"But so many of these sires are minus PTA..."

How much courage do you have?   New sire lines will not fall from the sky.   They have to be developed from whatever exists on the earth.   This means we either go back to old bulls with some semen floating about, and try to breed sons from current cows; go to foreign countries (Denmark or New Zealand have major Jersey populations) and hunt for their best native blood sires; or we take the milkiest daughters of "type" bulls, linebreed them, and sample enough sons to maybe get another "Generator".   Dr McDaniels in his research for the AJCA predicted this could be successful, in a three generation process.

Pedigree tells us what ancestors contributed to the bulls we are using.   It does not necessarily tell us what genes were passed to the next generation, at point of conception.   For those concerned they may be suffering inbreeding effects in their herd (stillborn calves, weak immune function, lower fertility, frail physiques, shorter herdlife) it is worth considering use of the Weeks Analysis ("aAa" Breeding Guide) as a tool to develop matings in your herd that result in "balance" of trait characteristics essential to a full functional lifetime in your Jerseys.   "aAa" reads the phenotype of the animal to tell you what trait tendencies are there, and suggests what mating phenotype will compensate for those tendencies.   It will protect you from inbreeding effects even as you use some bulls who raise your inbreeding coefficients.   It does this by balancing "Round" substance characteristics against "Sharp" angularity characteristics, so you avoid going too far in a single trait direction.   "Sharp" characters add dairy habits and performance enhancement, whereas "Round" characters add substance and stamina to the physique.   You obviously need both if you want a cow (or bull) to perform over a full lifetime.  "aAa" has simply found a way to quantify this in matings, based upon fifty years of observation by a group of independent breeders who maintained regular contact with each other under the guidance of Mr Bill Weeks of Vermont.

What do we really learn from the extensive influence of Secret Signal Observer?

We learn that he is the most influential sire in modern Jersey pedigrees, all out of proportion to his AI exposure (limited) and the contemporary breeding ability of his daughters.   Like many good sires that history now labels "great", he had opportunity as a result of being used by two breeders (Mrs Wilde at High Lawn; Ritter and Gonzales at Fallneva) cognizant of the process which produces and develops useful sires (linebreed the bull, within a line that has traits you are seeking, and then mate him to outcross females needing those traits).    His sons "Soldier" and "Quicksilver" had an even better opportunity, through broad AI exposure (within the first generation of Jersey sires that we could use from frozen semen within AI systems that had geared up to offer national distribution), but their key advantage came from timing because the breed was looking for a non-*LL, non-*RVC non-skim milk "outcross" source that could sire sons for AI young sire sampling with good indexes, and these two fit the bill on all counts.   They followed "Generator" and "Sleeping Surville" and each found a niche as a successful mate against one of those sires of mainstream pedigree saturation.   It all came together to allow these two to dominate the sire listings, even though other sires contemporary to them (Gramhil Leader Sophia Samson, Favorite Saint, HL Pompey Morgan, Noblemans Lotus Designer) had similarly high index levels but did not succeed in producing sons that could hold our attention, for whatever reasons.

The irony is that we probably should give the "May" family at High Lawn credit for the success of old "Chocolate Soldier" and the "Quartz" cow at Fallneva (prominent in the pedigree of Willrich Mercury *LL who was a great sire of lifetime milk) credit for the success of old "Quicksilver".   Udders came from the "May"s, with milk in them, and Frames came from "Quartz", with solids in them.   Old SSO did the job he was asked to do-- produce useful breeding progeny from two unique cows.   In the chauvinistic world of dairy indexing, sire lines get all the credit even though the dams did at least half the genetic "work".   When we look at the myriad male descendents of SSO, certainly it becomes clear that they are all about as good as the cows from which they come; likewise, if we are to found an outcross line to give us some escape from the vagaries of linebreeding to old SSO, it will depend upon using many sons of unique and relatively unrelated cows that possess traits to complement the SSO influences, once we identify what those may be.   SSO's dam after all had seven calvings, and we seem to recall only one calf-- Secret Signal Observer, a male-- and we only recall him from two sons, not from any daughters who founded families of any prominence.   His dam, therefore, was not so much a great cow but a great mate for the related Welcome High Lawn Torono bull who we know sired both sons and daughters of breeding merit.

We need to get more comfortable with linebreeding

SSO is the result of linebreeding synergy, as are those more successful of his descendants that keep his sire line in play.   He is proof, similar to the Ayrshire bull Selwood Betty's Commander and the Holstein bull Pawnee Farm Arlinda Chief, that linebred animals are the most consistent producing dairy animals, especially at immature ages.   He is also proof that you need other, unrelated lines of females, to bring out the latent greatness in any sireline for the broad commercial AI users.   This is why so many erudite breeders, for example Lyle Hunsberger (Lyrene Guernseys), felt that a great cow who produced a great breeding son would rarely have more than ordinary daughters, and the great cow who birthed great daughters would rarely herself produce a great son.   I think this has to do with the relationship of the cow to the general population of in-vogue sires.   I do know Lyle bred some of the best sires the Guernsey breed ever had, so I hesitate to question his opinions (especially with what we are learning about mitochondrial genes).