The analysis of nutritional value and selected traits of technological suitability of milk was performed on the basis of the available literature. This analysis concerned various animal species used for dairy purposes (cattle, buffalo, goats, sheep, camels, donkeys, and horses). It has been stated that a considerable diversity exists in the analyzed parameters and traits of milk, which results in various directions of milk utilization. Cow milk accounts for more than 80% of world milk production. It is the most universal raw material for processing, which is reflected in the broadest spectrum of manufactured products. Sheep and buffalo milk, regarding their high content of protein, including casein, and fat, make a very good raw material for processing, especially cheesemaking. Donkey and horse milk have the most comparable protein composition to human milk (low content of casein, lack of αs 1 -casein fraction and β-lactoglobulin, and high content of lysozyme). Donkey milk is additionally characterized by a fatty acid profile distinctive from milk of other analyzed animal species. Camel milk also has valuable nutritional properties as it contains a high proportion of antibacterial substances and 30 times higher concentration of vitamin C in comparison to cow milk. The composition of goat milk allows using it as the raw material for dairy processing and also to some extent as a therapeutical product (low content or lack of αs 1 -casein).

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In the presented research, BovineSNP50 microarrays (Illumina) were applied to determine runs of homozygosity in the genomes of 11 cattle breeds maintained in Poland. These cattle breeds represent three basic utility types: milk, meat and dual purpose. Analysis of runs of homozygosity allowed the evaluation of the level of autozygosity within each breed in order to calculate the genomic inbreeding coefficient (FROH), as well as to identify regions of the genome with a high frequency of ROH occurrence, which may reflect traces of directional selectin left in their genomes. Visible differences in the length and distribution of runs of homozygosity in the genomes of the analyzed cattle breeds have been observed. The highest mean number and mean sums of lengths of runs of homozygosity were characteristic for Hereford cattle and intermediate for the Holstein-Friesian Black-and-White variety, Holstein-Friesian Red-and-White variety, Simmental, Limousin, Montbeliarde and Charolais breeds. However, lower values were observed for cattle of conserved breeds. Moreover, the selected livestock differed in the level of inbreeding estimated using the FROH coefficient. In regions of the genome with a high frequency of ROH occurrence, which may reflect the impact of directional selection, a number of genes were observed that can be potentially related to the production traits which are under selection pressure for specific production types. The most important detected genes were GHR, MSTN, DGAT1, FABP4, and TRH, with a known influence on the milk and meat traits of the studied cattle breeds.

The aim of the study was to determine differences in the status of selected bioactive whey proteins and lipophilic vitamins in milk obtained from certified organic farms as compared to conventional farms (using traditional and intensive production systems). Significant relationships were noted with regard to production system and individual bioactive milk compounds, that is β‐lactoglobulin, lactoferrin, lysozyme, vitamins A, D3 and E, and β‐carotene (P = 0.001) and bovine serum albumin (BSA) (P = 0.016). Milk obtained from extensive farms, especially certified organic ones, was a valuable source of certain antioxidant compounds: β‐lactoglobulin (3.32 g/L), lactoferrin (123.8 mg/L), vitamin E (2.044 mg/L) and β‐carotene (0.257 mg/L) in the case of organic farms.

