Can I use fresh horse manure as bedding for my bin, or does it need to be aged?
fresh will heat up initially. After it heats and returns to a cooler state it should be fine. I wouldn't consider it as bedding though but I have no experience with manure as I have indoor bins.
I have read about some people keeping bins in cold garages and using fresh manure (and the associated microbial heating) to keep the bin warm during the winter months.
no. horse manure will heat up and kill your worms. age it a bit and then use as bedding. they will also eat the manure so it will act as both bedding+food.
Our family has had a horse for a few years now. we just traded a LARGE harse for a small horse. My worms are not happy at all, as their daily food supply went from about 70lbs to 40 lbs. I expect a dieback soon.
We have had 4 different horses and not all horse manure is the same. It depends on the horse and its diet. Also, pure manure is quite different than manure that is mixed with stall bedding, pellets, straw, and hay. Pure manure produces little heat, but mix it with high carbon stall beddings and it will get real hot. Maybe a plus in cold outdoor wormbeds.
I have 2 big outdoor windrow-type worm beds, with about 220 sq. ft. of surface space. They are covered by old carpets. Contrary to what is often written, I feed only fresh manure (less than 24 hours old). By using it fresh before it dries out, I don't need to wet it. Dried out horse manure is hard to re-wet. I have been rotating feeding areas so they get a fresh layer of food every 10 days. By that time it is black and not recognizable. No smell and no flies. My worms LOVE it!
I must warn you I live about 2 miles from the ocean and rarely gets over 80F.
He says it has rice hulls and wood shavings in it. I live near the ocean and it normally stays between 50 and 80. I guess I'll have to age ut myself. Do I just wait until it cools down?
For a small wormbin you can use it without pre-composting in small amounts. Try a few handfuls on top in a corner and observe. It usually takes some mass to cause heating.A little heat on top is ok anyway.
To compost it, wet it if needed and put it into a large pile, at least 3'x3'. It should heat up quick and then cool down in a few weeks. You can then use all you want.
You will need to add nothing else unless you wish to. Both bedding and food, horse manure is the perfect worm habitat that those guys selling worms use! Having an ample supply of horse manure will make you a successful worm farmer.
If I were a machinist, I would build a wonderful flow-through with a harvest bar/knife! All stainless. :)