[Chlortetracycline residues in the meat of slaughter calves in relation to transmissible microbial resistance to antibiotics].

The occurrence of chlortetracycline residues in the meat of slaughter calves in 62% herds under study (the additive of the medicated premix AUREOVIT to feed without observing the withdrawal times) did not influence significantly the Gram-negative resistant and R+ microflora isolated from the same material, in comparison with control herds that were administered no antibiotics. Neither was the spectrum of donors and transferring R plasmids influenced significantly nor the incidence of different resistance determinants. The effect of chlortetracycline addition to feed was negative (at P = 0.05) only in the occurrence of R+ microflora isolated from stable environment where the slaughtered calves had been housed.