7 weeks before Easter was the time I moved over from growing meat to growing for the pet trade at Easter . This is the time when I took off the future breeding stock and sold the rest .
Re:- your different buck ..
I know it's difficult when you have just a few animals but try to find at least seven generations of separation in the stock lines .. it will give you high quality stock .
If you cross in a different breed of buck you'll tend to get cross breed vigour this can often mak an outstanding result or a dismal failure .
Never take breeding stock from the doe that produces the highest number of Kits.
Go for the one which has about 8% less than her , for in nature the high producers are freaks and tend to have growth & development weaknesses etc. in the next couple of generations plus they tend to eat more .
This may sound daft, but it's true , this is some of the lots of advice I got from a guy called Roger Parkin . He used to be one of the old ministry of food officers ,mainly dealing with rabbits & farm stock for most of his career till he retired around the mid 1980's .