Dear Tahir,

You may found the information of the following link very useful in order to perform a multiple-trait analysis in SAS.

https://support.sas.com/documentation/cdl/en/statug/63033/HTML/default/viewer.htm#statug_mixed_sect033.htm

Hope this helps, best regards.

Thanks Miguel. Could you kindly tell me what is the difference between this SAS example and single trait BLUPs?

Dear Mohammad,

The example that Miguel Angel Sánchez-Castro shared with you is reasonable for what you are asking.

In this example, although it SEEMS that a single trait was used, as you only have one "Y" variable, the data were organized and model specified in a way that you are using a variance for each "Trait" including a covariance between them.

Thus, a multi-trait analysis is being performed. If you go to "Output 56.4.10 Solutions for Fixed and Random Effects", you can find the multi-trait BLUPs, in which you have an EBV for each animal for each trait.

So, the difference between this SAS example and single trait BLUPs is that in this example two traits are being used, and their BLUPs were calculated as a function of the variances and covariance estimates, and in the case of a single-trait BLUP, only the variance components of the trait being analyzed are used.

Thanks for the generous reply. What my point of view is that although the analysis is performed together for both traits, the output is given separate for each trait. For instance, if I have 300 animals with two traits, I get 600 EBVs, and not 300. So, can we call them multi-trait EBVs?

Mohammad Tahir , yes, you are right. You may add as many traits as you wish, but you need to properly define the G and R matrices accordingly, respecting the dimension of the data (number of observations and number of traits)! Thanks, Nick