trying to pick bulls for starting to AI with. usually use a stock bull so im a bit lost. would like to improve components. do i look for a high kg of combined fat and protein or high % ? am currently a simple 8500l 4.12 f and 3.23 p. 2 ton in and out of parlour feeding blocks silage EOD. am supplying Dale farm NI so am paid more for litres at the min but think that will be changing in the next few years and want to be ready.