Antimicrobial and Mycotoxin Reducing Properties of Lactic Acid Bacteria and Their Influence on Blood and Feces Parameters of Newborn Calves

SIMPLE SUMMARY: In this study, we hypothesized that the antimicrobial and mycotoxin-reducing properties of lactic acid bacteria (LAB) strains (separate and in combination) can lead to improvements in the health parameters of newborn calves. Considering that, during the first days of life, the formation and domination of the beneficial microbial communities in newborn calves’ digestive systems are very important, the suggested supplementation could lead to a better health status of the animals. In this study, feed supplements were prepared by applying acid whey (AW) for Lactiplantibacillus plantarum LUHS135 (L.pl135) and Lacticaseibacillus paracasei LUHS244 (L.pc244) biomass growth. The animal trial involved 48 Holstein female calves (12 animals in each group). Control calves were fed with a standard milk replacer, and treated groups (from the 2nd day of life until the 14th day) were supplemented with 50 mL of AW(L.pl135), AW(L.pc244), and their combination AW(L.pl135×L.pc244) (25 mL AW(L.pl135) + 25 mL AW(L.pc244)) in addition to standard milk replacer. It was found that both the tested strains and their combination inhibited the growth of Gram-positive and Gram-negative pathogens, reduced mycotoxin concentrations in vitro, and were non-resistant to all of the tested antibiotics. The tested supplements showed positive effects on the health parameters of newborn calves, reducing the risk of developing acidosis, decreasing the Enterobacteriaceae count, and increasing the LAB count in animal feces. However, more research with larger cohorts of calves is needed to confirm these data and to explain the mechanism of action of the tested supplements. ABSTRACT: The aim of this study was to evaluate the influence of in acid whey (AW) multiplied Lactiplantibacillus plantarum LUHS135 (L.pl135), Lacticaseibacillus paracasei LUHS244 (L.pc244), and their biomass combination on newborn calves’ feces and blood parameters. Additionally, the antimicrobial and mycotoxin-reducing properties and the resistance to antibiotics of the tested lactic acid bacteria (LAB) strains were analyzed. In order to ensure effective biomass growth in AW, technological parameters for the supplement preparation were selected. Control calves were fed with a standard milk replacer (SMR) and treated groups (from the 2nd day of life until the 14th day) were supplemented with 50 mL of AW(L.pl135), AW(L.pc244), and AW(L.pl135×L.pc244) (25 mL AW(L.pl135) + 25 mL AW(L.pc244)) in addition to SMR. It was established that L.pl135 and L.pc244 possess broad antimicrobial activities, are non-resistant to the tested antibiotics, and reduce mycotoxin concentrations in vitro. The optimal duration established for biomass growth was 48 h (LAB count higher than 7.00 log(10) CFU mL(−1) was found after 48 h of AW fermentation). It was established that additional feeding of newborn calves with AW(L.pl135), AW(L.pc244), and AW(L.pl135×L.pc244) increased lactobacilli (on average by 7.4%), and AW(L.pl135) and AW(L.pc244) reduced the numbers of Enterobacteriaceae in calves’ feces. The tested supplements also reduced the lactate concentration (on average, by 42.5%) in calves’ blood. Finally, the tested supplements had a positive influence on certain health parameters of newborn calves; however, further research is needed to validate the mechanisms of the beneficial effects.