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三、家畜利用饲料养分的机理和各种养分的特性 饲料的养分,多数都是不溶于水,分子结构极其复杂的。家畜无法直接利用这些养分。只有在消化道内将复杂的分子,消化成简单的小分子,才能被家畜吸收,进入体内。消化道实质上是一条由口腔到肛门,两端开口的管道。饲料在管道内受到物理、化学和生物的处理,分解为简单的养分,这就叫消化。 不同种类的家畜,由于消化道结构的不同,对饲料的消化能力也不同。牛羊等反刍动物有四个胃,最大的叫瘤胃,可容纳60—70%的食物,在此进行长时间的发酵。反刍动物的肠道亦很发达,其长度可超过体长20—27倍。因此消化能力最强。猪属于单胃动物,胃的容积相对较小,食物在胃内停留时间很短,一般不超过4小时即全部排空,肠道的长度亦相对较短,只有体长的14倍。
Third, the use of livestock feed nutrients and nutrient characteristics of various nutrients feed nutrients, most are insoluble in water, the molecular structure is extremely complex. Livestock can not directly use these nutrients. Only in the digestive tract complex molecules, digested into simple small molecules, can be absorbed by livestock, into the body. The digestive tract is essentially a pipe from the mouth to the anus, both ends of the opening. Feed in the pipeline by the physical, chemical and biological treatment, decomposition into simple nutrients, which is called digestion. Different types of livestock, due to different digestive tract structure, digestion of feed is also different. Ruminants such as cattle and sheep have four stomachs, the largest called the rumen, can accommodate 60-70% of the food, where the fermentation for a long time. The ruminant intestine is also well developed, its length can exceed body length 20-27 times. Therefore, the strongest digestion. Pig is a monogastric animal, stomach volume is relatively small, food stays in the stomach for a very short time, generally no more than 4 hours that is all emptying, the length of the intestine is also relatively short, only 14 times the body length.