The purpose of this study was to determine the daily energy requirements of
ponies native to the U.K., living on upland areas. This information can be used to
improve the management of ponies kept under these conditions.
The objectives of this thesis were to i) determine the effects of speed and terrain
on the energy costs of ponies when walking, ii) measure seasonal differences in the hair
coat, iii) estimate the effect of a wet winter coat on metabolic rate, iv) determine the
proportion of a day spent by free-living ponies in feeding, walking, standing and lying,
v) estimate the total distance moved daily by these ponies, and vi) describe the
relationship between weather conditions and the behaviour and location of ponies.
In the first study, the energy costs of walking were measured in four Shetland and
two Exmoor ponies by using open-circuit, indirect calorimetry. The energy cost of
activity, above that for standing, was independent of speed and averaged 1.02 J/kg
liveweight/m travelled. An Oxylog, a portable breath-by-breath oxygen analyser, was
used to determine effects of terrrain on the energy cost of walking using five Shetland
ponies. The mean (s.e.) energy expenditures (J/kg/m) were:- grass 1.7 (0.07); concrete
2.9 (0.15); 12 cm of mud 5.9 (0.21); uphill (+5.8°) 5.5 (0.31); downhill (-5.8°) 3.3 (0.23)
J/kg/m.
In the second study, physical parameters of the winter and summer hair coats of
six Shetland ponies were compared. Also, metabolic rate was monitored as a means of
assessing the effect of wetting ponies in winter coat. Coat density in the winter
2 • 2
averaged 96.2 (s.e. 8.01) mg/cm , 3.24 times the summer value of 29.5 (3.37) mg/cm .
Fibre diameter differed significantly between ponies within season. For some ponies
there were seasonal changes in fibre diameter. The number of fibres/cm" did not differ
significantly between seasons. Metabolic rate (determined by open-circuit, indirect
calorimetry) and body temperature were unaffected by wetting (to the skin) the dorsal
surface of Shetland ponies in winter coat. However, there were decreases in skin
temperature over the wetted area which suggested local vasoconstriction
In the third study, six Exmoor pony mares, kept in an enclosed area of fell in
Cumbria, were observed in late winter (W) when they were pregnant, and in summer (S)
when they were lactating. There were significant seasonal differences in the time spent
feeding 17.2 h (W), 13.5 h (S); walking 0.5 h (W), 1.2 h (S); and standing 4.6 h (W), 6.2
h (S); but not in lying 1.3 h (W & S). The total distance moved by the mares in 24 h;
3.1 - 5.7 km (W) and 3.7 - 4.9 km (S), was calculated as the sum of the distances moved
whilst grazing and walking. In winter, ponies preferentially grazed facing directly into
or away from the wind at all wind speeds, and preferred to stand in areas where wind
viii
speed was reduced. In the summer, the same orientations to the wind became evident at
wind speeds of 5 m/s. Ponies stood in the most exposed areas during the hottest parts of
the day, but stood in sheltered areas at night. Grazing speed and bite rate were
significantly greater (P<0.05) in the winter than in the summer
The results showed that the energy costs of activity (walking and grazing) were
greater in winter than in summer. Therefore, seasonal adjustments in energy
requirements are needed to allow for changes in activity as well as changes in heat loss.
Recommendations are made regarding the management strategies for ponies kept
outdoors.
