There is no proof that vigor is not passed down. In my experience I would believe it to be beneficial to bring in new blood and introduce new genetics into your herd if you have kept replacements. I dont see why someone wouldnt want to improve what they already have. No one has the perfect bull...
If it were me I would select the top 10 Females Seperate them and start using AI to bring in better genetics for replacements. Regarding bulls you can go wrong with an angus hereford or sim angus bull.
I figure if his heifers he throws arnet good enough to make the purebred herd theyd make great cows to use on an angus bull. Black with a blaze face? BOY!
About 4-5 acres... My reason for doing this is to give my 10 girls something to snack on from time to time. We were able to get the first wave on the ground we put out 100# of oats and 100# of rye grass. Planning on putting out another 100# tonight 50&50 split . I took the all natural approach...