PS2-22. Evaluation of the Adaptive Humoral Response in Cattle Treated with the Natural Additive Fator P Against Specific Salivary Antigens Isolated from the Tick Rhipicephalus Microplus.

Abstract The cattle tick R. microplus causes several negative impacts on the performance of livestock. The control of infestation causes economic losses for producers, contaminate food products, the environment and generates resistance to ticks. Fator P® is a natural additive employed in nutrition of livestock to promote superior performance, including immunity, and can be adjuvant for R. microplus control. We thus evaluated if antibody responses specific for tick salivary proteins were improved in animals infested with R. microplus with treatment using Fator P by enzyme immunoassay (ELISA). Purebred, castrated Holstein steers, aged 18 to 20 months were randomized into two groups (N = 8/group) based on weight, body condition score, paternity and innate tick loads. The study was blinded and both groups were confined in individual pens in a feed lot with an empty pen separating each animal; the test group received Fator P (dosed at 6.0 gr/animal/day) and both groups received 2.2% of body on a dry matter in diet, from August and December 2024. Animals in both groups were infested with 15.000 larvae (3 X 5.000) on days 38, 40 and 42 and, repeated on the days 94, 96, 98 after the beginning of treatment with Fator P and engorged female ticks (>4mm) were counted on days 14, 21 and 28 after the release of larvae. Blood samples for serum were collected on days -03, 28, 56, 70, 87, and 119 after the start of treatment with the additive. Levels of specific antibodies to five recombinant antigens cloned from genes encoding secreted proteins from salivary glands of R. microplus were measured in all sera by ELISA. The statistical methods used were Anova-Tukey and Mann-Whitney tests, with p-values < 0.05. In the teleogyne counts, the average results of the first and second infestation cycles showed a reduction of 32.6% (p = 0.2429) and 74.4% (p = 0.0024), respectively. Initially, the treated and control groups showed no statistically significant difference with variation 3.9% (p = 0.8909) to 20.8% (p = 0.7025) in the concentration of the antibodies evaluated. By day 70 levels of antibodies specific to all five antigens were significantly higher in Fator P treated animals than in controls and by day 119 levels of antibodies specific for all five antigens were 82% to 141% higher in Fator P treated animals compared with controls. Fator P may improve responses of B lymphocytes because they actively oxidize fatty acids when hyperproliferating in germinal center B cells (doi: 10.1038/s41590-020-0598-4). We predict that Fator P targets overall metabolic processes, including those that improve antibodies responses, including to tick saliva, explaining the reduction of tick loads that is also observed in bovines that receive this additive. Fator P has proven to be an important in boosting immunity and adjuvant in tick control.