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METABOLISM AND NUTRITION |
* State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China 100094; and Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China 100094
1 Corresponding author: tjm606{at}263.net
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Key Words: alfalfa • extract • fat • immunity • broiler
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Polysavone is a natural extract of alfalfa (Medicago sativa L.) and contains polysaccharides (18.63%), triterpenoid saponins (5.58%), and flavonoids (5.89%). Plant polysaccharides definitely possess an immunomodulating effect in many ways, and they regulate the balance of the neuroendocrine immune network (Nie and Zhang, 1999; Chen et al., 2002; Guo et al., 2004; Kong et al., 2006). The immune-enhancing function of alfalfa polysaccharides has been studied in broiler chickens and swine in China (Zhao et al., 1993, 2005; Jiang and Yu, 2005). Saponins are compounds found in a number of plants. Previous studies had suggested that alfalfa saponins may prevent hypercholesterolemia, reduce egg production, and depress growth in mammals and birds (Heywang and Bird, 1954; Anderson, 1957; Heywang et al., 1959; Malinow et al., 1977, 1979, 1980, 1981; Whitehead et al., 1981). Recently, Ilsley et al. (2005) reported that quillaja saponins may potentiate an immune response in the weaned piglet but have a detrimental effect on the utilization of feed. Flavonoids isolated from plants are used in the treatment of certain physiological disorders in humans, and some flavonoids exhibit unusual hormonal activities as estrogens when fed to livestock. Plant flavonoids are likely to be exploited as animal hormones and as antimicrobial, antiinflammatory, and antitumor compounds in the future (Dakora, 1995).
Studies in our laboratory have shown that polysavone may depress abdominal fat deposition and be beneficial to the growth of broiler chickens (Tong et al., 2004). In the current study, the influence of polysavone on abdominal fat deposition and the immunity of broiler chickens was investigated.
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MATERIALS AND METHODS |
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Polysavone is a solid compound that is obtained from alfalfa (Medicago sativa L.) by hot water extraction. Fresh alfalfa at full bloom was harvested and air-dried for 2 to 3 d to a 15% moisture content. The dried alfalfa was boiled in hot water at 100°C for 2 h. The contents were then filtered through 2 layers of gauze, and the extract was spray-dried. The extract consisted of polysaccharides (18.63%), saponins (5.58%), flavonoids (5.89%), CP (21.58%), moisture (9.87%), ash (18.64%), and unknown compounds (19.81%). Repetitious examination showed that the proportion of components in polysavone was constant within a minute range.
Selected Dose of Polysavone, and Experimental Birds and Treatment
All procedures were approved by the Beijing Administration Office of Laboratory Animals. In a preliminary experiment, we observed the effect of gradients of polysavone (0.01, 0.03, and 0.05%) on the serum anti-New-castle disease virus (NDV) antibody titer of broiler chickens, and found that at a dose of 0.05%, polysavone significantly improved the antibody titer, whereas at other concentrations, polysavone failed to increase the antibody titer of broiler chickens. In addition, in a study by Tong et al. (2004) of gradients of polysavone (0.03, 0.06, and 0.09%), 0.06% polysavone had the optimal effect of inhibiting abdominal fat deposition and promoting performance. Accordingly, in the current study, 0.06% polysavone was selected.
Two hundred 1-d-old male Arbor Acre broiler birds (Beijing Huadu Broiler Co., Beijing, China) were randomly allocated to 2 groups of 100 birds each, with 5 replicates of 20 birds each. Birds in the control group were supplied with a basal diet, and those in the polysavone group received an experimental diet supplemented with 0.06% polysavone at the expense of maize, based on the control diet; other factors were the same as those in the control group. The basal maize-soybean diet (Table 1
) was formulated to meet the NRC (1994) nutrient requirements. All birds were placed in wire cages in a temperature-controlled house. The ambient temperature was gradually decreased from 32°C on d 0 to 25°C on d 21 and then kept constant. Continuous lighting was provided throughout the trial. Feed and water were provided for ad libitum consumption. Fresh diets were prepared and supplied each day. Body weight and feed consumption per replicate were determined weekly. All birds were inoculated with the Newcastle disease IV strain vaccine (Qian Yuan Hao Biological Co., Ltd., Beijing, China) on d 7 and with the infectious bursal disease intermediate vaccine (Qian Yuan Hao Biological Co., Ltd.) on d 21 by intranasal and intraocular administration.
