The aim of the work is to investigate raw milk from different bulls' daughters to clear up the influence of cows' genetic predisposition to milk microbial contamination and somatic cell count (SCC). Particular attention is paid to develop productive cow milk yield, milk fat, milk protein and in recent years, the SCC heredity. The literature describes a variety of lines and families, representatives of the resistance to certain diseases (leucosis, mastitis, tuberculosis, brucellosis, foot disease), it shows the determination of a genetic factor for this trait. If the selection results show increased resistance to a disease, then this indicates a genetic disease resistance and shy. The paper focuses on microbial contamination of raw milk at 7 different studies of bull daughters in the same line for housing, feeding and conditions of use. Raw milk samples were obtained from the breed Latvian brown (LB) from dairy cows shed of cattle shed Saujas, which belongs to SIA Palsa and is located in the civil parish Varini, Smiltene county in the year 2008/2009. Compared between the lines of bulls' daughter milk yield of the sample average value of the uniformity of variance analysis shows that they significantly differ (F=2.452, p=0.039). Comparing each line of bulls' daughters SCC of the sample average value of the uniformity of variance analysis showed that the SCC was statistically significantly different (F=2.083, p=0.075) of the various lines of bulls daughters.

Antibiotic resistance of Staphylococcus is increasing worldwide. New antibiotics are used in big amounts in the meat production more and more. As a zoonosis, Staphylococcus aureus (S. aureus) is found in various species of animals and people, especially in those, who are working on commercial swine farms and slaughterhouses. The aim of the study was to find out the occurrence of S. aureus in different age groups of pigs on commercial swine farms in Latvia. Microbiological samples (n=702) including nasal, rectal, milk and air samples were collected during October 2013 from three closed farms of different sizes and several age groups of pigs and investigated with microbiological standard methods. S. aureus was found in all swine farms. The occurrence of S. aureus in Latvian pig farms was 41% and the highest occurrence of S. aureus was among 3-3.5 month old piglets. S. aureus was 1.8 times more frequently found in nasal than in rectal samples, and only in 28.38% of pigs S. aureus was in both - nasal and rectal samples. S. aureus was found also in sow milk in 13% of samples and in 3 samples of air (n=23).

Bovine colostrum is a mammary gland secret which, due to its high immunoglobulin concentration, is necessary for the transfer of passive immunity to the calf, preventing diseases caused by microbial infections in the newborn ruminants. Colostrum, however, may contain pathogens and can be an infection transmitter, affecting morbidity and mortality rates of calves in the farms. Total plate count and immunoglobulin concentration are two main factors affecting colostrum quality, therefore the aim of the study was to analyse Latvian dairy herd colostrum quality. Colostrum was collected from Holstein Black cows within the first six hours after calving, lactation period of animals ranged from 1st to 4th lactation. Colostrum samples (n=51, 50 mL) were collected from December 2018 to February 2019. Immunoglobulin concentration (n=51) was defined by colostrometer (COLOSTROMETERtm Biogenics, USA), total solids content by optical refractometer (Model BX, UK). Staphylococcus spp. colony–forming unit (CFU) (LVS EN ISO 6888-1+A1:2007), the presence of Listeria spp. (LVS EN ISO 11290-1+A1:2007) and Salmonella spp. (LVS EN ISO 6579-1:2017) were examined in the colostrum samples (n=20). Despite the high immunoglobulin concentration in the analysed samples, our research findings demonstrate suboptimal colostrum quality received by calves. That indicates the necessity for regular colostrum quality control and better management practise providing on the farm.

A total of 120 food samples from 6 traditional and 3 non-traditional (Oriental) public catering establishments in Latvia were taken. Preliminary all food samples were divided in three food groups (categories) depending on the components of the products and processing methods. Ready-to-eat foods (RTE) with high level of total amount of microorganisms (aerobic colony count-ACC) and total coliforms (TC), as well as appropriate infringements of hygienic requirements in public catering establishments which had an impact on microbial contamination were clarified. The reasons for microbiological contamination of RTE and the growth of the microorganisms were analyzed in dependence on food category group, the activity of hydrogen ions (pH) in food, food temperature at the sampling point, their processing mode and composition. Different indicator microorganisms including Staphylococcus, Enterobacter, Escherichia, Bacillus, yeasts, moulds and etc. were identified. The comparison between the temperature and pH and the level of microbiological contamination of the samples of food and hygienic practice in the catering establishments were clarified.

