Richard Ehrhardt, Michigan State University Extension Specialist, Small Ruminants
(Previously published on MSU Extension, Sheep & Goat)
Although breeding season for many is several months away, its sheep sale season across the nation and producers are on the hunt for their next stud ram. Once acquired, rams should be tested and stowed away for safe keeping until its their time to shine. In general, spermatogenesis (the production of viable sperm) can take up to 12 weeks to regenerate if rams experience health complications or heat stress. Therefore, talking about the 2022 breeding season now is timely and a read that is worthwhile.
Ensuring the health and reproductive viability of rams on your farm is critical to a successful breeding program. Because one ram can service 50+ ewes during an optimal breeding season, there is a lot more risk for flock reproductive problems associated with his fertility compared to those of individual ewes. One unsuccessful season can have a huge impact at lambing time and beyond. This risk can be minimized by following some fairly simple and straightforward steps.
Ram physical examination
Producers should become familiar with performing simple breeding exams on rams several weeks prior to the breeding season. This involves a simple exam of the ram’s reproductive capacity. The testicles should be palpated and should be firm but not soft. In many breeds, the testicles will appear soft and less firm during the spring, as most breeds are less fertile in the spring, and this is normal for breeds with clear seasonal breeding patterns In the late summer, however, the testicular firmness in rams from all breeds of sheep should improve as the days start to become shorter. The tail of the epididymis of the testes in located on the distal, bottom end of the testes and should be distinct by palpation, feeling like a “knob-like” structure. The epididymis of each testicle should be similar in feel and not swollen or enlarged. Comparisons among several rams’ testes and between testicles in a single ram can provide a sense of what is normal is what is not in this regard. Testicular size is also an indicator of fertility, although generally not as good of an indicator of fertility as firmness. Rams older than 18 months should have a scrotal circumference >35 centimeters [13.8 inches] at their greatest diameter, whereas younger rams should be >30 centimeters [11.8 inches].
The end of the penis can be displayed when rams are set on their rear ends and gentle pressure is applied to their abdomen. The urethral process is a very distinct looking structure located at the end of the penis consisting of a “worm-like” appendage. This unusual “worm like” appearance of the structure is normal, and the tissue should have a healthy pink color and be without signs of infection or injury. The prepuce of the ram is the external opening of the non-extended penis and should be clean without signs of infection, scabs or ulcers. Pizzle rot is a common problem found in rams, which appears as a sore or ulcer on the prepuce. It is related to both diet and environment, with high protein diets (>16% crude protein) and dirty/wet pens causing problems. Clean bedding and antibiotic ointment applied on a daily basis for a few weeks can often remedy this problem, however cumbersome to employ. Failure to treat this condition will limit the service capacity of the ram due to discomfort during mating.
Another important consideration in examining rams is sound hips. Hip soundness can become an issue in older rams especially and can be assessed by testing how much weight a ram can bear on his hips. Rams should be able to hold at least their own weight, so a reasonable test is if they can hold the weight of an adult shepherd. To test this, simply have an assistant hold the ram and then stand behind the ram. Place your hands with arms locked and extended in front of you on the rams hips and then lean forward to place the majority of your weight on your hands placed on the ram’s hips. The ram should be able to support this weight without buckling if his hips are sound for mating.
Preparing the ram’s feet and shearing
Hooves on rams should be trimmed at least 3 weeks prior to the breeding season. This allows enough time for healing if hooves are accidently trimmed a bit short. Accidental hoof injury during trimming performed just before turnout is a common issue that can be prevented with advance planning. Be sure to trim conservatively if performed closer to the breeding season. Producers should observe rams during the off-season for any signs of hoof infection (hoof rot, hoof scald, hoof abscess) and treat any signs of lameness immediately. It may take several weeks to treat hoof ailments, so this must be monitored on an ongoing basis. Hoof problems limit both the ram’s breeding performance and their ability to forage and feed, so they must be carefully managed.
Shearing should be performed 6-8 weeks before breeding when the breeding season is in August to October. Shearing should be done earlier that this (mid-September at the latest) if rams are to be used in the late fall or winter to allow enough fleece protection for cold weather. For spring mating, rams should be shorn a few weeks prior to outdoor housing if breeding is to take place on pasture.