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At 3, 4, 5, and 6 wk of age, 4 birds per replicate were randomly selected and weighed after feed deprivation for 12 h, and fresh blood was obtained by cardiac puncture into heparinized blood collection tubes for the lymphocyte proliferation assay and into nonheparinized tubes for the NDV hemagglutination inhibition (HI) assay. Immediately after blood sampling, the birds were killed by cervical dislocation. The carcasses were then opened and the abdominal fat pad, thymus, spleen, and bursa were removed and weighed. Relative organ weight was calculated as [organ weight (g)/BW (kg)].
Leukocyte Preparation
Fresh heparinized blood from 2 birds in each replicate at 4 and 6 wk of age was separated by Percoll gradient (Amersham Pharmacia Biotech, Uppsala, Sweden) centrifugation and washed 3 times with Hanks’ balanced salt solution to obtain peripheral blood mononuclear cells. Peripheral blood mononuclear cells were counted, and cell viability was determined by the trypan blue exclusion method. The cells were suspended and adjusted to 1 x107 cells/mL in RPMI 1640 medium (Sigma-Aldrich, Inc., St. Louis, MO) containing 100 U/mL of penicillin, 100 µg/mL of streptomycin, and 2 mM L-Gln (complete media), and then supplemented with 10% heat-inactivated fetal bovine serum (Qian Yuan Hao Biological Co., Ltd.).
Lymphocyte Blastogenesis Assay
A peripheral blood mononuclear cell suspension (1 x107 cells/mL) was tested for the blastogenic response to concanavalin A (ConA, Sigma-Aldrich Inc., St. Louis, MO) and lipopolysaccharide (LPS, from Escherichia coli, Sigma-Aldrich Inc.). A 100-µL quantity of cell suspension and ConA (or LPS) was added to a 96-well microtiter plate to provide a final concentration of 25 µg of ConA (or LPS)/mL. No cell suspension was added to control wells. After cultures were incubated for 48 h in a incubator at 37°C and 5% CO2, 10 µL of 3-(4,5-dimethylthiazolyl)-2,5-diphenyl tetrazolium bromide (5 mg/mL, Sigma-Aldrich, Inc.) was added to each well, and the plates were incubated for 4 h. A 90-µL quantity of sodium dodecanesulfonate (20%) was added to each well to stop the reaction. The plates were placed at room temperature for 24 h, and the results are reported as optical density at 570 nm with an automated microplate analyzer (318MC, Sanco Instrument Co. Ltd., Shanghai, China).
Assay of Serum HI Antibody
Newcastle disease virus HI antibody quantification was done by using the hemagglutination and HI procedures. The nonheparinized blood samples (1.5 mL/ chicken) were placed at 37°C for 2 h and then centrifuged at 829 xg/min for 30 min. Serum samples were collected and frozen at –20°C for assays. Briefly, HI tests were carried out by using serial 2-fold dilutions of serum and 4 hemagglutination units of the NDV antigen (Qian Yuan Hao Biological Co.). Serum dilutions ranged from 1:2 to 1:2,048. The geometric mean titer was expressed as reciprocal log2 values for the highest dilution that displayed HI.
Statistical Analysis
Data were analyzed by SPSS 11.00 software for Windows (SPSS Inc., Chicago, IL). The differences between groups were determined by 1-way ANOVA. Duncan’s multiple-range tests were performed. The level of statistical significance was set at P <0.05. Data were expressed as mean ±SD.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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The effects of polysavone on abdominal fat deposition and the performance of broiler chickens are summarized in Table 2. Birds in the polysavone group had significantly lower (P <0.05) relative abdominal fat weights compared with the control birds at wk 5 and 6. Polysavone had no significant (P >0.05) effect on feed intake, BW, and feed:gain ratio from 0 to 3 wk of age and at 4 to 6 wk of age. In general, there were no significant differences in feed intake (91.6 vs. 91.2), BW (2.006 vs. 2.036), and feed:gain ratio (2.03 vs. 2.00) between the 2 groups.
