How do you handle or solve flys and insects in the summertime. The
horse is constantly bothered with flys on his legs?

And I need advice on butchering a cow in the future.
And do you have some advice as to "humanely kill a cow" so
there is little to no pain?
hello archie (next time I want to see your real name!),

concerning flies / insects my experience says that cattle can endure
them, that's not the main problem

the greatest obstacles will be your personal abilities to process into
utilizing all that valuable content of the butchered animal without
loosing all those other excellent parts

above all you need a freezing room for the meat and many cookery
equipment for sausages etc., supposed you know the anatomy and how to
portion it

answering your question for best age of butchering I would direct your
attention to a new trend of cattle maintenance in Europe, called
"mother-cow breeding" (translated literally), where the young calf stays
one year with its mother - getting her milk, and then being butchered

have some patience, I'll look on the web to deliver you better hints

so long cheerfully
kauhl