Effect of fermented liquid food and zinc bacitracin on microbial metabolism in the gut and sensoric profile of m. longissimus dorsi from entire male and female pigs

The aim of this work in pigs was to evaluate the effect of fermented liquid food (FLF) and the combination of FLF plus short-term addition of an antibiotic food additive zinc bacitracin (FLF + ZB) compared with fed non-pelleted dry food (NPDF), on microbial metabolism in the gut and the effects on flavour and odour attributes and profiles of pig meat as well as boar odour from entire male and female pigs. At an average start weight of 60 kg, 108 pigs (54 males and 54 females) were equally allocated to three treatments according to pen-replicate, litter and sex. Microbial metabolism in the gut was studied in 24 pigs, eight from each treatment. For sensory profile evaluation (flavour, odour and tenderness) of pork loins from m. longissimus dorsi, 48 pigs (24 entire males and 24 females) were selected. The sensory evaluation of different qualities of flavour and odour as well as tenderness of cooked pork loins (LD) was done by a boar taint (skatole and androstenone) trained taste panel. To evaluate the odour and the flavour, a sensory profile analysis was performed which involved the following attributes: total off-odour/off-flavour, pig, urine, manure, naphthalene, rancid, sweet and sweat in the whole sample including both meat and fat. Giving FLF to pigs significantly changed the microbiota in the gastro-intestinal tract compared with NPDF. In particular the density of coliform bacteria was reduced in the gastro-intestinal tract of the pigs on FLF. Giving FLF demonstrated no effects on skatole concentration in caecum, colon, blood and backfat and boar odour attributes, whereas administration of FLF + ZB decreased the skatole concentrations and the typical boar odours, pig and manure odour, compared especially with the pigs on NPDF. However, meat from pigs given FLF either with or without zinc bacitracin had smaller but significantly worsened scores for three flavour attributes - pig flavour, rancid flavour and total off-flavour - compared with meat from NPDF pigs and the three flavour attributes were equally affected in both sexes. This seems to point to a significant worsening of meat flavour in pigs given FLF that is independent of sex and boar odour problems (skatole and androstenone).