Assessment of Fatty Liver Syndrome and Its Predisposing Factors in a Dairy Herd from Venezuela

The present on-farm research evaluated the occurrence of fatty liver syndrome and its predisposing risk factors for multiparous dairy cows from a commercial herd in Venezuela. Liver biopsy samples were collected at 35 days (d) prepartum (Holstein, ; Holstein × Carora crossbred, ) as well as 1 to 7？d (Holstein, ; Holstein × Carora crossbred, ) and 28 to 35？d (Holstein, ; Holstein × Carora crossbred, ) postpartum in order to analyse hepatic triacylglycerols (TAG, % wet basis) and glycogen concentrations. At postpartum, an occurrence of 72.0% for severe fatty liver along with 73.5% of subclinical ketosis (SCK) was found. The multiple regression model that best explained the association between milk production in the previous lactation (MYP) and TAG at first week postpartum was as follows: TAG, % = ？11.2 + 3.16 (prepartum body condition) + 0.0009176 (MYP) ( , ). Logistic regression indicated that Holstein × Carora crossbred cows tended to have 27% higher relative risk than Holstein to experience SCK, whereas prepartum liver TAG greater than 3% tended to be associated with a higher relative risk for SCK compared to cows with TAG ≤3%. 1. Introduction Fatty liver (hepatic lipidosis) and ketosis (elevated concentrations of ketone bodies in blood, milk, urine, and other body fluids) are metabolic alterations that occur in high producing dairy cows during the periparturient period. Although distinctly different, they are both part of a generalized lipid mobilization syndrome named fatty liver syndrome (FLS), severe fatty liver, or fat cow syndrome. Therefore, FLS is characterized by a high hepatic triacylglycerols infiltration and the subsequent ketosis development associated with retained fetal membranes and metritis at early lactation [1–3]. Dry matter intake reductions along with high energy demand for milk production are the main risk factors for FLS [4]. Fatty liver syndrome developed in cows with higher milk yield but quantitative relationships have not been defined. Overconditioning of dairy cows during the dry period predisposes to the development of hepatic lipidosis after calving, due to increased plasma levels of nonesterified fatty acids from lipolysis [5–7]. Another factor that could predispose to the development of FLS would be the length of dry period as stated by McCormack [8] but, at farm level, this and other possible risk factors are still poorly understood due in part to the invasive nature of the diagnostic technique for hepatic lipidosis. Moreover, the knowledge of the occurrence of FLS in herds from Venezuela is very limited. Therefore,