The
Impact of Nutrition and Feeding Practices on Equine Behaviour and Welfare
HPB
Davidson
Equine Studies Group, Waltham Centre for Pet
Nutrition, Leics, UK
Voice +44 1664 415530
Fax +44 1664 415440
nell.davidson@eu.effem.com
Introduction
There
is considerable variation in the management and feeding practices of the
domestic horse across the world (Harris, 2000). This reflects their
historical use and management, their current role, and the availability
and cost of suitable environments and feedstuffs. To what extent these
practices simulate a natural environment varies with each geographical
location and the purpose for which the horse is kept (e.g. horses in
Australia or North America tend to be managed on pastures to a greater
extent than those in Northern Europe). This management factor has an
impact on welfare, indicated by the lower incidence of Recurrent Airway
Obstruction for which one of the exacerbating factors is poor stable
ventilation and dusty bedding and hay. In addition to the available
resources, the desire for convenience to the owner/manager and a
perception of increased efficiency influences how the horse is managed.
In
an ideal world all horses would be given 24-hour access to appropriate
grazing, the constant companionship of con-specifics and freedom to
procreate. However such liberty would seriously limit their usefulness
(perceived and actual) to the majority of horse users. Limiting the uses
for which horses can be kept may result in an increase in the number of
abandoned/euthanized horses or a decline in the domestic horse population.
It may be that fewer horses kept in optimum conditions is far more
desirable than many managed sub-optimally, though there is room for debate
around the definition and range of sub-optimal conditions and their real
effects upon the well-being of the horse. It is probably more realistic
that we strive to strike a balance between the physiological and
psychological needs of the horse and the needs of the user.
This
abstract highlights a few of the areas in which nutrition and feeding
practices impact on the behaviour and welfare of the horse.
Nutrition
and Feeding Practices Impact on Welfare
The
horse has evolved specific digestive physiology and anatomy around its
natural diet (i.e. high fibre grazing and browsing) and feeding behaviour
of “trickle feeding” for long periods (Harris, 1999a). Any animal kept
under unnatural conditions, such as being stabled and offered high cereal,
large volume infrequent meals may have their welfare compromised.
For example, the horse only produces saliva when it chews – the
saliva lubricates the passage of food and buffers the acidic environment
of the stomach. Feeding the horse large, cereal-based, discrete meals has
an effect throughout the digestive system due to the low fibre and high
hydrolysable carbohydrate content. Undesirable consequences include a
reduction in the amount of saliva produced, which would allow the stomach
to remain more acidic for longer and, therefore, may allow undesirable,
gas-producing bacteria to survive (Meyer et al, 1975; Harris, 1999b) The
larger volume will mean that the food is pushed through more quickly to
the small intestine and hind-gut, increasing the risk of gastrointestinal
disturbances due to changes such the lysis of certain bacteria releasing
endotoxins which may be absorbed, increasing the risk colic, diarrhoea and
laminitis (Harris, 1999a).
There
are many areas of concern which are either directly caused, are
exacerbated by or could be improved with nutrition and/or particular
feeding practices (Davidson and Harris, 2002), such as:
General
Inappropriate Nutrition
Any
horse whether it is a healthy adult horse or a “vulnerable” horse
(i.e. those going through a “stressful” period, e.g. neonate, foal,
weanling, pregnant or lactating mare, senior, performance horse) can be at
risk if the appropriate nutrition is not offered. Different lifestages,
horse types, disciplines and workloads have different nutritional
requirements. Horses need to have their diet tailored and changed as their
role changes, and while each discipline has traditionally dictated how the
horse is managed and fed, we should discourage any practices that require
the horse to be maintained outside a healthy range or beyond its inherent
ability. Two examples are ponies and foals: Ponies are often allowed to
become obese and are then put on starvation diets – this “see-saw”
feeding can be dangerous and puts the pony at risk of conditions such as
laminitis and hyperlipaemia. Developmental Orthopaedic Disease (DOD) in
young horses, while multifactorial, is thought to be exacerbated by
feeding inappropriate and unbalanced diets to promote fast growth rates (Kronfeld
et al, 1990; McIlwraith, 2001).
