Recent research suggests wood shavings may not be as unpalatable to horses as generally supposed – especially for those on diets.
Ponies on a restricted diet can resort to eating their bedding, and wood shavings are often suggested as a good bedding material to discourage such behaviour.
However, horses and ponies on a severely restricted diet may actually consume considerable quantities of wood shavings, the latest issue of Equine Science Update reports.
The study was conducted by Gemma Curtis, from the Liverpool University Veterinary School, assisted by colleagues, and in collaboration with Clare Barfoot and Dr Pat Harris of the Equine Studies Group at the Waltham Centre for pet nutrition.
The aim was to compare the response of overweight ponies to two different restrictive diets: one of hay and chaff; the other of hay and feed balancer.
Two groups of six overweight ponies were put on one of two diets which provided food equivalent to only 1.25% of their body weight daily. The two diets were isoenergetic – each providing similar amounts of energy despite different composition. The ponies were weighed weekly and the food allowance adjusted accordingly.
The study was conducted during a 16-week period in the northern winter, from October to February. Each day, the ponies were turned out for 30 minutes exercise in grass paddocks, wearing anti-grazing muzzles.
Despite all ponies eating a similar amount of food, their faecal output varied (from ·52 per cent to 1·16 per cent of body weight daily.
Analysis of the data revealed wide ranges in apparent digestibility, which were improbably low for some animals. In fact, some animals appeared to excrete more than they had eaten, in terms of gross energy (GE) and acid detergent fibre (ADF).
The researchers suggest that the only biologically plausible explanation for the figures was that at least half of the animals had been supplementing their diet from an alternative “non-feed” source.
By comparing the expected feed digestibilities with the values obtained in the study, they calculated the quantities of wood shavings ingested. Some ponies had eaten negligible amounts, but others had eaten more than 3kg a day. Almost half (five of the 12) appeared to have consumed over 1kg of wood shavings a day.
They concluded that feed-restricted animals should be carefully observed, and where wood shaving ingestion is recognised or indicated by faecal bulking, the use of rubber matting alone should be considered.
Voluntary ingestion of wood shavings by obese horses under dietary restriction.
GC Curtis, CF Barfoot, AHA Dugdale, PA Harris,CMcG Argo.
British Journal of Nutrition (2011) 106, S178-S182