The influence of the conditions of a season, lactation month and keeping on the changes of milk composition and quality indices in a cow herd of Practical Instruction and Research Centre under Lithuanian Veterinary Academy

Place and methods of work fulfillment: the work was carried out in the Department of Animal Science of Lithuanian Veterinary Academy and Practical Instruction and Research Centre under Lithuanian Veterinary Academy in 2006 – 2008 years of postgraduate studies. 84 cows of equal period of lactation were selected: 58 cows in Muniškiai farm and 26 cows in Giraitė farm. Cows were selected considering that the most producing period of lactation would coincide with cattle-shed period. The conditions of cow keeping are different. In Muniškiai cattle-shed they are kept in standard conditions: they spend time in a pasture in summer and bound to standing places in winter. They are milked in their standing places. Giraitė cattle-shed is of cold type, where cattle are kept loosely. Here cows are kept in cold conditions in groups consisting of 30 – 40 cows. They are herded in a pasture in summer. The cows are milked in Swedish DeLaval “Tandem” type milker. The cows are fed with the same fodder and the schedule of work is also the same. The data has been analyzed statistically using “Excel” spreadsheet. Review of the work: in a period of 2006 – 2007 years milk yield of Lithuanian black-and-white cows was 434 kg less than of German, 768 kg less than of Dutch and 1409 kg less than of Danish black-and-white cows. Lithuanian black-and-white cows provided 25 – 77 kg of butterfat less than Dutch, German or Danish cows. Lithuanian black-and-white cows had proteins 0,05 % less than the same Danish cows, though 0,01 – 0,05 % more than German and Dutch black-and-white cows. Average milk yield in Practical Instruction and Research Centre under Lithuanian Veterinary Academy was 6219 kg of milk in a period of 2005 – 2006. Butterfat was 4,55 % and milk proteins 3,29 %. The sum of milk, butterfat and proteins amounted to 488 kg. Lithuanian black-and-white cows were the milkiest during the period of lactation. (0,25 % more than German black-and-white cows, 8,9 % more than Dutch and 27 % more than the same Danish cows in the same conditions of keeping). The fattiest milk in a cold cattle-shed (4,63 %) was of Danish black-and-white cows. The milk of Danish black-and-white cows was of the least fat (3,07 %) in standard conditions of keeping. The milk of Dutch black-and-white cows in standard conditions of keeping was 0,58 % less than the milk of Dutch black-and-white cows in a cold cattle-shed. The milk of German black-and-white cows was 0,26% fattier in standard conditions of keeping than of German black-and-white cows in a cold cattle-shed. The milk of Lithuanian black-and-white cows in standard conditions of keeping was fattier only 0,04 % than of the same cows in a cold cattle-shed. The milk of black-and-white cows of all species kept in cold cattle-sheds had more proteins than of the same species kept in standard conditions of keeping. The level of proteins in the milk of Lithuanian black-and-white cows kept in cold cattle-sheds was 0,08 % higher than of the same cows kept in standard conditions. Respectively, the level of proteins in the milk of German black-and-white cows was 0,14%, of Dutch black-and-white cows was 0,99 %, and of Danish black-and white cows was 1,5 % higher than from the cows kept in standard conditions of keeping. The number of somatic cells in the groups of both cows has been changing intensely. According to analyzed data the milk of Dutch and Danish black-and-white cows kept in standard conditions of keeping and Dutch black-and-white cows kept in cold cattle-sheds corresponds to the requirements of bought up milk. Conclusions: 1. The amount of milk of Lithuanian black-and-white cows kept in standard conditions was 9 % higher than of Lithuanian black-and-white cows kept in cold cattle-sheds; of German black-and-white cows kept in standard conditions 22 % higher than of the cows of the same breed kept in cold cattle-sheds; of Dutch black-and-white cows - 14,9 % higher than of the cows kept in cold cattle-sheds; and Danish black-and-white cows - 7 % higher than of the cows kept in cold cattle-sheds; 2. The amount of milk of Lithuanian black-and-white cows kept in cold cattle-sheds was higher than of other black-and-white cows in to the same cattle-sheds (14,4 % higher than of German black-and-white cows, 14,6 % higher than of Dutch black-and-white cows and 25 % higher than of Danish black-and-white cows). The is show of the better adaptation of Lithuanian black-and-white cows; 3. The largest amount of butterfat (4,63 %) was established in Danish black-and-white cows kept in cold cattle-sheds milk; 4. Butterfat and proteins changed independent of the month of lactation and the conditions of keeping; 5. The average largest amount of somatic cells (638 thousand/cm3) was in the milk of Danish black-and-white cows kept in cold cattle-sheds, and in the milk of German black-and-white cows (528 thousand/cm3) kept in standard conditions. The least amount of somatic cells (73 thousand/cm3) was in the milk of Dutch black-and-white cows kept in cols cattle-sheds