Underline Inheritability

With regard to underlines there has been really good conversation and I was asked a really good question regarding heritability. With that in mind I had a really good conversation this morning with a swine geneticist and here is what he had to say: Actually researchers have disagreed alot on the heritability of underlines – – varying from 7% to 42% in the past. Today most put it somewhere in the 30’s which is “medium”. The problem is more than one gene affects it, and those in front of the navel are controlled by a different gene than those behind, just as the shape and size of those in front are often different than those to the rear. Then we have the factors of spacing between each teat as well as between the two rows, which affects uniformity of access and milk production. Saving gilts and using boars with the underlines extending as far forward as possible did create better underlines. Always select boars with 4 nipples ahead of the sheathed very important, and always avoid any thick flat nipples on the sheath. Yes, the boar is as important as the sow, and in any herd, pb or commercial, is easily the constant source of maintenance and improvement of underlines combined with the quality selected in your sowherd. Accurate observation and evaluation on the baby pig at ear notching is very effective, and carrying a 1/4 ” leather punch in your hip pocket and simply punching a hole in the ear of any unsatisfactory pig (including ruptures, etc. too) makes sorting a lot easier and faster too at a later date. It’s a never ending task, but you end up with larger litters of more uniform pigs weaned.
Marc Howe