High
Cereal/Low Forage Diets
The welfare implications of
feeding high cereal/low forage diets are immense and beyond the scope of
this abstract, but in short, the horse’s digestive system has a finite
capacity for hydrolysable carbohydrates. Feeding large quantities of
cereals has been linked to a number of conditions, e.g. laminitis,
gastrointestinal disturbances, gastric ulcers and oral stereotypies. There
are two particularly vulnerable members of horse society – racehorses
and foals. Thoroughbred racehorses tend to be stabled for very long
periods, have limited access to grazing and are fed low forage/high cereal
diets, this is reflected in a higher incidence of gastrointestinal ulcers
(Murray et al, 1996) and behavioural stereotypies (Nicol, 1999) compared
to horses of other breeds and disciplines. However, in order to fulfill
their role they need high energy diets, one positive outcome of
nutritional research is the role of supplementary fat (usually vegetable
oil) as a means of providing more energy to horses without using cereals (Kronfeld
and Harris 1997). As long as the diet is balanced for the additional fat,
e.g. Vitamin E should be increased, there are thought to be a number of
advantages including increased rate of
fat mobilisation from the fat stores, glycogen sparing and better muscle
glycogen utilisation during sprinting activities.
There
is also a high prevalence of gastrointestinal ulcers found in foals,
Murray (1989) found 51% of foals (< 3 months old) studied, showed
lesions. While foals are not immediately associated with high cereal
diets, there are a number of factors that impinge upon the foal’s
well-being. A foal’s gastric mucosa is not fully developed at birth,
making it susceptible to lesions. In addition, if foals have access to or
are fed high cereal diets (e.g. the dam’s diet, weanling diets, or for
fast growth rates) this can exacerbate conditions, add to this a stressful
weaning and the foal’s welfare is at risk. Oral stereotypies, in
particular crib-biting in adult horses, have long been associated with
high cereal/low fibre diets (McGreevy et al, 1995). Recent work by Nicol
et al, 2001 has shown that crib-biting in foals is associated with gastric
inflammation and ulceration. It is crucial that we determine and encourage
weaning and feeding practices that minimise this risk.
Monotonous
Diets
In
the wild the horse forages (grazing and browsing) from a diet that varies
daily and seasonally (Gill, 1988; Hansen, 1976; Ralston, 1984). Given the
opportunity, and dependant on the quality and quantity of forage
available, horses will feed for up to 16-18 hours a day (Avery, 1996; Nash
and Thompson, 2001). Horses kept under restrictive conditions (e.g.
monoculture grazing, stabling) have reduced opportunity to forage as well
as a lack of autonomy over their food choice and a restricted and
monotonous menu. In the stabled horses studied by Goodwin et al (2001), a
preference was shown for the stable containing multiple forages versus the
stable with only a single forage available. In addition, the horses in the
single stable spent longer foraging in their straw bed and showed more
behaviours that were indicative of food seeking. This has suggested to us
that providing the horse with more than one source of forage will offer a
more realistic feeding opportunity and may discourage unwanted behaviour
such as bed-eating.
Recurrent Airways Obstruction (RAO)
There are many diseases that,
although they will not be cured or prevented by particular feeding
practices or nutrition, may be assisted if the appropriate dietary steps
are taken. RAO (previously known as Chronic Obstructive Pulmonary Disease)
is one such condition. The pathophysiology of RAO is not yet fully
understood but is believed to be multifactorial. Subsequent obstruction of
the airway is thought to be due to a hypersensitivity reaction to inhaled
antigens. It can be exacerbated by specific allergens and non-specific
irritants such as dusty bedding and hay. Research has suggested that oxidant/antioxidant imbalances may be involved in a number of
conditions, including those that affect lung health such as RAO. Recently
ascorbic acid (Vitamin C) levels were found to be lower in the lung
Epithelial Lining Fluid (ELF) and plasma of horses with RAO compared to
those of healthy horses (Deaton et al, 2001; Marlin et al, 2001).
