Setting replacement heifers up for reproductive success can hinge on a tricky balance of nutrition in the development phase between weaning and breeding.
At a workshop focusing on heifer selection and development at the University of Missouri’s Southwest Research Center last week, experts discussed how cow-calf producers should evaluate their current heifer development programs and set animals up for a productive lifetime in the cow herd.
Eric Bailey, MU Extension state beef nutrition specialist, encouraged producers to honestly assess their operations and capabilities to develop heifers. He suggested taking an inventory of resources including time, labor, facilities, equipment and the genetic merit of the cow herd and considering if they can raise heifers cheaper and more effectively than it would be to purchase them.
”One of the beautiful things of the Show-Me-Select heifer development program is it gives you the capability to tap into premier elite genetics from cow herds across the state and to really give yourself an opportunity to upgrade the genetic potential of your cows,” Bailey said.
For those who choose to develop their own replacement heifers, Bailey recommended breeding heifers between 13 and 15 months of age to calve at 22 to 24 months of age.
“Under most normal management systems, we’re going to have seven months from the time we wean that heifer off of her dam to when we are going to be inseminating her, whether that’s using artificial insemination or natural service, for the first time,” Bailey said.
This time period is essential to putting weight on heifers so they reach puberty and begin cycling, he explained, adding producers should consider getting heifers to gain weight efficiently in the context of on-farm profitability.
Getting heifers to size can be somewhat of a moving target, depending on the size of the animals and where they reach puberty, he continued. As an example, he explained a 500-pound heifer would need to gain about 300 pounds of weight in 200 days.
“On the surface, 300 pounds sounds like a lot and 200 days doesn’t sound like very much,” Bailey said, “but a pound-and-a-half average daily gain is our target.”
For backgrounders and feeders, 1.5-pound ADG isn’t overly optimistic but Bailey recommended cow-calf producers not used to growing cattle focus on balancing two critical components of the diet: energy and protein. He also stated there’s no one way of doing things and producers will need to find what works best for their management systems.
He recommended a diet that has about 65 percent total digestible nutrients and greater than 12.5 percent crude protein. “That’s what it’s going to take to get these animals to gain a pound and a half per day for seven months to get them to an acceptable breeding weight.”
He explained producers should feed heifers to a target weight of 55 to 65 percent of mature weight.
“Target weight is the most important concept I will tell you from a nutrition side of managing heifers from weaning to breeding that you could consider,” Bailey said, adding the concept has been studied for more than 40 years and researchers know heifers will begin to cycle at a certain target of their mature weight.
“There’s a really important piece of target weight that I don’t think we consider enough most of the time,” Bailey said, “and that’s the size of the mature herd.” A heifer with an expected mature size of 1,200 pounds would begin cycling at roughly 660 pounds, but ideally you would develop her to be in the 780-pound range, or 65 percent of her target weight, Bailey said. If developing heifers from a larger-sized cow herd base, those numbers would increase.
Bailey also acknowledged there will most likely be variation in a group of heifers. “Your target weight should be making sure the light end of your heifers that you’re developing are going to be in an adequate target weight before the breeding season begins, so feeding to these smaller heifers and making sure they’re caught up is pretty important,” he explained.
The nutritionist also discussed feeding strategies.
“The worst thing that you can do from a cyclicity standpoint is to send those heifers into a breeding season on a declining plane of nutrition,” Bailey said, adding feeding them hard early and then letting them coast into the breeding season will probably not be the most effective strategy.
“You’ve got to think about it in terms of the Missouri production system, a fescue-based forage system,” Bailey said. Fall-calving heifers to be bred in November and December will work well on stockpiled fescue because the forage quality is high. However, as stockpile diminishes, producers should consider maintaining feed quality as they switch to stored forages. Spring-calving heifers have the benefit of the spring flush of grass so producers may not have the same problems in running out of feed unless there is a drought or some other extreme situation.
“There’s no doubt in my mind that letting the heifers graze as much as possible — trying to get them to harvest the feed for you — that’s going to be the lowest cost path,” Bailey said.
However, a dry-lot development system has higher costs but nutrition can be managed more intensively to ensure heifers are fed to precise nutrient requirements, he pointed out.
In a perfect world, he said producers will have enough quality pasture available to heifers to meet the 65 percent TDN and 12.5 percent CP requirements — something that is possible on a fescue base with no supplement.
“The challenge will be that the quality of the forage out on pasture is changing,” Bailey said. “It’s very dynamic… There’s a lot of change there.”
If producers are going to use a hay-plus-supplement or pasture-plus-supplement feeding strategy, Bailey emphasized forage testing as these programs are less predictable.
“If you’re relying on the hay to provide a significant number of nutrients to those animals, you really need to have that hay tested and know what it is because there’s nothing going to sink your battleship faster than thinking you’ve got average quality grass that might test 55 to 58 percent TDN and it’s really poor quality that tests at 48 to 52 TDN,” he said. “That really changes the feeding management and plane of nutrition that those heifers are on.
“I can’t stress enough hay testing in this case. When you rely on these less predictable systems, forage quality and forage quantity are going to drive the success of those programs.”