Bulls, like all cattle, can either possess horns or be naturally hornless. While many breeds traditionally grow horns, genetic factors or human intervention can result in bulls without them. This means that encountering a bull without horns is a common occurrence in modern agriculture.
Natural Horn Variation
The presence or absence of horns in cattle is primarily determined by genetics, specifically a trait known as “polled.” This polled trait is dominant, meaning an animal only needs one copy of the polled gene to be hornless. Conversely, a horned animal must inherit two copies of the recessive horned gene, one from each parent. Therefore, breeding for polled cattle is a non-invasive way to ensure hornless offspring.
Numerous cattle breeds are naturally polled. Examples include Aberdeen Angus, Red Angus, Hereford (specifically Polled Hereford), and Galloway. In contrast, breeds like Holstein, Charolais, and Texas Longhorn are typically born with horns. Even within traditionally horned breeds, some individuals may carry the polled gene. Homozygous polled bulls will produce hornless calves regardless of whether the female is horned or polled.
Human Intervention and Horns
Human practices significantly influence whether a bull has horns. Dehorning and disbudding are common procedures performed to remove or prevent horn growth. Disbudding involves destroying the horn-producing cells (horn buds) in young calves before they attach to the skull, typically within the first few weeks or months of life. This method is less invasive and causes less pain than dehorning mature horns.
Reasons for these interventions include safety for handlers and other animals, as horns can cause injuries. Horned cattle also require more space during transport and at feed bunks, and horns can become entangled in fences. Common disbudding methods include chemical pastes or hot irons. Dehorning, performed on older animals with established horns, is a more involved procedure using tools like dehorning saws or scoops. Pain management, such as local anesthetics and anti-inflammatory drugs, is recommended for these procedures.
What are Horns?
Horns are permanent structures found on the heads of some animals, including cattle. They are distinct from antlers, which are shed and regrown annually. A horn consists of a bony core that extends from the skull, covered by a layer of keratin.
Horns begin to grow shortly after birth and continue growing throughout the animal’s life, although growth slows with age. The bony core is hollow and connects to the animal’s sinus cavity. In natural settings, horns serve various functions, such as defense against predators, establishing dominance within a herd, and aiding in self-grooming. Some theories also suggest horns may play a role in thermoregulation.