Nutritional preparation of the rams
Rams should be placed on a rising plane of nutrition starting approximately 4-6 weeks before the breeding season with a target body condition of 3.5 (on a scale of 1-5) at the start of breeding season. The length of this nutritional preparation period may need to be longer if rams are especially thin (need to gain >0.5 body condition score) in order to reach this target. This supplementation should primarily be in the form of energy; however, young, growing rams will also have a higher protein requirement than mature rams. But diets do not need to exceed 15% crude protein to meet the requirements even of growing rams, and 12% crude protein is usually sufficient for full-grown rams during this period. Quality forage will may meet this protein requirement in mature rams, and additional protein sources such as soybean meal or dried distillers grain may be supplemented along with the energy sources for growing rams to reach their higher requirements.
Supplementation should be provided as incremental increases over 1-2 weeks in addition to supplying forage of appropriate quality. This will aid the transition of rumen microbes onto grain and minimize potential digestive problems. The animals should be examined during this period to make sure they are gaining enough weight to reach target body condition. The level of nutrition may need to be as high as 2 times maintenance (the amount of nutrition that provides zero weight gain) to hit the appropriate body condition target over this time frame. This level of nutrition is similar to that provided to ewes during late pregnancy, and is roughly equivalent to 1-1.5 lbs. of grain per day in addition to forage. This nutritional backgrounding is important for any breeding season, but appears especially critical during the spring breeding period to ensure out-of-season breeding success.
During the breeding season, ram supplementation is seldom practical. This emphasizes the importance of having good condition on the ram before entering breeding, as he will most likely lose weight during the breeding period, particularly if on pasture.
Ram breeding soundness exam
A ram breeding soundness exam is a smart investment to make prior to any breeding season. This will allow a producer to screen out rams and ensure that only fertile rams are in the breeding flock. Performing the exam 2-3 weeks prior to the breeding season is indicated in case the first test result yields less than optimal results. Rams that have been inactive for long periods occasionally have higher levels of defective sperm which resolves as they become more active. Breeding soundness exams are performed by veterinarians or their designee who are trained reproductive technicians and involve both a semen evaluation and a detailed physical exam of the ram. The semen evaluation component provides a quantitative assessment of sperm concentration (number of viable, non-defective sperm based on and a qualitative assessment of sperm motility. Signs of reproductive disease can be assessed by staining techniques to identify white blood cells in the semen, an indication of infection. All of these tests are very helpful in assessing fertility and troubleshooting potential fertility problems. Infertile or sub-fertile rams are not as common during the fall breeding season, but they do exist, especially early in the mating season. A common cause of poor male fertility is housing in hot conditions. It may take a ram several months to recover normal sperms production after exposure to hot environmental conditions.
Ram groupings and coverage
Ram to ewe ratio should be altered based on the season of breeding (summer, fall, winter, or spring) and the age of ram, and altered further if estrus synchronization techniques are used. Fertile adult rams can serve at least 5 ewes per day, so over a 34 days breeding season (2 full estrus cycles), one ram could theoretically service over 150 ewes. It would be foolish to do this, however, as ewes do not cycle in a consistent pattern over time. In fact, ewes tend to cluster in estrus behavior at approximately 16-23 days following ram exposure. If teaser rams are used, then this cluster occurs relative to the introduction of the teaser ram(s). General recommendations to handle this cluster are to have ram to ewe ratios of 1 adult ram to 50 ewes during the fall breeding season (2% coverage). Coverage should be increased during spring breeding to 3-4% (1 ram to 25-33 ewes). Ram lambs (7-12 months) should be used at the same coverage rate (3-4%) during the fall breeding season and used at even a higher coverage rate, if at all, during the spring breeding season (>5%). It is advised to keep ram services at 5 or less per day to ensure high conception rates. This should be considered when estrus synchronization methods are used: teaser rams to cluster estrus, artificial means such as progesterone-impregnated CIDRs (controlled internal drug release devices), or the use of prostaglandin inhibitors.
Groups of rams can be used in larger flocks to improve coverage and lower risk of breeding failure if all rams are subjected to a breeding soundness exam. It is advised to house rams that are going to be used in the same breeding group together for at least a few days prior to breeding to get them used to each other and to minimize injury from fighting. It is best to pen such rams in a very small pen initially to limit dangerous lunging and injury, and then expand the pen size as they become used to each other. This will not eliminate competition and fighting, but it may avoid catastrophic injury that can occur when rams are first introduced to each other in a large pen or field.
Providing appropriate nutrition and hoof care in the months prior to the breeding season are essential in preparing rams for optimal fertility. An evaluation of a ram’s fertility is also highly recommended to prevent the devastating consequences of a breeding failure. Minimally, producers should learn how to perform simple physical exams of rams. However, it is optimal to invest in breeding soundness exams for all rams used to lower the risk of poor conception. Following these simple management guidelines will ensure rams are properly prepared for the next breeding season.