Many stallions lead largely solitary lives, but it need not be that way, the authors of a just-published review have concluded.
Researchers with the Free University of Berlin concluded that many stallions could be kept safely in groups, provided key conditions are met.
“It only poses a risk for injuries if the necessary requirements for this type of husbandry are not taken into account,” Heidrun Gehlen, Katrin Krumbach and Christa Thöne-Reineke wrote in the open-access journal Animals.
Crucial elements for safety include the absence of mares, a suitably sized area or pasture that provides good escape routes, suitable groupings that take into account the character of the stallions, multiple feeding and drinking places, as well as suitable lying and resting areas.
If such conditions can be met, then keeping stallions in groups represents the most species-appropriate form of husbandry for them, the trio concluded.
“Horses are very social animals that live in groups in the wild, and husbandry methods in recent years have increasingly aimed at species-appropriate management in groups,” they said.
“By contrast, however, stallions are still kept in the traditional way and, according to a survey from a province in Germany in which 20 farms keeping breeding stallions were examined, 74% of the stallions are still kept individually in indoor stalls.”
Gehlen and her fellow researchers set out in their review to determine whether stallion husbandry in groups was possible and desirable, or posed risks.
They examined a range of published studies, including a paper on an experiment at the Swiss National Stud on changing to group husbandry for stallions and its influence on animal welfare.
In all, the researchers analyzed material from 50 different sources.
“The results revealed that stallion husbandry in groups is possible but still rarely practiced,” they said. However, German research papers indicated a trend toward more group housing of stallions.
The review said repeated studies have shown that the still widespread individual husbandry of stallions has a negative impact on their psyche and body health.
“Almost half of all stallions showed undesirable patterns of behavior, mostly stallions in individual housing. In addition, many of the latter stallions had problems with their respiratory, digestive, and musculoskeletal systems, which improved when the husbandry conditions of the horses were changed, with the exception of problems with the digestive system.”
Problems arising from what they termed solitary confinement can center around behavior and handling.
The experiment at the Swiss National Stud involved breeding stallions being kept in a group outside the breeding season for a six-month period.
Stallions were socialised into the group, which lived in a four-acre pasture. Their time at pasture was preceded by a two-week acclimation period in neighboring stalls, where they were able to make contact with each other for the first time before being transferred outside with sufficient escape routes, a high number of feeding places, and no mare contact.
“Only minor injuries were observed, as well as a decrease in aggressive behavior during the first four days.
“The stallions played with each other and established social contact in the form of mutual grooming, which had a positive effect on the mental and physical health of the animals.
“A generally friendlier and more relaxed attitude toward humans was observed.”
The stud continued to put stallions in groups of 5–12 stallions each year. The stallions were found to display more ritual than agonistic interaction.
“This is important because ritual interaction does not involve any risk of injury.”
The review team said the unanimous tenor of the studies is that keeping stallions in groups is possible, and has a positive influence on the mental and physical health of the animals.
They acknowledged that unpredictable situations can always arise suddenly when stallions are kept in groups.
“There are also stallions with social problems that generally cannot be integrated into a group, for example, due to years of isolation.”
Alternatives to group housing are required for such horses, they said. Group housing is also rather unsuitable for farms where horses change frequently, they said.
“There are species-appropriate alternatives to keeping stallions in groups, some of which can also serve as an interim solution on the path to long-term species-appropriate keeping in groups through habituation.”
For example, a stallion could be boxed at night and allowed out during the day with a gelding, which is usually not problematic for them.
“In this way, the stallion is not kept alone in the box all the time.
“It is very rare that this is not possible and that the stallion is better off left alone. However, if this is the case, at least visual, auditory, and olfactory contact between the stallions should be possible.”
Boxes with the possibility of physical contact and withdrawal, in which the stallions stand next to each other, would be suitable for this purpose, they said.
“Another option is to keep the stallions separated in paddock boxes, ideally with adjacent pasture, as this allows social contact to be maintained across the fence. However, if the stallions are particularly incompatible, the adjacent paddock and pasture should be kept free.”
“Lastly, it should always be noted that castration should also be considered for animal welfare reasons for stallions that are not used for breeding and cannot be integrated into a species-appropriate husbandry.”
The authors said that although the prevailing assumption that stallions cannot be kept in groups may seem antiquated, it is important to recognise the safety requirements required around group management.
“Group husbandry can only be successful if the stress and discrimination of individual horses are avoided as much as possible, and it must be based on the premise of preventing injuries.
“The individuality of the respective stallion and that of the other group members, as well as the conditions on the respective farm, must be considered. This includes, above all, sufficient space.”
Different amounts of space are required depending on the group and the varying need for individual distance of each stallion. The design of the space available is also important.
“Dividing the space into functional areas prevents a concentration of horses and facilitates simultaneous care of all horses, which also minimizes the risk of injury. Dead-end situations must be avoided, and retreats for lower-ranking horses must be available.
“A sufficient number of separate feeding and drinking places, as well as lying and resting areas, must be available in order to avoid stress and injuries.”
This, they said, represents the needs of all horses regardless of their breed.
“The individuality of stallions should not be disregarded. Not every stallion is suitable for group housing.”
Social shortcomings and a high level of aggression can prevent integration.
Success rates for group husbandry will be influenced by the individual character of the stallion, its previous experience, changes in the group, management of the farm, and the organization of the group housing and husbandry system.
It could be beneficial if grouping took place outside the breeding season and mare contact was avoided.
“In conclusion, the keeping of stallions in groups is possible in principle,” they said.
“It only poses a risk if the necessary requirements for this type of husbandry are not taken into account.”
They said the integration of a stallion into an existing group should be carried out only by qualified and experienced horse owners, who must proceed professionally and step by step.”
Gehlen, H.; Krumbach, K.; Thöne-Reineke, C. Keeping Stallions in Groups—Species-Appropriate or Relevant to Animal Welfare? Animals 2021, 11, 1317. https://doi.org/10.3390/ani11051317