New
research indicates that weight loss resistant
horses may need further dietary restriction
New research confirms that some obese horses and
ponies may need to have their diets restricted
more severely than previously thought in order
to help them lose weight.
The studies were conducted by the Department of
Veterinary Clinical Science at the University
of Liverpool and funded by the government-initiated
Knowledge Transfer Partnership and the WALTHAM
Equine Studies Group. They showed that although
some obese animals will lose weight, in an appropriate
way, on a diet restricted to 1.25% of body weight
(dry matter basis) , others may need their diet
restricted to as little as 1% of body weight in
order to shift surplus pounds. Such animals have
been described as being ‘weight loss resistant’
in a recent report due to be presented at the
WALTHAM International Symposium in September.
The study, which was conducted over 16 weeks,
involved 12 overweight/obese horses and ponies
of mixed ages and breeds, with body condition
scores of between 7 and 9 (1 being emaciated and
9 being obese). They were individually housed
on wood-shavings and provided with a balanced
fibre-based diet at 1.25% of body weight. They
were allowed daily access to a bare paddock but
no structured exercise was given. Eight of the
horses achieved a slow, gradual but consistent
loss of body weight over the study period but
weight loss was much slower in the remaining four.
These four horses, deemed to be weight loss resistant,
were monitored for a further four weeks during
which their diet was reduced to 1% of body weight
daily. This significantly increased their rate
of weekly weight loss, to a level comparable to
the weight loss seen in the other eight horses
in the original study. It is thought that genetics
may account for such individual differences in
sensitivity to weight loss. In all cases the horses
remained healthy and no stereotypic behaviours
were seen.
Dr Caroline Argo explains: “It is important
to understand that the appetite of obese ponies
will drop to around 2% of body weight (dry matter)
yet their body weight will be maintained or they
may even continue to gain in weight. If weight
loss is to be stimulated, food intake must be
limited quite severely.”
Clare Barfoot BSc (Hons) RNutr, the research and
development manager for SPILLERS® and a member
of the research team continues: “Controlled
but balanced nutrition, under careful veterinary
guidance, is essential to promote weight loss
in overweight or obese horses and ponies, especially
when exercise is not an option but we have had
little evidence-based advice on how far the diet
can be restricted safely to help shed weight in
stubborn cases until now.”
“In
practice where exercise can be used to increase
energy expenditure, such severe restriction may
not be required; in this situation access to grazing
must be reduced, exercise increased and a low
calorie high fibre forage fed in a monitored way
alongside an appropriately formulated forage balancer.”
The WALTHAM® Equine Studies group was closely
involved with this study as it has been with other
ground breaking work on equine obesity, such as
showing that an obese body condition score was
associated with increased insulin resistance back
in 2003, and developing the cresty neck scoring
system.
