Efecto de la gestación, parto y lactancia en la función hemática y hepática de vacas Holstein en condiciones tropicales.

Specialized dairy cattle under tropical conditions present changes on physiology caused by environmental and handling aspects. These alterations of different functions affect the capacity to express genetic potential of production. The research was carried out at savanna of Bogotá, Colombia. Located at 2547 m above sea level, annual mean temperature 13 0C, relative humidity 80 % and annual precipitation685 mm. The study's main objective was to characterize the changes in hematic and hepatic functions of dairy cows during pregnancy, calving and lactation periods and under tropical highland conditions. Forty Holstein Friesian cows were included during their fifth, sixth, seventh and eight months of pregnancy day of calving and weeks 1,2,3, 4,8, 12, and 16 of lactation period. The results showed that hematocrit (HT), hemoglobin (HB), mean corpuscular volume (MCV) and mean corpuscle hemoglobin (MCH), presented significant changes (P <.o5) due to physiological fetal growth. During pregnancy and lactation, weight and concentration of hemoglobin of eritrocites were higher than the values reported by literature, which could indicate a special mechanism of adaptation to the low concentration of atmospheric oxygen in the site of the study. On calving day, a significant increase of HT, HB, MCH, an aspartate aminotransferase (ASAT) and a significant decrease of total protein (TP) and globulins (GLOB) were observed (P<.o5). This can be ascribed to the calving stress and to proteins use for production of colostrum. At birth and at the beginning of lactation significant increases of ASAT were found (P <.o5), a change related to fatty degeneration in liver. Primiparous cows presented the lowest concentrations of TR albumin (ALB), GLOB and urea, as the highest levels of MCV and MCH (p <.o5) pointing out different metabolic status in young animals. The present information describes changes and metabolic adjustments for pregnancy, calving and lactation, of dairy cows. In this way a change in liver functioning that compromises health status of Postpartum cows was detected.En condiciones tropicales, los bovinos especializados en producción de leche presentan cambios en su fisiología ocasionados por el ambiente y los sistemas de manejo. La alteración de diversas funciones afecta la capacidad de expresión del potencial genético de producción. Esta investigación se realizó en la Sabana de Bogotá, Colombia, ubicada a 2547 msnm, temperatura media 13 0C, humedad relativa 80 % y precipitación pluvial 685 mm año. El objetivo del trabajo fue caracterizar los cambios en la función hemática y hepática de vacas lecheras en los períodos de gestación, parto y lactancia en una zona tropical de altura. Se estudiaron 40 vacas Holstein Friesian, en el quinto, sexto, séptimo y octavo mes de gestación, el día del parto y las semanas 1, 2, 3, 4, 8, 12 y 16 de lactancia. Los resultados mostraron que en la gestación se presentan cambios significativos del hematocrito (HTO), hemoglobina (HB), volumen corpuscular medio (VCM) y hemoglobina corpuscular media (HCM) (P<.o5), como respuesta fisiológica al crecimiento fetal. Las vacas durante la gestación y la lactancia, mostraron mayor peso y concentración de hemoglobina en el eritrocito al reportado en la literatura, lo que puede indicar un mecanismo especial de adaptación a las bajas tensiones de oxígeno atmosférico de la zona de estudió. EI día del parto se produjo aumento significativo del HTO, HB, HCM y aspartato aminotransferasa (ASAT) y disminución significativa de la Proteína Total (PT) y globulinas (GLOB) (P<.o5), modificaciones normales atribuidas al proceso de estrés del parto y a la pérdida de proteínas para la formación de calostro. Al parto e inicio de la lactancia se encontró aumento significativo de la actividad de la ASAT (P<.o5), situación relacionada con infiltración de grasa en el hígado. Las vacas de primer parto presentaron la concentración más baja de PT, albúmina (ALB), GLOB y urea y el mayor valor de VCM y HCM (P<.o5) indicando diferencias en el estado metabólico de animales jóvenes. La información presentada describe ajustes y cambios metabólicos importantes en la gestación, parto y lactancia de vacas lecheras en la Sabana de Bogotá. Así mismo, se encontró alteración de la función hepática, lo que puede comprometer el estado de salud de la vaca en el posparto. Gestation, calvian and lactation effect on the hematic and hepatic function of Holstein cows in tropical conditions.Specialized dairy cattle under tropical conditions present changes on physiology caused by environmental and handling aspects. These alterations of different functions affect the capacity to express genetic potential of production. The research was carried out at savanna of Bogotá, Colombia. Located at 2547 m above sea level, annual mean temperature 13 0C, relative humidity 80 % and annual precipitation685 mm. The study's main objective was to characterize the changes in hematic and hepatic functions of dairy cows during pregnancy, calving and lactation periods and under tropical highland conditions. Forty Holstein Friesian cows were included during their fifth, sixth, seventh and eight months of pregnancy day of calving and weeks 1,2,3, 4,8, 12, and 16 of lactation period. The results showed that hematocrit (HT), hemoglobin (HB), mean corpuscular volume (MCV) and mean corpuscle hemoglobin (MCH), presented significant changes (P <.o5) due to physiological fetal growth. During pregnancy and lactation, weight and concentration of hemoglobin of eritrocites were higher than the values reported by literature, which could indicate a special mechanism of adaptation to the low concentration of atmospheric oxygen in the site of the study. On calving day, a significant increase of HT, HB, MCH, an aspartate aminotransferase (ASAT) and a significant decrease of total protein (TP) and globulins (GLOB) were observed (P<.o5). This can be ascribed to the calving stress and to proteins use for production of colostrum. At birth and at the beginning of lactation significant increases of ASAT were found (P <.o5), a change related to fatty degeneration in liver. Primiparous cows presented the lowest concentrations of TR albumin (ALB), GLOB and urea, as the highest levels of MCV and MCH (p <.o5) pointing out different metabolic status in young animals. The present information describes changes and metabolic adjustments for pregnancy, calving and lactation, of dairy cows. In this way a change in liver functioning that compromises health status of Postpartum cows was detected