The rapid development of modern swine technology and feed preparation technology has made the nutrition of essential trace elements in pig feed more scientific and practical, and the benefits have been greatly improved. However, due to the influence of related knowledge and technologies, there is still a serious shortage of nutrients for trace elements in pig feed in China. The lack of essential trace elements will ultimately affect the performance of pigs to a certain extent. The development of pork quality, ecological environment, and feed resources. 1 The main factors causing surplus and deficiency of essential trace elements in pig feed 1. l The content of essential trace elements in feedstuff raw materials is not fully taken into account in the feed preparation process. The content of essential trace elements in feedstuff feeds is affected by factors such as variety, soil type, climate type, etc., resulting in a large variation in feedstuff raw materials, so The uniform standard adds essential trace elements to the feed, often resulting in its deficiency or excess. In addition, in the traditional feed mix, the necessary trace elements contained in feed ingredients are usually not taken into account, and the necessary trace elements required for the growth of livestock and poultry need to be added separately. The addition of trace elements can improve pig production performance and carcass quality, and its cost is always low. Therefore, the amount of trace elements added often exceeds the requirement. 1.2 Misuse of trace elements Additives Non-scientific supplementation of trace element additives is necessary, and the addition of excess amounts is more common. It is more common to add high-Cu (125-250 mg/kg) and high-Zn (2000-3000 mg/kg) preparations to promote growth in pig feeds. Due to the low absorption rate of Cu and Zn, a large amount of Cu and Zn added in the feed is excreted to the soil and water. Currently, the National Feed Association of Canada limits the maximum amount of Cu and Zn in diets to 125 and 500 mg/kg, respectively. The Netherlands considers environmental protection and no longer allows the use of high Cu and high Zn in diets as growth promoters; Japan The upper limit is stipulated: Cu for lactating piglets (below 30kg) is 125mg/kg, Zn is 120mg/kg, for growing pigs (30-70kg) Cu is 45mg/kg, Zn is 55mg/kg, finishing pigs (7kg or more) Cu in the compound feed is 10mg/kg and Zn is 80mg/kg. 1.3 Bioavailability of essential trace elements The bioavailability of essential trace elements directly affects the physiological requirements and tolerability of pigs. The lower the bioavailability, the higher the demand and tolerance. The bioavailability of essential trace elements is influenced by a variety of factors, including the chemical form of trace elements in feed, the interactions between trace elements or other nutrients, and feeding conditions and the environment in pigs (Zhou Ming, 1993). The chemical form is the main factor affecting the bioavailability of trace elements, trace elements in different chemical forms, such as sulfate. There are significant differences in the bioavailability of organic elements such as inorganic salts such as hydrochlorides and methionine salts and tyrosine salts. In general, in inorganic minerals, oxides are the most difficult to absorb and sulfates are the most easily absorbed. However, between inorganic salts and organic salts, the bioavailability of organic trace elements is higher than that of inorganic trace elements. The synergy between trace elements or orange resistance (such as Cu, Fe, Zn, etc.) and other factors (anti-nutritional factors) will also affect the bioavailability of trace elements in feed to a certain extent (Yang Feng, 1994. 2001. Zhou Ming, 1996). For example, the absorption of Zn is influenced by the levels of Ca and P in diets; Mo.s and Fe cause the decline in the bioavailability of Cu in animals (Fan Ling, 1999); phytate and fiber levels, enzyme environment, The pH of gastrointestinal tissues, as well as fats and mycotoxins, affect the absorption of trace elements. Since the specific mechanism of the absorption of trace elements in animals is not completely understood, the actual biochemical utilization of only trace elements is actually determined. At present, there are no systematic studies and reports on the exact bioavailability of trace elements in feeds at home and abroad. 2 Effect of surplus and deficiency of essential trace elements on pig production 2.1 The surplus and deficiency of essential trace elements and the production performance of essential trace elements will reduce pig production performance. Roc et al. (1982) found that when the dietary CU content exceeds 375 mg/kg, the promoting effect of Cu on pigs disappears. Cu is antagonistic to other trace elements such as Fe, Zn, etc. Excess Cu or Zn can affect the utilization of each other. The high Cu content in the diet caused a relative reduction in the utilization of Fe and Zn, leading to deficiencies, manifested as increased diarrhea and skin diseases, and decreased weight gain. Li et al. (199) showed that dietary levels of 200 mg/kg Cu ​​reduced the pig's liver Fe content by 19.4%. Excessive addition of trace elements often causes abnormal changes in tissues and organs of the body, especially metabolic organs. The abnormal changes in these organs will inevitably further affect the absorption and utilization of nutrients by pigs, resulting in a decrease in production performance (Liu Yanqiang, 1994). . Excessive trace elements in the feed will also have a negative effect on the stability of the vitamin, leading to vitamin deficiency. Diets that use high levels of Cu, Fe, and Mn will greatly increase their natural tocopherol oxidation rates. High Cu can reduce the level of α-tocopherol in feed to almost zero within 22 days (Zhu Xi, 1991). Liang Xiaoyi (1998) reported that pigs fed with high Cu (greater than 125 mg/kg) had obvious acid rancidity after 2 weeks of storage. Excess Cu will also interfere with the availability of sulfur-containing compounds such as sulfamones, which have free sulfhydryl groups (-SH), thereby increasing the requirements for sulfur-containing compounds, especially sulfur-containing amino acids, in animals. Insufficient Cu in the pig diet also causes a decrease in pig performance. 