Design of macrocapsules to improve bacterial viability and supplementation with a probiotic for young calves

Abstract

The gastrointestinal tract of calves is sterile at birth, and intestinal microorganisms are introduced from fecal, vaginal and environmental microbiota. The balance of the intestinal ecosystem of calves can be altered in farming systems due to separation from their mothers, feeding with milk replacers and elimination of the benefits of cows' milk, inadequate colostrum intake, stressful situations and use of antibiotics. Such practices may cause morbidity and mortality of young calves which can be related to economic losses. Periodic administration of a probiotic inoculum of bovine origin may favor establishment of a stable and balanced intestinal microbiota, which would improve the health of the calves. The viability and number of microorganisms inoculated is vital because the suggested minimum level (SML) of bacteria to produce beneficial effects is 106CFU/ml. A technique that is currently being implemented to maintain the viability of probiotics is encapsulation, which consists of retaining the microorganisms within a porous gel matrix or within a semipermeable membrane containing a liquid core. In our study, we describe a new technique to produce alginate-starch macrocapsules, with the aim of producing probiotic macrocapsules to ensure bacterial viability during storage, and to facilitate administration of the inoculum to young calves with feed. To this end, we used the strain Lactobacillus casei DSPV 318T, a probiotic inoculum of bovine origin, and it was evaluated by two formulations for conformation of the capsules: one of sodium alginate (10g/l) and another of sodium alginate (5g/l)+corn starch (5g/l). These mixtures were dispersed into molds of 1 and 2ml, placed at -20°C, and, once frozen, submerged in a solution of CaCl2 (0.1M) for polymerization of alginate to maintain their shape and size. The capsules containing of 5g/l of alginate +5g/l of starch had the highest cellular count, and the incubation of the capsules in culture media for 9h increased the bacterial concentration. Viability of cells was maintained at the SML for 2mo by coating the capsules with chitosan and refrigerating at 4°C. This was reflected in a final product with a high concentration of probiotic accessible for artificial rearing of calves, with a sufficiently long expiration time, and with a size similar to the feed starter pellet, which allowed it to be mixed homogeneously with the feed which was fed to the calves.