Assistência clínica materna e neonatal às diferentes condições obstétricas em bovinos da raça Holandesa / Maternal and neonatal clinical assistance under distinct obstetrical conditions in Holstein cattle

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The novel reproductive biotechnologies (ET, IVF and Cloning) require more accurate control of pregnancy and parturition, due to obstetrical problems as a result of the large offspring syndrome or reduced calf vitality associated with placental anomalies. Hence, the reduction in neonatal mortality is justifiable as research in this area progresses, aiming maternal and neonatal well-being and livestock economic concernment. Dystocia may compromise dam-fetal blood flow and induces severe hypoxia at birth. Oxytocin employed as ecbolic treatment for uterine inertia can enhance calving stress. Therefore, the aims of this study were to identify abnormalities in neonatal Apgar score, body temperature, arterial blood gas analysis, glucose and cortisol assay at birth and after 1 hour of calving under distinct obstetrical conditions and to verify the changes on blood pressure (BP), heart rate, electrocardiogram record, glucose and cortisol assay of cows during the first stage of labor, intra-partum, immediately after calving and 1 hour later. Thirty Holstein cows and 30 Holstein calves were grouped according to the obstetrical condition into: Eutocia Group (EUT G; n=10); Dystocia Group with mild to severe obstetric assistance (DIST G; n=10) and Uterine Inertia Group treated with oxytocin (50UI) (OCT G; n=10). EUT G and OCT G cows showed stress-induced hyperglycemia 1 hour after calving. On the other hand, DIST G presented hyperglycemia yet during intra-partum. Dystocia also increased cortisol levels shortly after calving. During labor, DIST G presented significantly higher BP, due to uterine and abdominal strengthened contractions. Electrocardiogram recordings denoted normal sinus rhythm at all time points. DIST G neonates presented lower vitality (Apgar score) and higher stress (cortisol level) at birth compared to other groups. Calves were normothermic, despite the significative decrease in body temperature after 1 hour of birth, and remained normoglycemic. Moreover, base-excess, HCO3- and pO2 results were low, while Anion-gap and pCO2 were high, comparing to standard values. However, mixed acidosis (metabolic and respiratory; pH<7,2) was only noticeable in DIST G, suggesting higher fetal distress during calving and reduced blood supply (oxygenation). In addition, OCT G calves presented increased pCO2 and decreased pO2 at birth. Oxytocin infusion may cause a distinct pattern of uterine contraction, compromising neonatal hypoxia even more. The oxytocin infusion altered transitorily the maternal hemodynamic variables with a possible bradicardiac effect and intrapartum hypotension, causing lower neonatal respiratory adaptability, demanding more intensive care at birth. All newborns showed low hematocrit and hemoglobin concentration due to immature erythropoiesis and intense fetal erythrocyte metabolism. The present results indicate full maternal adaptation to labors requirement. Calves showed stark acid-base recovery during the critical period of adaptation to ex utero life, with also evident thermoregulation and glucose maintenance 1 hour after birth. The obstetrical condition presented at birth was determinant to neonatal clinical demeanor. Dystocia mainly compromised blood flow and oxygen supply and ultimately interfered with newborn vitality. Ponctual maternal circulatory alterations caused by oxytocin infusion were reversible and did not compromise neonatal outcome.

ASSUNTO(S)

bezerro oxytocin calf dystocia hemogasometria ocitocina distocia calving parto blood gas analysis

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