Breeding Season Management
Livestock Update, August 2006
Scott Greiner, Extension Animal Scientist, Sheep, Virginia Tech
A diligent amount of time spent studying performance information, pedigrees and other pertinent information is warranted as ram selection is the most important tool for making genetic progress in the flock. Of equal importance is the care and management of the newly acquired ram. Proper management and nutrition are essential for the ram to perform satisfactorily during the breeding season. With ram lambs, management prior, during, and after the first breeding season is particularly important.
Ram Lamb Management
Most often, ram lambs are coming off a high plane of nutrition heading into their first breeding season (completing a structured performance test, or managed on the farm for high growth rates to optimize maturity). To prepare ram lambs for the breeding season and prevent excess fat deposition, rams should be limit fed a grain ration and have access to pasture since completion of the test. Young rams should be managed to be in moderate body condition prior to the breeding season (not excessively fat or thin), to provide adequate reserves of energy for use during the breeding season. The rams should continue to receive grain supplementation at a rate of 2% of their bodyweight daily, along with an abundance of high quality forage. Provide adequate clean water, and a high selenium mineral formulated for sheep free-choice. A facility for rams that allows for ample exercise will help create rams that are physically fit for the breeding season. The facility should allow the rams to remain cool during hot days, so potential fertility problem due to heat stress can be avoided. It is advisable not to commingle a newly purchased ram lamb with older, mature rams. Particular care should be taken if rams from different sources need to be commingled, and all commingling should take place prior to the breeding season.
Many factors influence the breeding capacity of rams, including age, breed, nutrition, management, and environment. As a general guideline, ram lambs are capable of breeding 15 to 25 ewes during their first breeding season. Ram lambs should be observed closely to monitor their breeding behavior and libido to ensure they are servicing and settling ewes. The use of a marking harness, rotating colors every 17 days, is an excellent management tool for this purpose. The breeding season should be kept to a maximum of 60 days for young rams. This will prevent over-use, severe weight loss and reduced libido. Severe weight loss may impair future growth and development of the young ram, and reduce his lifetime usefulness. When practical, supplementing ram lambs with grain during the breeding season will reduce excessive weight loss. Rams used together in multiple-sire breeding pastures should be of similar age and size. Ram lambs cannot compete with mature rams in the same breeding pasture. A sound management practice is to rotate rams among different breeding pastures every 17-34 days. This practice decreases the breeding pressure on a single ram.
Preparing the Ewe Flock for the Breeding Season
Some advance planning and simple management practices will assist in having a successful breeding season. Vaccination of the ewe flock for Campylobacter (vibrio) and Chlamydia are important for abortion disease control. For ewe lambs and ewes not previously vaccinated, these products typically require an initial injection prior to the breeding season followed by a second vaccination during gestation. In subsequent years, a single booster vaccination is required. Follow product label directions when administering any vaccine. A month prior to the breeding season is also an opportune time to trim and inspect feet on the ewe flock, and perform preventative foot care. This is also a good time to make final culling decisions, and sell poor producing and thin ewes.
Flushing is the practice of increasing energy intake, and therefore body condition, during the 10-14 days prior to breeding. This practice has been shown to be effective in increasing ovulation rates, and thereby increasing lambing percentage by 10-20%. The response to flushing is affected by several factors, including the body condition of the ewe and time of the breeding season. Ewes that are in poor body condition will respond most favorably to the increase in energy, whereas fat ewes will show little if any response. Flushing can be accomplished by moving ewes to high quality pastures, or through providing .75 to 1.25 lb. corn or barley per head per day from 2 weeks pre-breeding through 4 weeks into the breeding season. Provide a high-selenium, sheep mineral free choice.
Like rams, ewes are also prone to heat stress during early breeding seasons. Prolonged exposure to high temperatures can have an effect on ewe fertility and embryo survival. To help reduce these embryo losses and resulting decrease in lamb crop, minimize handling during the heat of the day and allow the flock access to a cool, shaded area.
Ram Management After the Breeding Season
Young rams require a relatively high plane of nutrition following the breeding season to replenish body condition and meet demands for continued growth. Body condition and projected mature size of the ram will determine his nutrient requirements during the months following the breeding season. Rams should be kept away from ewes in an isolated facility or pasture after the breeding season. In the winter months, provide cover from extreme weather that may cause frostbite to the scrotum resulting in decreased fertility.
All stud rams should receive breeding soundness exams (BSE) to assure fertility on an annual basis. Assess the ram battery in early summer, so that new rams can be acquired in a timely fashion for the next breeding season.