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Concentraciones sanguíneas de ß-hidroxibutirato, NEFA, colesterol y urea en cabras lecheras de tres rebaños con sistemas intensivos de producción y su relación con el balance nutricionalRelationship between blood metabolites (β-hydroxybutirate, NEFA, cholesterol and urea) and nutritional balance in three dairy goat herds under confinement SUMMARYThe aim of this study was to assess some blood metabolites as indicators of nutritional balance in dairy goats under intensive conditions. Three dairy herds were selected and 21 goats chosen in each. Goats were separated into three groups of seven animals each according to their productive stage: pre-partum (PP), 3-6 weeks of lactation (T1) and 16-20 weeks of lactation (T2). Blood samples were obtained during the first milking of the day and β-hydroxybutirate (BHB), non-esterified fatty acids (NEFA), cholesterol, and urea were determined by colorimetric methods. Body condition score (BCS) and milk production were also registered. To establish protein (g/day) and metabolic energy (Mcal/day) content of the ration fed, a proximal chemical analysis was performed. Nutrient requirements of goats were determined by NRC. In the three herds, significant high values of NEFA (P<0.05) were coincident with a non -significant increase in milk production (P<0.05) and in one herd with a decrease in BCS (P<0.05), which suggests fat mobilization. Urea concentration was between 10.0 ± 1.5 and 16.2 ± 1.5 mmol/L, higher than that reported by other authors. Every herd and productive stage presented imbalances between the protein and energy contents of the ration supplied, with high protein and low energy intake, which was shown in the blood metabolites analyzed. Accordingly, selected blood metabolites allowed the identification of nutritional imbalances in the studied herds.Palabras clave: cabras, metabolitos sanguíneos, nutrición.

BackgroundKetogenesis is a secondary metabolic pathway to provide energy to dairy cows during early lactation; however when the production of ketone bodies (acetoacetate, acetone, ß- hydroxybutyrate) is above certain levels a subclinical disorder may appear. The aim of the present study was to investigate the association between serum concentrations of ß- hydroxybutyrate (BHBA) and fatty acid (FA) profile of milk with emphasis in conjugated linoleic acid (CLA) in a population of early lactation Holstein cows. Fifty cows between parity 1 and 5, ranging from 14 to 21 days in milk, were randomly selected from 3 farms of the central area of Chile for determination of serum BHBA concentrations, milk fat content, and milk FA profiles.ResultsCows were divided in low (n = 26) and high (n = 24) BHBA groups considering the median value of the serum concentration of BHBA (0.7 mmol/L) (SEM = 0.094). Mean milk fat % was 3.45 % and 3.60 % for cows in the low and high BHBA groups, respectively (P = 0.15). Concentrations of several FA were significantly different between both groups. Specifically, mean CLA concentrations were 0.40 % (4 ± 0.03 g/kg) and 0.33 % (3.3 ± 0.03 g/kg) for the low and high BHBA groups, respectively (P = 0.05).ConclusionsIt is concluded that early postpartum cows with serum BHBA > 0.7 mmol/L tended to have higher milk fat % and had significantly lower concentrations of CLA than early postpartum cows with BHBA ≤ 0.7 mmol/L.

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