Sheep exhibit remarkable diversity, with some breeds notable for the presence of horns. While many sheep breeds are known for their wool or meat production, horns are less common in female sheep, known as ewes. This makes breeds where ewes do grow horns particularly interesting.
Ewe Breeds with Prominent Horns
Several sheep breeds are recognized for ewes that commonly develop horns. The Dorset Horn is a well-established breed where both rams and ewes typically grow impressive, curving horns. Ewe horns are substantial, curving downwards and forwards, sometimes close to the face. The breed is also valued for its ability to lamb out of season.
Another breed where ewes consistently sport horns is the Jacob sheep. Jacob ewes are known for their distinctive spotted fleeces and often have two, four, or even six horns. Their horns vary in shape and size, with two-horned ewes typically having horns that curve upwards and outwards. This ancient breed originated in the Middle East and is popular globally for its unique appearance and heritage.
The Scottish Blackface is a hardy breed native to the Highlands of Scotland, where both sexes are horned. Ewes of this breed have horns that are smaller and more slender than those of the rams, typically curving backward and then slightly upwards. These sheep are renowned for their adaptability to harsh upland environments, thriving on sparse grazing. Their horns are a consistent characteristic across the breed.
Other breeds, such as the Navajo-Churro, also feature horned ewes. The Navajo-Churro sheep is a historically significant breed in the American Southwest, known for its long, coarse wool and horns in both sexes. Ewe horns can vary in shape, often sweeping outwards and backwards. This breed is valued for its hardiness and traditional use in textile production by the Navajo people.
Genetic and Hormonal Influences on Horn Presence
The presence or absence of horns in sheep is primarily determined by genetics, involving the “polled” gene. This gene has different alleles that dictate whether an animal will develop horns. Horn development is a complex trait influenced by multiple genes.
Hormones also play a significant role in horn growth, particularly sex hormones like testosterone. While testosterone is present in higher concentrations in rams, it also exists in ewes, albeit at lower levels. The interaction between genetic predisposition for horn growth and hormone levels influences horn development in ewes. Even with the genetic potential for horns, lower testosterone levels in ewes typically result in horns that are smaller and less massive compared to those of rams.
The horn trait is sex-influenced, meaning the same genes can produce different outcomes in males and females. For example, a genetic combination leading to large horns in a ram might result in smaller horns or no horns in a ewe. This hormonal influence explains why horn size and shape often differ between horned rams and ewes within the same breed.
Characteristics and Growth of Ewe Horns
Ewe horns are composed of keratin, the fibrous protein found in hooves and hair. They grow from specialized bony outgrowths of the skull, called horn cores, covered by a skin layer that produces the keratin sheath. Horns are permanent structures that continue to grow throughout an animal’s life.
Horn growth is not always uniform; environmental factors, nutrition, and reproductive status can influence the rate, sometimes leading to visible growth rings. These rings can indicate the ewe’s age or periods of stress or nutritional changes. Ewe horns are generally more slender and exhibit less curvature than rams’ horns, often growing in a more upright or backward-sweeping direction. While horns offer some protection, their primary function in ewes is less pronounced than in rams, where they are often used in dominance displays or territorial disputes.