The dairy industry is a successful result of the cooperation of whom?

Discuss briefly how pure lines are created in animal husbandry.

For how many years has the dairy industry been developed as a business (in $years$)?

If desirable traits (genes) are accumulated,what increases?

Meat,milk,and eggs mainly provide us with ...... .

$A$ cow which gives more milk per lactation is evolved into a pure line by mating with a superior bull of the same breed for $4-6$ generations. Which type of breeding is being referred to in this case?