| Whereas the adverse effects of long-term application and heavy use of antibiotics, and its threats to the human food safety and the health, looking for alternatives to antibiotic additives, and developing new green feed additives is the hot research for today and future of the animal husbandry. The green feed additives are used with insignificant toxicity and side effects, and can promote animal growth and prevent and control animal diseases. At present, combined with the analysis of existing research data for green feed additives, much of the interest was centered on the study of the effect added in animal diets with the single materials, such as the acidifier, probiotics, enzyme preparation and oligosaccharide. Pigs are often as the object of the study. There is little research that is directed to the comparison of the influence of different green additives on productive performance and immunological function of broiler. In addition, plant essential oil has been as a new feed additive used in the livestock, but the relative research about it is less. Under the same experimental conditions, the effects of probiotics, enzyme preparation, acidifier, plant essential oil and auromycin on Arbor Acres(AA) broilers productivity, slaughter performance, digestibility, intestinal microflora and immunity were examined in this study. This research helps us investigate the feasibility of the use of alternative feed additives for antibiotic to solve the problems of broiler drug residues. It would enrich the knowledge of researchers and help the scientific community to conduct more research on such daily requirements for boosting poultry production in a better way. It also provides the experimental basis to improve the efficiency and quality of the breeding livestock. This study is first compared the effects of the plant essential oil, probiotics, enzyme preparation and acidifier. The results are as follows:1.The broilers were randomly divided into probiotics, enzyme preparations, acidifier, plant essential oil and auromycin feed additive groups and control group. Broilers reared 43 d. The results indicate that the feed additive groups compared with the control group, the average daily gain(ADG) and average daily intake were higher and the feed gain ratio(FGR) were decreased. The effect of the plant essential oil was better than the probiotics, and the plant essential oil and chlortetracycline had the equivalent effect. The broiler groups breeding with green feed additives or auromycin had improved the apparent metabolizable energy(AME), the true metabolizable energy(TME) and the utilization rate of crude protein and energy with the extremely significant difference(P<0.01). The dressing percentage, semi-eviscerated rate, eviscerated rate, leg muscle and chest muscle rate were increased in vary degree and the percentage of abdominal fat was decreased in broiler reared with feed additives. The results showed that four kinds of green feed additives can improve the production performance, slaughter performance, and digestion of the broilers, and the effect was equivalent with auromycin.2. Breeding the broilers with probiotics, enzyme preparations, acidifier, plant essential oil or auromycin, 21 d and 42 d later, the number of Escherichia coli in the broiler intestinal tract jejunum and caecum were decreased, while the number of lactic acid bacteria was increased. The efficiency was not exactly the same by the different green feed additive, and both of the E.coli and the Lactobacillus were decreased after breeding with the auromycin. The investigation indicated that the intestinal contents of p H was significantly lower than that of the control broiler(P<0.01) breeding with the acidifier. The p H of the intestinal contents of other green feed additive groups was higher than that of the control broilers and was in range of normal value. These results indicated that the four types of green feed additive had the effect of promoting the beneficial microbiology whilst inhibiting the harmful bacteria.3. The broilers were reared with probiotics, enzyme preparations, acidifier, plant essential oil or auromycin feed additive 42 days. Except broilers blood Ig A content of the acidifier groups was high significantly(P<0.01) lower than that of the control broilers, the peripheral blood Ig A, Ig M, and Ig G of other groups broilers were increased in varying degrees. The peripheral blood T, B lymphocytes and TANAE+ cells from the experimental broilers were higher than that of the control broilers in different degree. The results indicated that the peripheral blood immunity of the broilers was enhanced after breeding with the green feed additives. The enhancement effects were similar with the treatment by the auromycin, and sometimes even better.4. The index of thymus, spleen and bursa of Fabricius in the experimental broilers were inordinately higher than the control broilers. Moreover, the number of Ig G, Ig M, and Ig A antibody producing cells in the thymus, spleen and bursa of Fabricius on broiler were increased than the control. The proliferation function of thymus and spleen T lymphocytes and spleen and bursa B lymphocytes were stimulated and strengthened than the control. The results showed that the application of the green feed additives can promote the development of the immune organs and enhance the immune functions of the broilers.5. The economic benefits of the five feed additives were examined, the efficiency from big to small ordered is plant essential oil, auromycin, acidifier, probiotics, and enzyme preparation. |
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