Calcium and magnesium urinary excretion in dairy cows with different fee of glucose metabolization / Excreção urinária de cálcio e magnésio em vacas leiteiras com diferentes taxas de metabolização de glicose

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)

Calcium and magnesium urinary excretion in dairy cows with different fee of glucose metabolization / Excreção urinária de cálcio e magnésio em vacas leiteiras com diferentes taxas de metabolização de glicose

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.[...]

Paraoxonase activity in the serum of peripartum dairy cows with different placental lactogen concentrations / Atividade sérica de Paraoxanase durante o periparto de vacas leiteiras com diferentes concentrações de Lactogênio Placentário

The action of the bovine placental lactogen (bPL) hormone on maternal metabolism is still poorly known. Some markers, such as the acute phase protein paraoxonase (PON1), are used as indicators of liver function and help to determine the metabolic condition during the transition period in dairy cows. The aim of this study was to evaluate the activity of paraoxonase (PON1) in the serum of peripartum dairy cows with different levels of bPL. Based on the plasma bPL concentration, 18 cows were divided equally into three groups: LOW ( < 2,68 ng bPL mL-1), MEDIUM (2,682,80 ng bPL mL-1), and HIGH ( > 2,80 ng bPL mL-1). The experiment was conducted between 21 days prepartum and 28 days postpartum. Serum samples were collected during the experiment for the determination of bPL concentrations and PON1 activity. The bPL concentration was significantly different between the experimental groups (P ≤ 0,0001) and the days of serum collection (P ≤ 0,0001). In the prepartum dairy cows, the PON1 levels were different between the groups (P ≤ 0,05) and the days of serum collection (P ≤ 0,05). Cows with high bPL concentration had lower serum PON1 activity (P ≤ 0,05), while cows with low hormone levels had higher enzyme activity (P ≤ 0,05). In the postpartum period, there was a significant difference between the days of serum collection (P ≤ 0,0001) and the interaction between groups and collections(P ≤ 0,01). The group with high concentrations of bPL had lower levels of PON1 (P ≤ 0,01), while thegroup with low bPL maintained higher concentrations of PON1 (P ≤ 0,01). It was concluded that thecows with higher concentrations of bPL in the prepartum period present a reduction in the serum activityof the PON1 enzyme during the peripartum period.(AU)

A ação do hormônio Lactogênio Placentário Bovino (bLP) no metabolismo materno ainda é poucoconhecida. Alguns marcadores, como a proteína de fase aguda Paraoxanase (PON1), são utilizadoscomo indicadores da função hepática auxiliando na determinação da condição metabólica no período de transição em vacas leiteiras. O objetivo deste trabalho foi avaliar a atividade sérica de PON1 duranteo periparto em vacas leiteiras com diferentes níveis de bLP. As vacas foram divididas em três gruposde acordo com as concentrações plasmáticas de bLP, em que BAIXO < 2,68 ng mL-1 (n=6), MÉDIO> 2,68 ng mL-1 e < 2,80 ng mL-1 (n=6) e ALTO > 2,80 ng mL-1 (n=6). O período experimental ocorreuentre os 21 dias pré-parto e 28 dias pós-parto. Amostras de soro foram coletadas para a determinaçãodas concentrações de bLP e atividade sérica de PON1. Houve diferença entre os três grupos (P ≤ 0,0001)de acordo com as concentrações de bLP, assim como entre os dias coletados (P ≤ 0,0001). No pré-parto,os níveis de PON1 apresentaram diferença entre grupos (P ≤ 0,05) e coletas (P ≤ 0,05). Vacas com altaconcentração de bLP apresentaram menor atividade sérica de PON1 (P ≤ 0,05), enquanto vacas combaixos níveis do hormônio obtiveram maior atividade da enzima (P ≤ 0,05). No pós-parto não houvediferença entre grupos (P ≥ 0,10), houve diferença entre os dias coletados (P ≤ 0,0001) e interação entregrupos e coletas (P ≤ 0,01). O grupo com altas concentrações de bLP apresentou menores níveis dePON1 (P ≤ 0,01), enquanto vacas do grupo com baixo bLP mantiveram maiores concentrações de PON1(P ≤ 0,01). Conclui-se que, vacas com maiores concentrações de bLP no período pré-parto apresentamredução na atividade sérica da enzima PON1 durante o período periparto.(AU)

