The dating game - Older stallions require thorough evaluations to gague potency
You have seen the signs little by little, and you are pretty sure that it is about time. The older stallion that you have been managing has had a poor season, and pregnancy rates are unacceptable. You are consulted as to whether or not he should be retired from the breeding shed. Sometimes the answer is easy if the stallion has no libido, very low sperm numbers or such an arthritis problem that mounting is becoming painful. Other times there are only slight problems and no readily apparent answers to explain the drop in conception. The decision to retire a stallion often becomes as much about economics and emotion as it is about science and statistics. Yet, for veterinarians, attention to good, complete semen analysis and the use of some newer tests will allow you to recommend either an early retirement for a particular stallion or a return engagement for next year's breeding season.
When evaluating the fertility of an older stallion, a complete analysis of the stallion, his book of mares and the entire breeding facility is warranted because there are so many places where the reproductive process can break down. Many older stallions slowly fall from the public eye and become less desirable breeders and are replaced by younger, more recognizable, trendier stallions. Additionally, there is the unfounded belief, especially among the racing community, that older stallions produce weaker, poorer-quality offspring. Consequently older stallions do not have their pick of the best broodmares and are often servicing older, poorer quality mares.
Dr. Ernest Baily of the Maxwell Gluck Research Center at the University of Kentucky refutes this belief."From an understanding of molecular genetics, there's no reason to expect age of the stallion to have any effect on the performance of the offspring," he says. "There is no basis to say that a horse's genetic contribution will improve or decline with age."
Still, this combination of older mare and older stallion combines for lower reproductive efficiency. One simple way to boost the production of an older stallion is to ensure mating to the best possible mares, preferably younger, proven producers. Older stallions also might become more particular in their preferences and habits. Some stallions will breed better at certain times of the day. Some older stallions prefer mares of a particular color or any number of other idiosyncrasies. Attention to these small details can help improve fertility in these stallions.
A complete physical examination of the older stallion should be the next step in this evaluation process. Medical problems unrelated to the reproductive system can have a significant effect on breeding ability. Dental care and nutritional status should be evaluated. Older horses need additional vitamins and minerals because their digestive systems are not as efficient as they once were. Stallions use tremendous energy and body reserves during the course of a breeding season, and older stallions are more affected by this daily strain. Older stallions should be neither too heavy nor too thin as both extremes will reduce fertility. Many supplements are available claiming to improve fertility, including vitamin E, chromatin and others. More research must be done before the exact relationship is confirmed between many of these products and the possibility of improved fertility. A good-quality diet with a balanced supplement is the best overall nutritional support for older stallions.
The musculoskeletal system of the older stallion also deserves special attention. Osteoarthritis and muscle, ligament and tendon problems all can affect a stallion's willingness and ability to tease and mount. A stallion that has strong libido, mounts (but cannot ejaculate) might be experiencing back pain or hock soreness or any number of other conditions that can manifest themselves as breeding difficulties. A thorough examination done before and after the breeding season will identify any potential problems. The use of glucosamine, chondroitin, various forms of hyaluronic acid and other products can make an older stallion much more comfortable, which translates into better performance in the shed.
The cardiovascular and respiratory system should also be examined. Many older stallions suffer from some form of decreased heart function, and the stress of breeding can be potentially deadly to these horses. Anemia, from many causes, can result in lowered libido and lack of interest in breeding as well.