Correlations between the number of somatic cells and some components of the milk content of the cows of the black-and-white breed
2008
Fenerova, J., Institute of Agriculture, Stara Zagora (Bulgaria) | Angelova, T., Institute of Agriculture, Stara Zagora (Bulgaria) | Krastanov, Zh., Institute of Agriculture, Stara Zagora (Bulgaria)
The study was carried out in the herd of the Agricultural Institute – Stara Zagora, with cows of the Black-and-White breed. The monthly tests were carried out during the autumn-winter period (October – March) of 2005-2006. The following quantitative characteristics were determined: test day milk yield (kg), butterfat (kg), protein (kg) and the qualitative characteristics – fat content (%), total protein (%) and number of somatic cells/ml in the milk. For the indicated period 400 individual milk samples were studied. The samples were divided into two groups depending on the lactation stage – up to 120 days of lactation (N=165) and after the 120th day of lactation (N=235). According to the somatic cells (SC) level the individual samples of each group were divided into three sub-groups: below 400 000 SC/ml, from 400 000 to 1 000 000 SC/ml and above 1 000 000 SC/ml. The obtained information was processed with the statistical package STATISTICA. The link between the studied characteristics was represented by linear correlations. High positive correlations were found for the milk yield with the butterfat (from +0.763 to +0.903) and the quantity of milk (from +0.917 to +0.954) at different SC levels. The relations of the SC in the milk and the qualitative characteristics were low and negative. The information for the somatic cells should be included in the selection of the cows from the dairy breeds because of the production of high quality milk and for resistance to mastitis diseases.
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