Investigation after investigation has proven that the financial variance is almost a wash - everything considered. But, there are other factors to bring into the decision to raise or buy replacements, and in the opinion of Dan Childs of Noble Foundation, for most commercial beef producers with herds of a few hundred (about 300) cows, or less, it is NOT economically feasible to raise their own replacements. Too many pounds per calf are sacrificed by using bulls strong in maternal traits, and too much of the resource base is given up for the development of the replacements. After adding the complexity of managing forage resources and multiple classes of animals, the analysis provides strong numbers and reasoning to PURCHASE replacement females rather than raise them.
Some of the other considerations that have been mentioned, such as familiarity with the 'home range' and climate, etc., have a measure of merit, but the MOST critical consideration is the genetic improvement to be anticipated and EXPECTED by the use of improving genetics with the bulls that one uses! This selection protocol is necessary whether a breeder buys his replacements, raises them, or acquires them by buying bred cows with replacements in utero, or has a professional operation raise them for him. The Genetic Quality of the BULL(S) which SIRE your replacements is crucial to your success.
I think that in the final analysis of your making the "buy/raise" decision, it comes down to the ultimate quality of the seedstock, both bulls AND cows, that you utilize for your FUTURE successes.
A GOOD BULL is half of your herd. A POOR BULL is your ENTIRE herd!
DOC HARRIS