Ram Management Considerations – Part One
Ewes might do most of the work on a sheep enterprise, but rams have a greater impact on improving flock genetics.
The excitement of ram sales, impressive pedigrees and performance data are all for nothing if rams don’t perform those 30 to 60 days in the fall. Much of the success we expect from rams is a result of our decision-making and ram management plans, both pre- and post-breeding season.
Here are some helpful reminders.
A larger scrotal circumference can be an initial screening tool for producers and is highly correlated to sperm concentration and volume.
A 20 to 30 percent increase in scrotal circumference from spring to fall is to be expected, with greater increases expected for seasonal breeds. For example, a recent study at Montana State University observed an eight-centimeter, 20-percent increase in scrotal circumference in Targhee rams from June to August.
Work done on range rams by Ruttle and Southward (1988) reported rams with a scrotal circumference of less than 30 centimeters usually were classified as unsatisfactory in their annual breeding soundness exams. If rams don’t measure up in the late summer and early fall, they don’t measure up, as can be seen in the table below.
Rams with a larger scrotal circumference, especially as ram lambs and yearlings, generally, will sire earlier maturing, more reproductively efficient ewe lambs.
Breeding soundness exams
There are several other factors that should be considered in breeding soundness exams.
Feet should be trimmed prior to turnout. Inspecting hooves, pasterns, knees and hocks for inflammation and soreness will identify potential problems. Examining while the ram is walking and running can better signal structural issues than stationary examination.
Examine the eyes. They should be clear and free of discharge.
Deworming is warranted if rams were managed on irrigated or sub-irrigated pasture throughout summer.
Rams’ front teeth – their incisors – should line up flush with dental pad. Feel upper molars through cheek for excessive wear or abscesses.
The body condition score (BCS) of rams should be a three to four on the five-point scale. Stamina, libido and semen characteristics will decline in under-conditioned rams. Unadapted, excessively fat rams will also struggle with stamina, libido and thermal regulation of testis.
Fat rams sell well at ram sales, yet should be put on a medium-quality grass hay after purchase to ensure rams are adapted to new environments prior to breeding
Palpate the testicles for firmness. They should be similar in firmness in tone to that of your forearm when making a fist. The scrotum should be free of cuts or lesions. Testicles should be symmetrical with no swelling of the lower portion, which could indicate epididymis.
Examine and palpate the prepuce for ulcers or scabs. Maintaining rams on a diet of less than 16 percent crude protein prior to breeding will help prevent or remediate pizzle rot.
Testicular inflammation or an enlarged epididymis may point to infectious agents such as Brucella ovis. Consulting with your attending veterinarian can help delineate disease versus physical injury.
Begin semen evaluations at least two months in advance of the breeding season. Semen testing rams greater than six years old should be a priority, as these generally show a decline in quality semen characteristics.
Formation of sperm, know as spermatogenesis, lasts 50 days, with an additional 12 to 14 days required for that new sperm to travel through the epididymal duct. Six to eight weeks advanced planning will allow finding a suitable replacement ram if semen quality problems are identified.
Semen abnormalities – for example, low concentration, poor motility or poor morphology – may be attributable to a physiological challenge 50 days prior, including fever, nutrient deficiency, heat stress or shipping stress.
Semen testing too early in the summer, in May or June for example, especially in more seasonal, European-type breeds, may indicate poor specimens when, in fact, these breed types should be retested closer to breeding season.
Semen testing twice within one day, especially for virgin rams where feasible, or 10 days later, might determine if the abnormalities were from environmental factors or permanent infertility.
Also, consider that some rams do not collect well as a result of the collection process and should be evaluated accordingly.
Consulting with the attending veterinarian can provide additional cull/keep criteria and other abnormalities that might have been experienced during collection.
This is part one of a two-part article on ram evaluation prior to breeding. Read next week’s Roundup for part two of the article. For additional information or specific ram feeding strategies for your operation, call 307-766-5374 or e-mail questions to firstname.lastname@example.org