Animal Feed Science and Technology, (1–2), 2007, 89–107
The present study was conducted to study the production and evaluation of potentially probiotic additives containing both live lactic acid bacteria (Pediococcus acidilactici NRRL B-5627, Lactococcus lactis subsp. lactis CECT 539, Lactobacillus casei subsp. casei CECT 4043 and Enterococcus faecium CECT 410) and antimicrobial metabolites with could be used as a replacement for antibiotics in weanling pig diets. The gastrointestinal transit tolerance of the four bacteria was determined by exposing washed cell suspensions at 30 °C to acidic conditions (pH 1.0, 2.0, 3.0, 4.0 and 5.0), to a simulated gastric juice (pH 2.0) containing pepsin (3 g/L) and sodium chloride (5 g/L), and to a simulated small intestinal juice (pH 8.0) containing pancreatin (1 g/L) and sodium chloride (5 g/L), mimicking the gastrointestinal environment. These studies showed that the four strains are capable of surviving the passage through the gastrointestinal conditions. Therefore, the production of biomass and antimicrobial products by these bacteria was performed in whey using a fed-batch fermentation technique that provided enhanced productions compared to those obtained in batch fermentations. The obtained fed-batch cultures preserved at −20 °C with skim milk showed a good viability after 3 months of storage. The four cultures exhibited low losses of viability in the piglet feed during their storage at room temperature for 8 days. These results offered the possibility of using the piglet feed as a vehicle to administer the four probiotic bacteria. The effects of the supplementation of separate potentially probiotic cultures and an antibiotic (colistin sulfate) to piglet diets on body weight gain, feed intake, feed efficiency and on the faecal coliform counts of weaned piglets were also studied. Although the best results were obtained in the groups receiving the antibiotic, a significant increase in body weight gain and final body weight was obtained in the groups fed diets supplemented with lactic acid bacteria as compared with the non-treated (controls) groups (P=0.05). The changes in the total coliform population in the control groups over time were not significant (P<0.05), while in the groups fed probiotics and antibiotic, the viable coliform counts significantly dropped at the last sampling (P<0.05). These results suggest that the lactic acid bacteria used in this study could be used as suitable strains for widespread use in the pig industry.