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Acta sci. vet. (Impr.); 39(suppl.1): s243-s252, 2011.

Artigo em Português | VETINDEX | ID: biblio-1412785

Resumo

Background: The advent of animal cloning from embryos reconstructed with nuclei from cells at different stages of differentiation has been responsible for the appearance of several anomalies in calves, with some alterations diagnosed during pregnancy and others after the birth of cloned animals. Despite efforts over the past five years, the rate of mortality after the birth of cloned calves is still high, at about 50%. Below is reported the research experience gained at the University of São Paulo in the period from 2005 to 2010, related to the birth of cloned calves from Nellore. Review: Research showed that cloned calves present cardiopulmonary disorders characterized by tachycardia with episodes of arrhythmia with bradycardia, increase in the 1st heart sound, presence or absence of heart murmurs in the 1st and 2nd heart sound associated with dyspnea, breathing harsh and crackling dry, moist and crackling. During the first days of life of cloned calves that died, ultrasound examination demonstrated the presence of concentric hypertrophy congenital cardiac and turbulent flow at the foramen of botal towards the right heart to left heart, indicating reversal of blood flow to the pattern observed in fetal life. As a result, mixture of arterial and venous blood occurs, compromising the ability of oxygen to the blood of cloned calves. The occurrence of macrosomia was observed in 20.9% of Nellore calves. It is believed that this syndrome is associated with disorders of carbohydrate metabolism in the placenta and/or fetus, leading to fetal gigantism, which mimicks excessive fetal growth seen in pregnant women with diabetes. We observed the occurrence of moderate to severe normocytic and normochromic anemia, with the anemia gradually appearing from 12 h of life onwards, reaching its maximum intensity at the end of the first week, to start a gradual recovery to normal values from the 15th day of life. The anemia observed in cloned calves was ferropriva, as such animals showed a significant decrease in serum iron levels associated with decreased transferrin saturation index (STI). Umbilical anomalies occurred in most clones. There was an increase in the thickness of the umbilical cord, which hindered its spontaneous rupture at birth. The umbilical arteries did not undergo retraction into the abdominal cavity, leaving them exposed in the remnant of the umbilical cord. In the first three days after birth, strong pulse of these arteries was noted in umbilical cord, making it necessary to use clamps on the arteries in order to prevent bleeding. There were also intra-abdominal hematomas involving the arteries and the urachus. Between 15 and 20 days of life, it was observed the occurrence of alopecia in about 75.0% of the calves, whose origin may be related to disturbances in the synthesis and absorption of vitamins, since the supplementation of calves with ADE vitamin complex decreased symptoms. Conclusion: The results confirm the occurrence of serious cardiopulmonary disorders characterized by tachycardia, hyperphonesis, presence of heart murmurs in the 1st and 2nd heart sounds, episodes of arrhythmia and bradycardia associated with dyspnea, rales, and coarse breath. As a result of the non-closure of the foramen of Botal and the Ductus Arteriosus, arterial and venous blood a mix, compromising the oxygen carrying capacity in the blood of cloned calves. There was also the occurrence of macrosomia, hypoglycemia, hypothermia, abnormal umbilical structures, anemia and alopecia

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