Cows for controlled grazing and biogas input

I’m looking for permaculture references on cows that are integrated efficiently and low maintenance for controlled grazing and using the manure for a biodigester(s) input.

ideally, the manure to biodigester input requires less manual feeding. I was thinking about having a living fodder edge around the the cow house or main feeding platform.

I’ve researched online but I haven’t found a system that integrates cows for grazing and biodigester input.

Ideally also, I’m very interested in joining humanure into the biodigesters together with food scraps, green and cow manure.

Hi,

the manure must somehow get into the digster. Chinese systems are build below ground - usually besides or inside the cow house. That allows to swipe the manure into the system from the cow house floor.
If the cows are on the pasture you won't get their manure for the biogas system - it would be simply too much work to collect all the manure from the ground...

A system that integrates cows for grazing and biodigester input sounds like something for a dairy operation.  Do you by chance have dairy cows?

Getting a conveyor belt to move the manure to the biodigester?

As for permaculture references for cows for controlled grazing and biogas input, I have no idea where to find something like that.

How much manure do you need daily for the digester?

depends. Digesters come in different sizes, from 1 to 10 to 20 m³ - even larger. You have to do the math for yourself. How much manure does a cow create per day? How many cows will you have?

If you build a 10 m³ digester and you have 2 cows the digester will be too large.
If you build a 1m³ digester and you have 20 cows the digester will be too small.

TH created a nice article about feeding some time ago: https://www.solarcities.eu/content/how-much-food-waste-can-you-feed-biodigester

Generally all types of cattle produce large amounts of manure: bulls (42 kg/day), beef cows (37 kg/day), steers (26 kg/day),
heifers (24 kg/day) and calves (12 kg/day).
Milk cows produce the most manure at 62 kg per day, which is about 10% of the weight of an average cow.
This Home Bi-gas unit may be of use, manually loaded.
https://www.homebiogas.com/product/homebiogas-7/

barn manure cleaner

There are smaller units available. Not sure if this is the info you're looking for but it could help you gather the material once you get cows set up.