Relationship between Milk Protein Polymorphism and Selected Cows' Reproductive Indices.

This research sought to determine the effect of selected milk protein polymorphisms on the reproduction parameters of 598 black and white Polish Holstein-Friesian cattle. The analyzed genes were kappa-casein (CSN3) and beta-lactoglobulin (BLG). The following reproductive indexes were selected: the age at first calving, the interpregnancy period, the calving interval, and the insemination index. The influence of the identified genotypes on the course of parturition in cows was also analyzed. Source data were collected for each cow from the beginning of the herd life and reproduction to its culling from the herd or the end of its third lactation. Data on the age at first calving, the amount of semen portions for artificial insemination (insemination index), the interpregnancy period, and the calving interval for each cow were also collected. A contingency analysis was performed through contingency tables using a Pearson's chi-squared test for each CSN3 and BLG genotype. The results show that the BB genotype of the kappa-casein gene was associated with the most favorable values of reproductive indicators. In the case of the calving interval, the values were significantly more favorable than those of other genotypes (p ≤ 0.05). No effect of beta-lactoglobulin polymorphism on the analyzed reproductive indices was observed. On the other hand, in the case of the interpregnancy period, significant statistical differences were obtained between the AA and BB genotypes. The analyzed kappa-casein and beta-lactoglobulin genotypes did not significantly influence the course of parturition in cows. To conclude, the genotype polymorphism BB CSN3 is the most favorable for the performance of the cows in the examined herd.

Microbiological, sensory, and physicochemical quality of curd cheeses originating from direct sales.

BACKGROUND AND AIM: Curd cheeses are characteristic elements of the dairy assortment, mainly in Central and Eastern European countries, and constitute a numerous and diverse group of dairy products. The aim of the study was to assess the physicochemical, microbiological, and sensory quality of curd cheeses available in marketplaces in Lublin, where they were purchased through direct sales from producers. MATERIALS AND METHODS: The research material was household-produced curd cheese purchased 4 times (at 2-week intervals) from three producers. The physicochemical parameters (i.e., the total protein and fat content, active acidity, and titratable acidity) were determined in the cheeses. Microbiological assays were performed to evaluate the total number of bacteria (on milk agar), the number of yeasts and molds (on Sabouraud medium), and the number of coliform bacteria (on MacConkey medium). A general sensory evaluation was performed by a five-person panel, who assessed the appearance and color, texture, flavor, and aroma of the samples. RESULTS: The cheeses exhibited significant differences in their protein and fat contents, but these values were within the allowable limits. Most of the evaluated cheeses had normal levels of active and titratable acidity; substantially lower titratable acidity and higher pH values were detected only in the samples from supplier A. The total number of bacteria in the curd cheese samples was high (3.2×108 colony-forming units [cfu]×g-1 cheese) and varied substantially (from 3.6×107 to 8.6×108 cfu×g-1). The growth of Gram-negative bacterial colonies on MacConkey medium was observed in the samples from suppliers B and C (5.5×103 and 1.7×104 cfu×g-1, respectively), which is an undesirable phenomenon. The number of colonies cultured on Sabouraud medium and identified as yeast-like microorganisms ranged from 1.8×104 (product from supplier A) to 4.9×105 cfu×g-1 (cheese from supplier C). The scores in the sensory evaluation of the tested curd cheeses were low. The highest mean scores were achieved for appearance and color (4.25-4.45 points). Conversely, flavor and aroma received the lowest score (3.17 points). The highest scores for both the overall assessment and each parameter separately were awarded to the curd cheese produced by supplier A. CONCLUSION: Our results suggest poor hygienic conditions during milk collection and processing, as well as during the distribution of these dairy products. Altogether, the purchase of products from direct sales may be associated with risks related to poor consumer health and food quality.

