39 Concentration of obestatin in different stages of ovarian activity in cattle

Abstract

The objective of the present study was to measure serum levels of obestatin by ELISA with the purpose of establishing parameters and being able to use it as an endocrine marker for the selection of reproductive characteristics of milk and beef cattle. In test 1, 15 Creole cows with genetic tendencies of Charolais, Angus, Brangus, and Gelbvieh were sampled in diestrus and 15 in proestrus, determining their structures with an Aloka Prosound ultrasound with a 7.5-MHz linear transducer. In test 2, 16 Holstein cows were sampled in 2 different ovarian stages, diestrus and proestrus. The standardized technique was a bovine obestatin 96-well ELISA kit from My Biosource Inc. The data were analysed by measuring central tendency and linear regression, where the average levels of obestatin were related to the corpus luteum size and size and number of follicles in milk and beef cattle. We found average levels of 556.99 and 453.35 pg for beef and dairy cattle, respectively (P<0.05). We also found a significant difference (P<0.05) in obestatin concentrations depending on the size of the follicles (751.74, 615.33, and 357.39 pg for follicles of 15, 10, and 5mm, respectively). We found a significant difference in concentration of obestatin (644.53, 550.69, and 455.88 pg; P<0.05) for corpus luteum sizes of >20mm, 10–20mm, and <10mm, respectively. In dairy cattle, obestatin levels were also evaluated at different stages of the cycle, and we found concentrations of 414.79 pg in diestrus and 530.48 pg in proestrus (P<0.05). We conclude that obestatin concentration is positively associated with a greater number and size of follicles as well as with larger corpus luteum because its effect on cell proliferation interacting positively with high levels of progesterone in the blood. We found higher concentrations in beef cattle than in dairy cattle.