To be or not to be horned—Consequences in cattle

Abstract

In cattle, both males and females of horned breeds have permanent horns which are directly connected with the frontal sinuses of the skull and are growing during their entire life. To date a large proportion of cattle is disbudded or dehorned, or increasingly bred for polledness. This review explores the possible consequences of cattle having horns or not, both for the cattle themselves and for the farmers. During natural selection horns may have provided advantages concerning predator defence or in competition for mates and resources. Additionally, there are indications that horns serve as honest signals in mate selection, as they reflect individual health. Presence or absence of horns will likely affect quality and quantity of social interactions as well as social relationships in a herd. It clearly affects the way of cattle fighting. Only few studies deal with social behaviour in horned herds in comparison to hornless herds, and they rely on single herd observations or need to be interpreted with caution because of confounding factors. However, it appears that horned cattle attempt to keep greater inter-individual distances and resort less to physical interactions than hornless cattle, leading to more stable social relationships under suitable environmental conditions and management. Cattle may, furthermore, use horns for self-grooming of body regions which are otherwise out of reach. Even less is known on possible physiological functions of horns. While there is good evidence regarding a thermoregulatory function, other claimed functions, e.g. concerning digestion, have not been scientifically investigated yet. Although farmers in favour of keeping horned cattle, for instance for ethical reasons, are able to reduce the increased risk of animal injuries and human accidents by providing improved housing and management conditions and maintaining a good human–animal relationship, it may be economically advantageous to keep hornless cattle. If disbudding/dehorning is carried out, the consequences in terms of stress and pain can be alleviated by a combination of local anaesthesia and anti-inflammatory treatment, as well as sedation of animals insufficiently used to handling. However, possible negative side effects of sedation should be addressed in future studies. Furthermore, the possibility of longer lasting pain after disbudding/dehorning is not sufficiently investigated yet. Finally, it is an open question whether the removal of horns alters the social behaviour of the animals, or is a mere symptomatic measure to adjust them to husbandry conditions that are insufficiently adapted to the species-specific needs of cattle.