| Purpose:In this experiment, the effects of microencapsulated preparation essential oils and organic acids on growth performance of broilers were studied and mechanisms of which were explored to clarify the theoretical foundation of microencapsulated essential oils and organic acids being used as functional feed additive in broiler.Method:Three hundred physical health one-day-old broilers were randomly divided into 5 treatment groups.5 replicates were performed in each group, and 12 broilers were in each replicate. The Group I (control group Ⅰ)was fed the basal diet. The Group II (control group II) was fed with the basal diet added 30 mg/kg of zinc bacitracin and 6 mg/kg of colistin sulfate. The Group III, Ⅳ, V (experimental group III, Ⅳ, Ⅴ) were fed with the basic diet added with 150mg/kg, 200mg/kg and 250mg/kg of microencapsulated preparation essential oils and organic acids. Duration of the trial was 70d and was divided into initial stage (1-21 days), mid stage (22-42 days) and late stage (43-70 days). Slaughter tests were carried out at twenty-first and seventieth days. Growth performance, slaughter performance and muscle quality, serum biochemical parameters, immune organ index, intestinal morphological structure and mucosal immune function, duodenal digestive enzyme activity, gastrointestinal contents pH, intestinal flora and fecal components in the five groups were all determined and analysed.Results:1 Growth performanceIn initial stage, average daily gain and average body weight gain in group II were significantly higher than that in group I (P＜0.05), and there were no significant differences among the group III, IV, V (P>0.05). Feed/gain ratio in group Ⅳ was lowest, and significantly lower than group 1 (P＜0.05), but there were no significant differences among the group II, III, IV, V (P>0.05). The broiler average daily feed intake and survival among all groups were not significant difference (P>0.05). In 22 to 70 days,all the indexes were not significant differences(P>0.05).In whole stage, the feed/gain ratio in group IV was significant lower than in group I (P＜0.05), and no significant differences (P>0.05) were observed among group II, III, IV, V. The broiler average daily feed intake, average daily gain and average body weight gain and survival among all groups were not significant difference (P>0.05).2 Slaughter performance and Muscle qualitySlaughter rate, eviscerated rate, eviscerated yield and abdominal fat percentage of each group was not significant difference (P>0.05), but the breast muscle and leg muscle rates of group IV was significantly higher than group I (P＜0.05), among other groups were not significantly different (P>0.05). The breast muscle ph45min and ph24h of group III was significantly higher than group I (P＜0.05). The water loss rate of group IV was the lowest and significantly lower than group I (P＜0.01). The leg muscle crude protein content of group III was significantly higher than group I and II (P＜0.05).3 Blood biochemical parametersIn initial stage, the uric acid (UA) content of group V was significantly lower than group I (P＜0.05), among other groups there were no significantly different (P>0.05). The content of albumin (ALB) and total protein (TP) in the serum of five groups were no significant difference (P>0.05). In late stage, total protein (TP) content was significantly higher in group II and IV than in group I (P＜0.05). The uric acid (UA) content of group IV was significantly lower than that of group I (P＜0.05).4 Immune organ indexIn initial stage, spleen index in group IV and V was significantly higher than that in group I (P＜0.05). In whole stage, the spleen index of group IV was significantly higher than that of group I (P＜0.05). But there were no significant differences of thymus and bursa index among five groups (P>0.05).5 Intestinal morphology and mucosal immune functionIn initial stage, duodenum and ileum villus height of group IV was significantly higher than that of group I (P＜0.05). The duodenum and jejunum crypt depth of group II and IV was significantly lower than that of group I (P＜0.05), the duodenum V/C of group II was significantly higher than group I (P<0.05), the jejunum V/C of group Ⅱ and IV was significantly higher than group I (P＜0.05). Duodenal mucosa protein sIgA content of group II was significantly higher than that of group I (P＜0.05). Duodenum, jejunum and ileum mast cell amount of group IV were all significantly lower than that of group I (P＜0.05, P＜0.01 respectively).In late stage, the duodenal’s villus height and V/C,ileum’s villus height and V/C of group IV was significantly higher than group I (P＜0.05). The duodenal mucosa protein slgA content of group IV and V was significantly higher than group I (P＜0.05, P＜0.01 respectively). The duodenum mast cell amount of group Ⅱ、 Ⅲ、 Ⅳ and V were great significantly lower than group I (P<0.01). Jejunum mast cell amount of group IV were great significantly lower than group I、 III(P＜0.01). Ileum mast cells amount of group Ⅳ were great significantly lower than group I, Ⅱand Ⅴ(P＜0.01).6 Digestive enzyme activity of duodenumIn initial stage, the amylase and chymotrypsin activity of group III was significantly higher than that of group I (P<0.05). In late stage, the amylase and chymotrypsin activity of group IV was significantly higher than that of group I (P＜0.05).7 Gastrointestinal contents pHIn initial stage, the duodenal contents pH value of group IV was significantly lower than group I (P＜0.05). The jejunum and ileum contents pH values were not significantly different among all groups (P>0.05). In late stage, the duodenal contents pH value of group IV was significantly lower than group I (P＜0.05).The jejunum content pH value of group V was significantly lower than group I (P＜0.05).The ileum content pH value was not significant difference among all groups (P> 0.05).8 Cecum microfloraIn initial stage, escherichia coli and salmonella of group IV, V was significant and great significantly lower than group I (P<0.05, P<0.01 respectively). Lactobacillus was not significant differences among all groups (P>0.05). In late stage, salmonella and escherichia coli in cecal of group IV was significant and great significantly lower than group I (P<0.05, P<0.01 respectively). Lactobacillus of the group IV was significantly higher than group I (P＜0.05).9 Nitrogen and phosphorus in fecesIn initial stage, fecal nitrogen and phosphorus content of group V was significantly lower than group I (P<0.05). Fecal nitrogen content of group IV was significantly lower than group I at the56th day (P<0.05), and there were no remarkable difference of fecal phosphorus content among other groups (P>0.05).Conclusion:1. The Microencapsulated preparation essential oils and organic acids added to feed can improve the growth and slaughter performance of broilers.2. The certain amount of Microencapsulated preparation essential oils and organic acids in broiler feed can improve meat quality and serum biochemical indices, immune function and digestive enzyme activity, can reduce faecal nitrogen and phosphorus content, and improve the intestinal tissue structure and promote intestinal micro ecological balance.3. The optimized amount of microencapsulated essential oils and organic acids as an additive in broiler feed is 200mg/kg. |
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