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Evaluating rams Veterinarians encourage breeding soundness evaluations

by Wyoming Livestock Roundup

“It’s important to do breeding soundness testing because we have good solid rams, and we want to utilize them to their fullest extent,” Cleon Kimberling, a veterinarian who has been instrumental in ram breeding soundness research, explained. “Large scrotal circumference in healthy breeding rams increases twinning. It’s also really important is our ability to shorten the lambing period.” 

Kimberling was joined by veterinarian Geri Parsons during a June 25 webinar titled “Ram Breeding Soundness Evaluation,” which looked inside the importance of a breeding soundness exam and how the exams are conducted.

The exam

The breeding soundness examination looks beyond semen quality, said Kimberling, noting, “A total physical examination of the ram is conducted, with an emphasis on the reproductive tract.” 

The breeding soundness exam, rather, assesses “a ram’s potential ability to impregnate a given number of ewes over a defined period of time,” he said. “It’s not a fertility check, though.”

While the breeding soundness exam involves a physical and reproductive exam, Kimberling encouraged producers that the exam should also include observation of rams in their natural environment.

“We can identify rams that form ‘buddy groups’ that might have little interest in ewes at all,” he said. “Studies at Dubois, Idaho show that 10 to 15 percent of all rams do not have any interest in ewes. We can spot those when they are in their normal environment and get rid of them.” 

While rams only “work” for a short time each year, Kimberling said it’s important to keep them in good condition throughout the year.

“Don’t just pull the rams in 30 days before breeding, put them on corn and try to get them in shape,” he cautioned. “Rams are like a fine-tuned athlete. They’ve got work to do and need to be in good body condition way before we start the breeding season.”

Producers should strive for a ram with a body condition score of three to four, avoiding both extremely thin or over-fat rams.

“If they’re in the wool, we have to put our hands on the rams,” Kimberling said. “If there is a long staple length, the body condition is masked.”

Physical exam

In an overall exam, Parsons said they begin looking at the general overall health condition.

“We want to make sure they are bright and alert, as well as free of eye and nose discharge,” she said. “We make sure there are no external parasites or fungus.”

The mouth and mucus membranes should be slightly moist and pink.

“If a ram’s mucus membranes are pale, it may indicate an internal parasitism problem,” Parsons notes. “Pale mucus membranes mean we need to take a fecal sample to figure out if they have parasites or not.”

Parsons encouraged producers to make sure teeth are in good shape. 

“We also want to make sure there is no lameness present,” she continues, noting bumble foot, ovine contagious foot rot or foot abscesses are common. “It’s really important the ram is able to move freely and mount ewes to do its job.”

Reproductive exam

In the reproduction portion of the exam, Parsons explained they begin with palpation of the testicles, epididymis and spermatic cords up to the attachments into the body, to make sure they are even, there are no lumps, bumps, hard or soft spots, swelling or edema. 

“We also want to make sure there’s no difference in size in the testes and making sure they’re uniformly firm,” she said. “Significant differences in size can sometimes indicate atrophy or disease.”

One of the most common causes of infertility in males is epididymitis. 

“Epididymitis doesn’t go away in the ram,” Parsons explained. “The sperm are formed in the body of the testes, but they are stored and mature in the epididymis. When it is blocked off, nothing is moved through and the testicle is done for.” 

A scrotal circumference is also taken in the reproductive exam.

“A satisfactory score for a ram lamb is a minimal circumference of 30 centimeters, and an exceptional score is 36 centimeters,” Parsons said. “For rams over 14 months of age, we need a minimum of 33 scrotal circumference, and for exceptional, we want a ram with a scrotal circumference of greater than 40 centimeters.”

Scrotal circumference is importance because it indicates fertility.

“A ram with a larger scrotal circumference can service more ewes in a heat cycle than one with a small scrotal circumference,” Parsons said.

In addition, larger scrotal circumference increases the probability of twinning and early female maturation age. 

Moving through the reproductive exam, Parsons examines the prepuce, sheath and penis, which may restrict breeding ability. 

Semen samples

Following reproductive physical exams, semen samples are taken using electrical stimuli. 

“The semen sample is viewed in a lab under a microscope,” Parsons said. “We use a phase contrast microscope, which is important so we can view all potential defects.”

Semen motility and morphology are both analyzed in the sample to make sure sperm are able to move forward progressively.

“At that point, we also look to see if there are any white cells in the sample, which can indicate disease,” she added. “As long as the penis is extended when we collect the sample, the white cells will come from the reproductive or urinary tracts. If the penis is not extended, we are more likely to get debris, skin cells or potentially white cells from inside the sheath.”

Morphology of cells are also examined, including both the size and shape. Sperm should be a consistent size and shape, with the tails attacked in the mid-line of the sperm. Tails should also be straight.

“The head of the sperm cell – the acrosome – is responsible for penetration of the sperm into the egg, so if there is anything messed up on the top, it will make the sperm unviable,” Parsons explained. “If there is anything wrong with our sperm, ewes won’t get bred.”

Classifying rams

After the exam, Parsons said rams are rated excellent, satisfactory, questionable and unsatisfactory. 

“For a ram to be excellent, he has to be excellent in every single category,” she said. “The classification system is based on one ram impregnating 100 ewes in an 18-day heat cycle.”

“There are many things that, looking over the fenceline, we don’t see,” Parsons commented. “Often these things wouldn’t be noticed until all of our ewes come up open.”

The American Sheep Industry Association’s Let’s Grow program funded this webinar. 

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at

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