An equal mix of barley hay and straw proved effective in encouraging winter weight loss among ponies, researchers in Britain report.
Researchers carried out the study, which involved 40 ponies, at the Redwings Horse Sanctuary.
The issue of obesity among British equids has been widely reported, with almost 30% of horses and ponies classified as overweight or obese in the country.
Native breeds, such as Welsh Cobs, Exmoor and Shetland ponies, seem particularly susceptible to weight gain and owners often struggle to get the weight off. Obesity is also linked to an imbalance in hormones, including insulin and cortisol, which can cause laminitis.
Dr Ruth Morgan and her colleagues, in a short communication in the journal Veterinary Record, point out that achieving weight loss among obese horses and ponies at risk of laminitis is an important but often challenging objective.
The study team hypothesised that supplementing poor winter pasture with a 50:50 mix of barley straw and hay and rather than hay alone would lead to weight loss in grazing ponies over winter.
The 40 overweight ponies were divided into two groups, one of which received the hay/straw mix, while the others received hay alone.
Over the study period, all 25 animals that received the hay/straw mix lost weight, dropping an average of 27kg. Among the 15 animals who received hay only, only three lost weight. Overall, the hay-only group gained weight, with an average of 6kg per animal.
“This study suggests that straw is a cost-effective and low-energy roughage, which may be a useful alternative to hay alone when trying to induce weight loss in grazing equids over winter,” the study team concluded.
“There were no episodes of colic or laminitis during the study period in either group.”
Redwings cares for a large population of native ponies, with their diets often supplemented with hay during the winter when the grass is poor.
However, its vets had concerns that some ponies were still gaining weight, putting them at a higher risk of laminitis in the spring and summer.
They joined with researchers at the University of Edinburgh to see if they could come up with a way to safely encourage weight loss in these ponies over winter, so any weight they gain on spring grass wouldn’t have such an impact on their hormones.
While there is an anecdotal risk of colic in ponies who are fed straw, there were no such incidents recorded throughout the study.
Roxane Kirton, who undertook the study while working as a welfare veterinary surgeon at Redwings, said: “This was a significant result for Redwings, and will hopefully be a useful study for all owners of native ponies, as we had previously found it very difficult to help this particular group lose weight.
“With such a large horse population to care for, we can’t and don’t want to put every pony on a crash diet. Restricting food has such an impact on a horse’s behaviour and welfare, so we were keen to look at more creative, long-term management options.
“When discussing human obesity, we often talk about making sustainable lifestyle changes and it shouldn’t be any different for horses.”
Dr Morgan, a researcher at the University of Edinburgh, added: “Straw is much lower in calories than hay and it takes horses longer to eat it as it is less digestible.
“Both of these features are great, both for weight loss and for the welfare of the horses, who like to eat for up to 20 hours a day.
“We’ve all watched horses scoff all their hay allowance in a short period of time and then stand watching us by the gate.
“Straw occupies the horses for much longer but without increasing their calorie intake.
“We would, however, warn owners to make sure their pony’s teeth are in good shape before introducing straw as it does take more chewing — this will also reduce the risk of colic. We hope the success of the trial means this research will go on to help even more ponies.”
The study team comprised Morgan, Kirton, Miranda Carlotta Maria Dosi, Sarah Hallsworth and John Keen.
Inducing weight loss in native ponies: is straw a viable alternative to hay?
Miranda Carlotta Maria Dosi, Roxane Kirton, Sarah Hallsworth, John A. Keen and Ruth Anna Morgan.
Vet Record, http://dx.doi.org/10.1136/vr.105793
The abstract can be read here.