Abstract
Diarrhea represents the main challenge to maintain the survival of heifers in the neonatal period, since it is responsible for 57% of calves mortality in pre-weaning and, as a result, causes significant economic losses to milk and dairy farmers. In São Paulo state, the observed prevalence for diarrhea between D7 and D14 was around 85%. Risk factors associated with diarrhea are age, failure to transfer passive immunity, stress, concomitant illness, time of year (spring and summer), and hygiene. Among the major etiological factors that determine neonatal diarrhea are strains of enterotoxigenic Escherichia coli (E. coli) (ETEC) and Shiga toxin-producing E. coli (STEC). The general objective of this research is to evaluate the dynamics of TGI colonization and the production of Escherichia coli specific antibodies in Holstein calves, which are daughters of cows vaccinated in the prepartum period. To this project, twenty Holstein cows and their respective daughters from eutocic births, will be selected. The calves will receive, from their respective mothers, the volume of colostrum and transition milk in a volume equivalent to 15% of their live weight. Evaluations of cows and calves will occur immediately after birth (D1), D3, D7 and D14. Samples of colostrum and transitional milk from cows will be obtained. The calves will be evaluated for their faecal score, dry matter in the faeces, besides the collection of serum, rectal mucus and faeces. Mammary secretion, serum and rectal mucus will be used for the measurement of both total IgG and IgA, and for specific IgG and IgA against E. coli using the enzime-linked immunosorbent assay (ELISA). The dynamics of colonization of the gastrointestinal tract of calves will be performed through real-time PCR of the faeces. The data will be analyzed with appropriate statistical tests according to their behavior. (AU)
|