Digestive characteristics and nutrient absorption of Pigs

   I. digestive characteristics of pigs

   pig is a monogastric omnivore. In wild conditions, it is always searching for and eating all kinds of food. In modern farming systems, pigs can be domesticated into separate meals, or pigs will feed frequently during the day as long as they continue to feed freely. Although pigs generally feed during the day, they can also be converted to night feeding in some cases, such as hot weather. At present, there is no evidence that the nutrition utilization efficiency of pigs is affected by the daily feeding time.

The oral teeth of    pigs chewed the feed carefully, and the chewing time was related to the softness of the feed and the age of the animals. In general, the chewing time of rough feed is long, and the chewing time is shortened with the increase of age. The pig feed should be properly crushed to reduce the energy consumption of chewing and contribute to the digestion of enzymes in the stomach and intestines at the same time. The crude fiber in pig diet is mainly digested by microbial fermentation in large intestine and intestine, and its digestibility is weak.

   II. Absorption of nutrients in pigs

   (1) there are three ways of absorption of digestible nutrients in pigs.

   1, pinocytosis absorption: pinocytosis is the absorption of substances in human cells by extending pseudopodia or invagination of the membrane where they come into contact with substances. It can be in the form of molecules, clumps or aggregates; the absorption of immune balls in colostrum by newborn mammals is pinocytosis absorption, which is of great significance for newborn animals to obtain antibodies.

   2, passive absorption: passive absorption is through filtration, osmosis, simple diffusion and facilitation diffusion (need carrier) and other forms of absorption of digested nutrients into the human blood and lymphatic system; this form of absorption does not need to consume body energy; some substances with low molecular weight, such as simple peptides, various ions, electrolytes and water are passive absorption.

   3. Active absorption: opposite to passive absorption, active absorption must consume energy through the body, which is a form of material transport with reverse electrochemical gradient by relying on cell wall "mercury protein". This form of absorption is the main way for higher animals to absorb nutrients.

   (2) Utilization of amino acids in feed materials

   in most natural raw materials, amino acids can not be completely digested, absorbed and utilized. Therefore, it is important to understand the absorption and utilization of amino acids in common raw materials in pigs. Two terms are explained here: digestibility and utilization. Digestibility refers to the amount of amino acids absorbed in the intestine of the feed; utilization rate refers to the proportion of amino acids in the feed actually used for growth. Although the concept is simple, the actual determination of these two values is very complicated.

   most nutritionists tend to adopt digestibility as a reasonable indicator of utilization.