The flocks bred
"The animals of the flocks conceived" or "The animals mated"
produced striped, speckled, and spotted young
"gave birth to babies with stripes and spots"
It can be made explicit that this happened over several years. AT: "During the several years following, Jacob separated" (See: rc://en/ta/man/translate/figs-explicit)
he separated out his flocks for himself alone
"he set his flocks apart"