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The effects of polysavone on relative immune organ weights are shown in Table 3. Polysavone improved the relative thymus and spleen weights (P <0.05) compared with those of the control group at 6 wk of age. At 4 and 5 wk of age, relative bursa weights in the polysavone group were significantly higher (P <0.05) than those of the control group.
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The effects of polysavone on lymphocyte proliferation and the serum HI antibody titer of broiler chickens are presented in Tables 4 and 5. At 4 and 6 wk of age, the proliferation of T and B lymphocytes in the polysavone group was significantly greater (P <0.05) than that of the control group. Polysavone resulted in a significant increase (P <0.05) in serum HI antibody titer at 4 and 5 wk of age.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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In the current study, polysavone had no adverse effects on the performance of broiler chickens, which was consistent with the study of Tong et al. (2004). Previous studies have suggested that alfalfa saponins have adverse effects on the performance of birds (Heywang and Bird, 1954; Anderson, 1957; Heywang et al., 1959; Whitehead et al., 1981) and the adverse effects of saponins have been attributed to depressed feed consumption because of the bitter taste (Cheeke et al., 1983; Milgate and Roberts, 1995). Jenkins and Atwal (1994) found that dietary triterpenoid saponins had adverse effects on the growth and feed consumption of chicks when fed at a level of 0.30% (gypsophila saponins) or higher (quillaja saponins), whereas steroidal saponins (sarsaponins) had no effect up to a level of 0.90%. Therefore, it was concluded that the effects of saponins may depend on the level in the diets and the type of saponin.
Diets containing alfalfa saponins at levels of greater than 0.10% (Anderson, 1957) and 0.15% (Heywang and Bird, 1954) had adverse effects on the performance of broiler chickens. In the current study, the content of saponins in the diet was only 0.003% and may not have been enough to cause bitterness, thereby reducing feed intake and performance, in spite of triterpenoid saponins being present in polysavone. Previously, Heywang et al. (1959) reported a lack of effect of alfalfa meal on performance, which was also found by Kocaoglu et al. (2004), and this may have been due to the less adverse effect of saponins in alfalfa meal compared with extracted alfalfa saponins. Similarly, the saponins in polysavone are different from extracted alfalfa saponins, which may be another cause of the lack of an adverse effect of polysavone on performance.
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ACKNOWLEDGMENTS |
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Received for publication January 19, 2007. Accepted for publication May 19, 2007.
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REFERENCES |
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Cheeke, P. R., J. S. Powley, H. S. Nakaue, and G. H. Arscott. 1983. Feed preference responses of several avian species fed alfalfa meal, high- and low-saponin alfalfa, and quinine sulfate. Can. J. Anim. Sci. 63:707–710.
Chen, H. L., B. T. Li, J. Y. Zhang, D. F. Li, B. Y. Chang, and L. T. Xu. 2002. Research development on the immunomodulatory effect of polysaccharide and its mechanism. Chin. Pharmacol. Bull. 18:249–252.
Dakora, F. D. 1995. Plant flavonoids: Biological molecules for useful exploitation. J. Plant Physiol. 22:87–99.
Guo, F. C., R. P. Kwakkel, B. A. Williams, and H. K. Parmentier. 2004. Effects of mushroom and herb polysaccharides on cellular and humoral immune responses of Eimeria tenella-infected chickens. Poult. Sci. 83:1124–1132.
Heywang, B. W., and H. R. Bird. 1954. The effect of alfalfa saponin on the growth, diet consumption, and efficiency of diet utilization of chicks. Poult. Sci. 34:239–241.[Web of Science]
Heywang, B. W., C. R. Thompson, and A. R. Kemmerer. 1959. Effect of alfalfa saponin on laying chickens. Poult. Sci. 38:968–971.[Web of Science]
Ilsley, S. E., H. M. Miller, and C. Kamel. 2005. Effects of dietary quillaja saponin and curcumin on the performance and immune status of weaned piglets. J. Anim. Sci. 83:82–88.
