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Maternal colostrum (MC) is an important source of nutrients and immune factors for newborn calves. However, when colostrum is unavailable or of poor quality, a colostrum replacer (CR) may be a suitable alternative to MC. As stock-raising farmers must make informed decisions about colostrum feeding management, this study was conducted to determine the effect of feeding MC versus CR on the promotion of immunological status, growth, and health in pre-weaned Japanese black (JB) calves. Sixteen newborn JB calves were fed MC after birth, and 16 JB calves were fed CR. For the MC group, the numbers of γδ T cells, CD4+ cells, CD8+ cells, CD4+CD8+ cells, B cells, and MHC class II+ cells were significantly higher compared with the CR group. Furthermore, the expression levels of interleukin (IL)-1ß-, IL-2-, and interferon-γ (IFN-γ)-encoding mRNAs were significantly higher in the MC group compared with the CR group. A lower incidence of disease in 1-month-old calves and higher carcass weight in the MC group were observed compared with the CR group. These results suggest that CR activates the immune system delayed in calves compared with MC. MC increases populations of various immunocompetent cells, which can reduce infection rates and improve body weight gain.

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Intestinal coccidiosis caused by Eimeria protozoan species is an economically important disease, especially in poultry and cattle. Anti-coccidial drugs commonly used for controlling coccidiosis are toltrazuril (TTZ) and diclazuril (DCZ). In this study, the efficacies of TTZ and DCZ were compared using a murine model, and the effect of these treatments on the induction of acquired resistance was evaluated. Male C57BL/6J mice were inoculated with 1,000 sporulated E. vermiformis oocytes and treated with TTZ or DCZ. The recommended TTZ dose for cattle (15 mg/kg) completely prevented oocyte excretion. But, mice required 5 mg/kg of DCZ, which is five times the recommended dose for cattle, to reduce oocyte excretion. In E. vermiformis re-infection, TTZ (15 mg/kg) and DCZ (5 mg/kg) treatments did not interfere with the development of acquired resistance. Bodyweight gain was significantly higher in the TTZ-treated group than in the control (untreated/infected) group and the DCZ-treated group, and no significant difference in bodyweight gain was observed between the TTZ-treated group and the healthy (uninfected/untreated) group. Analysis of T lymphocyte subsets in the spleen and mesenteric lymph nodes indicated that the relative populations of CD4+ and CD8+ T cells were reduced in the DCZ-treated and control (untreated/infected) groups, suggesting there was immunosuppression during the infection. However, no reductions in T cell populations were observed in the TTZ-treated group. The results indicated that an optimal anti-coccidial drug is one that can completely break the parasite life cycle in the host animal.

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Toxoplasmosis is a widespread protozoan zoonosis. Since ingesting undercooked meat harboring Toxoplasma gondii cyst is considered one of the major transmission routes to humans, the screening of T. gondii in meat-producing animals can reduce the risk of food-borne toxoplasmosis in humans. Among serological diagnostic methods, Luciferase-linked Antibody Capture Assay (LACA) has been found to be a promising platform with high sensitivity and specificity. In this study, we aimed to evaluate recombinant nanoluciferase fused-T. gondii antigens (rNluc-GRA6, rNluc-GRA7, rNluc-GRA8 and rNluc-BAG1) for their potential use in LACA for pigs. As a result, the sensitivity of GRA6-, GRA7-, GRA8- and BAG1-LACA were 70.0%, 80.0%, 80.0% and 30.0% with specificity 87.0%, 81.5%, 74.1% and 50.0%, respectively. The cocktail LACA using a mixture of rNluc-GRA6, rNluc-GRA7 and rNluc-GRA8 indicated higher sensitivity (90.0%) and a similar specificity (96.3%) in comparison with the commercial ELISA kit. Compared to the Dye-Test as a reference test, cocktail LACA showed strong agreement (kappa value=0.811) when we assessed pig sera collected at the slaughterhouse. In addition, we also successfully established the rapid LACA format for the detection of Toxoplasma infection in pigs (called Rapid-LACA) in which the test could be performed within 30 min. In Rapid-LACA, the protein A pre-coated/blocked plates could be preserved at -30°C, 4°C or room temperature conditions for at least two months without compromising on the quality of assay.

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High-intensity exercise and competition are associated with depressed immune function. Young horses, which participate in high-intensity exercise and competitions, are at increased risk for the development of infectious disease due to depression of immune function. The effects of branched-chain amino acid (BCAA) supplementation on the immune status of young racing horses were evaluated, determining whether BCAA might help to avoid or reduce immune suppression during exercise and competitions. Twenty horses (10 male and 10 female) were treated with BCAA supplementation; another twenty untreated horses (10 male and 10 female) constituted control group. Peripheral blood was collected from each animal and evaluated for lymphocyte subsets, phagocytosis analysis of monocytes and granulocytes, lymphocyte proliferative response, and expression of cytokine-encoding messenger ribonucleic acids (mRNAs). The numbers of CD4+, CD8+, and major histocompatibility complex (MHC) class II+ cells in females of the treated group were significantly higher than those in females of the control group. The lymphocyte proliferative response in female of the treated group also was significantly higher than that in females of the control group. In addition, expression of mRNAs encoding interleukin-1ß (IL-1ß) and interferon-γ (IFN-γ) in females of the treated group was significantly higher than that in females of the control group. There were no significant differences between males of the treated and control groups. The results of this study indicated the positive effects of BCAA supplementation in counteracting immunosuppression in young female racing horses during and following high-intensity exercise.

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