Lactation
The period after calving during which a cow gives milk, usually measured as 305 days in dairy records.
Also: milking period, lactation period
A lactation begins when a cow calves and lasts until she is dried off. Milk yield rises for the first six to eight weeks, peaks, then slowly falls. Dairy recording schemes compare cows on a standard 305-day lactation, which leaves about two months dry before the next calf in a yearly cycle. A high-yielding Holstein may give well over 10,000 litres in a lactation, while many native breeds give far less but on simpler feed and in harder climates. Zebu cows often have shorter lactations and may stop milking if the calf is taken away. The number of lactations a cow completes is a common measure of her working life.