The aim of this study was to evaluate the effects of four Lactobacillus transformant strains on mice, including recombinant Lactobacillus casei (L. casei), Lactobacillus pentosus (L. pentosus), Lactobacillus plantarum (L. plantarum), and Lactobacillus paracasei (L. paracasei) that expressed porcine lactoferrin with a level of 20.5, 23.6, 27.2 and 21.6 µg/ml, respectively. Treatment groups of mice were fed with 200 µl of 10⁹ CFU of recombinant Lactobacillus strain in basal diet as a feed additive, respectively, until 14 days experimental period. Compared to the control group, feeding with recombinant L. casei, L. pentosus, L. plantarum or L. paracasei improved growth performance of mice, followed by the increasing of average daily gain (ADG) by 14% and average daily feed intake (ADFI) by 6%, and the decreasing of feed efficiency (F/G) by 7%. Supplementation with recombinant Lactobacillus augmented the production of total IgG and sIgA by 11.2 and 33% in mice, respectively. Moreover, the levels of IL-2 and TNF-α were respectively shown increasing by 27 and 46%, and the levels of IL-4 were shown a significant reduction by 39% in mice received recombinant Lactobacillus strains. In the intestinal tract of treatment groups of mice, the total viable counts of E. coli were decreased and the total viable counts of Lactobacillus and Bifidobacterium were increased by 5 and 2.7% compared to the control. After E. coli K88 and porcine pseudorabies virus (PRV) challenged, approximate 10 and 30%, respectively, of the control mice exhibited abnormal health with the symptoms that feeble body, relatively dark hair, loss of body weight, and death, which did not observed in the mice received the recombinant Lactobacillus expressing porcine lactoferrin. In contrast, the recombinant L. pentosus and L. plantarum treatment expressing porcine lactoferrin showed a better beneficial effect on the health of animal.

Key words: Antibacterial and antiviral activity, Lactobacillus probiotics, Porcine lactoferrin