缺锌对雏鸡增重、骨生长及血锌含量的探讨

EFFECT OF ZINC LEVELS IN DIET ON GAIN IN WEIGHT GROWTH OF BONE AND ZINC CONCENTRATION IN BLOOD OF CHICKS

本研究采用1日龄Lohmann肉鸡144只,随机分为Ⅰ、Ⅱ、Ⅲ3组,其日粮含锌量分别为9ppm(缺锌组)、24ppm和69ppm(对照组),雌雄群养。7周龄时,Ⅰ、Ⅱ和Ⅲ组鸡的平均体重分别为444.18克、1367.86克和1307.28克。各周龄中对照组鸡全血及血浆锌含量均显著高于缺锌组;Ⅱ组多介于Ⅰ、Ⅲ组之间,说明血液锌含量受摄入锌量和周龄的影响。缺锌时,血浆锌量的变化比全血锌量的变化更敏感。56日龄时,缺锌组鸡股骨骺端软骨生长区,原发细胞层比其它组薄,差异极显著(P<0.01),Ⅰ、Ⅱ、Ⅲ组分别为0.23,2.56和3.97μ;肥大区比Ⅱ、Ⅲ组明显增厚(P<0.05),分别是31.03、18.79和11.29μ;三组的钙化区分别是9.71、8.69和7.65μ;骨化区厚度为18.23、77.96和108.61μ.此结果表明缺锌严重阻碍骨的生长。缺锌鸡羽生长缓慢,折损脱落明显,羽轴上有结节。

In this study, 144 Lohmann broiler chicks, one day old, were randomly divided into 3 groups with males and females mixed up. Three replicates were arranged for each group. Plastic cages, feed troughs and water bowls were used. The chicks were allowed to drink glass-distilled water freely and were fed ad libitum with semi-purified diet in which starch-egg white-powder was the main component. The Zn levels of 3 groups (Ⅰ, Ⅱ, Ⅲ ) were 9, 24 and 69ppm respectively. The average weights of groups Ⅰ, Ⅱ, Ⅲ at 7 weeks of age were 444.18, 1367.86 and 1307.28 grams respectively, Generally speaking, the Zn levels of the whole blood and plasma were higher in group Ⅲ and lower in group I with those in group Ⅱ in between. The results illustrate that the Zn levels of whole blood and plasma were affected by the Zn intake and the week ages of the chicks. To a certain extent,blood plasma increased with the amount of Zn absorbed , while the Zn in red blood cells was chiefly in carbonic anhydrase, in which Zn supply must be guaranteed,hence Zn dificiency was reflected more sensitively in blood plasma than in whole blood. In the growing part of epiphyseal cartilage of femurs in group I ( 0.23μ ) , the original germ layer was thinner ( p< 0.01 ) than that in group Ⅱ ( 2.56μ ) and in group Ⅲ ( 3.97μ ) . On the contrary, the hypertrophied cell area in group I (31.03μ) became thicker (p<0.05)than that in group Ⅱ ( 18.79μ ) and group Ⅲ ( 11.29μ ). The thickness of calcifying area of group Ⅰ, Ⅱ, Ⅲ were 9.71, 8.69 and 7.65μ respectively while the thickness of the bone formation area were 18.23, 77.69 and 108.61μ respectively. Growth of feathers in chicks of Zn deficiency was slow and poor. The pearl-like tubercles on the feather-axis of wing appeared.