Isolation and Screening of Lactic Acid Bacterial Strains with Antibacterial Properties from the Vaginas of Healthy Cows

In the present study, eight strains were isolated from 20 cow vagina samples and identified using phenotype, biochemical analysis, sugar fermentation tests, and 16S rRNA sequence analysis. Among eight strains, only SQ0048 was identified as Lactobacillus johnsonii based on a series of biochemical testing (including the adhesion test, catalase test, bacteriocin production test, antibacterial test, and pH value), suggesting that its biological activity was superior to the other seven strains. Furthermore, SQ0048 had the lowest pH value (4.32) and the shortest fermentation time (8 h) compared with the other strains. The adhesion rate of SQ0048 was significantly higher than that of Lactobacillus delbrueckii, with an average adhesion number of 304 ± 2.67. The hydrogen peroxide production testing in SQ0048 was positive;in addition, bacteriocin gene of SQ0048, encoding an approximately 10-kDa product, was successfully cloned, expressed, and detected using the SDS-PAGE method. Meanwhile, SQ0048 had a weak inhibitory effect on Staphylococcus aureus and Escherichia coli. However, the expression products of the bacteriocin gene of SQ0048 had a very strong inhibitory effect on S. aureus and E. coli, with inhibition zone sizes of 18 ± 0.45 mm and 15 ± 0.60 mm, respectively. These data showed that SQ0048 has excellent antibacterial properties compared with other isolated strains and is a potential probiotic candidate to improve the health of the vaginas of cows by inhibiting pathogenic microorganisms.

Green tea polyphenols supplementation alters immunometabolism and oxidative stress in dairy cows with hyperketonemia

Peripartal cows often experience negative energy balance,and are therefore prone to suffering from metabolic diseases such as hyperketonemia,which causes financial losses in dairy farms.This study aimed to investigate the effect of green tea polyphenol(GTP)supplementation during the periparturient period on production performance,oxidative stress and immunometabolism in dairy cows with hyperketonemia.One hundred Holstein cows were assigned to GTP(0.2 g/kg DM;n=50)or control(without GTP;n=50)group based on body weight,previous milk yield,and parity on d 15 before expected parturition.Subsequently,10 cows with hyperketonemia were selected from each group,according to bloodβ-hydroxybutyric acid(BHBA)concentration between 1.2 and 2.9 mmol/L from 2 to 3 d postpartum.All cows were fed a close-up diet and a lactation diet with or without GTP supply from 15 d prepartum until 30 d postpartum.Milk and blood samples were obtained from 20 cows selected with hyperketonemia on 10,20,and 30 d postpartum.Compared with control cows,greater milk yield and lower somatic cell count were observed in GTP cows.The GTP group had lower concentrations of BHBA,free fatty acids,cholesterol,triglyceride,reactive oxygen species,malondialdehyde,and hydrogen peroxide,greater concentrations of glucose,lower activities of aspartate aminotransferase,alanine aminotransferase,and glutamyl transpeptidase,alongside greater ac-tivities of superoxide dismutase,glutathione peroxidase,and total antioxidant capacity.Additionally,GTP supplementation up-regulated concentrations of interleukin-6 and interleukin-10,but down-regulated concentrations of tumor necrosis factor-α,interleukin-1β,interleukin-2,interleukin-8,and interferon-γin plasma.Greater concentrations of plasma immunoglobulin G were also detected in the GTP group.Overall,the data suggested that GTP supplementation from 15 d prepartum to 30 d postpartum improved the milk yield and health status in cows with hvoerketonemia during early lactation.