Date of Graduation
Davis College of Agriculture, Natural Resources and Design
Animal and Nutritional Sciences
E. Keith Inskeep.
Factors affecting pregnancy maintenance between 28 and 67 days of gestation were studied in dairy cows (N = 211). Beginning on day 28 to 37 post breeding, cows were examined by ultrasonography for a viable pregnancy. Pregnant cows were re-examined for pregnancy losses during the late embryonic (≤day 45) and early fetal stages up to day 67. Overall pregnancy loss was 11%, mostly occurring before day 45. Cows with two corpora lutea maintained fewer pregnancies than cows with one corpus luteum. Pregnancy retention was less when concentrations of progesterone were low during days 28 to 37. The embryo apparently died before luteal regression. Pregnancy retention declined as body condition and age of the cow increased. Pregnancy retention between days 28 and 67 of pregnancy was associated with luteal function during d 28 to 37.
Starbuck, Melanie J., "Retention of early pregnancy and its relationship to serum progesterone in dairy cattle" (2002). Graduate Theses, Dissertations, and Problem Reports. 1502.