Paraoxonase activity in the serum of peripartum dairy cows with different placental lactogen concentrations / Atividade sérica de Paraoxanase durante o periparto de vacas leiteiras com diferentes concentrações de Lactogênio Placentário

The action of the bovine placental lactogen (bPL) hormone on maternal metabolism is still poorly known. Some markers, such as the acute phase protein paraoxonase (PON1), are used as indicators of liver function and help to determine the metabolic condition during the transition period in dairy cows. The aim of this study was to evaluate the activity of paraoxonase (PON1) in the serum of peripartum dairy cows with different levels of bPL. Based on the plasma bPL concentration, 18 cows were divided equally into three groups: LOW ( 2,80 ng bPL mL-1). The experiment was conducted between 21 days prepartum and 28 days postpartum. Serum samples were collected during the experiment for the determination of bPL concentrations and PON1 activity. The bPL concentration was significantly different between the experimental groups (P ≤ 0,0001) and the days of serum collection (P ≤ 0,0001). In the prepartum dairy cows, the PON1 levels were different between the groups (P ≤ 0,05) and the days of serum collection (P ≤ 0,05). Cows with high bPL concentration had lower serum PON1 activity (P ≤ 0,05), while cows with low hormone levels had higher enzyme activity (P ≤ 0,05). In the postpartum period, there was a significant difference between the days of serum collection (P ≤ 0,0001) and the interaction between groups and collections(P ≤ 0,01). The group with high concentrations of bPL had lower levels of PON1 (P ≤ 0,01), while thegroup with low bPL maintained higher concentrations of PON1 (P ≤ 0,01). It was concluded that thecows with higher concentrations of bPL in the prepartum period present a reduction in the serum activityof the PON1 enzyme during the peripartum period.

A ação do hormônio Lactogênio Placentário Bovino (bLP) no metabolismo materno ainda é poucoconhecida. Alguns marcadores, como a proteína de fase aguda Paraoxanase (PON1), são utilizadoscomo indicadores da função hepática auxiliando na determinação da condição metabólica no período de transição em vacas leiteiras. O objetivo deste trabalho foi avaliar a atividade sérica de PON1 duranteo periparto em vacas leiteiras com diferentes níveis de bLP. As vacas foram divididas em três gruposde acordo com as concentrações plasmáticas de bLP, em que BAIXO 2,68 ng mL-1 e 2,80 ng mL-1 (n=6). O período experimental ocorreuentre os 21 dias pré-parto e 28 dias pós-parto. Amostras de soro foram coletadas para a determinaçãodas concentrações de bLP e atividade sérica de PON1. Houve diferença entre os três grupos (P ≤ 0,0001)de acordo com as concentrações de bLP, assim como entre os dias coletados (P ≤ 0,0001). No pré-parto,os níveis de PON1 apresentaram diferença entre grupos (P ≤ 0,05) e coletas (P ≤ 0,05). Vacas com altaconcentração de bLP apresentaram menor atividade sérica de PON1 (P ≤ 0,05), enquanto vacas combaixos níveis do hormônio obtiveram maior atividade da enzima (P ≤ 0,05). No pós-parto não houvediferença entre grupos (P ≥ 0,10), houve diferença entre os dias coletados (P ≤ 0,0001) e interação entregrupos e coletas (P ≤ 0,01). O grupo com altas concentrações de bLP apresentou menores níveis dePON1 (P ≤ 0,01), enquanto vacas do grupo com baixo bLP mantiveram maiores concentrações de PON1(P ≤ 0,01). Conclui-se que, vacas com maiores concentrações de bLP no período pré-parto apresentamredução na atividade sérica da enzima PON1 durante o período periparto.