Pasture Breeding: Nature at Work

Pasture Breeding: Nature at Work

Pasture breeding mares is something of a dying art in the equine industry. Yet this technique can bring with it benefits for breeders large and small.


Pasture breeding mares is something of a dying art in the equine industry. The closer control that can be exercised with hand breeding and the advent of artificial insemination (AI)--which has increased the number of mares which can be covered by a single stallion--has pushed pasture breeding to the back burner. Yet this technique can bring with it benefits for breeders large and small.

It is a technique that needs little explanation. A stallion is turned out with a band of mares and Nature takes its course. There are advantages and pitfalls to the approach, and we will take a look at them with the help of James McCall, PhD, of Mount Holly, Ark. In addition to laboring in the academic world, he has trained racehorses and during a 40-year career with equines has managed some 300 stallions, a number of which were used in pasture breeding programs. He also is the author of the book The Stallion, A Breeding Guide for Owners and Handlers as well as a plethora of magazine articles about horses. Obviously, the book on stallions covers much more than just pasture breeding, but that subject is dealt with in some detail. McCall, who has retired from the academic world, stands two cutting horse stallions in Arkansas and competes in major cutting horse contests.

The advantages to pasture breeding, he feels, are obvious--little hands-on handling is required and normally there is an increased conception rate. The disadvantages, he says, include the potential for injury to the stallion and a smaller book for the pasture breeding stallion. (A good ratio, he believes, is 20 mares--plus or minus five--per stallion.)

At the same time, he is quick to point out that in all of the years he has been involved in pasture breeding, only one stallion in his custody suffered what could be termed a major injury. That horse was kicked in the testicles by a mare and was put out of commission for a period of time. However, the injury was not a permanent one. A colleague heavily involved in pasture breeding through the years also reported only one serious injury, he says. That involved a stallion kicked in the penis. He had to be removed from the breeding band for a time, but he recovered.

McCall says pasture breeding stallions are going to suffer a variety of nicks and scrapes foreign to the stabled stallion which is hand bred or used in an AI program. But normally, he says, there are only minor wounds.

Behavior of Stallions

One of the major problems in pasture breeding stallions in today's equine world, McCall says, is that a number of stallions are sequestered in the show ring world where they have little outdoor socialization with other horses. They are confined to box stalls and are in the company of other horses only in the closely structured show ring or stable, where there is almost no horse-to-horse interaction. When their show ring career is over, they suddenly are asked to return to a natural state and become a breeding stallion. Oddly enough, McCall says, some of them do it with little problem, while others have to be integrated into a pasture breeding program slowly and carefully.

A good approach, he says, is to turn the inexperienced stallion into a paddock or secure pasture with a single mare which is in full estrus and receptive to the stallion's advances. If that experience proves to be a positive one, other mares can be added to the harem.

On the other hand, some stallions which have led confined lives take to pasture breeding like the proverbial duck to water. McCall remembers an imported Thoroughbred racehorse from France which had spent his entire adult life on the track.

"That stallion had been babied to the hilt," McCall says. "I had him one month, then I turned him out with a band of 20 mares. He went right to breeding like an experienced range horse."

Another Thoroughbred which quickly took to pasture breeding, he says, was Yankee Lad, a runner which finished fourth in the Preakness during his 3-year-old year in the late 1960s. Yankee Lad was managed for a time by McCall. The stallion sired Touch of Class, the gold medal-winning mare in Grand Prix jumping at the 1984 Olympics with Joe Fargis aboard. Touch of Class was the first horse to post two clear rounds and, in winning two Gold Medals, cleared an incredible 90 of 91 jumps at the Olympics.

Sometimes the stories involving "hothouse" stallions being turned out for pasture breeding carry with them a touch of humor. Such is the case with Rod Hiatt of Bottineau, N.D., a PMU (pregnant mare urine) breeder. Many of the PMU ranchers use pasture breeding as a labor-saving device and because of a high rate of conception.

Hiatt was seeking to upgrade his program and handle the increased demand for foals, so he sold his draft horse stallions and purchased Thoroughbreds. In places like New York, Nebraska, and Florida, he picked up stallions which had completed their racing careers. They had solid pedigrees, but weren't in demand for breeding programs. Some of the stallions were 10 or 11 years old.

One Thoroughbred stallion which was turned out, Hiatt says, went racing toward the band of mares, only to discover that they were on the other side of a small stream. He had never encountered such a fearful obstacle before and refused to cross it. "That night," Hiatt chuckled with the memory, "the mares got tired of waiting and they crossed the stream to him."

Some of Hiatt's new purchases were totally unfamiliar with terrain that wasn't cushiony sand that had been harrowed and smoothed each day. "I turned one out," Hiatt recalls, "and he went running toward the mares. He came to a little dip in the ground and stumbled and fell."

Hiatt watched fearfully as the stallion struggled to his feet, worried that the horse had been crippled before ever covering a mare. The stallion, however, shook off the tumble and ran on toward the broodmare band.

