Spontaneous combustion of hay was thought to be the cause of a fire in stables that killed five much loved family horses at a property in the north western Sydney suburb of Glenorie.

The horses were found dead inside after the fire was extinguished.

The accident prompted a sympathetic warning from NSW Department of Primary Industries (DPI) to stable owners who may be storing more hay for feed than normal in the drought, instead of the more usual practice of keeping smaller quantities used more quickly.

“Unfortunately, although recommendations for storing hay suggest not keeping it in or near stables, people do so because their stables are commonly the only area available under cover,” DPI research leader of animal welfare Lynette Chave said.

Ms Chave, herself a horse owner and lover who lives near the property where the fire occurred, sympathised with the owners.

“Often it is also the most practical area for storage for close access to horses, saving owners carrying bales of hay long distances – this creates a dilemma,” Ms Chave said.

“However, storing additional hay in a loft in the stable, for example, can increase the risk of fire.”

DPI district agronomist at Wagga Wagga, Nigel Phillips, says the danger of spontaneous combustion does not occur when hay is properly dried before storage, because it won’t generate the necessary heat.

Hay needs to be below 14 per cent moisture to slow down microbial activity that is the source of heating in hay.

The compactness of surrounding hay can enable heat to build up to the point of combustion.

At or below 22pc moisture there may be some heating of the hay and horse owners need to ensure there is enough airflow through the stack to bring it down below 14pc moisture for long-term preservation and to minimise any risk of combustion.

The risk of combustion increases dramatically above 30pc moisture.

Often hay can be stored at the correct moisture content but gets wet through leaking sheds or water moving under the stack.

This may result in hay quality losses and a potential fire risk.

Hay stacks should be checked regularly for any water damage.

NSW DPI’s website contains a factsheet on fire safety in stables at www.agric.nsw.gov.au/reader/aw-pamphlet/aw-pamphlet5.htm or search What happens when hay heats on the Victorian DPI site, www.dpi.vic.gov.au

Contact Lynette Chave, West Pennant Hills, (02) 9872 0571, or Nigel Phillips, (02) 6938 1981.