Dynamics of the within-herd prevalence of Mycoplasma bovis intramammary infection in endemically infected dairy herds.

We aimed to identify the dynamics of the within-herd prevalence of Mycoplasma (M.) bovis intramammary infection (IMI) in four dairy herds, estimate prevalence of M. bovis in colostrum and clinical mastitis cases and compare M. bovis strains from calves' respiratory and cow clinical mastitis samples. Within a six-month study period, cow composite milk samples (CMS) were collected three times during routine milk recording, first milking colostrum samples from all calving cows and udder quarter milk samples from clinical mastitis cases. Calf respiratory samples were collected from calves with respiratory disease. Pooled milk samples were analysed for M. bovis with the Mastitis 4B polymerase chain reaction (PCR) test kit (DNA Diagnostic A/S). Prevalence estimates were calculated with Bayesian framework in R statistical programme. cg-MLST was used for M. bovis genotyping. In Herd I and II first testing M. bovis IMI within-herd prevalence (95 % credibility interval (CI)) was 4.7 % (2.9; 6.8) and 3.4 % (2.3; 4.6), changing to 1.0 % (0.1; 1.7) and 0.8 % (0.1; 1.4) in Herd I and 0.4 % (0.0; 0.7) in Herd II at the next samplings. In Herd III and IV first testing M. bovis IMI within-herd prevalence was 12.3 % (9.7; 15.2) and 7.8 % (6.2; 9.5), changing to 4.6 % (3.0; 6.4) and 3.2 % (1.9; 4.8) in Herd III and to 2.8 % (1.9; 3.8) and 4.9 % (3.6; 6.4) in Herd IV at the next samplings. The estimated prevalence of M. bovis in colostrum ranged between 1.7 % (0.2; 2.8) and 4.7 % (2.7; 7.1) and in clinical mastitis cases between 3.7 % (1.7; 6.4) and 11.0 % (7.5; 15.2) in the study herds. M. bovis strains isolated from cows and calves clustered within herds indicating possible transmission of M. bovis between dairy cows and calves. Prevalence of M. bovis in colostrum and clinical mastitis cases as well as the within-herd prevalence of M. bovis IMI was low in endemically infected dairy herds.

Elimination of selected mastitis pathogens during the dry period.

We aimed to evaluate the elimination of 4 different mastitis pathogens, Streptococcus agalactiae, Mycoplasma bovis, Staphylococcus aureus, and Streptococcus uberis, from infected udder quarters during the dry period using quantitative PCR. The second purpose of this study was to evaluate the association between milk haptoglobin (Hp) concentration and the presence of udder pathogens (Strep. agalactiae, Staph. aureus, M. bovis, and Strep. uberis) in udder quarter milk samples before and after dry period. Aseptic udder quarter milk samples (n = 1,001) were collected from 133 dairy cows at dry off and at the first milking after calving from 1 large dairy herd. Bacterial DNA of Strep. agalactiae, Staph. aureus, Strep. uberis, and M. bovis in the udder quarter milk samples was identified with commercial quantitative PCR analysis Mastitis 4B (DNA Diagnostic A/S, Risskov, Denmark). Milk Hp concentration (mg/L) was measured from udder quarter milk samples. The elimination rates during the dry period for M. bovis, Staph. aureus, Strep. agalactiae, and Strep. uberis were 86.7, 93.6, 96.2, and 100.0%, respectively. The new IMI rate was 3.0% for M. bovis, 2.9% for Staph. aureus, 2.4% for Strep. agalactiae, and 3.1% for Strep. uberis. The milk Hp concentration was significantly higher in udder quarter milk samples with blood and in samples positive for Strep. agalactiae at dry off and for Staph. aureus postcalving. Elevated milk Hp concentration was not associated with the presence of M. bovis in the udder quarter milk samples. In conclusion, elimination of Staph. aureus, Strep. agalactiae, and Strep. uberis during the dry period was high; the elimination of M. bovis from infected udder quarters was lower, but probably spontaneous. Additionally, milk Hp concentration may be used as a marker for udder inflammation when combined with the bacteriological results at dry off and postpartum.

