Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
A Maternal Breeding Index for Suffolk Sheep Task: EGENES were asked to develop a maternal index for the Suffolk breed. It was suggested that this index mimic the Dorset maternal index and include litter size, maternal ability and eight week weight as the selection criteria. It was requested that mature size was not used as selection criteria. Suffolk genetic parameters: Compared with the Dorset breed the genetic parameters for Suffolk sheep are broadly similar; eight week weight has the same heritability but larger variation, maternal ability has a smaller heritability with less variance and litter size born is slightly more heritable with greater variance. Two indexes were modelled by EGENEs, the second option presented here was a modification to reflect the differences in the genetic parameters (i.e. it was more Suffolk specific). Suffolk Maternal Index EBV Index Relative Genetic weight emphasis (%) response* 8 week weight 0.37 45 0.623 Scan weight 0 0 1.013 Muscle depth 0 0 0.223 Fat depth 0 0 0.108 Maternal ability 1.57 45 0.617 Mature size 0 0 0.494 Litter size 7.15 10 0.138 CT_lean 0 0 0.249 CT_fat 0 0 0.213 CT_musc 0 0 0.245 * Gain in EBVs per generation when the selection intensity is equal to 1 standard deviation (approximately the best 38% of animals selected). A Base for the New Index The Suffolk Terminal Sire Index is an economic index. A “desired gains” approach has been applied to the construction of the Suffolk Maternal Index and this index will be rescaled to reflect a mean of 100 and standard deviation of 40 index points for lambs born in 2005. The range of index values is relatively wide. Selecting 2010/2011 born animals on the basis of the new Maternal Index will result in the top 10% expressing maternal indexes of 222 (with some having indexes exceeding 300 points). The lowest 10% have indexes averaging roughly 70 index points.