Holstein cows give birth for the first time when they are about two years old. Immediately after giving birth, the cow produces milk instinctively and automatically. It is known that Holstein cows are characterized by their large production of milk that is unparalleled.
Holstein cows are kept in dairy farms for the main goal of obtaining the highest milk productivity. Therefore, they are fed and farmers work to increase their milk production in all ways. with all of these nutritional and hormonal adjustments, the Holstein cow produces about 25,000 pounds of milk per lactation cycle! which is a very large number in the dairy industry.
A question that is logically asked by many farmers who is looking to maximize their profit from Holsteins cows is whether pregnancy in urgently needed to produce milk. In this article, we’re answering this question. We’re also studying the effect of pregnancy hormones of the lactational and milk production in Holstein cows. Keep following!
Do Holstein Cows Have To Be Pregnant To Produce Milk?
Yes, cows must be pregnant to produce milk, Since milk is not secreted on its own, but is secreted by the cows based on physiological changes that occur during pregnancy.
During pregnancy, huge changes occur in the cow’s body, including hormonal changes that stimulate milk production. Androgens and estrogens stimulate the secretion of prolactin hormone from the pituitary gland. The concentration of androgens increases in pregnant cows, especially when calving approaches, which leads to an increase in prolactin.
Holstein cows produce milk for ten consecutive months after giving birth before they are given a rest period (the dry period) for about two months in which the udder regains its health and prepares for a new lactation cycle before the birth of the next calf. They are also kept for three to four lactation cycles, and then culled and utilized for their meat.
Now, let’s dive more on how these hormones affects milk production:
Role Of Hormones In Milk Production
Hormones play a very important role in milk production, starting with stimulating the growth and formation of mammary glands. When pregnancy occurs, there is a significant increase in the growth of the cow’s mammary gland, which is four glands present in the cow’s udder.
During the first part of pregnancy, most ductal development occurs, while the lobular-alveolar system forms in the middle and later stages of pregnancy. There are several hormones that stimulate the development of mammary glands in cows such as estrogen, progesterone, prolactin, and somatotropin.
The placenta also has a role in the development of the cow’s mammary gland during pregnancy. It secretes hormones with breast-stimulating properties called placental lactogens.
The Prolactin hormone has an important role in the development, differentiation, and function of cow mammary tissues. It is also the hormone responsible for the secretion of milk during lactation.
When a cow gives birth to her baby, the colostrum is produced in the udder automatically. which is what some call the therapeutic miracle of nature. colostrum is saturated with nutrients and antibodies that enhance immune functions and support the growth of calves muscles. As soon as the calf latches on to the udder teat or is milked by the milking machine, milk growth is stimulated and the milk production cycle continues. 
How Many Litres Of Milk Does A Holstein Cow Produce Per Day?
Cows are supposed to produce enough for their baby and more than it in reasonable proportions. For example, a Holstein calf that weighs 90 pounds needs 9 pounds, which is the ratio recognized in almost all calves. Calves usually need to drink milk equivalent to about 10 percent of their weight per day to keep up with their body needs and grow healthily.
But since Holstein cows are deliberately bred with the main aim of increasing milk production to get the biggest profit. Holstein cows produce about 75 pounds of milk every day! This is equivalent to seven times what her infant needs, who is forcibly taken away from his mother on the first day of his birth, to fully seize milk production!
The Lactation Cycle Of Holstein Cows
The lactation cycle of Holstein cows lasts about a year. The cow starts milking from the first hours after birth. the amount of milk produced by the cow gradually increases to reach its peak by about 7 weeks of lactation, after that the amount of milk begins to gradually decrease until the end of lactation. The lactation cycle is about 360 days, during which a number of changes occur throughout the different stages of lactation.
- The lactation cycle is divided into four stages,
- Early lactation is 120 days.
- Intermediate lactation is 120 days.
- Late lactation 120 days.
- Dry period, It is healthy to last up to 65 days.
How Long Are Holstein Cows Pregnant?
The gestation period for Holstein cows is approx. 275-277 days. However, this period is not fixed in all Holstein cows. There are some factors that lead to prolonging the pregnancy period in Holstein cows. These factors include:
- Increased age of cow
- Pregnancy in male fetuses.
- Increased fetal weight.