BLOOD-PLASMA LIPEMIA IN THE POST-PARTUM P ERIOD IN COWS IN RELATION TO THEIR CONCEPTION

A relationship of total lipid cholesterol concentrations in blood plas ma to conception after the first insemination was investigated in clin ically healthy cows. Blood samples were taken on the day of parturitio n, on the day of the first post partum estrus, on the day of the first insemination and on day 21 after insemination. The lowest average con centration of total lipids (2.57 g/l) and cholesterol (2.41 mmol/l) wa s determined on the day of parturition and the highest at the time of the first insemination (5.06 g/l and 5.09 mmol/l, resp.) while the dif ference is significant. Although there was not any statistically signi ficant difference in total lipid and cholesterol concentrations betwee n the pregnant and nonpregnant cows after A.I. on the day of parturiti on (2.77 g/l vs. 2.46 g/l and 2.63 mmol/l vs. 2.30 mmol/l) nor on the day of the first estrus (4.64 g/l vs. 4.58 g/l and 4.46 mmol/l vs. 4.2 2 mmol/l), on the day of the first insemination (5.22 g/l vs. 4.97 g/l and 5.24 mmol/l vs. 5.02 mmol/l) and on day 21 after insemination (5. 21 g/l vs. 5.08 g/l and 5.03 mmol/l vs. 4.81 mmol/l), ii is apparent t hat the cows with the higher blood plasma lipemia, and so with the hig her energy reserves, had higher conception rates. In the cows which di d not conceive the blood plasma lipemia was lower in all periods of ob servation.