Jenkins, K. J., and A. S. Atwal. 1994. Effects of dietary saponins on fecal bile acids and neutral sterols, and availability of vitamins A and E in the chick. J. Nutr. Biochem. 5:134–135.[Web of Science]
Jiang, Z. Y., and L. Yu. 2005. Study on the effect of water soluble alfalfa polysaccharides on nutrition and immunity in broiler chickens. Feed Ind. 26:15–16.
Kocaoglu, G. B., K. M. Iscan, F. Uyanik, M. Eren, and A. A. Can. 2004. Effect of alfalfa meal in diets of laying quails on performance, egg quality and some serum parameters. Arch. Anim. Nutr. 58:255–263.[Web of Science][Medline]
Kong, X. F., Y. L. Hu, Y. L. Yin, G. Y. Wu, R. Rui, D. Y. Wang, and C. B. Yang. 2006. Chinese herbal ingredients are effective immune stimulators for chickens infected with the Newcastle disease virus. Poult. Sci. 85:2169–2175.
Malinow, M. R., P. McLaughlin, L. Papworth, C. Stafford, G. O. Kohler, A. L. Livingstone, and P. R. Cheeke. 1977. Effects of alfalfa saponins on intestinal cholesterol absorption in rats. Am. J. Clin. Nutr. 30:2061–2067.
Malinow, M. R., P. McLaughlin, C. Stafford, A. L. Livingston, G. O. Kohler, and P. R. Cheeke. 1979. Comparative effects of alfalfa saponins and alfalfa fiber on cholesterol absorption in rats. Am. J. Clin. Nutr. 32:1810–1812.
Malinow, M. R., P. McLaughlin, C. Stafford, A. L. Livingston, and G. O. Kohler. 1980. Alfalfa saponins and alfalfa seeds. Dietary effects in cholesterol-fed rabbits. Atherosclerosis 37:433–438.[Web of Science][Medline]
Malinow, M. R., W. E. Conner, P. McLaughlin, C. Stafford, D. S. Lin, A. L. Livingston, G. O. Kohler, and W. P. McNulty. 1981. Cholesterol and bile acid balance in Macaca fascicularis effects of alfalfa saponins. J. Clin. Invest. 67:156–162.[Web of Science][Medline]
Matsuki, T., R. Horai, K. Sudo, and Y. Iwakura. 2003. IL-1 plays an important role in lipid metabolism by regulating insulin levels under physiological conditions. J. Exp. Med. 198:877–888.
Milgate, J., and D. C. K. Roberts. 1995. The nutrition and biological significance of saponins. Nutr. Res. 15:1223–1249.[Web of Science]
Nie, W., and Y. X. Zhang. 1999. Progress of the immunomodulating effect of polysaccharides and their mechanisms. Chin. Pharmacol. Bull. 15:484–487.
NRC (National Research Council). 1994. Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC.
Tong, J. M., R. N. Sa, Z. W. Shan, X. M. Zhu, and Q. Zhang. 2004. Effect of polysavone on performance in broiler chickens and weaning pigs. Chin. Anim. Husb. Vet. Med. 31:19–21.
Whitehead, C. C., J. M. McNab, and H. D. Griffin. 1981. The effects of low dietary concentrations of saponin on liver lipid accumulation and performance in laying hens. Br. Poult. Sci. 22:281–288.[Web of Science][Medline]
Zhao, K., J. X. Li, H. H. Zhang, D. S. Guo, B. B. Jia, S. H. Wang, and S. J. Zhang. 2005. Studies on the effect of alfalfa polysaccharide on the immune efficacy of swine fever vaccine. J. Henan Agric. Univ. 39:425–429.
Zhao, W. S., Y. Q. Zhang, and L. J. Run. 1993. Effect of immunoenhancement of polysaccharide from alfalfa. Acta Pharmacol. Sin. 14:273–276.[Web of Science]
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