Both stories have a happy ending. The two stallions were placed with a total of 25 mares that spring, and all 25 became pregnant despite the fact that neither stallion had ever covered a mare before.

Starting Young

If a stallion is earmarked for a pasture breeding career early on, McCall says, many introduction problems can be avoided if he has a lot of socialization with other horses while maturing. "If I earmarked a young stallion for pasture breeding, I'd segregate him from mares and fillies at about 14 months or earlier," McCall said, "but I'd keep him in the company of other colts and geldings (for socialization)."

The socialization that occurs between stallions and mares in a pasture breeding scenario can have some rather strange quirks. For example, if a stallion is turned out with a group of mares in the spring, quite often they will become a closed society and will reject any other mare introduced to the group several weeks later.

A personal anecdote--some years ago, we bought a yearling Thoroughbred stud colt at a Fasig-Tipton sale in Lexington. The purpose of the purchase was to turn the colt in with a band of ranch mares in Montana. The mares were primarily of Morgan ancestry, and the rancher wanted to add a little length of leg to the offspring. In return for purchasing the colt, we were able to turn a couple of our mares out with him.

All went well and the young colt was turned out with a few mares as a 2-year-old. At three, his band was enlarged. He grew into a handsome horse which never lost his "people" roots. When we'd go out to the range to view him, he'd come on a run to be petted and praised. Then, he would whirl about and race back to his band.

A few years into the program, a close mutual friend purchased four Arabian mares of old-time working horse lineage. He desired to turn them out with the Thoroughbred stallion and his band several weeks into the breeding season. It was a disaster. We trailered the mares across the range until we were near the stallion and his band. The mares were then released. The stallion came toward them at a run, but it wasn't to welcome them into the fold. His ears were pinned and he charged into the startled mares with a vengeance. They turned and fled for their lives with the stallion in hot pursuit. He didn't stop until they were a few hundred yards from the band.

From that point on, there was an invisible line of demarcation. It was almost as though the stallion had stepped off 100 yards and that was as close as the four mares were allowed. He didn't relent, and the mares eventually were taken from the range, as non-pregnant as when they had arrived.

When this problem occurs, McCall says, it normally is with a seasoned breeding stallion, such as the Thoroughbred in question. A stallion experiencing his first breeding season in the pasture normally will accept new mares without question.

"However," he writes in his book, "sometimes a seasoned pasture breeding stallion will reject late arrivals once his herd has been established. To minimize this occurrence, it is a good idea to introduce new mares when they are in heat and receptive to the stallion. This does not always ensure acceptance into the herd, but it does increase the odds."

If a stallion absolutely refuses to tolerate a particular mare, he says, she should instantly be removed from the herd as she is at risk of injury from the stallion.

Greater Success

Generally, McCall says, pasture breeding increases conception rates. A successful hand breeding program can produce a pregnancy rate of 80%, while pasture breeding healthy mares can boost that to 90%.

Turning a mare out with a stallion will not solve physical reproductive problems such as urine pooling, infection, or other maladies, he says, but it can solve problems that are more psychological in nature.

In one instance, he recalls, he was having trouble getting several mares pregnant through either hand breeding or AI. He could find no physical reason for them to be barren, but the mares were of the nervous, temperamental variety. At wits end, he turned them out to a pasture with a stallion. They were pregnant within three weeks.

"I believe that returning them to nature," he wrote in his book, "allowed them to relax and let down, thus enhancing their ability to become pregnant. This solution to solving infertility would not have worked had these mares not been otherwise reproductively sound."

Timing is Important

Normally, McCall says, the optimum time for pasture breeding in North America is in April, May, and June--following the rhythms of nature. However, he says, it appears that turning a stallion in with a group of mares earlier than that can stimulate them to begin cycling.

He tells the story of a breeding experiment he conducted in the mid-1970s in Maryland when he was standing two stallions to outside mares. In addition, he had a band of 15 barren mares on the farm. He turned one stallion out with seven mares and another with eight at the end of January and left them with the mares until the end of February, when outside mares began arriving. When the groups were disbanded at the end of February, 13 of the 15 mares were pregnant. He repeated the program the following year and again had an 87% pregnancy rate.

Pasture breeding mares with foals at side normally isn't a problem and generally poses no threat to the youngster from the stallion, McCall says. Under normal circumstances, the mare will isolate herself from the band when giving birth and once the foal is up and running about, will rejoin it. Removing the mare from the band to foal, then bringing her and the foal back, can produce re-introduction problems.

Pasture breeding might not be for everyone, but it can be a convenient approach under certain circumstances. However, it is not something to be entered into lightly. Advice from experienced breeders and a veterinarian should be sought before embarking on a pasture breeding program.

About the Author

Les Sellnow

Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at or by calling 800/582-5604.

Stay on top of the most recent Horse Health news with FREE weekly newsletters from Learn More