中甸犏牛乳中体细胞数及其与乳成分的相关性研究

旨在探讨中甸犏牛乳中体细胞数(SCC)变化范围及其与乳理化指标的相关性,为制定犏牛乳相关理化指标正常值范围提供参考。采集中甸犏牛乳样92份,测定乳脂肪、乳蛋白、乳糖、乳中SCC、乳尿素氮(MUN)和乳冰点(MFP)等8项指标,分析SCC与乳各成分的相关性。结果表明:犏牛乳的主要营养成分含量高,其中乳脂肪、乳蛋白、乳糖、总固形物和非脂固形物平均含量分别为6.42%、4.23%、4.91%、18.01%和10.59%。乳中SCC平均值为80.12万/mL,其中SCC≤50万/mL的个体占52.17%,50万/mLSCC≤75万/mL的占10.87%,SCC75万/mL的占36.96%,提示部分犏牛的乳房健康状况及其所产的乳质量问题值得关注;SCC与乳蛋白呈极显著正相关(P0.01),与乳脂肪呈显著正相关(P0.05),与乳糖呈极显著负相关(P0.01),与总固形物、非脂固形物、乳脂乳蛋白比、MUN和MFP呈弱正相关(P0.05),提示乳中SCC对主要乳营养成分的影响大,相关程度高。犏牛的MFP值为-0.587℃,为冰点低的乳品,这可能与犏牛适应高海拔寒冷气候形成的机制等有关;犏牛乳中MUN为7.52 mg/dL,表明饲喂犏牛的蛋白质饲料不足或质量不佳。本研究获得中甸犏牛乳中SCC变化范围及其与乳理化指标的相关性,为犏牛乳质量控制提供了重要参考依据。

Somatic Cell Count and Its Correlations with Other Milk Components of Zhongdian Cattle-yak

The range of somatic cell count (SCC) and the correlations between SCC and other milk components were discussed in this paper,so as to provide a reference for making the normal ranges of physical and chemical indexes of milk from Zhongdian cattle-yak.92 milk samples were collected,8 indexes including cattle-yak milk,such as milk fat,lactoprotein,lactose,SCC,milk urea nitrogen (MUN),milk freezing point (MFP),etc.were determined,and Pearson correlation between SCC and other milk components were analyzed.The results showed that the average contents of milk fat,lactoprotein,lactose,total solids and nonfat solids were 6.24％,4.23％,4.91％,18.01％ and 10.59％,respectively.It indicated that main nutritional components were high in milk of Zhongdian cattle-yak.The average SCC was 80.12 thousand/mL,and the individuals with SCC≤500 thousand/mL,500 thousand/mL ＜SCC≤750 thousand/mL and SCC ＞750 thousand/mL accounted for 52.17％,10.87％ and 36.96％ of the total individuals,respectively,which indicated that healthy status of udder and milk quality of some cattle-yak needed more attention.SCC had an extremely and significantly positive correlation with lactoprotein content (P＜0.01),a significantly positive correlation with milk fat content (P＜ 0.05),and an extremely and significantly negative correlation with lactose content (P＜0.01).Besides,SCC had weak positive correlations with contents of total solids and nonfat solids,ratio of milk fat to lactoprotein,MUN and MFP (P＞0.05),respectively.It showed that SCC had a strong influence on the main nutritional components of milk.Zhongdian cattle-yak had an average MFP of-0.587℃,indicating that its milk products had low MFP,which might relate to the fact that cattle-yak had formed a mechanism to adapt to high altitude and cold climate.The average MUN was 7.52 mg/dL in cattle-yak milk.It indicated that protein diet used to feed cattleyak was insufficient or with poor quality.This study obtained milk SCC range and its correlations with other physical and chemical indexes,providing important reference for the quality control of milk from Zhongdian cattle-yak.