SRU said:
what are you getting at? does this animal exist?
SRU, i didn't have a specific one in mind, but there probably is one. what i am getting at is there seems to be very few line bred by design maine bulls out there. i know of a couple that are definately by design, rather than by phenotype only, which there are plenty of and are therefore somewhat linebred, especially with irish whiskey having cunia at least 18 times, even though his grandam was not maine. however, there are very few with the same animal to see if they need to be in the same generation, one back, stacked on the maternal or paternal side against another one or two in the same generation to emphasize traits of interest. it seems most lines are based on what nicks rather than concentrating good traits and eliminating bad ones. it's probably the high cull rate in the first half sib mating that creates a lot of diversity that people don't want to mess with. also, they won't be used to seeing the frame go away.
look at black gold 500 amaa 500. depending on how you count, cunia is his sire and grandsire, so he's 75% cunia. linebreeding might put cunia in the same position in the third generation, or perhaps skip one generation to the 4th and put him there once or twice and fiddle around with whether what you need or have is better through the cow or the bull. i can't comment on smithbuilts udders, but his full sister sprouted a bull that supposedly had udders that broke down. don't know if they can be fixed (perhaps that's why he disappeared), while keeping the other traits this combo allows, suffice it to say, there are very few organized examples of this in the maine breed.
to me, line breeding could address combining two extremes like the posty legs with sickle hocks, won't name bulls, but it has been done repeatedly. or more classicly to cluster a good bull and add a trait or two while trying to avoid the trap of single trait selection and creating a bigger problem than you started with.
CAB, since i have never done this, and am only going to try, if you got extremely lucky, you could do this in the third generation without proving a bull. you would then have to prove him, so i guess i would say 4 generations. perhaps this is why it isn't done. the key with the bad recessives is to find them early and often, not avoid or hide them to make short term gains monetarily. i have no idea how much faster you could do it compared to 25 years ago. it will probably be similar to gudgell and simpson when they offered their anxiety line breds, everyone was scared of them till anxiety the 3rd and 2nd? and lord wilton kinda faded. they even lowered their percentage anxiety just to suit the customers. sousel i think took over and was heavy into mischief (who he purchased for $150, had a reputation as a shy breeder, and was extremely thin) when he crossed him on one of his cows and struck lightnening. he then noticed he had linebred by "accident" as he looked at the pedigree of his offspring. i'm sure the same thing would happen as you would have to compete against all the performance composite breeds. if you think people are leery of PHA/TH, just wait when they see a bull go through that the auctioneer says, look at this linebred bull, it will probably be a tough road to haul, but i'm gonna do it somehow before the fullbloods go away. it's really interesting that the traits most people in other breeds are chasing are the exact same ones.