The work was written in Lithuanian Veterinary Academy, Faculty of Animal Husbandry, Department of Animal Science, and milk collection company of D. Čeičienė in Raseiniai district during years 2008 – 2010 of Master studies.

Objective of work: to analyze the composition and quality of milk bought by milk collection company of D. Čeičienė.

The following tasks were set for the achievement of the objective of the work: 1. To assess the composition and quality indicators of milk subject to the farm size and season; 2. To assess the composition and quality indicators of milk subject to cows’ keeping method.

One milk collection station of the company was selected for this work. The work analyzes the changes of milk composition and quality in this collection station over 2009, subject to the number of cows kept, season and cattle keeping method.

The work was written based on the data of protocols of State Enterprise “Pieno tyrimai” as well as milk stocktaking records.

In order to appropriately attain the set objectives and tasks, the work was divided into two stages: 1. In the first stage of the research, the searching for special scientific literature and other useful sources of reference as well as systemization and analysis of the collected information were carried out. 2. In the second stage of the research, the analysis and comparison of quantity, composition and quality of milk were carried out in the milk collection station. The farms were divided by number of cows kept: 1-5; 6-10; 11-20; 21-40, and more than 41 cows kept. Farms keeping more than 41 cows were divided by the way the cows are kept: tethered or free. The changes of milk quantity, composition and quality indicators were compared over the season.

During the research, the following estimations and calculations were carried out: number of milk producers (n = 51), number of cows kept (n = 480), quantity of milk (kg), fat content of milk (%), protein content of milk (%), milk recalculation coefficient (kp), number of somatic cells (thou./ml), overall bacterial contamination (thou./ml). Microsoft Office Excel application was used.

Conclusions: 1. Farms keeping more than 41 cows produced milk with the highest fat and protein content, exceeding that of dairy farmers keeping 6-10 cows respectively by 0.23 % and 0.08 %; 2. The smallest dairy farmers produced milk with the lowest number of somatic cells, while the largest number was found in the milk produced by farmers keeping 21-40 cows; 3. At summer time, the number of somatic cells in the milk was the highest, and the overall bacterial contamination of the milk was the lowest; 4. Regardless of the number of cows kept in the farm, the largest fat and protein content was recorded in autumn and winter; 5. Overall bacterial contamination of milk among the milk producers in general was the lowest in summer, and the highest in spring, except the largest milk producers, where the highest overall bacterial contamination was established in winter; 6. Fat and protein content of milk of cows kept free exceeded the corresponding indicators of tethered cows by 0.05 and 0.02 % respectively; 7. Overall bacterial contamination and number of somatic cells of tethered cows’ milk exceeded those of cows kept free by 61 thou./ml and 66 thou./ml respectively.

Raktažodžiai: milk, guality, analysis