New Gain statistics

New Breeding Values for existing Sitka spruce Parents of Families (PoF) following independent analysis progeny test data.

  • new-gain-statisticsPrior to the formation of the new Sitka spruce Breeding Co-operative (SSBC) in February 2014, Forest Research organised a thorough and independent re-analysis of all the Sitka spruce progeny testing data ever collected over a 40-year period. Experienced animal breeders from Edinburgh University were asked to work out Breeding Values relative to unimproved QCI stock for diameter, stem straightness, branching quality and wood density according to standard animal breeding techniques. Best Linear Unbiased Predictor or BLUP is a statistical technique common to animal breeding but now widely used in tree breeding. Computational power has now matched the theory devised in the 1950s which allows each tree to be included in pedigree analysis with other trees where one or both parents are common, are cousins or even grandparent. A massive job of comparison, weighting for site quality and inclusion of genetic correlations with related traits is involved to determine an overall BLUP Breeding Value for each parent and family.  The huge dataset analysed by the Animal Breeders included mainly old data previously analysed in isolation (i.e. not in such a complete and comparative way) and also some new full-sibling data which had not previously been analysed at all.
  • As a result of this new and independent analysis, it is inevitable that some Breeding Values (BVs) will vary relative to those previously published, although not greatly so.  The table below presents the new BVs for some of the most popular recent Parents’ of Families. A general observation is a slight lowering of diameter percentage BVs and a slight increase in straightness BVs. We hope that the industry will accept that these new data are to be considered as the most up-to-date currently available. All new seed attributable to the same parentage of a previous PoF will be presented to the market with these revised BVs.
  • A new trait for which there is little field data at the moment is Acoustic Velocity (AV). AV assessments are used as a surrogate for micro-fibril angle which in turn is correlated to wood stiffness, a characteristic of increasing interest to many parts of the growing and processing industry. Data for the few families assessed to date for AV are presented below. The table will be updated as more full-sibling families are assessed for AV by the SSBC
  • See Full Sibling Gain table June 2015 (pdf) – New_Breeding_Values gain table_v2a
  • Revised predicted gains for Sitka spruce tested clonal seed orchards are available here:  Revised predicted gains for Sitka spruce