Within-herd prevalence of intramammary infection caused by Mycoplasma bovis and associations between cow udder health, milk yield, and composition.

Subclinical mastitis is one of the major health problems in dairy herds due to decreased milk production and reduced milk quality. The aim of this study was to examine the within-herd prevalence of subclinical intramammary infection caused by Mycoplasma bovis and to evaluate associations between M. bovis and cow daily milk yield, udder health, and milk composition. Individual cow composite milk samples (n = 522) were collected from all lactating dairy cows in 1 Estonian dairy farm in November 2014. Daily milk yield, days in milk, and parity were recorded. Collected milk samples were analyzed for somatic cell count, milk protein, fat, and urea content. The presence of M. bovis, Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus uberis in the milk samples was confirmed by quantitative PCR analysis. The within-herd prevalence of M. bovis was 17.2% in the study herd. No association was observed between days in milk and parity to the presence of M. bovis in milk. According to linear regression analysis, the daily milk yield from cows positive for M. bovis was on average 3.0 kg lower compared with cows negative for M. bovis. In addition, the presence of M. bovis in milk samples was significantly associated with higher somatic cell count and lower fat and urea content compared with milk samples negative for M. bovis. In conclusion, subclinical M. bovis intramammary infection is associated with decreased milk yield and lower milk quality.

Effect of infusing lactoferrin hydrolysate into bovine mammary glands with subclinical mastitis.

The therapeutic effect of administering lactoferrin hydrolysate (LFH) into the mammary glands of cows with subclinical mastitis was evaluated. Seven millilitres of a preparation of LFH (7% protein) was infused into 35 quarters of 25 cows with subclinical mastitis. The numbers of bacteria in the milk from infected quarters decreased, and bacteria disappeared by the 14th day after the administration of LFH. The mean somatic cell counts (SCC) peaked one day after administration of LFH and the counts were significantly p < 0.01) decreased on days 7, 14 and 21 compared to those before the administration of LFH. The mean lactoferrin concentration in the milk peaked on days 2 or 3 and then gradually decreased to day 14, returning to the level before the administration of LFH. It appears that administration of LFH may have a therapeutic effect when infused into the quarters of cows with subclinical mastitis.

Lactoferrin concentration in milk of bovine clinical mastitis.

The lactoferrin (LF) concentration in the milk from dairy cows with clinical mastitis was determined to evaluate the relationship between the LF concentration (LFC) in milk and the non-specific defensive capability of the udder. The mean LFC in 368 milk samples from 319 cows with clinical mastitis was significantly higher (p < 0.01) than that of normal cows. The mean LFC in milk from quarters infected with Mycoplasma bovis or Staphylococcus aureus was significantly higher (p < 0.05) than that of quarters infected with coagulase-negative staphylococci (CNS). In Escherichia coli mastitis, the level of LFC in milk from cows with peracute mastitis was significantly lower (p < 0.01) than that from cows with acute mastitis. In cases of mastitis due to E. coli, the mean LFC in milk from cows that needed more than 10 days to recover from the mastitis or were not cured was significantly lower (p < 0.05) than that for cows which took less than 10 days to be cured. The mean LFC in milk from cows with peracute E. coli mastitis was significantly lower (p < 0.05) than that for cows with mastitis associated with environmental streptococci or CNS, although these low LF levels were somewhat increased after 46 h from the occurrence of mastitis. These results suggest that the decreased levels of LF in peracute E. coli mastitis may be associated with the progress of inflammation in the early phase of mastitis.

[Farmer's lung in the east of Hokkaido. A follow-up study in 1985].

The follow-up study of 16 patients with farmer's lung and 35 farmers having antibody to thermophilic actinomyces was performed. The following results were obtained. Three patients out of 16 patients with farmer's lung were readmitted to the hospital. The patients out of 11 believed that the dust respirator is useful for prevention against the development of farmer's lung. Any new patient was not found out from farmers having antibody to thermophilic actinomyces in 1985.