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The results showed that 100% of the human colostrum samples had antipoliomyelitic activity whereas only "80 per cent of the milk specimens obtained between 101 and 340 days after delivery" had such activity. He also tested cow's milk (not specified as colostrum) and found that milk samples from 2 of 9 cows contained antipoliomyelitic activity. [31]
The cows teat is a projection of the mammary gland that is sealed during their dry period. A dry cow refers to a dairy cow that is in a stage of their lactation cycle where milk production ceases prior to calving. This part of their lactation cycle is referred to as the cows dry period and typically last between 40 and 65 days. [1]
Once bred, a heifer is pregnant for nine months and, after giving birth, is then considered a cow. During pregnancy, the udder begins to develop further. After calving, a cow will nurse its calf briefly and then typically be milked two to three times daily. Cows produce about 80 pounds of milk per day, though some can produce well over 100 pounds.
The production of milk requires that the cow be in lactation, which is a result of the cow having given birth to a calf. The cycle of insemination, pregnancy, parturition, and lactation is followed by a "dry" period of about two months before calving, which allows udder tissue to regenerate.
The milk is separated after that. The milk can then be separated depending on which dairy products it will be used to create, including fluid milk, cheese, and yogurt.
The hormonal endocrine control system drives milk production during pregnancy and the first few days after the birth. When the milk supply is more firmly established, autocrine (or local) control system begins. During this stage, the more that milk is removed from the breasts, the more the breast will produce milk.
To produce milk from dairy cattle, most calves are separated from their mothers soon after birth and fed milk replacement in order to retain the cows' milk for human consumption. [156] Animal welfare advocates are critical of this practice, stating that this breaks the natural bond between the mother and her calf. [156]
RELATED: Bird flu in cows: 1 in 5 pasteurized milk samples had traces of virus, FDA says The testing under the federal order and the National Milk Testing Strategy will begin on Dec. 16.