Ovarian Characteristics and Reproductive Performance of the Aged Cow1

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.