A study was conducted to determine efficiency of an organic acids additive on pigs metabolic processes and diggestive tract microflora. The pigs of control group were fed without an organic acids additive. The feed of the trial group piglets contained 6 kg of organic acids additive per tonne feed, for starter pigs - 4 kg per tonne feed, for finished pigs - 3 kg per tonne feed. The study indicated that at the age of 130 days, pig mass in the trial group was 54.08 kg an average, but in the control group - 51.06 kg, which showed that pigs from the trial group had by 6% higher average mass than in the control group (p is less than 0.005). At the age of 160 days, pig mass in the trial group was an average 94.3 kg, in the control group - 90.63 kg; pigs from the trial group had by 4% higher mass than in the control group (p is less than 0.005). Feed consumption for the trial group was by 1% less than in the control group. Average daily gain for the trial group was 0.663 kg, which was by 6% more than for the control group pigs (p is less than 0.005). Feed conversion in the trial group was 3.06 kg, but in the control group - 3.275 kg, i.e. 6.4% higher than in the trial group. Analyses of Jejunum microflora showed that use of acidifier additive reduced Mould colony formed units - CFU amount in 1 g of the trial group sample by 6%. Staphylococcus species amount in the trial group was 500 CFU in 1 g of sample, but in the control group - 40000 CFU, i.e. 80 times more. In the trial group, Lactic acid bacteria CFU amount in 1 g of sample was by 6% higher than in the control group. The results of Rectum microflora analyses showed that Staphylococcus species amount in the trial group was 12000 CFU in 1 g of sample, but in the control group it was by 34% higher.

A study was conducted to determine efficiency of a phytoadditive on pig growth processes and digestive tract microflora. The pigs of control group were fed without the phytoadditive. The feed of the trial group piglets contained 0.5% of the phytoadditive per tonne feed, for starter pigs and finished pigs - 0.2% per tonne feed. The study indicated that at the age of 170 days, pig mass in the trial group was 111.67+-1.22 kg on average, but in the control group - 101.79+-0.81 kg, which showed that pigs from the trial group had by 9.7% higher average mass than in the control group (p is less than 0.05). Average daily gain for the trial group was 0.777+-0.009 kg, which was by 12 % more than for the control group pigs (p is less than 0.05). Feed conversion in the trial group was 2.928 kg, but in the control group - 3.129 kg, which was by 6.4% higher than in the trial group. Gastric microflora analyses showed that use of phytoadditive reduced mould colony forming units (CFU) amount in the trial group decreased by 24 times. Duodenum microflora analyses showed that use of phytoadditive reduced mould CFU amount by 25%, yeast CFU amount by 34%, Escherichia coli mesophilic and termophilic forms CFU by 16.3% compared to the control. A lactic acid bacterium CFU in the trial group was 2.5 times higher compared to the control. Rectum microflora analyses showed that use of phytoadditive reduced mould CFU amount by 31.6%, yeast CFU amount - by 62%, Escherichia coli mesophilic and termophilic forms by 57 % and 15.6 % respectively. Lactic acid bacteria CFU amount in 1 g of sample in the trial group increased by 5.1 times.

Udder secretion samples from mastitic and healthy udders were examined at the Department of Veterinary Medicine of the LUA Research Centre "Sigra". In total, 117 samples from 117 cows were investigated. Somatic cell count was recorded for cows with clinical and subclinical infections, and uninfected cows. The mean somatic cell counts for cows with clinical and subclinical mastitis were 1 825 250+-417 697 cells ml*[-1) and 967 866+-75 796 cells ml*[-1), respectively. For healthy cows the mean somatic cell count was 87 666+-15 384 cells ml*[-1). Gram-positive microorganisms from the genera Micrococcus, Staphylococcus, Streptococcus, and Corynebacterium, and gram-negative microorganisms from the genera Enterobacter, Klebsiella, Salmonella, Escheria and Pseudomonas were isolated from samples from mastitic quarters.