In order to prevent and control the diarrhea, currently many enterprises add high doses of zinc oxide in the food for suckling pig. It is a common kind of behavior, but many farmers say that although the use of high zinc reduced the rate of diarrhea, but it has negative impact on the growing and immune function. Breeders shows ‘love and hate’ on zinc oxide, how to deal with this problem?
In order to prevent and control the production of diarrhea in weaned piglets issues, animal nutritionists and producers have been trying to actually find an ideal solution. Now, high doses of zinc oxide as an inexpensive means to control the diarrhea are generally used. Zinc is Porocelsus first discovered in 1570. Todd et al in 1934 for the first time that zinc is necessary for higher animal nutrition elements. The study found that zinc is necessary for animal life activity of trace elements. Zinc content in vivo in the trace elements in the second place, and nearly 300 in the six enzymes in the activity of various enzymes and zinc related. It bears 20 different biological functions, involving almost all aspects of the metabolism of organisms. Therefore, zinc is animal body to maintain normal operation of life an important element.
From the perspective of livestock production, physiological functions of zinc are reflected in the growth and development of animals. With a higher level of zinc feed, animal daily gain, feed volume increase, which is generally believed that the following two factors: on the one hand by increasing the appetite, improve digestion and feed intake and feed to promote growth; the other hand, by improve immunity, increase the body's antioxidant capacity, increased protein synthesis of certain enzymes, promoting insulin and insulin-like growth factor I (IGF-I) synthesis and secretion, etc., to enhance anabolic to promote body growth. Zinc on the growth of young animals, in addition to a variety of zinc enzymes by forming outside, but also involved in hormone synthesis and effect. Therefore, the common variety of animals, zinc deficiency is characterized by growth retardation.
Meanwhile, the zinc in maintaining animal central immune organs (thymus, bursa of Fabricius) and peripheral immune organs (lymph nodes, spleen, tonsils) the structure and function plays an important role. Appropriate levels of zinc can promote the development of immune cells, DNA synthesis and cell differentiation and proliferation. Zinc deficiency can cause inhibition of lymphocyte proliferation, immune cells can cause changes in morphology, as well as spleen, thymus and other immune-related tissues and organs weight down, reduce the secretion of thymosin.
Zinc also affects the growth of animals’ skin and hairs. Animals with deficiency zinc often show that: coarse hair disorder and with varying degrees of hair removal, and even stripped; skin damage in the nose and mouth around, especially hind legs below the knee; hoof, horn abnormalities. Lamb of severe zinc deficiency, the shell off and cracked hoof, horn of normal ring structure disappeared and eventually fall off. Zinc by regulating the secretion of gonadal activity and sex hormones influence the normal development of sexual organs, sexual function to normal play. Zinc and membrane phospholipid and protein sulfhydryl interactions to stabilize the biofilm. Function and structure of the biofilm plays a key role. Zinc and zinc can induce metallothionein (ZnMT). Protection of membrane protein conformation and inhibition of many heavy metals cause free radicals induced peroxidation. The study also found that zinc on animal bones, the brain of animals also affect the development of the system.
On January 26, 2007, China began to ask for promoting the development of feed additives and veterinary drug use pollution-free, green, organic livestock growth, long-term high zinc addition on the current aquaculture industry has certain hazards.
Firstly, the impact on the environment, which is the primary hazard. Now the whole community in the emphasis on "sustainable development", "environmentally friendly." The use of high doses of zinc can be said against the historical trend of the behavior. Fed high doses of zinc (3kg / t) after digestion and absorption by pigs, fecal excretion of zinc up to 16832.26mg/kg. Studies have shown that feeding high doses of zinc daily dietary zinc excretion in pigs fed the basal diet of pigs is 33 times, such a high dose of zinc into the environment via fecal excretion, zinc accumulation and soil pollution. Excessive excretion of zinc by the body after the animal, but also pollution of groundwater, hinder the sustainable development of animal husbandry.
Secondly, high doses of zinc will adversely affect the growth of pigs. The first is the growth inhibition. Study found that after weaning 3 to 5 weeks, diets 3000mg/kg zinc oxide or zinc methionine 500mg/kg could significantly increase weaning weight and daily gain, improved growth performance; but long-term feeding of high zinc diet, inhibit the growth of weaned piglets, reduced weight gain. In addition, from the actual production found that high doses of zinc feeding time a little longer, pigs will be pale skin, coarse hair curl and so disorder.
Thirdly, the test diet to add more than 30 times the normal requirement of zinc (3kg / t), as zinc and iron and copper antagonism, reducing the absorption of iron and copper, resulting in significantly decreased hemoglobin, animal anemia, and thus long-term use led to a large number of pig deaths, affecting production efficiency.
Currently, there are some research results show that adding dose of vitamin C, vitamin E in the dietary can also improve the body's antioxidant capacity. But unfortunately, these substances do not have the ability to promote mucosal cell proliferation. In addition, vitamin C and vitamin E have antioxidant capacity in the feed, but the cost is a big problem.