AI advances in the beef industry: improved conception rates
The earliest documented use of artificial insemination was in 1780 when an Italian physiologist produced puppies using this method, but it wasn’t until about 1900 that extensive studies with farm animals began in Russia.
By 1938, AI was being done in the U.S. in dairy herds, with extended and cooled liquid semen, packaged in glass ampoules (vials).
Carl Rugg, owner of Bovine Elite, LLC, said when he first became interested in AI, the process was performed by large animal veterinarians, who serviced the cattle herds in their area, and then later by specialized AI technicians who were employees of AI cooperatives.
“The semen distributor would bring the veterinarian semen from three or four bulls, and in those early years it was mainly dairy bulls. The semen would be collected, extended with a media to extend the life of the semen sample, placed in sealed glass ampules and kept cold in an ice bath. The extended semen would be drawn up into a plastic pipette to breed the cow. The fresh cooled semen would last two to five days, depending on the quality of the semen and the fertility of the bull,” he said.
“When I was a boy in western New York, my father had Holstein dairy cows, and started using AI on his dairy cows in the late 1950s. The veterinarian or technician would come to our farm in his truck and discuss with dad the merits of the bulls he had available that day. My dad would select a bull, the technician would retrieve the ampule of semen from the ice water bath and go breed the cow,” Rugg said.
“Dad never had a bull on the place. Conception rates were high with the cooled fresh semen. In those early days with fresh semen, pregnancy rate was well above 70% in our herd. Dad always had our cows in proper condition for best reproductive efficiency. The biggest issue was catching the cow in heat at the right time. My dad would observe the cows morning and evening for signs of estrus and put a chalk mark on the one to be bred. Even if we weren’t there when the technician came, the cow would be in a stall and he’d know which one to breed. I had my own set of 4-H dairy heifers and always studied the bulls when it came time to AI those heifers for their first calf.”
A lot of progress has been made in reproductive and semen technology since those early days. The advent of frozen semen revolutionized the AI industry. Importations of some European breeds were only possible by using frozen semen and AI, due to restrictions on importing live animals.
Rugg received his master’s degree in reproductive physiology from Colorado State University in Fort Collins. “This was about the time we moved to the next phase of AI in cattle, packaging and freezing the semen in French straws. We continue to use this technique and packaging method, which allows the semen to freeze and thaw with higher recovery and ultimately a better conception rate with frozen semen. This was a significant improvement over the process of freezing and storing semen in glass ampules.”
Conception rates with frozen semen have improved even more in recent decades. Being able to ultrasound the cow’s ovaries and determine the time of ovulation has helped researchers figure out the best time to inseminate cattle. This has enabled the AI industry to obtain even better conception rates. Today the AI process is easier with use of synchronization protocols. All the cows in the herd can be bred on the same day instead of having to watch them for signs of heat during the breeding season. Many ranchers today use AI for their heifers, using a sire selected for calving ease. Some like to synchronize and breed the heifers about three weeks before the cows are bred. This gives the heifers more time to rebreed after calving. Some ranchers like to keep replacement heifers from those first-calf heifers. Those calves will have the most modern genetics, and if they were born easily, they tend to be easy calvers themselves when they become cows. During the past 20 years the biggest breakthrough has been development of more effective synchronization protocols, making AI much easier. All the cows can be bred on the same day instead of having to watch for signs of heat. Conception rates have also improved.
USE OF HEAT SYNCHRONIZATION
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 heat-synchronizing tool, the CIDR (controlled internal drug release) works well on young cows that may have prolonged anestrus (lack of estrus). Cows 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% of non-cycling cows came into heat the first three days after removal of the CIDR insert and an injection of Lutalyze, compared to only 19% of anestrus cows that returned to heat after treatment with just Lutalyze, and 11% in the control group (that returned to heat with no treatment). In some herds, as many as 80% of anestrus cows have been stimulated to cycle after use of the CIDR and Lutalyse. This protocol is a good way to increase timely rebreeding rates on 2-year-olds.
The CIDR insert is a T-shaped device. It is placed into the vagina of the cow or heifer, where it steadily releases progesterone until it is removed seven 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. 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.
Because of the high concentration of progesterone on the device, people using these should wear protective gloves when handling them. Wearing clean gloves also prevents introducing contamination into the vagina of the females you’re working with. The way the CIDR works is simple. It continually releases progesterone, keeping blood levels of this hormone very high during the seven days it’s in the vagina. Upon removal of the insert (especially after an injection of Lutalyse on day six, 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 seven, 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 six 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 an effective tool to get them bred and rebred on time, so they can stay in the herd.
Willie Altenburg, a cattleman in Colorado who runs registered Simmental and Angus cattle and works for Select Sires said heat synchronization has worked very well for heifers for many years but was more difficult in cows. “Invention of the CIDR and use of prostaglandin really helped us in that area, and now we are doing a lot more cow AI,” he said.
It can be a challenge to breed several hundred cows in one day, however. “The AI organizations now have portable breeding barns and technicians who can come do this chute-side service for the whole operation, and get those cows all bred in a few hours,” Altenburg said. It’s more economically feasible for cattlemen to use AI now. In some parts of the country there are many grain farmers who also run cattle, and the time of year for AI is the same time they need to be in the fields.
Conception/pregnancy rates are as good now with timed AI as they are with heat-checking and breeding. This has made AI more appealing to producers who are concerned about labor.
And getting heifers to calve early in the season more than pays for the AI with the added weaning weights of their calves. Improved genetics is a plus, calving ease is a plus, but if those calves are 10 days older they are 20 pounds heavier, which also gives heifers’ calves a chance to fit more uniformly with the mature cows’ calves.
Heifers are very easy to AI because you don’t have to sort calves off. Most AI technicians can go to a ranch, with just a cowboy or two to push cattle through the chute, and do 200-300 heifers before lunch.
“Our goal is to have six out of every 10 animals that leave the breeding shed be pregnant on the first day of the breeding season,” Altenburg said. “That gets breeders’ attention. When you say 60% pregnancy rate that doesn’t sound very good, but when you say this another way — that six out of every 10 females are pregnant on the first day of breeding season — this makes a difference, especially in terms of your needed bull power, with bulls costing $3,000 to $10,000 apiece,” Altenburg said.
At an AI school at Fort Collins a few years ago, the cost of using AI versus buying bulls was discussed. “The cost per pregnancy for a bull — figuring in the fences that he wrecked and the feed he ate — if you used him for 3.5 years and he gave you 25 calves per year, was $74 per calf. “Then we figured the AI side, with fixed time insemination, breeding the cows, and cleanup bulls, and came up with $62 per calf,” Altenburg said. ❖
— Smith Thomas is a cattle rancher, horseman, freelance writer and book author, ranching with her husband near Salmon, Idaho. She can be reached at firstname.lastname@example.org.
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