| Ball milling and jet milling xylooligosaccharides(XOS) were acquired by processing regular XOS with superfine comminution technology, and then the experiment was conducted to study the effects of XOS with different particle size on bacterial proliferation in vitro and growth performance, intestinal microflora, antioxidant capacity and humoral immunity of broilers. The study includes four parts and the results are presented as follows:Trial1:the aim of this experiment was to determine the antibacterial function of XOS with different particle size in vitro. Activated E.coil, Salmonella and Lactobacillus strains were inoculated into culture tubes with liquid mediums (LB, TSB, MRS) which contained50,100,200,400and800mg/kg of regular, ball milling and jet milling XOS, and the results were presented as antibacterial rate (%). The results showed that jet malling XOS group(JGX) had a significantly higher antibacterial rate of E.coli than that of regular XOS group(RGX) and ball milling XOS group(BGX, P<0.05). About Salmonella antibacterial rate, the effects of JGX was better than RGX (P<0.05) and BGX (P>0.05). The antibacterial rate of E.coli had no significant difference between the dosage of100and200mg/kg (P>0.05), but they were significantly increased compared with the level of50mg/kg (P<0.05); XOS at800mg/kg resulted in the highest antibacterial rate of Salmonella (P<0.01); as for200and400mg/kg, there were no significantly differences compared with each other (P>0.05), and were higher than the antibacterial rate of50mg/kg (P<0.01). XOS with different particle size showed inhibitory effects on Lactobacillus, and the particle size or dosage effects irregularly fluctuated.Trial2:this experiment was conducted to study the effects of XOS with different particle size on performance, cecal flora, volatile fatty acid (VFA) and intestinal pH of AA broilers. A total of480one-day-old AA broilers were randomly allocated to the control group(CG) and three test groups with8replicates of8broilers each. Broilers of control group were fed a basal diet, and the test groups were fed the basal diet supplemented with100mg/kg regular XOS(regular XOS group, RGX), ball milling XOS (ball milling XOS group, BMX), jet milling XOS (jet milling XOS group, JMX) respectively. The results showed that21-d body weight (BW) and average daily gain (ADG) in1-21d of RGX was significantly lower than that of CG (P<0.05). Meanwhile, BMX and JMX enhanced the21-d BW and ADG (P>0.05). In22-42d, JMX got the best growth performance that advanced42-d BW by1.52%and decreased feed conversion ratio (FCR) by2.08%(P>0.05). As for1-42d, JMX decreased FCR by3.24%(P<0.05). At21and42d, test groups advanced cacel Lactobacillus counts and decreased E.coil and Salmonella counts. At the same time, test groups increased the content of total volatile fatty acid (TVFA) and butyrate proportion, while decreased acetate proportion. JMX significantly increased the counts of Lactobacillus in cacel at21d (P<0.05); At42d, BMX incresed the content of TVFA significantly (P<0.05) and decreased acetate proportion (P<0.01), at the same time, JMX decreased the acetate proportion (P<0.05), and about propionate proportion, BMX and JMX had the similar increasing pattern (P<0.01). All test groups reduced the pH in intestinal at differente age except for RGX at42d (P>0.05).Trial3:the aim of this experiment was to study the effects of XOS with different particle size on immune organ index, antioxidant and immune function in serum and mucosa of broilers. Treatments were the same as in Trial2. The results showed that test groups incresed immune organ index except the spleen index of RGX which was slightly decresed at21d (P>0.05). At42d, the thymus index of RGX slightly decreased and was lower than that of JMX (P<0.05). XOS decresed serum H2O2and MDA content at21and42d, meanwhile incresed the T-SOD, CAT activity in jejunal and ileal mucosa (P>0.05). In serum of broilers at21d, RGX significantly increased IgA content (P<0.05), which was higher than that of BMX (P<0.01); At the same time, serum SIgA content of BMX was higher than other groups (P<0.01), while IgA content was lower than that of JMX (P<0.05). At42d, serum IgA content of RGX and JMX were higher than that of BMX (P<0.01). While serum SIgA content of all test groups were lower than that of control group, especially for RGX and JMX which was significantly decreased effect(P<0.01). Test groups contin different particle size XOS increased serum SA content at21and42d. All XOS groups increased the mucosal immune function except BMG, which slightly decreased IgA and SIgA content in jejunal mucosa and SA content in ileal mucosa (P>0.05). At42d, JMX had the hightest IgA, SIgA and SA content of jejunal and ileal mucosa among all the test group.Trial4:this experiment was conducted to study the effects of regular and jet milling XOS on performance of broilers. A total of336one-day-old AA broilers were randomly allocated to the control group and six test groups with6replicates of8broilers each. Broilers of control group were fed a basal diet, and the test groups were fed the basal diet supplemented with50,75,100mg/kg regular XOS(regular â… , regular â…¡, regularâ…¢) and jet milling XOS (jet milling â… , jet milling â…¡, jet millingâ…¢), respectively. The results showed that regular and jet milling XOS had no significant effects on ADG, ADFI and BW of AA broilers (P>0.05), though jet milling I was better than oters. Jet millingâ…¢ significantly increased the FCR at1-41d (P<0.05). |
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