Using Ram Lambs for Breeding

Ted H. Doane, Extension Sheep Specialist, University of Nebraska-Lincoln
(Previously published online the University of Nebraska-Lincoln Extension: August 1986)

Although this publication is a bit dated, it still provides quality content as it relates to the use of ram lambs for the upcoming breeding season. As producers begin to search for their next sire for 2022, remember not to discount some of the younger stock. As with anything else, diligent management and attention to detail will be of great benefit in the long run when it comes to the potential use of ram lambs in your operation.

This NebGuide explains how ram lambs can be most efficiently used in a breeding program and provides management suggestions for a successful program.

Are you planning to use a ram lamb this breeding season? If so, you should consider the capabilities and limitations of ram lambs.

It may be true that some well-grown, aggressive, vigorous, highly fertile ram lambs can settle 50 ewes and maybe more. However, these rams are exceptions. A good rule to follow for practical ram management is 15-20 ewes for a ram lamb and 35-50 ewes for a mature ram. Researchers have shown that ram lambs generally have fully developed reproductive organs at 150 days of age, with spermatogenesis beginning as early as 80-100 days. Therefore, live sperm may be ejaculated as early as 112 days of age. However, there is considerable variation due to breed, nutrition, and management. In addition, some rams are not mature enough for live motile sperm to be ejaculated until 180 days of age.

When can a ram lamb be used for extensive breeding? A good rule is that a ram lamb is generally large enough to breed 15-25 ewes when he reaches 50-60% of his mature weight. For example, a projected 300-pound mature ram can be ready to turn into a breeding pen when he reaches 150-180 pounds live weight. A projected mature 200-pound ram can be used when he is 120 pounds. The two factors of age and size are critical to the breeding capabilities of ram lambs.

The following breeding management techniques make for a highly fertile ram lamb.

A ram lamb at five months can usually settle a few ewes, but he will be a much more aggressive breeder at seven months. A January-born lamb is ready for breeding in August; therefore as the breeding season progresses, February and March-born lambs come of age for September to November breeding.

The following chart identifies the minimum weight of ram lambs used for breeding.

Expected mature weight (lbs.) Immature (50-60%) breeding weight (lbs.)
150 75 – 90
200 100 – 120
250 125 – 150
300 150 – 180

Ram lambs should be fed separately from mature rams. A growing ration through the breeding season is a must to keep lambs healthy. Although they may not eat as much during breeding season as non-breeding season, they need a minimum of 2% of their body weight in grain, as well as a liberal roughage intake. When the breeding season is over (2 months) the lamb should be taller, but he may weigh less due to the activity of breeding.

Never allow ram lambs and mature rams to run together in breeding pens. The older rams are more dominant and can injure the lighter, less experienced lambs.

Shear rams before breeding season, especially lambs. They may become exhausted especially on extremely warm days. Hot weather or high body temperature can make a ram temporarily sterile. High body temperatures can be caused by either heat stress or disease. After a prolonged high body temperature, it takes 3-6 weeks to regenerate live sperm. This would be costly during the breeding season.

Limit the number of females for ram lambs at the beginning of the breeding season to 10-15. After a few days, more may be added.

Use marking harnesses to determine the activity of the ram. Change colors every 14-17 days to determine if the ewes are being settled the first cycle. If a high percent of ewes are returning after 17 days, you should evaluate the ram. A semen check is in order. A semen evaluation before breeding season may eliminate this problem later in the season

Always check the testes for abnormal condition. Although ram lambs seldom have epididymitis, it is a good policy to check for this disease. Also, examine testes for size and number. Sometimes a testicle is small and abnormal and it is not noticed without palpation. The scrotal circumference should be at least 9.5 inches mid-point of testes at five months. The larger the circumference of the scrotum, the more potential for fertility of the ram.

Take care of your ram lamb and he will take care of the flock.