September 11th, 2020
Currently, the team uses a base index for selection. Will changing to a Smith-Hazel index improve accuracy of selection?
Crossing, Evaluation, Selection
\(\Delta_g = (i * \sigma_g * r)/L\)
Use of a Smith-Hazel index will increase accuracy of selection thereby increase genetic gains
|Parents_PYT-UYT||Compared BASEINDEX and SHINDEX when parents are selected at current baseline (PYT-UYT)|
|Parents_PYT||Compared BASEINDEX and SHINDEX when parents are selected at PYT|
|Parents_CE||Compared BASEINDEX and SHINDEX when parents are selected at CE|
A 20 year burn-in period was modeled using the baseline. The burn-in was followed by a 20 year evaluation period to measure rates of genetic gain for all treatments. Genetic gain was measured by assessing changes in genetic merit at F1. Genotype-by-year interaction variance was assumed to be equivalent to genetic variance (based on average correlation between locations being equal to 0.5). 30 replications done. We used the genetic covariance among traits and weights as provided by the breeders.
Treatments 3:1 (Parents @CE, @PYT and @PYT_UYT)
The Smith-Hazel index did not have an advantage over a base index unless under very low evaluation accuracy situations
Treatments 3:1 (Parents @CE, parents @PYT and Parents @PYT-UYT)
The smith-hazel index has clear advantage at the CE stage where accuracy is quite low.
The Smith-Hazel index has merit over a base index in situations where the level of accuracy in the evaluation strategy is low. However, at stages where there is high accuracy to estimate breeding value, its advantages do not warrant its prioritization as an improvement plan because its contribution to genetic gains is not significantly different from the base index.