Analysis of the somatic cell count in raw milk

Gere, Tibor

The formation of somatic cell count in cow milk under given conditions of keeping, feeding, and milking technology, as well as genetic and environmental conditions influencing udder health state characterised by cell count were investigated in a dairy farm well managed considering Hungarian circumstances. For this purpose 130,920 different data of the milk of 1061 cows deriving from 178 bulls of the farm in question were collected and processed. Data processing included somatic cell count in milk samples, chemical composition of the milk, regime of production (i. e. milking in the morning and/or in the evening, milk production per month, quarter, half-year, and lactation), and descent of the breeding bull. Date processing was carried out using software packages available in the computer software of the Chair of Animal Husbandry of Charles Robert College. Data collecting and processing is related to the period from 1 January till 31 December 1996. Data of a total of 5235 milkings were processed. According to the results of statistical data processing a greater part, 13.7 per cent, of the variation of somatic cell count can be attributed to the cows, and a smaller but still considerable part, 5.8 per cent, to the bulls. The high value of the rest, 60.81 per cent, indicates that there are also a lot of factors influencing the variation of somatic cell count in addition to the evaluated ones. Most of the inheritable coefficients correspond to h2 values quoted in literature. In respect of breeding, it seems important that h2 coefficients calculated on the basis of the first lactation were considerably higher than the values calculated on the basis of all lactations, seven in number (h2 = 0.54 and 0.14, respectively). Somatic cell counts calculated in monthly average exhibited relatively low fluctuations; some extreme values observed were caused by a transitional lack of straw. There was no difference in somatic cell counts between cows milked in the morning, or in the evening, or twice a day, whereas cell count exhibited a rather great variability under changing environmental conditions in other words, there was a strong dependence on environment, extreme CV% values having amounted to 24 and 51 per cent, respectively.

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