that had a calving problem and any heifer that required anything more than a little assist—no calf puller.
We raised your own bulls. A bull for heifers had to be born unassisted to a first calf heifer and come from a sire with appropriate calving EPDs. We also had an upper limit for that bull calf’s birthweight.
When buying bulls, don’t look at the individual birth weight. An EPD is far more predictive of the performance of offspring than individual weights. You can also ignore or pay little attention to the birth weight EPD. While birth weight EPDs are closely correlated with calving ease, it is calving ease that you want; so look closely at the “calving ease direct” and “calving ease maternal” EPDs and keep them in balance if you are raising your own replacement heifers. You want calves that can be born unassisted and heifers that can calve unassisted.
There may be some antagonism between “calving ease direct” and “calving ease maternal,” so you will want to ensure that you don’t focus on just one of those traits. Also, remember that your cows are the mothers of your replacement heifers. Therefore, you want to ensure a reasonable level of calving ease in the sires used in your mature cowherd so that heifers can calve unassisted.
When I was younger, I would tell people I was calving or we would hear the question, “Are you calving?” For far too long, we did way too much of the calving. I’m surely glad that I finally learned that we are not supposed to calve; the heifers are.
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