Determination of polymorphism of IS-1311 sequence in Mycobacterium avium subspecies paratuberculosis strains isolated from milk samples.

The study was aimed at the genetic typing of Mycobacterium avium subspecies paratuberculosis (MAP) with PCR-REA method based on the polymorphism of IS-1311 sequence. MAP strains were isolated from milk samples collected from cows free of disease symptoms and anti-MAP antibodies. Samples of udder milk were collected from 310 cows originating from the herd with a low seroprevalence of paratuberculosis; every 5 samples were pooled. The polymorphism typing of the IS-1311 sequence of the isolated strains demonstrated the presence of two types of the mycobacterium: sheep and cattle ones, of which the bovine type constituted 98.5%.

Modeling the kinetics of survival of Staphylococcus aureus in regional yogurt from goat's milk.

The aim of this study was to determine the kinetics of the survival of the test strain of Staphylococcus aureus in the product investigated. Yogurt samples were contaminated with S. aure to an initial level of 10(3)-10(4) cfu/g. The samples were then stored at four temperatures: 4, 6, 20, 22°C. During storage, the number of S. aureus forming colonies in a gram of yogurt was determined every two hours. Based on the results of the analysis culture the curves of survival were plotted. Three primary models were selected to describe the kinetics of changes in the count of bacteria: Cole's model, a modified model of Gompertz and the model of Baranyi and Roberts. Analysis of the model fit carried out based on the average values of Pearson's correlation coefficient, between the modeled and measured values, showed that the Cole's model had the worst fit. The modified Gompertz model showed the count of S. aureus as a negative value. These drawbacks were not observed in the model of Baranyi and Roberts. For this reason, this model best reflects the kinetics of changes in the number of staphylococci in yogurt.

Quality of milk of cows in the first lactation vs. presence of anti-Ostertagia antibodies in their milk.

Invasions of gastrointestinal nematodes in dairy cows may affect animals productivity. The most frequently detected internal parasite of dairy cattle is Ostertagia ostertagi. The objective of this study was to determine O. ostertagi invasion extensiveness in selected herds of dairy cattle, with special consideration to cows being in the first lactation, and to analyze the milk yield and contents of basic constituents of milk originating from sero-positive cows. Five herds of dairy cattle (403), with different populations of cows, were selected for the study. Invasion extensiveness in particular herds was determined and ranged from 11.9% to 27.27%. Cows being in the first lactation, the udder milk of which was shown to contain anti-O. ostertagi antibodies, were producing on average 470 kg of milk annually less than cows being in the same lactation period. The analysis of results did not confirm the statistical significance of this difference, likewise it did not demonstrate any statistically significant differences in contents of fat, protein and dry matter. Despite a lack of the statistical significance a producer suffers great economic losses. The conducted study proves that the occurrence of O. ostertagi invasion in herds of dairy cattle is a global problem and that it affects cost-effectiveness of milk production.

The presence of anti-Hypoderma antibodies in udder milk samples, and correlation with selected parameters of dairy performance.

Hypodermosis is responsible for significant economic losses and remains a current problem in animal husbandry. This study determined the extent of Hypoderma spp. invasion in north-eastern Poland in dairy herds. The extent of the invasion, determined on the basis of positive results of an ELISA assay (Bovine Hypodermosis Milk Screening of Institut Pourquier), varied in herds. Statistical analysis performed on the results of milk productivity and content of basic components revealed a decrease in the milk yield and changes in milk protein in animals revealing positive, doubtful and negative results. Statistically significant differences were absent as regards the content of milk fat or milk total solids. The milk yield and the content of particular milk components were determined using the AT4 method, as part of a control program carried out by the Polish Federation of Cattle Breeders and Dairy Farmers (PFHBiPM).