牛奶中脂肪酸与常规营养成分含量的影响因素分析

本试验旨在研究季节对牛奶中脂肪酸含量的影响以及不同地区、泌乳期、季节和胎次对牛奶常规营养成分的影响。对来自DHI中心的9872份牛奶样本中的脂肪酸含量数据和3430份牛奶样本中的乳脂、蛋白质、乳糖与总固形物含量数据,按季节、地区、泌乳期、胎次进行分组,然后进行单因素方差分析。结果如下:(1)季节对牛奶中脂肪酸含量产生极显著影响(P<0.01):夏季乳脂中饱和脂肪酸极显著高于其他季节(P<0.01),不饱和脂肪酸极显著低于其他季节(P<0.01)。游离脂肪酸春季最高且极显著高于其他季节(P<0.01)。(2)不同地区对乳脂、乳糖、总固形物产生极显著影响(P<0.01):宁夏蛋白质含量最高,且显著高于河南、湖北与内蒙古(P<0.05)。而宁夏与内蒙古之间乳脂、乳蛋白、总固形物无显著差异(P>0.05)。湖北与宁夏牛奶总成分含量较高。(3)泌乳期对牛奶成分含量产生极显著影响(P<0.01):泌乳前期乳脂、蛋白质、总固形物含量最低,且显著低于泌乳中期、泌乳晚期、泌乳延长期(>305d)(P<0.05)。泌乳前期与泌乳中期乳糖含量较高,且极显著高于泌乳晚期、泌乳延长期(P<0.01)。(4)不同季节对乳常规营养成分含量产生极显著影响(P<0.01):夏季各项指标最低,且极显著低于春季、秋季、冬季(P<0.01)。(5)不同胎次对乳蛋白、乳糖、总固形物含量产生极显著影响(P<0.01),一胎牛乳中各种成分含量最高,且极显著高于三胎次奶牛(P<0.01)。

Fatty Acids and Conventional Nutrients in Milk and Their Influencing Factors

The purpose of this experiment is to study the influence of seasons on the content of fatty acids in milk and the effects of different regions,lactation periods,seasons and parity on conventional milk ingredients.A oneway ANOVA was performed on the data of fatty acids in 9872 milk samples and the contents of milk fat,protein,lactose and total solids in 3430 milk samples.The main results are as follows:(1)Season has a very significant effect on fatty acid content(P<0.01).Saturated fatty acids in summer milk fat are extremely significantly higher than other seasons(P<0.01),and unsaturated fatty acids are extremely significantly lower than other seasons(P<0.01).Free fatty acids are highest in spring and significantly higher than other seasons(P<0.01).(2)Different regions have extremely significant effects on milk fat,lactose,and total solids(P<0.01).Western Region has the highest protein content,and is significantly higher than North Central,Central Region and Northern Region(P<0.05).There was no significant difference in milk fat,milk protein and dry matter between Ningxia and Inner Mongolia(P>0.05).The total content of milk in the central and western regions is relatively high.(3)The lactation period has a very significant effect on the content of milk components(P<0.01).The content of milk fat,protein and total solids was the lowest in the early lactation period,and was significantly lower than that in the middle lactation period,late lactation period and prolonged lactation period(>305 d)(P<0.05).The lactose content was higher in the early and middle lactation period,and was extremely significantly higher than that in the late lactation period and prolonged lactation period(P<0.01).(4)Different seasons have a very significant effect on the content of conventional milk nutrition components(P<0.01).The indicators in summer are the lowest,and are significantly lower than those in spring,autumn,and winter(P<0.01).(5)Different parities have a very significant effect on protein,lactose,and total solids(P<0.01).The milk of the first parity cow has the highest content of various milk components,and is extremely significantly higher than that of the third parity milk(P<0.01).