Survey of the prevalence and types of infertility in beef cows and heifers.

Thirty to 180 days after natural mating to bulls, 8,184 beef cows and heifers were palpated rectally for pregnancy determination. Of these, 7,396 (90%) were pregnant and 815 (10%) were not pregnant. Regarding the nonpregnant cattle, 315 (38.7%) had a normal uterus and a functional corpus luteum, suggesting that they were cycling; the rest had palpable pathologic findings: 455 (55.8%) had ovarian inactivity and uterine atrophy; 16 (2%) had pyometra; 12 (1.5%) had a mummified fetus; 7 (0.9%) had chronic metritis; 6 (0.8%) had an involuting uterus; and 4 (0.5%) had adhesions of the uterus, ovaries, or a combination of both. For the purpose of comparison, the cattle were grouped according to age: group 1-1,035 nulliparous heifers 18 to 24 months of age; group 2-1,137 primiparous heifers 30 to 36 months of age; group 3-5,548 multiparous cows between 4 and 9 years of age; and group 4-464 cows 9 years of age or older. The pregnancy rates were 79.1, 72.2, 96.8, and 78.2, respectively, for these groups. The pregnancy rate for 4- to 9-year-old cows was significantly greater (P less than 0.05) than that for the other age groups.