A study on the transformed number of somatic cells in cows milk in relation to some factors
2009
Petkov, P., Thracian University, Stara Zagora (Bulgaria) | Iliev, T., Thracian University, Stara Zagora (Bulgaria) | Najdenova, N., Thracian University, Stara Zagora (Bulgaria)
The study included 69 cows of the Bulgarian Black-and-White breed at the 1st, 2nd and 3rd lactation. They were calved in the period March-September, and the control of their milk productivity was carried out from April 2008 to January 2009. The cows were daughters of 25 bulls and were reared in two farms. The study aimed to assess the influence of the environmental factors, morphological and functional characteristics of the udders on the log-transformation of the number of somatic cells in the milk and the correlation between the studied parameters. The animals were reared free-stall in cattle sheds and the milking was with a central milk line or in a milking parlour - 2х6. Of all the eight studied factors the significant ones were the effects of the milking system, stage of lactation, quantity of milk per milking and teat shape - P0.05 – P0.001. The average number of logarithmically transformed somatic cells for the model was 2.91±0.053. A number higher than that was found for the cows with prolapsed udder - 3.13, slightly conic teat shape - 3.19, average milk flow up to 1.5 kg/min - 3.04, milking with a central milk line - 3.07, milk yield up to 10 kg/milking 3.05, during the first lactation period - 3.43, duration of the milking for over 8.1 minutes - 2.98 and evening milking - 2.99. The log-number of cells decreased as the lactation month increased, for the cows with milk yielded above 12.1 kg/milking and when the average milk flow was above 2.1 kg/min, as well as in cows with cylindrical teats. The correlation coefficients of the log-transformed somatic cells with the studied factors were negative, most of them were around zero and were insignificant. With lactation month, milk yield per milking and average milk flow the correlations were low, highly significant and ranged from -0.149 to -0.167 (P0.001).
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