Lactation milk yield refers to the total amount of milk produced by a cow during a specific lactation period. It is the milk yield from calving (when the cow starts being milked) till the beginning of the dry period (the end of that lactation period). This period is usually +/-305 days.

305-day milk yield is the milk yield from calving till exactly 305-days. 305-days is usually used for uniform evaluation of milk yield between cows.

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