| The main objective of this investigation was to conduct a retrospective trend analysis from 1915 to present on ancestral breeding, genetic relationships, and inbreeding of King Ranch linebred Quarter Horses. Results were from analysis of eight-generation pedigrees of 16 stallions and 74 mares used for breeding on King Ranch in 2007. A composite pedigree file (n=463 animals) was based on numeric codes for each animal and its sire and dam, tracing ancestry back to Old Sorrel (born in 1915). Results revealed the average influence of F was 89.2+/-0.8 and 80.8+/-1.8% (P<0.05), and for the U influence was 31.7+/-3.3 and 27.2+/-1.1% (P>0.10) for stallions and mares, respectively. Computed mean genetic relationship coefficients of stallions and mares to Old Sorrel were 6.4+/-1.0 and 10.8+/-0.6% (P<0.01), to Mr. San Peppy were 13.4+/-2.1 and 21.6+/-1.38% (P<0.01), and to Peppy San Badger were 25.2+/-3.8 and 27.2+/-1.3% (P<0.10), respectively. Mean inbreeding coefficients for stallions and for mares was 1.6+/-0.7% and 3.49+/-0.5%, respectively. Application of these procedures is of potential value to maintain genetic integrity and(or) relationships, while minimizing inbreeding, within this famous line of Quarter Horses, with application to other horse lines and breeds. |
