Why we select and breed for clean underlines

Why we select and breed for clean underlines

Trait selection for sheaths is a priority at Rockley when it comes to selling and buying bulls. Our clients need animals with clean underlines to alleviate the risks of damage from harsh terrain that could result in mating problems and economic loss. Clean underlines is one of our 7 elite breeding attributes because we understand that our bulls’ number one job is to sire calves for our clients throughout a long working life.

As we strive to breed an increasing percentage of polled cattle at Rockley, we pay particular attention to sheaths.

We favour sheaths that are light and clean, with a small and tight opening and where the underline is firmly and evenly attached for its whole length. A light sheath is unlikely to become pendulous, which increases the chances of injury from contact with the ground or from the animal standing on its sheath when lying down or standing up. A small, tight opening provides protection against infection, while a firm and evenly attached underline helps create the desired angle during service.

We are wary of sheaths that are heavy and large, pendulous and loosely attached, with areas of loose skin at the navel or around the sheath and poor attachment to the body near the naval or around the sheath.

We believe clean-sheathed, polled bulls can be bred successfully through careful selection. We are continually searching to identify polled sires who are tidy in the sheath, that don’t continually hang out their prepuce. The key is to be cautious when using generational bred polled bulls, that are more likely to have a protruding prepuce than horned bulls and Polled/Horned (PH) bulls.

Certain bulls can have 5 to 10 cm of prepuce protruding below the end of the sheath. This makes them more susceptible to injury and infection that may mean the bull can no longer serve cows. In our experience, sheath problems that are apparent in a young bull are likely to worsen as the bull ages.

These images are of Rockley cattle.

An ideal sheath on a 2-year-old bull: well suspended, well angled, loose and light, and showing no tendency to be pendulous

Moderate, acceptable sheath on a 4-year-old bull. Borderline in our view, but selection is always a compromise & he has other highly desirable traits.

A protruding prepuce on a young 2-year-old polled bull. In this case, it is light and quite fine and retracted the majority of the time which is deemed acceptable for our program.

An 8-year-old female with a excellent navel flap that is clean and hanging close to the abdominal wall. The navel flap in females is believed to be correlated with sheath size in bulls

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For more information, please call me (Ashley) on 0408 780 810.

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