When Does a Cow Start to Give Milk?
A cow starts to give milk between the ages of two and two-and-a half years, after the birth of its first calf. For the first few days the milk is unfit for human consumption and is fed to the calf which is afterwards reared separately.
During the milking or lactation period that follows the cow’s yield usually reaches a maximum after four to six weeks and continues in decreasing quantities for nine to ten months.
To ensure a steady supply of milk, farmers arrange for their cows to calve every 12 months. Attention to breeding has led to steady improvements in yields. A good cow may produce up to 2,000 gallons during the lactation period. Cows are normally milked twice a day, morning and evening.
Except for the smallest herds, milking in advanced countries is usually done by machines which suck the milk from the cows’ udder and transfer it to covered containers, but there are still many countries where milking is largely done by hand, in the traditional way.
A cow will produce large amounts of milk over its lifetime. Certain breeds produce more milk than others; however, different breeds produce within a range of around 6,800 to 17,000 kg (15,000 to 37,500 lbs) of milk per lactation. The Holstein Friesian is the main breed of dairy cattle in Australia, and said to have the “world’s highest” productivity, at 10000L of milk per year.
The average for a single dairy cow in the US in 2007 was 9164.4 kg (20,204 lbs) per year, excluding milk consumed by her calves, whereas the same average value for a single cow in Israel was reported in the Philippine press to be 12,240 kg in 2009.
Production levels peak at around 40 to 60 days after calving. The cow is then bred. Production declines steadily afterwards, until, at about 305 days after calving, the cow is ‘dried off’, and milking ceases. About sixty days later, one year after the birth of her previous calf, a cow will calve again.
High production cows are more difficult to breed at a one-year interval. Many farms take the view that 13 or even 14 month cycles are more appropriate for this type of cow.
Dairy cows may continue to be economically productive for much lactation. In most cases, 10 lactations are possible. The chances of problems arising which may lead to a cow being culled are high, however; the average herd life of US Holstein is today fewer than 3 lactations. This requires more herd replacements to be reared or purchased.