Kirschvink (2001) suggests that feeding an appropriate antioxidant
cocktail may modulate the oxidant/antioxidant balance and airway
inflammation, thus improving lung function of horses in remission.
Supplementation
Horses
receive supplements for many reasons, e.g. to improve either perceived or
real shortfalls in health, condition, behaviour or performance. If a
well-balanced diet, tailored for the horse’s role is not providing all
the nutrients that are required then correct supplementation may provide
some benefits. However, there are a number of areas for concern.
Additional nutrients may unbalance the diet, while any “super-dosing”
of nutrients may cause toxicity issues. Many supplements have little or no
proof of efficacy (Harris and Harris, 1998; Davidson, 1999), and have
claims that are unsubstantiated. Possibly the two greatest welfare issues
around supplements are the use of pain relief to enhance performance and
the often indiscriminate use of behavioural modifiers. Pain management
should be undertaken with the advice of a veterinary surgeon and the
knowledge that pain often serves to prevent further damage being caused
while the body repairs itself. As there are now many pain relief
supplements, available over the counter, there is a great risk of abuse,
through inappropriate usage.
The
other supplement area of concern is the management of behaviour problems.
Behavioural modification through both dietary intervention (e.g.
supplements that induce sedation) and behavioural modification techniques
(e.g. “flooding”) has increased exponentially, and is often carried
out without the appropriate advice and by people with little or no
understanding of the ontogeny of behavioural problems. The supplements
available for behavioural modification, as with many others, have rarely
been clinically tested and may in fact mask the problem or exacerbate it,
and it is vital to determine the true cause of the problem as in many
cases the source may be pain (Casey, 1999). While it may be appropriate
and beneficial to make dietary changes (e.g. reducing the absolute calorie
intake or the source of part of the calorie intake from hydrolysable
carbohydrates to fat, increasing forage), diet is only one management
factor that may need addressing. It is advisable that the determination of
the problem and the subsequent treatment is carried out with advice from
those trained in this field, otherwise the safety of people and the
welfare of the horses may be compromised.
Conclusions
Good nutrition and feeding
practices are essential to the well-being of the horse. While there are a
few examples where nutrition will enhance the performance of a horse
(although you cannot increase intrinsic ability), there are far more
instances where poor nutrition may seriously limit health and potential.
Any investigation into the welfare conditions of horses should include an
evaluation of the nutrition and feeding practices. Conversely, the advice
we give on what and how to feed horses directly impacts on their welfare
and should be given with that in mind.
References
Avery
A (1996) Pastures for Horses A Winning Resource. RIRDC Gillingham Printers,
Adelaide.
Casey
RA Recognising the importance of pain in the diagnosis of equine behaviour
problems In Harris
PA, Gomarsall G, Davidson HPB, Green R (Eds),
Proceedings BEVA Specialist Meeting on Nutrition and Behaviour.
Newmarket: Equine Veterinary Journal Ltd, pp 25
–28.
Davidson
HPB (1999) Herbs – a sage of all wisdom or a waste of thyme? In Harris
PA, Gomarsall G, Davidson HPB, Green R (Eds),
Proceedings BEVA Specialist
Meeting on Nutrition and Behaviour.
Newmarket: Equine Veterinary Journal Ltd, pp 32-34.
Davidson
HPB, Harris PA (in press, 2002) Nutrition and Welfare. In Waran N (Ed), The
Welfare of Horses. Kluwer
Academic Publishers, The Netherlands.
Deaton
C, Marlin DJ, Smith N, Roberts C, Kelly F, Harris P, Schroter RC (2001)
Systemic and pulmonary bioavailability of two different forms of ascorbic
acid in equids. In Proceedings Waltham Inter Symp, pp 88.
Gill
EL (1988) Factors affecting body condition of New Forest ponies. PhD
thesis Department of Biology, University of Southampton.
Goodwin
D, Davidson HPB, Harris PA (2001 in press) foraging enrichment for stabled
horses: effects on behaviour and selection. Eq Vet J.
Hansen
RM (1976) Foods of free roaming horses in Southern New Mexico .
