Treatment for Bovine Pathogenic Diseases during the First Year of Life Does Not Alter Antral Follicle Counts in Angus Heifers at a Year of Age

There is evidence that infections of the mammary gland or the uterus may stimulate immune responses that decrease the number of primordial follicles in the ovary in dairy cows. Beef heifers between 18 and 30 mo of age that were persistently infected with Bovine Viral Diarrhea Virus (BVDV) also had decreased numbers of primordial follicles in their ovaries. The number of primordial follicles in the ovary is positively correlated with the number of antral follicles that can be detected by ultrasonographic examination of the ovaries. Therefore, it was hypothesized that Angus heifers that were treated for bovine respiratory disease, infectious keratoconjunctivitis, or infectious pododermatitis during the first year of life would have decreased numbers of antral follicles detectable by ultrasonography at a year of age. Angus heifers (n = 346) were submitted for an ultrasonographic examination to determine antral follicle count at a year of age. Data were analyzed independently for each pathogenic disease, even if some heifers were treated for multiple conditions during the first year of life; however, multiple treatments for the same disease were treated as a single case. Incidences of the diseases were 18 cases of bovine respiratory disease (5.2%), 39 cases of infectious keratoconjunctivitis (11.3%), and 7 cases of infectious pododermatitis (2.0%). Number of antral follicles detected by ultrasonography was analyzed using the GLM procedure of SAS with status for each disease (treated or not treated) as a class effect. Treatment for bovine respiratory disease (untreated = 21.6 ± 0.5 antral follicles, treated = 22.6 ± 2.1 antral follicles; P = 0.66), infectious keratoconjunctivitis (untreated = 21.7 ± 0.5 antral follicles, treated = 21.4 ± 1.5 antral follicles; P = 0.86), or infectious pododermatitis (untreated = 21.8 ± 0.5 antral follicles, treated = 17.9 ± 3.4 antral follicles; P = 0.26) did not influence the number of antral follicles detected by ultrasonography in yearling Angus beef heifers. These results indicate that treatment for bovine respiratory disease, infectious keratoconjunctivitis, or infectious pododermatitis during the first year of life do not alter the number of antral follicles detectable by ultrasonography in yearling beef heifers. Responses may differ based on the target tissues with immune responses in the mammary gland and reproductive tract having a bigger impact on ovarian reserves than targets in peripheral tissues. USDA is an equal opportunity provider and employer.