IN THIS ISSUE...

• Bianchi Charolais

• Left-wing Wing-nuts

• Rebreeding Two Year Olds

• Times of Change

• World According To Hooter

Young cows need a higher plane of nutrition than mature cows. Only after a heifer meets her potential for milk production and body requirements for maintenance and growth will she channel energy into reproduction. Reproduction is a luxury that only occurs when all other body needs are met. The 2 year old year is difficult because this is the age she’s shedding her baby teeth and her permanent teeth are coming in. She may not be eating as well as normal, due to mouth discomfort. If she is lactating she’ll rob body fat to keep up her milk production. A young cow losing weight will generally not come into heat.

One Producer’s Tactics to Keep Young Cows in the Herd
Greg Shaw (Shaw Cattle Company, purebred Hereford breeders near Caldwell, Idaho) says their program includes heavy reliance on AI. “We breed our heifers to start calving 2 weeks before the cow herd to give them a little more time in which to rebreed. We have a fairly short breeding season. We synchronize and AI the whole group, then watch them for one more heat cycle to breed any that return. After that we put bulls in for 30 days. Basically our heifers have a 52 day breeding season. By doing this, all the heifers calve in the front half of our calving season and are well grouped,” says Shaw.

“Even before calving, our heifers are kept separate from the mature cows. We can manage their nutrition a little different,” he says. It’s also easier to keep track of and check on their calves, which sometimes need more attention health-wise than calves from mature cows.
“Young cows tend to get crowded away from the feed. They don’t compete with the older cows very well. So we keep the 2 year olds separate, clear through their first breeding season,” he says. They calve about 200 heifers in their spring herd, but after calving the pairs are put into small groups of about 50 each.

“They stay in groups of about 50, and it’s easier to manage them, checking calves, etc. For their next breeding season they are all synchronized again and AI’d and watched through their next heat cycle, then we put them with a bull. This has worked very well, and keeping them separate from the main cow herd has increased our conception rate on these young cows,” says Shaw. Body condition scores have stayed higher.

The heifers start calving about January 10 and the cows about January 20. The heifers are nearly done calving by the end of February and start being rebred about April 25. By that time there’s usually some green grass. “Sometimes we need to feed them just a little longer until the grass is well started,” says Shaw.

Winter feeding period is relatively short. Before they calve, the heifers are on grass until late fall. “We try to stockpile forage so they can stay on grass until about December 20. We may supplement them for the last month of grazing with some protein. When we do start feeding hay we give them stock-cow quality alfalfa. After they calve, we feed them grass hay for the first 30 days,” he explains. There are less health problems in the calves if the mamas are not milking too heavily when the calf is young.

“As calves get to be 30 days old we start putting the mamas on a better quality hay. They start milking a little more and are getting ready to breed. This has worked best for us. This keeps the heifer from milking so much that the calf gets sick.” Some people start feeding more quantity and quality as soon as the calves are born, and this often leads to problems. “We buy a lot of our hay, but grow our own grass hay and save it for right after they calve.”
As they calve, the heifers are moved into another groups. “As soon as there are 50 pairs in a pasture, we start a new group,” he explains. This helps with calf health, since the calves in each group are all about the same age. A herd can quickly have more sickness problems if you’re putting new calves in with older ones that may have already been sick—and the pasture more contaminated.

“We have a cut-off date and start a new group. That way if we do have a disease problem in the calves, it’s generally confined to one group and we might be able to keep it isolated in one group,” says Shaw.

After calves are 30 days old they stop feeding grass hay and switch to alfalfa and the young cows start cycling again by the breeding time. “We have a very good breed-back, better than in earlier years. The way we used to do it, we’d have the heifers calve separately but when we got ready to synchronize and AI, all the cows with certain age group of calves would be together, whether they were cows or first calvers. We had less luck with the breedback on heifers, and realized they were being crowded away from the feed too much. When we changed our management so we could keep them separate clear through their breeding season, we increased their conception rates by 10 to 15 percent. Now we have an excellent rate of conception even on their first AI cycle as 2 year olds. This has really paid off,” he says. After the heifers are bred they go to grass. A cleanup bull is put with them and stays with them for about 30 days.

“This past year we started keeping the 3 year olds with the 2 year olds. These young cows now stay 2 years in that group, separate from the adult cows. I think this will pay off, also. It seems like the 2 and 3 year olds can co-mingle and do well together; the 3 year olds don’t seem to crowd out the 2 year olds from the feed like mature cows do,” he says. The 3 year olds can also benefit from a little more care and management.

“You have so much money invested in young cows, getting them to this point, you hate to have them lose out just because they can’t quite compete with the older cows. They haven’t started returning your investment and you don’t want to lose them just because they needed a little better management to stay in the herd,” says Shaw.

“Once the 3 year olds’ calves are weaned, those cows go into the main herd,” he says. By the time they are 4 they can compete. Young cows are still growing until they are 3 or 4 years old, so this program helps optimize their potential. They are not fed any more or any longer than the older cows; keeping them separate just reduces competition so they can get their share.

“A tighter management on our heifers increases labor costs, but it gives the young cows a better chance,” says Shaw. He also tries to have a complete mineral program for them, since mineral deficiency can be a cause of reduced reproductive success.

“We are very critical about fertility, however. If they are open, they are sold. We don’t make any exceptions.” As a seedstock producer, he wants the cattle to function by the same rules a commercial rancher must have. “We don’t want to be breeding infertile cattle or any that need a lot of pampering, like grain. For registered cows, ours are run pretty much like commercial cattle; they are run in fairly large groups and go to summer grass in large groups, and have a fairly short breeding season. We try to run them as ‘real world’ as possible. This helps our customers get the kind of bulls that will work well for them in their own programs and sire the kind of daughters they need,” says Shaw.

