Application of high-volume zinc oxide to prevent diarrhea in weaned piglets

I. Introduction

Zinc has been used in pig feed in the past, mainly to prevent the symptoms of zinc deficiency, and to achieve the purpose of promoting growth; and its appropriate dosage has not only been consistent in academic research, but has also provided a reference for commercial feed formulations. However, recent studies have suggested that feeding high doses (ie, drug dosages) of zinc oxide to weaned piglets can control the occurrence of E. coli scours (Holm, 1988; Poulsen, 1989); and this amount is 2400 to 3000 ppm. The safe use of piglets raised by NRC and Brink et al, 1959 has been exceeded.

This report is aimed at (1) the utility of zinc and the lack of symptoms (2) the source of zinc and its utilization (3) the application of high-volume zinc oxide, which is discussed in three aspects.

Second, the role of zinc and lack of symptoms:

Zinc is one of the essential substances for physiological functions, such as how to regulate the balance of acid and acid to achieve immunity, and is also a component of some enzymes or an activator of enzymes (Joseph and David, 1993). Its main functions are as follows:

(1) Prevention of incomplete keratosis

(2) Participation in the role of the enzyme system

(3) promote wound healing

(4) related to the growth of bones and hair

Related lack of symptoms: incomplete keratosis, slow activity, growth retardation, rough hair, and slow wound healing. Generally, in the normal diet of cattle and sheep, there is less deficiency; however, in the diet of pigs, there is often zinc deficiency, which leads to the occurrence of incomplete keratosis. Therefore, it is often necessary to supplement the pig diet. Add appropriate amount of zinc to prevent the occurrence of symptoms and promote growth.

Third, the type of zinc source and its utilization rate

Table 1, the composition specification table of zinc source

(1) Relevant tests on poultry:

In a report published by Reberson and Schaible in 1958 and 1960, it was pointed out that different zinc sources (sulfates, oxides, carbonates) were used in poultry experiments, and there was no significant difference in bioavailability (bioavaillbility). The results were similar to those of Pensack et al, 1958; Edwards, 1959.

Wedekind and Baker, 1990, added ZnSO4.7H2O in 0, 2.5, 5, 10, 15, 40, 100 ppm zinc content to a soy flour base diet containing 13 ppm zinc, and fed a biological analysis to a one-week-old broiler. (bioassay) experiments found that regardless of weight gain (g), plasma Zn (ug / dl), or total tibia Zn (ug) are linearly related to the food intake of zinc added, rather than the total zinc content of the diet The food intake is related.

According to the test results in the table below, the amount of zinc available for feeding from chickens mainly comes from the additional zinc added, which is independent of the zinc content of the basic diet of 13 ppm, which is mainly due to the extremely low bioavailability of zinc in soybeans (Baker & Halpin, 1988). The weight gain, plasma Zn, and total tibia Zn showed a linear increase with the amount of additional zinc added, and the slope of the line was slower after each of 20, 40 ppm.

Table 2, Rewponse of Chicks to Supplemental Zinc Sulfate

In addition, Wedekind and Baker used ZnSO4 in the same period. H2O and ZnO were used as additional zinc sources. When ZnO was used as the zinc source in terms of weight gain, the bioavailability was only ZnSO4. 61.2% of H2O is in Tibia Zn, and ZnO is ZnSO4. 44.1% of H2O. Differences in the bioavailability of different zinc sources have previously been reported in the same conclusion (Erdman et al., 1980, 1983; Fordyce et al., 1987).

Zn deposited in Tibia is considered to be only an absorption, and weight gain is the degree to which the efficiency of Zn is actually reflected (BL O ́DELL). The results of these studies show that the difference in metabolic utilization efficiency of different zinc sources is mainly due to the difference between the absorption rate and the bioavailability. The difference in metabolic utilization is mainly due to the degree of endogenous zinc loss, and the degree of endogenous zinc loss is determined by the amount of absorbable zinc supplied for assimilation; that is, the bioavailability is higher. A good source of zinc provides more zinc that can be absorbed. In contrast, the loss of endogenous zinc is also increased, thus making its metabolic efficiency worse (Weigand and Kirchgessner, 1980). In other words, this is also why ZnO is only ZnSO4 in the Tibia Zn absorption rate. 44.1% of H2O; but in terms of weight gain, it reached 61.2%. This also explains why ZnO is generally used as a source of zinc in poultry diets.

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(2) Relevant tests on hog:

In the past, in pigs, the experiment of adding different zinc sources to compare the weight gain cases to determine their respective utilization rates (Hill et al., 1986; Swinkels et al., 1991) was not as described in the aforementioned Wedkind et al. The test can clearly distinguish the difference of each zinc source.

Wedekind et al, 1994, also applied to the hog test by bioassay. The additional basal diets at each stage listed in Table 3 were additionally supplemented with 0, 5, 10, 20, 40, 80 ppm of zinc (with ZnSO4.H2O as the zinc source). Plasma Zn (ug/ml) was measured at 4, 6, 10, and 12 weeks of age, and the amount of Zn (ug/g) in metacarpal and coccygeal was measured after the end of the test. The results showed that all three were linearly related to suppl. Zn intake, but there was no significant difference in body weight between the groups. If the Zn requirement is measured on the basis of maximum weight gain (Lewis et al., 1956, 1957; Smith et al., 1961), the current NRC recommendation is clearly above the need. Like other minerals, Zn plays a very important role in immunocompetence and reproduction. Therefore, the amount of Zn required for reproduction should be greater than that required for growth only (Underwood, 1981); and when animals are subjected to considerable urgency, the demand for Zn is relatively increased (Klasing, 1992). However, past experiments have failed to understand the maximum requirement for Zn for reproduction or immunization; bone is the largest reservoir of Zn in animals. Therefore, the value of the amount of Zn contained in bones and plasma is far more suitable as an indicator of the amount of Zn required in terms of growth.

