1933 L. G. D. Acland in 30 Sept. 15/7 Cast for age, etc., means ‘culled’ for etc. This term is used for stud sheep rather than flock sheep.
1950 Sept. 217/3 Cast-for-age ewes..are sold in late summer or autumn.
1965 J. S. Gunn i. 13 Cast for age, a term to describe sheep that are got rid of..because they are too old.