Research Of Fast Measuring Method Of Somatic Cell Count In Cow Milk

Somatic cell count(SCC) in milk is a very important index of raw milk quality, and it has been accepted as the world standard for mastitis diagnosis. In many country of developed dairy industry, SCC measuring has been a daily work, and extensive research work have been done to improve the technology of SCC determination. With the development of dairy industry of our country, more attention will be payed to SCC measuring, and more research work will be carried out In this study A novel SCC determination method was tested : Somatic cell membrane was destroyed by surfactant, and DNA released from somatic cell increased the viscosity of the milk. So SCC could be measured by measuring the viscosity of the milk if the relation between viscosity and SCC revealed.In this thesis, somatic cell in milk was destroyed by lauryl sodium sulfate(SDS),and the viscosity was measured by Lamb-lewis viscosimeter .An ultrasound measure system was set up,and milk was measured by ultrasound after SDS added, and the relation between SCC and acoustics parameter was studied. The main result of this paper is presented as below1.A11 the factors of somatic cell count ,time ,temperature, and pH of buffer solution had significant influence on viscosity (P<0.001).Among these factors,_the influence of SCC was the greatest. The viscosity of the sample increased gradually after SDS added to the sample, and about 5-7minutes later the increasement stoped. The viscosity of the sample was the highest and stablest when the pH of buffer solution was 7.5.Viscosity linearly decreased as temperature rises, and the higher of SCC the decrease speed faster..2.The viscosity of sample was positive linearly correlated with SCC when sample were treated the same way .The R~2 of regress equations were all above 0.99.The relation of SCC ,viscosity and temperature could be described by this equation: SCC= 4.78744× η+3.72755×T-89.91337(P<0.001,R~2 = 0.9775 ).The difference of SCC measured through viscosity and measured by microscope was checked by t test and found there was no significant difference between two methods. It suggest that SCC could be effectively measured by means of visicosity.3.The figures of ultrasound wave of different SCC samples were different There was nocorrelation between ultrasound velocity and SCC. Both of attenuation and power spectral density had a positive correlation with SCC.The regress equation of attenuation and SCC was a = 0.00686 x SCC + 2.91142 (i><0.001,R2=0.8688) .The regress equation of power spectral density and SCC was F = -0.0107 xSCC + 8.89023 (P<0.001,R2=0.9424).