Alterations in lipolysis activity during: - Ovine Pregnancy Ketosis. - The transition period of dairy cattle.

Abstract

The most common metabolic disease affecting the adipose tissue in sheep and dairy cattle is ketosis. In these days it is thought that food (poor quality or an inadequate quantity) is one of the most important causes of ketosis. In this study we used ewes (2 ketotic and 2 control animals) and dairy cattle (6 Holstein Frisian dairy cattle) adipocyte tissue and blood. The aim of the study in ewes is to see if the rate of lipolysis changes when we incubated the adipocyte tissue with isoproterenol, insulin and beta-hydroxybutyrate (BHB) and the combination of isoproterenol insulin and the combination of BHB and insulin is different between ewes with or without ketosis. The aim of the study in dairy cattle is to see if there is an alteration in the lipolysis rate during the transition period (last week of gestation until the third week of lactation). We also tested of the differences are seen in the different incubations we did. In the ewes isoproterenol stimulates the lipolysis rate, BHB inhibits the lipolysis rate and insulin had little or no effect. The combinations of insulin with isoproterenol also elevated the lipolysis rate and the combination of insulin and BHB reduces the lipolysis rate. Not any of these effects where significantly. The blood samples where taken to confirm if the ewe was ketotic or not. In dairy cattle the incubations we tested are isoproterenol, insulin 50 pM, 100 pM, 500 pM, BHB and the combination of isoproterenol with insulin 50 pM and isoproterenol combined with insulin 500 pM. Isoproterenol stimulates the lipolysis, insulin had little or no effect, BHB caused a reduction in lipolysis activity and the combination of isoproterenol and insulin elevated the lipolytic activity. Only the reduction of lipolysis caused by BHB is significant.