AGB-0064
QUESTION
Which system of mating is used for the improvement of non-descript animals?
OPTIONS
(A) Grading up
(B) Criss-crossing
(C) Cross breeding
(D) Selfing
ANSWER
(A) Grading up
EXPLANATION
Grading up improves non-descript animals by repeatedly mating them with superior purebred sires of a desired breed. Each generation increases the expected genetic contribution of the improved breed, whereas criss-crossing maintains two-breed alternation, crossbreeding is broader than the specific upgrading system, and selfing is not a practical livestock breeding method.