Ontogeny: Preparing the Foal for its Adult Life
Jan Ladewig
Institute of Animal Husbandry and Animal Health
The Royal Veterinary and Agricultural University
Copenhagen, Denmark
Voice  +45 35283031     Fax  +45 35283022      jal@kvl.dk

Introduction

From the time of birth till adulthood the young horse goes through a number of phases during which its species-specific behaviour pattern develops. This behavioural development is a result of hereditary behaviour programs and learned behaviour patterns. Some aspects of the development occur relatively independent of the environment, but others depend upon a certain stimulation from the environment. Thus, specific key factors must be present (or absent) in the environment during specific periods in order for a foal to develop normally. In contrast, if these specific key factors are absent (or present), the development does not proceed normally or the development of an abnormal behaviour pattern may result. In some cases such a course may be permanent and result in behaviour problems that last throughout life. 

In addition to the development of natural behaviour patterns, domestic horses must learn an additional behaviour repertoire. Much of this learning occurs unnoticed, but part of it is brought about through training. This learning about the domestic environment undoubtedly follows the pattern of the development of natural behaviour, and so may occur more effectively during specific periods. 

In order to raise horses that are optimally prepared for the various tasks, for which they are used, it is important to understand the different phases of behaviour development and what factors are important for this development. It is important that the young horse learns social communication with horses, and since most domestic horses live in some kind of social relationship with humans, it is equally important that the young horse learns social communication with humans. In addition, since normal development in many cases requires specific features of the environment, the way foals are housed is important. Considering the importance of these different aspects of horse husbandry, it is somewhat surprising how relatively few studies have looked at the behavioural development of the young horse and how most of our knowledge is based on general experience alone.

Stages of Development in the Foal

The time period from the embryonic state through birth till adulthood can be divided into various stages. It is important to realise, however, that it is a continuous process and that the transition from one stage to the next is far from clear-cut and that a large degree of individual variation can be seen as far as the age at which transition occurs.

During the neonatal period, which lasts only about two hours, the foal learns to stand and to walk. Similarly, although the search for the udder to a large extent is inherited behaviour, its perfection is certainly learned. The following two weeks represents the time of greatest sensory development. Consequently, too little sensory exposure can result in reduced sensory capacity. The period is characterised by the foal’s bonding to its mother. It remains close to her and learns behaviour strategies from her responses to the environment as well as from its own experiences.

Around four weeks of age the foal enters the socialisation phase during which social contact with its peers starts. Social play behaviour and mutual grooming is shown particularly during this phase, as well as appeasing behaviour towards adult horses (mouth clapping). From the fourth month onward, foals gradually become more independent from their mothers and progress towards adult patterns of spatial relationships, social interactions, and maintenance behaviours.

Ontogeny of Behaviour Patterns

Behavioural development is the result of the continuous interaction of genetic and environmental factors. The genetic code is fixed, but an animal will not develop appropriately without the right cues from the environment. Some behaviours are innate, such as suckling, standing, running, neighing, and mouth clapping. These behaviours are nearly complete the first time they are expressed although they are still fine-tuned and modified by learning. Innate behaviours tend to be triggered by fairly general events or impressions (e.g. sign stimuli), i.e. they are less open to modification by the environment. Learned behaviours take much longer to develop and are obviously much more affected by the environment. The advantage of learning is that it increases an animal's flexibility and the ability to adapt within one lifetime.

Thus, adaptation of behaviour occurs over generations by selection (innate behaviour), and is modified within the lifetime of the individual (learned behaviour). The way in which behaviour develops does not support a clear division, and the definitions of learned and innate behaviours are relative.

Environmental Influences on Behavioural Development

Optimal behaviour development means encouraging the development of the right skills at the right time. In the wild this often happens as a result of sensitive learning phases and interaction with certain horses at appropriate ages. In the domestic situation most horses are deprived of some of this opportunity to interact and learn from others. Specific and goal directed training can help to ensure the development of a confident and well-mannered horse with the fundamental skills, which it will require later in life. 

As far as the development of natural behaviour is concerned, the specific periods during which learning is achieved are termed critical or sensitive periods. The bonding which takes place between a mare and her foal may be called critical because if it does not occur within a relatively short time after birth, it may not occur at all. In contrast, habituation towards people may occur faster in a young foal, i.e. at a time when its natural tendency to react fearfully is less, as opposed to later when it is more inclined to react fearfully. Consequently, the earlier period could be termed sensitive. Thus, critical periods can be defined as periods during which a certain exposure must occur in order for behaviour change to happen, whereas sensitive period can be defined as periods during which exposure exerts a larger effect than at other times (Bateson, 1979).

The distinction between critical and sensitive periods is important in light of recent practice of exposure of newborn foals to various stimulation from humans, a practice that has been termed  “Imprint Training” (Miller, 1989; 2001) and the recent criticism of the method (Heird et al, 1986; Jezierski et al, 1999; Larose and Hausberger, 1998; Mal and McCall, 1996; Mal et al, 1994; Søndergaard and Jago, 2001; Williams et al, 2001). 