J Range Mngt 29(4): 437.
Harris
PA (1999a) How understanding the digestive process can help minimise
digestive disturbances due to diet and feeding practices.
In Harris PA, Gomarsall G,
Davidson HPB, Green R (Ed), Proceedings
BEVA Specialist meeting on Nutrition and Behaviour. Newmarket: Equine Veterinary Journal Ltd, pp 45-50.
Harris
PA (1999b) Feeding and management advice for Tying up. In Harris
PA, Gomarsall G, Davidson HPB and Green, R (Eds),
Proceedings BEVA Specialist
meeting on Nutrition and Behaviour.
Newmarket: Equine Veterinary Journal, pp 100-104.
Harris
PA (2000) Feeding Practices in the UK and Germany. In Proceedings
Equine Nutrition Conference for Feed Manufacturers,
KER Inc, pp 241-267.
Harris
PA, Harris RC (1998) Nutritional ergogenic aids in the horse – uses and
abuses. In Lindner A (Ed), Proceedings
of the Conference on Equine Sports Medicine and Science. Wageningen
Press, The Netherlands, pp 203-218.
Kirschvink N, Fievez L,
BounetV, Art T, Degand G, Smith N, Marlin D, Roberts C, Harris P, Lekeux P
(in press, 2001) Effect of nutritional antioxidant supplementation on
systemic and pulmonary antioxidant status, airway inflammation and lung
function in heaves-affected horses. Eq
Vet J.
Kronfeld
DS, Meacham TN, Donoghue, S (1990) Dietary aspects of developmental
orthopedic disease in young horses. Vet
Clinics of N Am: Equine Pract 6 (2): 451 – 465.
Kronfeld
DS, Harris PA (1997) Feeding the equine athlete for competition. In The Veterinarians Practical Reference to Equine Nutrition. Purina
Mills and AAEP, pp 61-79.
Marlin DJ, Deaton CD, Smith
NC, Roberts CA, Kelly F, Harris P, Schroter RC (2001) Development of a
model of acute, resolving pulmonary oxidative stress in the horse by ozone
exposure. In Proceedings World
Equine Airways Symposium, Edinburgh,
pp 30.
McGreevy
P, Nicol CJ, Cripps P, Green L, French N (1995) Management factors
associated with stereotypic and redirected behaviour in the thoroughbred
horse. Eq Vet J 27: 86-91.
McIlWraith CW (2001)
Developmental orthopaedic disease (DOD) in horses a multifactorial
process. Proceedings 17th
Symposium of Equine Nutrition and Physiology Society, pp 2-23.
Meyer H, Ahlswede L,
Reinhardt HJ (1975) Untersuchungen uber Frebdauer, Kaufrequenz und
Futterzerkleinerung beim Pferd .Deutsche
Tierarzliche Wochenschrift 82: 49-96.
Murray MJ, Grodinsky C,
Anderson CW, Radue PF, Schmidt GR (1989) Gastric ulcers in horses: a
comparison of endoscopic findings in horses with and without clinical
signs. Eq Vet J Suppl 7: 68-72.
Murray
MJ, Schusser GF, Pipers FS, Gross SJ (1996) Factors associated with
gastric lesions in Thoroughbred horses. Eq
Vet J 28(5):368-374.
Nash DG, Thompson B (2001) Grazing behaviour of
Thoroughbred weanlings on temperate pastures.
Proceedings 17th Equine Nutrition and Physiology Symposium,
pp 326-327.
Nicol
CJ (1999) Stereotypies and their relation to management. In Harris
PA, Gomarsall G, Davidson HPB ,Green R (Eds),
Proceedings of the BEVA
Specialist Meeting on Nutrition and Behaviour.
Newmarket: Equine Veterinary Journal Ltd, pp 11-14.
Nicol CJ, Davidson HPB, Harris PA, Waters AJ, Wilson AD
(2001 in press) Crib-biting is associated with mucosal
inflammation and ulceration in young horses Eq
Vet J.
Ralston SL (1984) Controls of feeding in
horses. J Anim Sci 59(5): 1354-136.
|
