Ovarian Characteristics and Reproductive Performance of the Aged Cow1

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Abstract
The reproductive performance of 152 grade Hereford cows that were 14 to 15 years of age at either death or slaughter resulted in an observed mean of 9.3 ± 0.3 calves and a calculated mean lifetime reproductive capacity of 10.4 calves. The median was 10 calves and the modal number was 12. As dictated by the criterion "failure to bear a calf during two successive years," 15 years was the age at which over 50 percent of the herd became infertile.