Relationship between luteal size and plasma progesterone concentration in pregnant and non-pregnant Indian crossbred dairy cows

Abstract

The relationship between luteal size and plasma progesterone concentration in purebred cows has been investigated previously. However, there is limited information on this topic in Indian crossbred cows. This study aimed to evaluate the relationship between luteal size parameters (diameter and area) and plasma progesterone concentration in healthy pregnant and non-pregnant Indian crossbred cows. Fifty healthy lactating crossbred cows were artificially inseminated after estrus detection and retrospectively classified into pregnant (n=29) and non-pregnant (n=21) based on the results of ultrasonographic pregnancy diagnosis. Data on luteal diameter, luteal area, and plasma progesterone concentration collected on Days 7, 14, and 20 in non-pregnant cows and on Days 7, 14, 20, 25, 30, 35, 40, and 60 in pregnant cows were analyzed. Spearmans correlation test was used to evaluate the association between the corpus luteum size parameters and the plasma progesterone concentration. Luteal area was positively correlated with plasma progesterone concentration in both pregnant ({rho}=0.48, P<0.001) and non-pregnant ({rho}=0.43, P=0.001) cows. Luteal diameter had a relatively weaker correlation with plasma progesterone concentration in both pregnant ({rho}=0.45, P<0.001) and non-pregnant ({rho}=0.24, P=0.058) cows. These results suggest that luteal area is a better indicator of CL function than luteal diameter in healthy Indian crossbred cows.