奶牛血清中T_4和T_3浓度变及其与日产奶量关系研究

STUDY ON THE CHANGES OF T4 AND T3 CONCENTRATION IN THE SERUM OF DAIRY COWS TO DAILY YIELD

本研究采用放射免疫法，测定了中国荷斯坦牛泌乳盛、中、后期血清中Ｔ４和Ｔ３浓度。结果表明：奶牛泌乳中期和后期血清Ｔ４浓度（５３．１９和６４．３９ｎｍｏｌ／Ｌ）分别明显高于盛期（４７．６４，Ｐ＜０．０５）；Ｔ４浓度在泌乳后期和中期之间也存在着显著差异（Ｐ＜０．０５）。Ｔ３浓度在整个泌乳期无明显变化（Ｐ＞０．０５）。奶牛在三个泌乳时期中的日产奶量与Ｔ４浓度所占比率的灰色关联度（０．９５１、０．９６８和０．８１４）最大；Ｔ４浓度变化对日产奶量的影响作用较Ｔ３大。

T4 and T3 concentration in the serum of Holstein cows at peak.mid and late stages of lactation were with radioimmunoassay(RIA) In this study,The results showed T4 concentration in the serum of dairy cow at mid (53.19nmol/L) and late stage of lactation(64.39nmol/L);repectively,was significantly higher(P<0.05 or 0.01)than at peak stage of lactation(7.64nmol/l).T4 concentration also existed Significant difference(P<0.05)between mid and late stage of lactation.The changes of T3 concentrationwas insignificant(P>0.05) during the whole lactation.Grey-correlationdegrees of T4 concentration ratio was the biggest to daily yield amongthree Stages of lactation,and their grey-correlation degrees were 0.951,0.968 and 0.814.respectively.The changes of T4 concentration on the effect of daily yield was bigger than T3.