4.4.3. Experiment 3: Comparison of Bacterial Growth in Semen Diluted with Two Different Types of Antibiotic-Free Extenders

Antibiotic-free semen extenders BTS and Androstar Premium were inoculated as described in Section 4.2.2 with one of the pure strains of bacteria: Staph. spp., E. coli, Ps. aer. and P. stuartii. The spiked extender media were used for diluting three different ejaculates. This resulted in 2 (extender) × 4 (bacterial strains) × 3 (boars) = 24 samples contaminated with an individual bacterial mixture consisting of the natural bacterial content from the ejaculate and the inoculated pure bacteria. All samples were stored at 17 °C for up to 144 h. Immediately after inoculation (0 h), after 48 h and 144 h of storage, colony counts were determined for all samples as described in Section 4.2.1.