Rick, I'm not sure how to answer you because I'm not sure what you call the “necessary muscle shape to compete”. We win some and lose some up here, but we have more club pigs spoken for than we'll probably farrow. I've followed the stress gene since the later 60's when 43% of all Polands were estimated to carry it, and if you looked at them cross-eyed they'd likely drop dead. I honestly believe that the appearance of the muscle depends more upon the skeletal structure it's draped over and the optical illusion created by the degree and nature of the fat present.
When I was at Iowa State, those of us on the livestock, meat animal evaluation, and meats judging teams would kill a pig, lamb, and steer (or heifer) every Monday and freeze upright. Then the rest of the week we peeled the hides off, then scraped the fat off, boned out all the muscle, and finally were left with the skeleton to observe. It was a tremendous learning experience which has really helped me as a breeder in all of those species. I personally probed, and later scanned first hundreds, then thousands of pigs each year. But today I hear judges comment in their placings on muscle and in places on an animal where carcass work would virtually show such situations to be impossible. Too often pigs are said to meatier than others when they simply have another inch of fat on each side of the loin. Realize an 8 or 10 inch LEA is not that wide.
By the late 70's, early 80's, we knew heterozygotes (Carriers) had about .15 to .2 inches greater LEA than negatives, a slightly larger more vertical placed OVAL shaped ham (with an evident separation of ham muscles), with”tighter”, trimmer (“chisel”) shaped jowls, a 5 to 10% thinner skin, and were shorter sided. However, a number of studies showed that most of the time these phenotypic differences were very subjective to the eye and could not be done with any degree of acceptable accuracy. At the same time we had most Polands that were steep rumped with low tail settings which was accentuated by popular highly arched rainbow tops.
At that time I wanted Polands as square and correct in the rump with tails out on the corner as all those good Durocs and Yorks I was raising and selling at Stro-Wold Farms (which were all negatives). I discovered that as I raised the tails up on my Polands, the carriers were really shortened in length of rump bones, and the whole ham and rump seemed to just “roll forward” with the tail not out on the corner but more like in the middle of the top of the ham. Look at pictures of our carriers today and notice the shape and placement of their “Oval” hams and tails compared to the square rumps and muscle appearance of negative boars in other breeds. I decided then that I didn't need Carriers.
In addition, I've always felt the place of a purebred was for what it could contribute to the total pork industry. In the 60's I sat on the Iowa Poland China Breeders' Association board and represented them on the Iowa Purebred Swine Council from which we created the Iowa Pork Producers Assn, and was an original board member there with my terms ending in 1974. I've always supported their check-off efforts and the research they've paid for. I also spent some time in management of a major packer. We learned Carriers had a 10% lower marbling score, 6 to 8% lower meat colour scores, and 4 to 9% lower structure scores and drip loss of the loin was about 5% higher. There was no indication that the effects of the gene differed between barrows, gilts or boars. Nearly 40% of all Carriers possessed these meat quality problems which came be known as PSE (pale,soft, and exudative) pork.
Soft and exudative pork has poorer water-holding capacity and will shrink as much as 7 percent during handling and processing, making it undesirable for packers and consumers. PSE and dark, firm and dry (DFD) pork products are of lower value to the packing industry.
They are used in less-expensive, further-processed products rather than being sold as higher-priced, fresh products. These problems indicated that the negative effects of the PSS gene on carcass quality traits should preclude its use in commercial swine breeding programs. The National Pork Producers Council adopted a resolution in 1997 to rid the U.S. pork population of the PSS gene, and I still support it, especially as the production of high quality pork becomes increasingly important to consumer demand.
I honestly feel that the fitting practices and rations, together with Paylean, used today have more to do with your desired “shape” or “look”. And, in regards to whether or not my negative Polands have that “necessary muscle shape” - - they may not because the complaint I hear most often is “they're too long” (but I need length so my females can carry, then nurse, large litters of pigs and I've never liked short pigs). Rick (and anyone else), I'll always respect your right to disagree (if I had all the answers I should be a lot richer than I am).