Rearing methods for foals under domestic conditions differ considerably from natural rearing conditions, e.g. in that many foals are stabled for part of the day or grow up with the dam only. Thus, the effects of the social environment in relation to housing can exert a large effect on behaviours such as social behaviour (e.g. play or aggressive behaviour; Søndergaard and Schougaard, 2000; Christensen et al, 2002), as well as influencing locomotory behaviour (Barneveld et al, 1999). In addition, most foals are prematurely weaned or fostered by humans or mechanical means.  A result of such management procedures is that many foals experience some degree of deprivation (Glendinning, 1974; Williams, 1974; Houpt and Hintz, 1983; Houpt et al, 1982).  Also the way weaning is imposed on the foal may affect its behavioural development (e.g. gradual weaning, short-time separations prior to weaning, weaning singly or in groups; Apter and Householder, 1996; Heleski et al, 1999; Houpt et al, 1984; McCall et al, 1985; Malinowski et al, 1990; Hoffmann et al, 1995; Moons and Zanella, 2001; Søndergaard, 1998). 

References

Apter RC, Householder DD (1996) Weaning and weaning management of foals: A review and some recommendations. J Eq Vet Sci 16: 428-435.

Barneveld A, van Weeren R, Knaap J (1999) Influence of early exercise on the locomotion system. 50^th Annual Meeting of the European Association for Animal Production, Zurich.

Bateson P (1979) How do sensitive periods arise and what are they for? Anim Behav 27: 470-486.

Christensen JW, Ladewig J, Søndergaard E, Malmkvist J (2002) Effects of individual versus group stabling on social behaviour in domestic stallions. Appl Anim Behav Sci 75: 233-248.

Glendinning SA (1974) A system of rearing foals on an automatic calf-feeding machine. Eq Vet J 6: 12-16.

Heird JC, Whitaker DD, Bell RW, Ramsey CB, Lokey CE (1986) The effects of handling at different ages on the subsequent learning ability of 2-year-old horses. Appl Anim Beh Sci 15: 15-25.

Heleski CR, Shelle AC, Nielsen BD, Zanella AJ (1999) Comparison of behavior and welfare in weanling horses under two industry-practiced weaning methods. Proceedings 33^rd International Congress of the ISAE, Lillehammer, Norway, p 96.

Houpt KA, Hintz HF (1983) Some effects of maternal deprivation on maintenance behavior, spatial relationships and responses to environmental novelty in foals. Appl Anim Ethol 9: 221-230.

Hoffmann RM, Kronfeld DS, Holland JL, Greiwe-Crandell KM (1995) Preweaning diet and stall weaning method influences on stress response in foals. J Anim Sci 73: 2922-2930.

Houpt KA, Parsons MS, Hintz HF (1982) Learning ability of orphan foals, of normal foals and of their mothers. J Anim Sci 55: 1027-1032.

Houpt KA, Hintz HF, Butler WR (1984) A preliminary study of two methods of weaning foals. Appl Anim Behav Sci 12: 177-181.

Jezierski T, Jaworski Z, Górecka A (1999) Effects of handling on behaviour and heart rate in Konik horses: Comparison of stable and forest reared youngstock. Appl Anim Beh Sci 62: 1-11.

Larose C, Hausberger M (1998) Effects of handling on the behaviour of foals. Proceedings 32^nd International Congress of the ISAE, July 21-25, Clermont-Ferrand, France, 120.

Mal ME, McCall CA (1996) The influence of handling during different ages on a halter training test in foals. Appl Anim Beh Sci 50: 115-120.

Mal ME, McCall CA, Cummins KA, Newland MC (1994) Influence of preweaning handling methods on post-weaning learning ability and manageability of foals. Appl Anim Beh Sci 40: 187-195.

Malinowski K, Hallquist NA, Helyar L, Sherman AR, Scanes CG (1990) Effect of different separation protocols between mares and foals on plasma cortisol and cell-mediated immune response. J Eq Vet Sci 10: 363-368.

McCall CA, Potter GD, Kreider JL (1985) Locomotor, vocal and other behavioral responses to varying methods of weaning foals. Appl Anim Behav Sci 14: 27-35.

Miller R (1989) Imprint training the newborn foal. Large Anim Vet 44: 18-22. 

Miller R (2001) Fallacious studies of foal imprint training. J Eq Vet Sci 21: 102-105.

Moons C, Zanella AJ (2001) Effect of short-term separations on weaning stress in foals. Proceedings 35^th International Congress of the ISAE, August 4-9, Davis, California.

Søndergaard E (1998) Reaction to separation on mares and foals. Proceedings 32^nd  International Congress of the ISAE, July 21-25, Clermont-Ferrand, France, 120.

Søndergaard E, Schougaard H (2000) The effect of social environment on feed intake, growth and health in young Danish Warmblood horses. 51^st Annual Meeting of the European Association for Animal Production, The Hague.

Søndergaard E, Jago J (2001) The effect of early handling of young foals on their subsequent reaction to humans, novelty and the foal-mare relationship. Proceedings 35^th International Congress of the ISAE, Davis, California, p 63.

Williams JL, Friend TH, Toscano MJ, Sisto AM, Nevill CH (2001) The effects of an imprint-training procedure on six month old foals. Proceedings 35^th International Congress of the ISAE, August 4-9, Davis, California, p 141.

Williams, M (1974) The effect of artificial rearing on the social behaviour of foals. Eq Vet J 6: 17-18.