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Expectation of Life in Dairy Cows^*

Iowa State College, Ames, Iowa

ABSTRACT

Although the expectation of life in humans has been widely investigated and the information obtained about it extensively used by insurance companies and other agencies, there is little information relative to the expected span of life in dairy cattle or other farm animals. Such information on dairy cattle would be useful to the breeder, the buyer and the experimenter, who could then gauge their programs and objectives on something more substantial than guesses.

It is known that replacement rates in dairy herds are rather high, for investigations (1, 2, 5) show it is necessary to replace approximately 21 to 28 per cent of the milking herd annually. Although there is a relationship between replacement rates and expectation of life in dairy cows, these replacement rates yield no accurate information on the expected life span of cows of different ages.

Lush and Lacy (1) and A. D. B. Smith (4) have each made life expectancy tables for dairy cattle.

^* Journal Paper No. J652 of the Iowa Agricultural Experiment Station, Ames, Iowa. Project No. 31.