Horses that are kept indoors need a fluffy, absorbent bed to keep them dry and warm.
There are a number of options available on the market, but when buying something in such large quantities it is important to ensure they are as sustain-ably and renewably sourced as possible.
Follow Their Lead
The UK leads the pack in this department with a number of recycled (& recyclable), renewable and sustainable options. But they can be found in the US and Australia too, the more we support responsibly sourced and managed companies, the further their reach will grow.

Auboise
Made from organically cultivated hemp which composts readily and is an annually renewable resource. Your bedding can be traced back to the field where it was grown. Located in the UK.

Bedmax
Shavings made specifically for horses from renewable forestry timber in the UK (they also use pine where available for it’s antiseptic properties). The product is virtually dust free, absolutely natural with no additives. Located in the UK.

Bluefrog
Bedding made from government managed Irish Coillte forests, planed to a specific size & sterilized naturally which also removes excess dust. Located in Northern Ireland.

easibed
Dust free bedding options that carry the Organic Farmers & Growers Association approval which means they may be spread on organic farmland as compost once soiled. Located in the UK.

Eco Animal Bedding
This bedding is made form recycled corrugated food-grade cardboard. A recycled product that is hygienic, absorbent, dust and odor-free. Located in Australia.

ecobale
Another recycled cardboard option, the cardboard has great insulating properties, it’s biodegradable and safe for horses with allergies. Located in the UK.

EcoBed
And yet another recycled cardboard option. Providing most of the same benefits as the two above. Located in the UK.
Side Note
Anytime you purchase bedding from recycled timber products you should always sift through it for chunks & branches prior to bedding your animal.
There is also a new bedding out called White Horse Bedding which is wood pellets which are low in dust. I have using this for a couple of weeks now and this has saved me considerable time mucking out.
To find out more see their website: http://www.whitehorsebedding.co.uk