Rakkyo (Allium chinense), is a Japanese leek that is primarily used to make a popular sweet or sour pickled dish. Lactic acid bacteria are often involved in the preparation steps of fermented pickles, which helps in the effective preservation of the natural bioactive compounds of fruits and vegetable, and thereby exert several health benefits including immunomodulation and growth per-formance. This work aimed to evaluate the in vivo effects of adding Lactiplantibacillus plantarum N14 fermented rakkyo pickled juice as feed supplement on the immunocompetence and production performance of pigs. We first analyzed the nutritional composition, which revealed that the proportion of protein, lipid, and water-soluble fiber content were estimated as of 4%, 5%, and 5% in rakkyo residual liquid or juice, while 22%, 15% and 14%, respectively, were estimated in rakkyo residual powder. For the in vivo feeding trials, three groups of pigs were treated either with 5%, 20%, or 40% mixture (v/v) of fermented rakkyo pickled juice and the grinded residual liquid supplemented in the drinking water in addition to standard feed. The results of the feeding trials showed that the administration of a juice mixture of 5% or 20% (fermented pickled juice and residual liquid) had a similar trend of effects in improving the complement activity, phagocytic activity and leucocytes counts in the peripheral blood when compared to pigs fed with 40% mixture or untreated controls. Those changes were related to an improved resistance to enteric infections. Moreover, animals receiving a mixture of fermented pickled juice and fermented rakkyo residues had a higher growth rate and carcass quality than controls. The results suggested that the use of 5% mixture of fermented rakkyo pickled juice and the residual liquid through drinking water could be a cost-effective approach to promote the immune-health and production performance of pigs. This approach would contribute not only to the sustainable management of food wastes but also to the application of a value-added feed supplement for the promotion of animal health and production.
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