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Acta sci. vet. (Impr.); 41: Pub. 1128, 2013. tab

Artigo em Inglês | VETINDEX | ID: biblio-1372417

Resumo

Background: Production diseases, such as those associated with improper nutrition or management are common in transitional high-yielding dairy cows. The diseases listed in this include: the fat liver syndrome, ketosis, oxidative stress, laminitis, mastitis, milk fever, retained placenta, metritis and infertility. The diseases occur mainly around calving. They are all interrelated and form the so-called periparturient disease complex. The term transition is to underscore the important physiological, metabolic, nutritional and endocrine changes occurring in this time frame. Diagnosing liver lipidosis and susceptibility of ketosis in dairy cows may include liver biopsy or ecography, but a less invasive and more economical analytical method may be the measurement of blood biochemical metabolites. The objective of the present study was to determine a relationship among blood indicators of hepatic function and lipid content in the liver during transitional period in high-yielding dairy cows. Materials, Methods & Results: Late pregnant and calved cows (n = 40) were selected from a Holstein dairy herd and allocated to four groups: a late pregnant cows (n = 10) from day 15 to day 5 before calving; late pregnant cows (n = 10) from day 4 to day 1 before calving; clinically puerperal healthy cows (n = 10) and clinically ketotic puerperal cows (n = 10). Liver and blood samples were taken from all cows. The blood metabolites concentrations were determined by photometric methods using a Cobas Mira automatic analyzer. Liver specimens were histopathologically analyzed for lipid contents using a freezing microtome. The statistical analysis of the obtained data was carried out by ANOVA-procedure. The results of present investigation have shown that the lipid content in the liver and the blood non-esterificed fatty acids, ß-hydroxybutyrate, total bilirubin concentrations and the AST activities were significantly higher (P < 0.05) as well the blood glucose, total cholesterol, triglycerides and albumin concentrations were significantly lower (P < 0.05) in puerperal ketotic cows as compared to the values of these parameters in the blood of healthy cows in the transition period. Discussion: Liver biopsy is the only reliable method to determine severity of fatty liver in dairy cattle in the transitional period. Blood, urine and milk metabolites or blood enzyme activity have been proposed as diagnostic tools. This investigation demonstrated that in healthy transitional cows a mild fatty infiltration occurred in liver during the late pregnancy and early lactation. The histopathological examination showed a moderate to severe degree of fatty liver in ketotic cows. The lipomobilisation markers, serum BHB and NEFA concentrations, were markedly enhanced in puerperal ketotic cows. However, liver steatosis compromised hepatocyte metabolism, leading to signifi cantly weaker circulating concentrations of glucose, TG and total cholesterol, and induced some cellular lesions as evidenced by significant increases in the serum bilirubin concentrations and in the AST enzyme activities in puerperal ketotic cows. All these biochemical metabolites may be used as important biochemical indicators in the determination of the functional status of the liver in high-yielding dairy cows during the transition period.

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