Informe de práctica profesional. Identificación del calostro y la leche como vehículos de transmisión vertical de VlB de vacas holstein a terneras mediante elisa y PCR.

Abstract

Bovine leucosis is a chronic, viral and contagious disease of adult cattle, with higher incidence in dairy herds. It is characterized by asymptomatic presentations, persistent linfocitosis and linfosarcomatosis. Milk and colostrum are considered as a vertical transmission vehicle for bovine leukosis. It is important to identify whether pure Holstein calves born from carrier and non-carrier mothers acquire the virus through colostrum or milk consumption from positive cows. The objective of the present study was to determine the presence of bovine leukosis virus (VLB) and antibodies against it, using PCR and ELISA in samples of colostrum, milk and blood of cows and their potential transmission to their offspring. Initially samples of colostrum, milk (50 ml with Bronopol) and blood of 8 pure Holstein heifers and their respective mothers were collected on days 0, 15, 30, 45 and 60 after delivery. In addition, one of the calves was selected to follow up from day 0 to day 15, in order to determine the exact moment of VLB infection. Of the analyzed samples the seroprevalence in cows was 87.5% for ELISA in blood, 87.5% for ELISA in milk, additionally the presence of the virus in 75% was determined using a PCR in blood. In the case of the calves for day 0, the prevalence before consumption of colostrum was 0% until that moment, at day 15 the prevalence rose to 87.5% for ELISA and 25% in PCR; and on day 30 to 60 the prevalence was maintained in 87.5% for ELISA and 37.5% in PCR.