The practice might be different in different countries, but in many countries (I know the most about NZ) dairy cows are impregnated every year to keep their milk supply at a high level. The dairy cows are slaughtered after about 4 years, so there are far more calves born than can be used by the industry. This means that a decent proportion of the female calves are slaughtered alongside their brothers at a few days old so sex selection of sperm won’t change the number of unwanted calves. If there was a way to induce lactation without pregnancy that would make sex selection very useful.
The practice might be different in different countries, but in many countries (I know the most about NZ) dairy cows are impregnated every year to keep their milk supply at a high level. The dairy cows are slaughtered after about 4 years, so there are far more calves born than can be used by the industry. This means that a decent proportion of the female calves are slaughtered alongside their brothers at a few days old so sex selection of sperm won’t change the number of unwanted calves. If there was a way to induce lactation without pregnancy that would make sex selection very useful.