There are a couple of reasons for this compatibility. Firstly, it may be because in the situations where the most desirable gene is dominant, the different parents contribute that dominant gene in different locii. If either parent is homozygous for that gene then the pup's phenotype will also exhibit this. Each parent's strengths balance the weaknesses of the other. Secondly, in the situations where the most desirable gene is recessive both parents are able to pass on that gene. If they are both homozygous for that gene, then this is automatic.
Usually, these crosses work in both directions but not always as the sire is likely to have much more influence than the maternal grandsire. It should also be remembered that sire/maternal grandsire nicks only constitute three quarters of the pedigree. Also, as with all genetic matters we can never know which genes are to be passed on from each parent. However, we can increase the possibility of securing the most desirable ones by employing techniques such as breeding to proven crosses.
When Acacia Park was at stud we had an inkling that he had an affinity with
the Tangaloa line. His NSW Greyhound Of the Year, Classy Spider was out of a
Tangairn bitch, while his Qld Greyhound Of the Year, Wallowa Flash was out of
a Tangaloa bitch.
It was therefore no real surprise when Acacia Ablaze (a son
of Acacia Park) showed that he also was very compatible with Tangaloa. This
came through bitches by Pretty Short (and his sons), Eaglehawk Star and Tangairn.
Most of Acacia Ablaze's best progeny have Tangaloa in their damline:- Totally
Ablaze (and his illustrious litter-mates), Incacia Runaway, Shape Shifter, Rocking
Rambo, Smart Attitude, Sergeant Carter and Hotshot. Tranquil Flame (by Acacia
Ablaze - Placid Dove, by Eaglehawk Star), a top class race bitch in her own
right, was twice bred to Light Of Fire (from the Tangaloa sire-line). The result:-
multi-track record holder Awesome Assassin and his classy full brother Lilli
Pilli Lad.
Leading Victorian stud dog, Head Honcho has had wonderful success with bitches
by Waverly Supreme line sires >From Chariot Supreme
bitches came Brookside Cindy, Go Diesel, Rare Deceit, Royal Honcho & Crowned
Honcho; from Shining Chariot bitches came Chersam Honcho, Mandatario,
Jones Junior, Clearwater Boy & Fine Carousel; from Malawi's Prince bitches
came Fiery Sal, Honcho Classic & Koutafidamedes; while an Alf bitch produced
WA champ Gemarly Park, a Double Summit bitch got Top Honcho, a Malawi bitch
threw Brookside Red and a Nitrogen bitch got the speedster Off Tap.
He has also done very well with New Tears bitches getting
progeny like Fibba, Fraud, You Idiot, Slipaway Charlie, Queen Amidala and Star
Of Mine. It is also worth noting that Labyrinth and Trousers are from a bitch
by Light Of Fire (a son of New Tears).
The best of Casino Tom's pups have been from bitches by the brothers Amerigo Man (Tommie Streaker, Leonie's Osti, Casino Jack) and West Cape (Spoken Joe)
Curryhill Brute*, a speed machine from Ireland has a real affinity with Brother Fox lines. Many of his best offspring were from Brother Fox bitches:- Silver Chisel, Silver Cassie, Mekong Tiger, London Legend & Barrantes.Curryhill Brute's son Brutess got his best stock such as Lady Beaver, Canobi, Desefiar, Gaylene and Dynamic Driver out of Brother Fox line bitches. Now we are seeing that the daughters of Curryhill Brute* have produced very well when put to Brother Fox line sires. Deep North, Justin Bale, Nine Inch Nails, Placid Boy, Waiwera Marika & Armstrong Lad are some examples, but the best of all has to be the superstar of 1998, Rapid Journey.
Del Bairn was a smart dog of the early seventies but was lightly used at stud siring just 69 litters. Three of his daughters were mated with Tangaloa. From these unions came two of the outstanding dogs of that era:- Tangairn (x Del Bairn Babe) and Eaglehawk Star (x Country Coast). Undoubtedly an indication these two dogs were very compatible.
Credibility (Worth Doing - No Liability, by Pretty Short) went brilliantly with bitches with more Pretty Short blood. Reliability, Bearability, Fine Devil, Gotta Be Tricky, As Directed, Fiery Asset & Berella Xanadu all fit this criteria while Faithful Hawk, arguably his best performed pup is out of a bitch with a double cross of Pretty Short.
Shining Chariot (Chariot Supreme - Shining Light, by Satan's Legend) produced some outstanding dogs from bitches with Satan's Legend close up in their pedigree. Golden Currency, Benjason, Another Currency, Suzy Also, Quaroun & Material Legend were just some of them.
These have been just some examples of this kind of compatibility. You can discover many others just like them in the volumes of "Australian Winning Lines". Browse through the listings of Maternal Grandsires and Sires of both City winners and Feature winners and it is easy to spot these nicks. I would then suggest checking in the Stud Book to see how often these crosses were attempted and you will soon have a good idea just how compatible the lines are. It is probably more appropriate to talk in terms of "degree of compatibility" than to simply say that lines are or are not compatible.
One of the more remarkable articles to come from the thoroughbred world was one by Louis Mihalyka which appeared in the Bloodhorse Review of March 1994 concerning the lack of compatiblity between the champion stallions Northern Dancer and Bold Ruler. Apparently 22% of the progeny of Northern Dancer were stakeswinners, yet none of his 17 foals from Bold Ruler mares achieved this distinction and yet 15 of those same mares produced 20 stakeswinners to other stallions. Undoubtedly, there would be similar occurrences in the greyhounds. Maybe the reason for the failure of a stud dog or brood-bitch is simply that he/she was mated with incompatible lines. What if Northern Dancer had only served Bold Ruler mares. Would he still be considered as one of the greatest stallions of all time!!!