BLOOD PARAMETERS DURING EARLY LACTATION A ND THEIR RELATIONSHIP TO OVARIAN-FUNCTION IN DAIRY-COWS

This study on 65 dairy cows (Simmental x Red Holstein crossbreds) from 11 farms was carried out to examine the relationship between blood pa rameters and ovarian function. Multiparous cows which were due to calv e between January and August 1992 were used in the study. Starting 2 w eeks before the expected calving date a series of blood samples was ta ken. During the subsequent lactation period the genital organs of the cows were examined at regular intervals. The blood samples were tested for the concentrations of 17 parameters (electrolytes, enzymes, hormo nes, metabolites). The interval between calving and following ovulatio n (INT) was determined based on progesterone measurements and clinical findings (x) over bar +/- s: 39 +/- 12 days). To illustrate the chang es in the blood parameters some of the values were presented graphical ly and the median and quartile values were calculated for various time periods ante-and post-partum The relationship between ovarian finding s and laboratory results was analysed using logistic regression. For t his, 54 of the animals considered here were assigned to two groups: IN T less or more than 30 days (20 and 34 cows, respectively). The statis tical model was based on INT as the target variable, while blood value s before and after parturition and the lactation number served as expl anatory variables. A relationship between blood values and the time of the first ovulation after birth could be established for the followin g three parameters: insulin-like-growth factor 1, albumin and urea.