Avaliação do teste de redução do cromo no leite de vacas com cetose subclínica

Abstract

Subclinical ketosis is one of the major metabolic diseases affecting the dairy herd. Cows with high concentrations of ketone bodies have considerable levels of alcohols, such as Isopropanol, in body fluids. In this sense, two studies were carried out, where the purpose of the first one was to evaluate the effects of subclinical ketosis on the presence of alcohol in fluid milk, through the Chromium Reduction Test. The second study was developed to evaluate the relationship of subclinical ketosis caused by high levels of butyrate in the diet, on the fluid milk positivity in the Chromium Reduction Test. In study 1, 200 Holstein cows were used, producing on average 20 liters / day, with ± 155 days in milk, which were submitted to individual milk and blood collection. After collection of biological material, the blood was analyzed for levels of β-hydroxybutyrate (BHB), and milk for the presence of alcohol by the chromium reduction test. Only one animal had subclinical ketosis (1.3 mmol / L BHB), the batch average being 0.69 mmol / L BHB. In addition, 5 animals wered positive for alcohol in fluid milk. However, it was not possible, with this study, to accept or reject the hypothesis of the project, due to the low number of cases of ketosis. The second study, carried out in another farm, 10 dairy cows (4 Holstein and 6 Jersey) were used, randomly divided into two groups: Control group (n = 5), which received the diet offered at the farm; Treatment group (n = 5), which received the property diet plus Butyrate (CM3000® - Sodium Butyrate 30% - Microencapsulated, Vetanco, Brazil) at a level of 1.5 g / kg body weight (BW) over a period of 8 days. Individual milk and blood samples were collected daily. The milk sample was analyzed for the presence of alcohol and samples of blood for the concentration of BHB. BHB blood levels were higher (p <0.0001) in GT when compared with GC (0,91 mmol/L e 0,64 mmol/L), respectively. However, only one GT animal had positive samples for alcohol in milk. Thus, it is possible to affirm that in this study doses of 1.5 g / kg of PV did not cause subclinical ketosis. Therefore, because of the low levels of BHBA found, it was not possible with this study to accept or reject the hypothesis that cows with subclinical ketosis positivate the ethyl alcohol test.