Excreção urinária de cálcio e magnésio em vacas leiteiras com diferentes taxas de metabolização de glicose
Schwegler, ElizabethMontagner, PaulaSchmitt, EduardoSchneider, AugustoRohenkohl, Marina Menoncin WeschenfelderKrause, Ana Rita TavaresPereira, Rubens AlvesHalfen, JéssicaDel Pinto, Francisco Augusto BurkertCorrêa, Marcio Nunes
Background: The post-partum period in dairy cows is accompanied by a low glucose metabolism in adipose tissue and skeletal muscle tissue, being glucose conducted to the milk production. In humans, low glucose metabolism is associated with metabolic syndromes, the high glucose levels reduce tubular reabsorption of Magnesium (Mg) and Calcium (Ca), leading to hypomagnesemia and hypocalcemia. These minerals are important to the dairy cow, as their decrease leads to diseases. The aim of this study was to evaluate the relationship between glucose metabolism rate with the urinary excretion of Ca and Mg in multiparous dairy cows during the post-partum period.Materials, Methods & Results: Twenty dairy cows were used from a commercial farm southern Brazil, in the semi-extensive system. Glucose tolerance tests were performed (TTG) on day 9 relative to calving. The cows were categorized into three groups according to the glucose metabolism rate (area under the glucose curve, glucose half-life and glucose consumption rate): High Glucose Metabolization (GA); Intermediate Glucose Metabolizing (GI); and Low Glucose Metabolization (GL). Blood and urine samples were collected on days 0, + 3, + 6, + 9, +16 and +23 in relation to calving for to determine the levels of Ca, Mg, insulin (Ins), non-esterified fatty acids (NEFA) and Glu. In urine was evaluated the excretion of Ca and Mg. The cows were milked twice a day (at 3:00 a.m. and 3:00 p.m.) and the milk yield (kg/cow) was recorded daily and averages were generated every five days from day 15 to day 60 postpartum. The statistical analyses were performed with the MIXED procedure to assess the main effect of group, time (in days) and their interaction by using version 9.2 SAS software.[...](AU)
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