(by the time you have paid to hand-rear a lamb, you wont make any money from it).
Our last five pets just went off and fetched over £85 a piece. They were fed predominantly on Jersey milk then creep for a short while then a lamb pellet. Even if I'd used lamb replacement powder, I would still have made a profit.
Like most farmers, we do not expect nor want a 'reasonable hourly rate' for our time. Running a sustainable business, making a living doing something fascinating and highly enjoyable that keeps us fit seems to us to be a pretty good return for our labour.

(Check my tag line.

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Having said all of which, I think it is a very good idea to have an outlet for orphans - even if you have a setup where you can rear them not at a loss, if you have a bad lambing it can leave you short of time to manage everything that is needed.