Table 3. Zn requirements and design values ​​for each feeding stage of pigs

If it is determined by biological analysis, the different utilization rates of different zinc sources applied to the pigs, as shown in Table 4, are obviously ZnSO4. The utilization of H2O is the best. This result is in broiler test with Wedkine et al., 1992. The utilization rate of ZnMET is ZnSO4. The 206% result of H2O is just the opposite.

Table 4. Relative bioavailability of different zinc sources*

*corn-soybean meal basal diet

In addition, if ZnSO4. When H2O and ZnMET were added to the diet supplemented with crystalline amino acid as the main protein source, the utilization rate of ZnMET was found to be only ZnSO4. 17% of H2O. This is due to the complete lack of phytate and fiber by crystalline amino acid diet. Of course, in addition to both fiber and phytate, there are still Ca and other influencing factors. Oberleas et al., 1962; O ́dell et al., 1964; Ellis et al., 1982; Fordyce et al., 1987 and many other reports indicate that high calcium diets can highlight phytate effects on Zn bioavailability. degree. However, excessive calcium corn-soybean meal diets increase the chance of pigs developing parakeratosis (Tucker and Salmon, 1955; Lewis et al., 1956, 1957; Luecke et al., 1957).

From the above inference, the difference in the utilization rate of different zinc sources can be roughly summarized as

(1) The difference in animal species.

(2) Mutual antagonism with other nutrient molecules in the diet.

4. Report on prevention of diarrhea in piglets by high zinc content

It is a major issue in recent years to apply ZnO with a high zinc content of 2400~3000ppm (which should be regarded as the amount of drug) in weaned piglets to prevent the occurrence of pig squatting (E. coli scours) (Holm, 1988; Pouisem, 1989). This amount is far more than the safe use of piglets proposed by the 1988 NRC, but some recent studies in the United States (Fryer et al., 1992; Tokach et al., 1992) added 3,000 mg of Zn to the piglet diet, but found There are no significant harmful or beneficial effects. In these reports, we can find the following problems: (1) Why use ZnO as a source of additional Zn? (b) Why is the amount of zinc added by the NRC recommended safe dosage of 100ppm, which is the amount of 2400~3000ppm? (3) Is there any difference in the age of the test piglets?

A considerable amount of plasma Zn concentration can be obtained from the amount of added Zn in the feed, but when the amount of Zn fed is less than 1 g/day, the correlation cannot be shown; only under >1 g/day, the two are in a straight line. Related. According to NRC, 1980, zinc is a trace element with a fast conversion rate and a short residence period. When any substance in the body cannot be excreted in the same amount as the absorption, it is the starting point for the substance to start to stay in the body. This shows that when the amount of high zinc is ingested, the plasma Zn value increases linearly with it.

(B) Two trials by Trial 2, Trial 3 found that the weight gain and feed intake of B+3000 ppm Zn (ZnO) increased by 17% and 14%, respectively, compared with the control group, Poolsen, 1989; Fryer , 1992 also proposed: especially after 28 days of lactation, direct feeding B + 3000 ppm (ZnO), the effect is more obvious. The addition of ZnSO4 or ZnMET has a plasma Zn value of 4 mg/L or more. According to Trial, the optimum value of plasma Zn is between 1.5 and 3.0 mg/L, but the addition of ZnO is in good agreement with its range. Therefore, both ADG and FI have an improved effect compared with the control group. This result is similar to the above-mentioned results of the zinc source, and it can be seen that it may be more tolerant due to the bioavailability of ZnO.

(3) From the divorced age of the three pigs listed in Table 5, the average weight gain effect of each group in Trial 2 is better than that of Trial 3; Tokach et al., 1992 also proposed: 21 days old The weaned piglets (average weight 5.4 kg) fed directly to the 3000 ppm Zn diet also showed no benefit for weight gain. Perhaps early weaning reduces the ability of piglets to remove excess Zn from the body, which may lead to high levels of Zn in the blood, which interfere with the induction of ZnO in weight gain.

(4) Comparison with Cu: In addition to providing the relevant enzyme components of blood cell formation, Cu has a similar antibiotic effect, which can promote growth, and is more obvious with the increase of dosage (between 100 and 250 ppm), especially The best use of 250ppm (Hong Ping, feed ingredients); Root and Madhen, 1982; Edmonds et al, 1985). However, in Trial 3, the treatment group did not improve more than the control group.

In the three trials of Joseph and David, no sputum occurred in each of the piglets treated, so it was impossible to compare the effect of adding high zinc to prevent diarrhea.

V. Conclusion

Because Zn plays a very important role in immunocompetence and reproduction, it is one of the main components of enzyme composition or activation; in pig diets, it is often necessary to add an appropriate amount of zinc to Prevent the occurrence of symptoms and promote growth.

Although in this report, the addition of high levels of zinc does not clearly indicate the expected effect of preventing diarrhea. However, this amount of safety added by the NRC is not only poisonous, but it still has better weight gain effect. It is worthy of further discussion and determination of its prevention of diarrhea.

In addition, as far as the above discussion is concerned, if plasma Zn or bone Zn is used as a reference point, ZnSO4 is reduced. When the amount of H2O or ZnLys is such that the plasma Zn value is also in the range of 1.5 to 3.0 mg/L, it is also possible to add ZnO (3000 ppm Zn). If you consider the price of adding zinc source, you should discuss it again.