Do Cows Only Produce Milk When Pregnant? 6 Things You Need To Know

Cows can only produce milk during pregnancy and for up to 12 months post-birth. Milk production in cows is a complex process that involves different hormones, including oestrogen, progesterone, oxytocin, and prolactin.

Oestrogen and progesterone hormones are responsible for developing the mammary glands. Oxytocin is responsible for milk secretion. Prolactin is produced during milk removal whether by a calf, hand, or machine. Prolactin is a key stimulator in milk production.

Things That Impact Dairy Milk Production

1. Breed

The breed of a cow can have a significant impact on milk quantity and quality. For example, an average Holstein cow can produce more than 20,000 pounds of milk per lactation, compared to only around 16,000 pounds of milk for a Jersey cow.

Dairy cows that have been bred for high yields can be extremely productive but they also tend to have higher maintenance costs associated with their increased production.

The breed of a cow also impacts her ability to adapt to varying environments and climates, which can have an effect on milk production. For example, Holsteins are known to be heat intolerant during summer months.

2. Feed And Water Supply

The quality of feed is just as important as the quantity. Diet formulation is a critical component of dairy cow management. A dairy cow’s diet should have protein (amino acids), minerals, carbohydrates, vitamins, and fats for growth, maintenance, and production.

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Here are the sources of each component:

  • Protein: alfalfa, corn, soybean meal
  • Minerals: calcium and phosphorous are found in legumes and green forages
  • Carbohydrates: forage, grains, and roughage
  • Vitamins: vitamin D from sunlight, vitamin A from fresh forage, and Vitamin E from plant oils
  • Fats: most feeds contain fat. For example, carbohydrates and some processed protein contain 3% fat.

Feed ratio depends on the stage of lactation, body size and condition, climate, and age. For example, feed ration during the dry period should be high in energy and low in proteins and carbohydrates. Lactating cows’ feed should have high levels of protein and energy.

Milk is 87% water so limiting water intake will result in less production. Dairy cattle on pasture should always have access to free-choice clean and fresh water.

3. Milking Frequency

Milking frequency also affects the amount of milk a cow produces. Cows that are milked 2-3 times per day produce more milk than cows that are milked once a day.

This study was conducted to determine the effect of milking frequency on milk production in early lactation. The result was that cows milked 6 times for the first 21 days then 3 times per day produced the most milk.

4. Health

The effect of diseases on dairy cattle can be direct or indirect. Direct impact on milk produced is caused by diseases that affect the udder such as mastitis. Although mastitis may not last long, its impact can last an entire lactation.

An indirect effect is caused by lameness which causes reduced feed intake resulting in decreasing milk yield.

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Other diseases that can affect cows’ milk include ketosis, acidosis, foot and mouth, retained placenta, and many more.

5. Climate Change

Climate change has a direct impact on the dairy industry because it influences animal growth, reproduction, and production. Heat stress, caused by climate change, is one of the challenges faced by dairy farmers all over the world.

Heat stress is common during longer and hotter summers. Global warming is another contributing factor to heat stress. Excess heat decreases feed intake resulting in fewer gallons of milk.

6. Lactation Cycle

The lactation cycle of female cows has four phases: early, mid, late, and dry period. Milk yield, body condition, and feed intake vary in these stages. Milk production is high in the early stage and starts to decrease during the late stage.

The early stage is for calving and peak lactation. Immediately after calving, the mother cow’s appetite is low which means low production. 10 to 12 weeks after calving, the appetite is at full potential so milk yield increases.

In the mid and late stages production declines because this is where cows create energy reserves for their next lactation. So energy is still required for proper management of the pregnancy.

Dry period length and management influence overall health and production. Drying-off length should be 6-8 weeks, longer periods lead to excess weight and low production.


What Causes A Cow To Be Pregnant?

Cows can get pregnant through natural breeding or artificial insemination. Natural breeding is common in small dairy farms but in modern agriculture, natural methods are rare. Modern agriculture utilizes artificial insemination which involves using semen from high-quality sires to increase productivity.

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What Is The Gestation Period For A Cow?

The gestation period for a cow is 279 to 287 days. The period varies by sex of calf and breed. Cows with female calves have shorter gestation than cows with male calves.


Tabitha is a writer and farmer, living on a farm where she helps in raising cows, dairy goats, sheep, chickens, and ducks while growing vegetables and fruit. She is passionate about good food, nature and is a firm believer in raising animals in a way that’s sustainable and humane.

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