2.2 The surplus and deficiency of essential trace elements and pork quality Due to the antagonistic effects of Cu and Fe and Zn, the high Cu diet increased the pig's requirement for Fe and Zn (Underivttl, 1977), thereby increasing the possibility of poisoning. At the same time, it will also cause a large accumulation of Cu (mainly liver, kidney), Fe and Zn in the pig's body tissues, and ultimately reduce the food safety of livestock products. According to Qian Wei (1998), the addition of 150 and 350 mg Cu per kilogram of pig feed resulted in 154 and 407 mg of Cu in the liver of pigs, respectively, and human consumption of this high Cu pork liver causes chronic poisoning or other adverse consequences. High Cu (12-25 mg/kg feed) has an adverse effect on pork quality. According to Greer (1979), high dietary Cu (up to 250 mg/kg) in pig diets can cause backfat change in pigs, especially barrows. soft. Other studies have shown that high dietary Cu supplementation in pig diets can lead to increased kidney fat content, lower stearic acid in fats, increased oleic acid and palmitic acid, softer body fat, and easier oxidation of back fats, resulting in an 80% incidence of oxidation (ç¥ Zhou et al., 1994). Iron is not only an important component of hemoglobin and myoglobin, but also plays a decisive role in the formation of flesh color. It is also a cofactor for the antioxidant system catalase, which plays an important role in preventing lipid oxidation and maintaining pork flavor. However, when Fe in the diet reached 200 mg/Kg, the content of non-heme iron and lipid peroxidation products increased significantly. Therefore, the use of high Cu in pig diets and the control of Fe in diets should be avoided. 2.3 The surplus and deficiency of essential trace elements and the use of essential trace elements in the ecological environment are relatively low in pigs. Excessive use of necessary trace elements, in addition to causing a large number of deposition in livestock and poultry, this type of element will be excreted with the feces, causing some pollution to the environment. Especially in the current level of intensive pig production increased significantly. With the rapid increase in stocking density and feeding scale and the fact that most feed companies or aquaculture companies still use inorganic forms of trace elements for commercial purposes, long-term inevitably causes air pollution. Water, soil and other serious environmental damage. Guan Shui et al. (1995) reported that pigs fed with high Cu (CuSO4, 150, 200, 250, and 300 mg/kg) diets accounted for 98.95%, 97.86%, and 87.3% of their daily intake of Cu respectively. % and 96.06%. When a large amount of Cu enters the soil, the amount of Cu in the soil and vegetation increases accordingly. Feenstra et al. (1993) used Cu-rich pig manure (containing Cu 700-3000 mg/kg) to fertilize the grassland. The harvested hay had a Cu content of 42 mg/kg and the sheep died of poisoning after eating. Contaminated manure with high concentrations of essential trace elements can reduce the ability of the body to self-purify once it contaminates the water source, causing deterioration of water quality and death of aquatic organisms. The sensitivity of fish to high copper far exceeds that of mammals. For fish, the lethal dose of Cu at 96 h is 0.1 mg/kg. In addition, manure is a good organic fertilizer, but if the content of essential trace elements such as Cu, Zn and Sn is higher, the effect of fertilizer use will be greatly reduced, because the high copper in feces is a short-term stress factor (high in alkaline, caused by One of hypoxia, etc.) can inhibit or kill bacteria that decompose organic matter and reduce the decomposition rate of feces. Excessive addition of trace elements in animal husbandry production not only destroys the ecological environment of the farm and surrounding areas and affects human health, but also adversely affects the sustainable development of animal husbandry in the development of livestock ranching. At present, countries such as Britain and the United States are no longer advocating the use of high-Cu diets in livestock and poultry production. Japan has also passed legislation to reduce the Cu dietary Cu limit to 45 mg/kg in 1997, and has reduced the dietary Cu limit of growing-finishing pigs. To 10mg/kg. 2.4 The lack of surplus trace elements and lack of feed resources Feed is the material basis for pig production. At present, the shortage of feed resources has become a limiting factor in the further development of pig production in China. On the other hand, poor feed management and low feed conversion rates cause waste. In addition to the fact that the limited resources are not fully utilized, the waste of feed resources is also manifested in the unbalanced nutrition of compound feeds and the inefficient use of limited nutrient elements. The key way to solve this problem is to increase the science of feed utilization and exchange more feed products with limited feed. The utilization of feed resources is influenced by the surplus and deficiency of essential trace elements. Eliminating or reducing the surplus and deficiency of essential trace elements, increasing the relative utilization of essential trace element raw materials, and thus reducing the demand for feed ingredients, can alleviate the shortage of grain in China. Ventilator block diagram Medical Invasive Breathing Machine Invasive Breathing Machine,Medical Invasive Ventilator,Invasive Mechanical Ventilation,Invasive Positive Pressure Ventilation Guangzhou Zhongzhinan Supply Chain Co.,Ltd. , https://www.gzzhongzhinan.com
One. Main mechanical ventilation modes
(1) Intermittent Positive Pressure Ventilation (IPPV): positive pressure in the inspiratory phase and zero pressure in the expiratory phase. 1. Working principle: The ventilator generates positive pressure in the inspiratory phase and presses the gas into the lungs. After the pressure rises to a certain level or the inhaled volume reaches a certain level, the ventilator stops supplying air, the exhalation valve opens, and the patient's thorax Passive collapse of the lungs and exhalation. 2. Clinical application: Various patients with respiratory failure mainly based on ventilation function, such as COPD.
