This study aimed to identify the existent of microbiota in the fresh semen of collared peccary (Pecari tajacu), kept in captivity, and their susceptibility patterns to antimicrobial drugs. Ten males of this species were submitted into experimental induced ejaculation procedures throughout 14 months. The microorganisms found in the semen were evaluated within the following criteria: morphology, biochemistry, colony forming unit (CFU mL-1), and antibiotic sensitivity. 225 Gram-positive strains were isolated, out of 88 samples. They were identified as following: Streptococcus (30.2%), Staphylococcus (30.2%), Micrococcus (33.7%), Corynebacterium (2.2%), Enterococcus (1.7%), and Bacillus (1.7%). The cell counting of contaminated semen material was under 300 CFU mL-1. The evaluation of sensitivity against eleven antibiotics revealed that most of the bacteria found were sensitive to Gentamicin, Cephalothin, Amikacin, Ampicillin, Ceftriaxone, Cephotaxin and Penicillin. During the evaluation period, the presence of microorganisms in the semen here analyzed did not influence the quality of the semen production of the donor animals. Semen contamination is probably coming from the surrounding environment in which the animals were kept, during collection procedures. This study suggests that Gentamicin and Amikacin are better choices over Tetracycline as diluters of collared peccary's semen.