Parasites of the digestive tract in cows managed in alternative (organic and biodynamic) as well as conventional farms in West Pomerania

The aim of the study was to determine the species composition, prevalence and intensity of parasitic enteric infections in cows in relation to farm management system. Prevalence of gastrointestinal nematodes and Eimeria protozoans was determined from coproscopic examinations using Willis-Schlaf flotation. The species composition of coccidia was determined from morphological characters and the time of oocyst sporulation. Fluke liver eggs were detected by decantation. The average rates of parasitic infections were 67.42%, in the biodynamic farm, 62.14%, in the organic farms, and 63.26%, in the conventional cattle farm. Cows managed in the biodynamic farm suffered from infections by Eimeria protozoans and gastrointestinal nematodes, whereas Eimeria, gastrointestinal nematodes and Moniezia sp. were found in the organic farms. In cows of the conventional farm, we found Eimeria, gastrointestinal nematodes, Moniezia sp. and trematodes: Fasciola hepatica and Paramphistomum sp. The average intensity of Eimeria sp. infection in cows by farming system was as follows: 71 OPG (oocysts per gram of feces) in the biodynamic farm, 57 OPG in the organic farm and 71 OPG in the conventional farm. The mean intensity of gastrointestinal parasites was 290 EPG (eggs per gram feces) in the biodynamic farm, 455 EPG in the organic farm, and 228 EPG in the conventional farm. The average Moniezia infection intensity in cows was 125 EPG, in the organic farm, and 50 EPG (eggs per gram feces), in the conventional farm. It is noteworthy that the intensity of gastrointestinal nematode infection of cows in the biodynamic farm was very low (290 EPG) despite a high prevalence of infection (67.42%). A similar situation though was found in the cows managed in the conventional way.

Concentrations of toxic heavy metals and trace elements in raw milk of Simmental and Holstein-Friesian cows from organic farm.

Concentrations of toxic heavy metals (cadmium (Cd), lead (Pb)) and major nutritional and trace elements (Ca, Mg, P, Cu, Fe, Mn, Se, Zn) were analyzed in the milk of Simmental (n = 20) and Holstein-Friesian (n = 20) cows from an organic farm. Elements were determined using inductively coupled plasma emission atomic spectrometry. The conducted research showed that the milk of Simmental cows was characterized by the more advantageous mineral composition and lower concentration of noxious heavy metals compared to the milk of Holstein-Friesian cows. In the milk of Simmental cows, significantly lower concentrations of Pb and Cd (P < 0.001) and Cu (P < 0.05) and significantly higher concentrations of Fe and Mg (P < 0.05) as well as nonsignificantly higher concentrations of Ca, Mn, and Se were found. In the milk of both breeds, very low Cu concentrations were recorded. The higher-than-recommended concentration of Pb in milk was also found. In the milk of both breeds, the significant positive correlations between concentrations of the following elements were observed: Pb-Cd, Pb-Se, Cd-Se, Cd-Mn, Zn-Cu, Zn-P, Ca-P, Ca-Mg, and Mg-P. The correlations between other elements within each of the analyzed breeds separately were also found.

Selenium concentration and glutathione peroxidase (GSH-Px) activity in serum of cows at different stages of lactation.

The aim of the study was to evaluate the activity of glutathione peroxidase (GSH-Px) and the concentration of selenium in Holstein-Friesian cows at different stages of lactation. Selenium was determined spectrofluorimetrically and GSH-Px activity using a Sigma CGP1 Glutathione Peroxidase Cellular Activity Assay kit. Mean serum selenium concentration was highest in early-lactation multiparous cows (0.18 µg/ml) and the lowest in dry cows (0.111 µg/ml). In early lactation, serum selenium concentration was significantly (P ≤ 0.01) higher in multiparous cows than in cows from the other groups. Mean GSH-Px activity in the serum of dry cows was over twice lower than in late-lactation cows (P ≤ 0.01) and over four times lower than in first-calving heifers and multiparous cows in early lactation (P ≤ 0.01). The coefficients of Spearman's rank correlation between GSH-Px activity and selenium concentration in the cows at different stages of lactation were not significant. A significant (P ≤ 0.01) mean positive correlation (0.46) was found between GSH-Px activity and serum selenium concentration for all the cows analysed together. The highest Se concentration and GSH-Px activity found in the serum of cows during the first stage of lactation may suggest that the generation of reactive oxygen species and their derivatives was higher during this period compared to the other stages, thus placing the cows at a greater risk of oxidative stress. It is therefore essential to give particular attention during this period to meeting the cows' requirement for selenium and other feed components that increase, directly or indirectly, the capacity of the body's antioxidant system.