麦洼牦牛全泌乳期乳中矿物质元素变化规律研究

Study on Changes in Mineral Elements Contents of Yak Milk during the Lactation Cycle

为阐明牦牛乳中矿物质元素含量在全泌乳期的变化规律，试验采集了四川省龙日种畜场麦洼牦牛产犊当天到180d（即0～180d）内共12个时间点的乳样。采用微波消解法处理乳样，用电感耦合等离子体发射光谱仪（ICP—OES）测定牦牛乳中14种矿物质元素，分别为4种大量元素（钾（K）、钙（Ca）、镁（Mg）、磷（P））和10种微量元素（硼（B）、钡（Ba）、镉（Cd）、钴（Co）、铜（Cu）、钼（Mo）、镍（Ni）、钛（Ti）、锌（Zn）、锰（Mn）），并以牦牛产犊后30d采集的乳样数据为基准进行统计分析。结果显示，麦洼牦牛初乳中K、Ca、Mg、P4种大量元素含量较高。与30d的常乳含量相比，K的含量在0d时差异极显著（P〈0．01），在120d时差异显著（P〈0．05）；Ca的含量在5d时差异显著（P〈0．05）；Mg的含量在180d时差异显著（P〈0．05）；P的含量变化差异不显著（P〉0．05）。在0～180d泌乳期内微量元素随泌乳期的变化也较明显，与30d的常乳含量相比，Ba的含量在0和1d时差异极显著（P〈0．01），在2、3、4、5和180d时差异显著（P〈0．05）；Mo、Ni、Zn的含量在180d时差异显著（P〈0．05）；B、Cd、Cu、Ti、Mn的含量随泌乳期变化差异均不显著（P〉0．05）。综上所述，牦牛乳中K、Ca、Mg、Ba、Mo、Ni、Zn的含量随泌乳期的变化差异显著（P〈0．05），P、B、Cd、Cu、Ti、Mn的含量变化不显著（P〉0．05）；整体上看，K、Mg、P、Ba、Zn的含量变化呈先降低后增加的趋势，而Ca的含量呈现出先增加后降低的趋势。

To clarify the changes of mineral elements of yak milk during the lactation cycle, milk samples at 12 time points from 0 to 180 d during the lactation cycle were collected from Maiwa yak at Longri livestock breeding station in Sichuan province. After milk samples were prepared using microwave digestion, fourteen elements were analyzed by the ICP-OES for four macro elements （ potassium, calcium, magnesium, phosphorus） and ten micro elements （ boron, barium, cadmium, cobalt, copper, molybdenum, nickel, titanium, zinc ,manganese）. The statistical analysis based on the statistics data from the samples on day 30 was proceeded. The results showed that the concentrations of K,Ca, Mg and P in Maiwa yak colostrum were higher. The concentrations of K on day 0 （P〈0.01） ,120 （P〈0.05） ,Ca on day 5 （P〈0.05） ,Mg on day 180 （P〈0.05） had significant differences as compared with that of mineral elements on day 30, but no significant difference was observed in the concentration of P （P〈0.05） during the lactation cycle. The results also suggested that the concentrations of trace elements were significantly affected by the lactation cycle. The concentrations of Ba on day 0 and 1 （P〈0.01） ,2,3,4,5 and 180 （P〈0.05） ,Mo on day 180 （P〈0.05） ,Ni on day 180（P〈0.05） ,Zn on day 180（P〈0.05） had significant differences as compared with that of mineral elements on day 30, but there were no significant differences on B, Cd, Cu, Ti, Mn during the lactation cycle. In conclusion, the concentrations of K, Ca, Mg, Ba, Mo, Ni, Zn had significant differences during the lactation cycle （P〈0.05）, but no significant differences were observed in the concentrations of P,B,Cd,Cu,Ti,Mn （P〈0.05）. Overall,the concentrations of K,Mg,P,Ba, Zn were all firstly decreasing and then increasing,while Ca content was firstly increasing and then decreasing.