בראשית ל:לט פירוש: רש״י, רשב״ם, רד״ק וSiftei Chakhamim

אל המקלות means at the sight of the rods.

ויחמו הצאן, this is a masculine construction.

ויחמו, a reference to the males. However, as we learned earlier, the females would be in heat simultaneously.