Correlation Between Bovine Milk Somatic Cell Counts And Nitrogenous Compounds Content In Milk

452 milk samples were collected from 30 Holstein dairy cows in a farm of Huhhot suburb from April to October in 2005 and 530 milk samples were collected at random from 6 farms from March to December in 2006. Altogether 982 samples were collected within two years. All data of samples were divided into 4 groups according to it's SCC,the SCC groups were divided as follows:<20,20-50,50-100 and≥100(×104/mL).Milk somatic cell counts(SCC),total protein,casein(includingα-CN,β-CN andκ-CN),whey protein,free amino nitrogen(FAN),milk urea nitrogen (MUN),nonprotein nitrogen(NPN) content and casein/total protein,whey protein/total protein,MUN/NPN were determined or calculated. The results showed that:1. Total milk protein,casein,whey protein,FAN,MUN content,casein/total protein , whey protein/total protein , MUN/NPN were highly significantly differently in groups of SCC(P<0.001).NPN content was significantly differently in groups of SCC(P<0.05).No difference in groups of SCC for proportion ofα-CN,β-CN andκ-CN in casein.2. Total protein, whey protein , and whey protein/total protein were highly significantly positively correlation with SCC(P<0.001);FAN was much significantly positively correlation with SCC(P<0.05);Casein/total protein,MUN,MUN/NPN were highly significantly negatively correlation with SCC(P<0.001);Casein content,α-CN/CN,β-CN/CN,κ-CN/CN,NPN content had no relationship with SCC.3. Casein content had highly significantly positively correlation with total protein content(P<0.01),had highly significantly negatively correlation with FAN content(P<0.001).Total protein content had highly significantly positively correlation withα-CN/CN and whey protein content(P<0.001).4.α-CN/CN had highly significantly positively correlation with whey protein conten(tP<0.01),had significantly negatively correlation with casein/total protein(P<0.05),had highly significantly negatively correlation withβ-CN/CN,κ-CN/CN(P<0.001).β-CN/CN had highly significantly negatively correlation withκ-CN/CN(P<0.001),had significantly negatively correlation with FAN(P<0.05).κ-CN/CN had significantly positively correlation with NPN content (P<0.05).5. Whey protein content had highly significantly negatively correlation with MUN conten(tP<0.01),had highly significantly positively correlation with FAN content(P<0.01).6. MUN content had highly significantly positively correlation with NPN content(P<0.001).7. The mean SCC and mastitis proportion of 30 dairy cows in a farm of Huhhot suburb from May to October in 2005 were decreased gradually,but the mean SCC was increased suddenly and mastitis proportion was increased after a sort in September. May and September were HSCC period from May to October of the year,the mean SCC were 77.1×104/mL and 96.39×104/mL respectively,mastitis proportion were 80.00% and 41.38% respectively. The mean SCC and mastitis proportion were lowest in October,28.17×104/mL and 13.33% respectively. Nitrogenous Compounds content of samples between month from May to October were significantly differently(P<0.001).8. The analysis results showed according to the difference of managent in 6 farms in 2006, casein,total milk protein,whey protein,MUN,NPN content;casein/total protein,whey protein/total protein were highly significantly differently in groups of SCC(P<0.0001). The better of the managent,the lower of the SCC in raw milk,the higher of casein/total protein,MUN,NPN content in raw milk. The worse of the managent,the higher of casein,total milk protein,whey protein content and whey protein/total protein in raw milk.