Evaluation of Relationship between Serum Progesterone levels and Size of Normal and Vacuolated Corpus Luteum and Comparison of Fertility in Holstein dairy cows

The corpus luteum is a temporary endocrine structure in female mammals that is involved in the production of relatively high levels of progesterone and moderate levels of estradiol and inhibin A. In present study we aimed to determine the range of these two kinds of CLs and progesterone secreted from them and the fertility rate. On days 7 to 9 of estrus cycle, ovaries were examined using rectal and ultrasonic methods. The used apparatus was Hitachi v900 frequency 7.5 MHz linear. Then, the type of CL was diagnosed. 10CC blood samples were obtained. Plasma was isolated at the laboratory using centrifuge at 3000RPS for 10 minutes and was kept at -20°C till using. Ultrasonographic evaluation showed of 100 examined diestrus cows, 33 cases had vacuolated CL and 67 of them had non vacuolated CL. By dimensioning the CLs using ultrasonographic method and calculating the area it revealed that the size of vacuolated CLs is 357.391mm2 and the mean square is 348.53 mm2 (table 1). Statistical analysis showed no significant difference among the size and area. As shown in the diagram 2, the mean value of serum progesterone CL is 9.34 ng/ml and 8.36 ng/ml in vacuolated and non-vacuolated, respectively. Statistical analysis showed no significant difference among the groups in term of serum progesterone (P=0.64). Also, subsequence administration of PG and induction of estrus and AI, of 33 cases with vacuolated CL on day 30 after AI, 18 of them were pregnant and 13 of them were non pregnant. Also, of 67 cases with nonvacuolated CL, 41 of them were pregnant and 26 of them were non pregnant. Statistical analysis showed no significant difference among the groups in term of serum progesterone (P=0.369).