(2) Intermittent positive and negative pressure ventilation (IPNPV): the inspiratory phase is positive pressure and the expiratory phase is negative pressure. 1. How it works: The ventilator works both in the inspiratory and exhaled phases. 2. Clinical application: Expiratory negative pressure can cause alveolar collapse and cause iatrogenic atelectasis.
(3) Continuous positive pressure airway ventilation (CPAP): Refers to the patient's spontaneous breathing and artificial positive airway pressure during the entire respiratory cycle. 1. Working principle: Inspiratory phase gives continuous positive pressure air flow, and exhalation phase also gives a certain resistance, so that the airway pressure of inhalation and exhalation phases are higher than atmospheric pressure. 2. Advantages: The continuous positive pressure airflow during inhalation is greater than the inspiratory airflow, which saves the patient's inhalation effort, increases FRC, and prevents the collapse of the airway and alveoli. Can be used for exercise before going offline. 3. Disadvantages: great interference to circulation, large pressure injury of lung tissue.
(4) Intermittent command ventilation and synchronized intermittent command ventilation (IMV / SIMV) IMV: There is no synchronization device, the ventilator air supply does not require the patient's spontaneous breathing trigger, and the time of each air supply in the breathing cycle is not constant. 2. SIMV: There is a synchronization device. The ventilator gives the patient a commanded breath according to the pre-designed breathing parameters every minute. The patient can breathe spontaneously without being affected by the ventilator. 3. Advantages: It exerts its ability to regulate breathing while offline; it has less influence on circulation and lungs than IPPV; it reduces the use of shock medicine to a certain extent. 4. Application: It is generally considered to be used when off-line. When R <5 times / min, it still maintains a good oxygenation state. You can consider off-line. Generally, PSV is added to avoid respiratory muscle fatigue.
(5) Mandatory ventilation per minute (MMV) When spontaneous breathing> preset minute ventilation, the ventilator does not command ventilation, but only provides a continuous positive pressure. 2. When spontaneous breathing is less than the preset minute ventilation volume, the ventilator performs command ventilation to increase the minute ventilation volume to reach the preset level.
(6) Pressure Support Ventilation (PSV) Definition: Under the prerequisite of spontaneous breathing, each inhalation receives a certain level of pressure support, increasing the patient's inhalation depth and inhalation volume. 2. How it works: The inspiratory pressure begins with the patient's inspiratory action, and ends when the inspiratory flow rate decreases to a certain level or the patient attempts to exhale hard. Compared with IPPV, the pressure it supports is constant, and it is adjusted by the feedback of the inspiratory flow rate. Compared with SIMV, it can get pressure support for each inhalation, but the level of support can be set according to different needs. 3. Application: SIMV + PSV: used for preparation before off-line, can reduce breathing work and oxygen consumption Indications: Exercise the ventilator; prepare before going offline; the ventilator is weak due to various reasons; severe flail chest causes abnormal breathing. 5. Note: Generally not used alone, it will produce insufficient or excessive ventilation.
(7) Volume Supported Ventilation (VSV): Each breath is triggered by the patient's spontaneous breathing. The patient can also breathe without any support and can reach the expected TV and MV levels. The ventilator will allow the patient to be truly autonomous Breathing also applies to preparations before going offline.
(8) Capacity control of pressure regulation
(IX) Biphasic or bilevel positive pressure ventilation How it works: P1 is equivalent to inspiratory pressure, P2 is equivalent to breathing pressure, T1 is equivalent to inspiratory time, and T2 is equivalent to exhalation time. 2. Clinical application: (1) When P1 = inspiratory pressure, T1 = inspiratory time, P2 = 0 or PEEP, T2 = expiratory time, which is equivalent to IPPV. (2) When P1 = PEEP, T1 = infinity, P2 = 0, T2 = O, which is equivalent to CPAP. (3) When P1 = inspiratory pressure, T1 = inspiratory time, P2-0 or PEEP, T2 = desired controlled inhalation cycle, equivalent to SIMV.