Global milk production is undeniably dominated by 2 dairy breeds recognized worldwide: Holstein-Friesian and Jersey. A third breed, Simmental, serves as a dual-purpose breed. The objective of the present research was to establish potential changes in the fractional components of bovine milk protein (mainly whey) in relation to the health status of a dairy cow's mammary glands, which is closely determined by somatic cell count (SCC). The milk of 3 breeds was studied: Polish Holstein-Friesian (Black and Red-White varieties), Simmental, and Jersey. The cows were housed in freestall barns and fed according to the total mixed ration feeding system for both winter and summer periods. Milk samples were collected individually from each cow twice a year, in the winter and summer seasons. A total of 1,822 milk samples were evaluated (946 in winter and 876 in summer). The milk was examined for SCC, crude protein, casein, and whey fraction proteins (α-lactalbumin, β-lactoglobulin, lactoferrin, BSA, and lysozyme). The research material for each breed was split into 4 groups based on SCC (group I: ≤100,000 cells/mL; group II: 101,000 to 400,000 cells/mL; group III: 401,000 to 500,000 cells/mL; and group IV: 501,000 to 1,000,000 cells/mL). It was found that an increase of SCC promulgated a progressive decline in the daily yield of milk, which was significantly true for the Polish Holstein-Friesian. The level of crude protein decreased slightly as SCC increased, and casein concentration (r=-0.591) also followed this trend of decline. Elevation of SCC produced a decrease of major albumins (i.e., α-lactalbumin and β-lactoglobulin). However, SCC increase induced an increase in the immunoactive proteins (lactoferrin and lysozyme) as well as BSA. The interactions of a breed with increased SCC, which can be measured based on the BSA content of the milk, has indicated various levels of susceptibility to the increase in different breeds. This is confirmed by different values of correlation coefficients for these relationships: 0.71 in the Holstein-Friesian, 0.58 in Simmental, and 0.47 in the Jersey cows. Holstein-Friesian cows are more sensitive to mammary gland infections causing a greater decline of their daily milk yields, which, in turn, is reflected in an increase of the negative value of the correlation coefficients between SCC and milk efficiency (-0.24). In the other 2 breeds, the correlations were also negative, but substantially lower (-0.12 and -0.15).

The milk obtained from six cow breeds (Polish Holstein‐Friesian Black‐White and Red‐White, Simmental, Jersey, Polish Red and Polish Black‐White) managed in the Lubelskie region and the Bieszczady Mountains was analysed. A total of 3618 milk samples collected between 2005 and 2008 were evaluated for the total solids content, percentage concentrations of fat, protein and lactose, and the freezing point: the mean milk freezing point was −0.538°C. The freezing point of milk was influenced by breed, successive lactations, lactation stage and the geographic region. In milk with a high urea concentration (over 300 mg/L), the increased apparent protein level caused a decrease in the milk freezing point values. The combined influence of geographic region and production season showed significant interactions for daily milk yield and total solids content (P < 0.01) and the milk freezing point (P < 0.05).

the study included milk obtained from cows of three native cattle breeds, i.e. white-backed (bg), Polish red (rP) and Polish black-and-white (Zb) kept under conventional conditions. the reference group consisted of milk from Polish holstein-friesian cows (Phf) maintained in the intensive system and milk from simmental cows (sm) kept under conventional conditions. the following parameters were determined in 976 samples of milk: content of fat, protein, casein, lactose and solids; acidity (pH value); heat stability; rennet coagulation time; content of α-lactalbumin, β-lactoglobulin, serum albumin, lactoferrin and lysozyme. additionally, a certain proportion of samples was investigated for fatty acid profile and content of macro-and microelements. cows of native breeds produced milk of higher nutritional value (higher content of whey proteins and polyunsaturated fatty acids, including cla) and more suitable for processing as compared to Phf cows. milk from cows of the Polish red breed was the most valuable in terms of these parameters, which can be associated with a distinctive phylogenetic origin of this breed. the favourable parameters in regard to the nutritional value and technological suitability of milk obtained from analysed population of cows of 3 breeds included in the programme of genetic resources conservation are therefore an important reason of validity for subsequent implementation of this programme. key words: local cattle breeds, milk, nutritional value, technological suitabilityCow's milk is a good raw material for processing, including the manufacture of cheese. Current worldwide production of cheese exceeds 20 million tonnes, including 633,500 tonnes of cheese produced in Poland (FAOSTAT, 2011). The number of cheeses available worldwide is very large and they not only serve to satisfy hunger This work was conducted as part of Ministry of Science and Higher Education project no. NN 311 02 83 34.

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