Heifer Management Starts at Weaning
Getting 2 year olds rebred actually starts when you make the decision to keep them—feeding them properly through their first winter so they grow well without becoming fat. A heifer who reaches about 65 percent of her projected mature weight by first breeding season will have a good chance of breeding early, but body weight at that first breeding should be due to frame and growth, not fat. Yet she must have enough body condition for optimum fertility (body condition score on heifers should about 6). On a big framed heifer, be careful you don’t mistake frame (size) and weight for body condition. A large-framed heifer with below average body condition may not breed on time as a yearling, and will have a hard time rebreeding as a 2 year old. She may be a hard keeper and slow breeder all her life. Watch body condition after breeding, and make sure heifers stay at about BSC 6 through their second winter, before calving.

It’s easier to get/keep weight on a heifer BEFORE she calves (when nutritional requirements are not as high as when she starts producing milk) than to try to “pick her up” after she calves. If you rough a group of heifers through winter before they calve, it will take a lot of feed to try to make up for it after calving, and some never catch up.

Use of Heat Synchronization to Assist Rebreeding
Many producers who utilize AI also use some method of heat synchronization. This not only makes it easier to have the cows or heifers grouped for insemination (saving time and labor for doing AI) but also helps “jump start” the estrous cycle in some individuals that haven’t started cycling yet. The heat-inducing drugs won’t work for an animal that is not in adequate body condition to cycle (or has some other inherent problem that inhibits reproduction) but can be a useful aid for the majority of healthy heifers and cows.

One relatively new heat synchronizing tool, the CIDR (controlled internal drug release) works quite well on young cows that may have prolonged anestrus (lack of estrus). Cows with nursing calves may not come back into heat because of the physical demands of lactation, and this is especially true with 2 year olds suckling their first calves. Early research with the CIDR showed that 45 percent of non-cycling beef cows came into heat the first 3 days after removal of the CIDR insert and an injection of Lutalyze, compared to only 19 percent of the anestrus cows that returned to heat after treatment with just Lutalyze, and 11 percent in the control group (that returned to heat with no treatment). In some herds, as many as 80 percent of anestrus cows have been stimulated to cycle after use of the CIDR and Lutalyse. This protocol is becoming a good way to increase timely rebreeding rates on 2 year olds.
The CIDR insert is a T-shaped device that is placed into the vagina of the cow or heifer, where it steadily releases progesterone until it is removed 7 days later. It’s easy to insert. The T-shaped “wings” at one end can be pulled together so it becomes a straight rod—which can then be deposited into the vagina with a plastic applicator. On the end opposite the wings is a string that hangs out of the vulva so you can pull out the CIDR later. Many people cut the tails off, however, so that only a short portion protrudes, since curious herdmates (especially in a group of heifers) may sniff and chew on them, pulling them out prematurely. The nylon backbone of the device is covered with a silicon skin impregnated with progesterone—the hormone that keeps the animal from coming into heat.

CIDRs were used with good success in other countries for several years before they were approved for use in the US in 2002. Because of the high concentration of progesterone on the device, people using these should always wear protective gloves when handling them. Wearing clean gloves is also wise because you don’t want to introduce any contamination into the vagina of the females you’re working with.
The way the CIDR works is quite simple. It continually releases progesterone, keeping blood levels of this hormone very high in the cow/heifer during the 7 days it’s in the vagina. Upon removal of the insert (especially after an injection of Lutalyse on day 6) the sudden drop in progesterone triggers onset of estrus and ovulation. Some ranchers, to save time and handling of the cattle, give the Lutalyse injection on day 7, at the same time they are pulling out the CIDRs. This works almost as well as following the recommended protocol of giving the injection on day 6 and pulling the CIDR out on the following day.
The big advantage to using CIDRs in heifers is that it will often enable yearling heifers to be bred at a slightly younger age (so they can be calving ahead of the cow herd and have more time to recover from calving) and also helps stimulate them to come into heat on time after calving—overcoming the anestrus caused by lactation demand. If heifers and 2 year olds are healthy, with adequate body condition, this can be a very effective tool to get them bred and rebred on time, so they can stay in the herd.

Preventing Dystocia Can Shorten Breed-Back Interval
Heifers that calve quickly and easily are stressed much less than heifers experiencing a prolonged birth. The reproductive tract recovers more quickly and the heifer is able to return to heat on schedule. To ensure maximum chance for rebreeding, heifers should be bred to bulls that sire easy-born calves, and should also be watched and assisted at calving if assistance is needed. Some heifers may still have large calves (no matter what they are bred to) if they themselves were large at birth.

Studies in Montana in the 1980’s found that giving assistance (to speed up the birth) if a heifer hasn’t delivered her calf within 1 hour after the tips of the calf’s feet start to show at the vulva can make a big difference in breedback. For every 10 minutes the birth is delayed beyond that “golden hour”, another 2 days is generally added to the time it takes the heifer to recover and cycle. Another study showed that heifers experiencing prolonged birth were 35 percent more likely to be open at the end of the breeding season.

Some stockmen breed heifers a few weeks ahead of the cow herd, not only to give the heifers more time to recover from calving so they have a better chance of rebreeding on schedule, but also so they can devote all their attention to the heifers. If the rest of the herd has not yet begun calving, it’s easier to watch the heifers and assist them as needed.