After feed manufacturing, final concentration of phenolic components in the feed was determined (Table 2). The most
stable phenolic component quantified in the feed was thymol from TZ feed. No differences in the final concentration after
feed manufacturing were detected for this phenol. Nevertheless, its isomer carvacrol (TC feed), showed a different behavior,
since a degradation close to 16% was detected. Similar results were obtained for BHT, this phenolic component experimented
a reduction close to 15%. As it was stated in Section 2, the rosemary extract used was composed of two major diterpenes,
carnosic acid and its lactone derived carnosol in a ratio of concentration 1:1. Attending to the chemical behavior of these
components, and as it was expected; carnosic acid suffered a potent degradation, being in the feed at concentrations under
the limit of detection for the diode array detector. Nonetheless, carnosol, just reduced its concentration by 17%