Sand is a common bedding material used as a resting surface for dairy freestalls.Using Sand as Bedding have many positiv......

试验旨在研究散栏与栓系两种饲养方式对西门塔尔牛生长过程中不同时期血清部分激素和神经递质水平变化的影响。选用50头体重相近（33......