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Mares’ milk is characterised by unique nutritional profile. In this study, the microbiological analysis of mares’ milk was performed. The presence of total bacteria, total lactic bacteria, Lactobacillus spp., Streptococcus lactis, Salmonella spp. and coliforms was investigated. Moreover, the influence of refrigerated and frozen storage on the total bacteria count, vitamin C, acidity and colour of milk was examined. Pathogenic Salmonella spp. and coliforms were not detected in the raw milk. It was revealed that mares’ milk can be stored for 72 hours under refrigeration at a temperature of +4 °C without reducing its microbiological quality. Most of the physicochemical properties remained unchanged, while colour measurements demonstrated a change in b* value after 48 h of refrigerated storage. Vitamin C content remained relatively stable during a week-long storage. Freezing of milk improved its microbiological status and caused significant changes in all colour components (L*, a*, b*). The obtained results demonstrated that mares’ milk had a high microbiological quality, favourable chemical composition and high vitamin C content which make this product a valuable potential component of functional foods.

The aim of this study was to analyse the metabolic activity of lactic acid bacteria and yeast based of changes in electrical conductivity and electrical impedance during fermentation of goat milk and mixtures of goat’s milk and mare’s milk (1:1, 1:2). As a result of fermentation, conductivity increased 1.4-fold. The conductivity of kefir prepared from goat and mare milk mixed at a ratio of 1:2 (6.210 Ω-3∙cm-1) was lower than that of the 1:1 mixture or of goat milk alone (7.242 Ω-3∙cm-1). A significant dependence of electrical conductivity and pH (0.970 ≤ r ≤ 0.993) was recorded during fermentation. The addition of mare milk to goat milk significantly slowed down the growth of LAB (Δλ = 0.8 h) and yeasts during kefir production.

The aim of this study was to conduct lactic acid-alcoholic fermentation using mesophilic lactic acid bacteria (LAB) for mare’s milk and its mixture with goat and sheep milk, followed by instrumental and sensory characteristic of the texture profile in the produced kefirs. It was shown that kefirs made from a mixture of goat and sheep milk are firmer, have greater values of consistency and the viscosity index than those produced from mare’s milk alone. Kefir storage for 3 weeks causes changes in their mechanical properties. Exceptions are found for firmness of kefirs made from both mixtures and the viscosity index of kefir made from sheep milk, which remained stable. The most divergent texture profile of the tested kefirs was reflected in the sensory examined descriptors of prickling, dense and mouth-coating sensation.

The first aim of the study was to compare selected meat quality parameters in porkers without the gene RYR1T (ryanodine receptor gene). These were porkers slaughtered at 100 to 115 kg and 116 to 130 kg live weight. The second aim of the study was to determine the occurrence frequency of standard-quality meat (red, firm, nonexudative [RFN]) and the occurence frequency of defective meat (pale, soft, exudative [PSE] and acid, soft, exudative [ASE]). The analysis was conducted on the longissimus lumborum muscle in 114 crossbred porkers. The porkers were a cross of Camborough 22 sows and boars from lines 337PIC (Pig Improvement Company), Norsvin Landrace and Pietrain. All of the animals were provided with identical environmental and nutritional conditions. The average weight of the slaughtered animals in the light and heavy groups was 110 kg and 122 kg, respectively. Both groups had the same average post-slaughter meatiness (56.5%). A statistical analysis of selected meat-quality parameters did not show any significant differences between the weight groups. On the other hand, the classification based on carcass quality showed an occurence frequency of defective meat in heavier crossbred porkers (116 to 130 kg) that was three times higher than in those crossbred animals which weighed 100 to 115 kg when slaughtered. In porkers without the gene RYR1T, the defective meat types PSE and ASE occurred with a frequency of 17.54%.

Apart from the well-known role of somatic cell count as a parameter reflecting the inflammatory status of the mammary gland, the composition of cells isolated from milk is considered as a valuable material for gene expression studies in mammals. Due to its unique composition, in recent years an increasing interest in mare's milk consumption has been observed. Thus, investigating the genetic background of horse's milk variability presents and interesting study model. Relying on 39 milk samples collected from mares representing three breeds (Polish Primitive Horse, Polish Cold-blooded Horse, Polish Warmblood Horse) we aimed to investigate the utility of equine milk somatic cells as a source of mRNA and to screen the best reference genes for RT-qPCR using geNorm and NormFinder algorithms. The results showed that despite relatively low somatic cell counts in mare's milk, the amount and the quality of the extracted RNA are sufficient for gene expression studies. The analysis of the utility of 7 potential reference genes for RT-qPCR experiments for the normalization of equine milk somatic cells revealed some differences between the outcomes of the applied algorithms, although in both cases the KRT8 and TOP2B genes were pointed as the most stable. Analysis by geNorm showed that the combination of 4 reference genes (ACTB, GAPDH, TOP2B and KRT8) is required for apropriate RT-qPCR experiments normalization, whereas NormFinder algorithm pointed the combination of KRT8 and RPS9 genes as the most suitable. The trial study of the relative transcript abundance of the beta-casein gene with the use of various types and numbers of internal control genes confirmed once again that the selection of proper reference gene combinations is crucial for the final results of each real-time PCR experiment.