Effect Of Dietary Antibiotics On The Nutritional Physiology Of Riboflavin In Broilers And Its Mechanism

Four experiments were conducted to evaluate the effect of antibiotics on nutritional physiology of riboflavin in broilers, and to find out its mechanism of biochemistry, histology and microbiology. The results were showed as follows. Experiment 1. Study on antibiotics affecting nutritional physiology of riboflavin in broilers. This Study was to investigate the effect of antibiotics on nutritional physiology of riboflavin in broilers and choose two antibiotics which have significant effect. 420 Arbor Acres were assigned into 7 diets supplemented aureomycin 100mg/kg, virginiamycin 20mg/kg, colistin 20mg/kg, flavomvcin 5mg/kg, olaquindox 50 mg/kg and riboflavin 2.0mg/kg respectively . At the end of 3 weeks, the data of feed intake, weight gain, feed conversion rate and paralysis morbility were analyzed and riboflavin content in liver, blood were tested. The results showed (1) The supplementation of those five antibiotics significantly improved weight gain and feed intake of broilers at day 21 (p<0.05). The supplementation of colistin, olaquindox and flavomycin significantly decreased feed conversion rate (p<0.05). Different antibiotics and riboflavin 2.0mg/kg made no significantly difference on the performance (p<0.OS). (2) The supplementation of different antibiotics decreased paralysis morbility by 29.4%- 50.3%, and that of riboflavin 2.0mg/kg decreased it by 54.0%. (3) The supplementation of aureomycin, colistin, flavomvcin and riboflavin 2.0mg/kg also significantly increased the riboflavin content in liver (j,<0.0S) . But all of them made no effect on that of blood. In viewpoint of performance, the results of colistin and flavomycin were better, but in viewpoint of biochemistry, aureomycin and colistin were better than others. Considering the effect of antibiotics on growth performance of broilers, aureomycin and colistin were chosen to be used in the next experiments. Experiment 2. Effect of different levels of aureomycin and colistin on nutritional physiology of riboflavin in broilers. A total of 840 AA broilers were randomly allotted into 15 dietary 4 treatments by a 5 X 3 factorial design. Experimental diets were formulated to contain 2 levels of each antibiotics(aureomvcin: 50,100mg/kg; colistin: 10,20mg/kg) and 3 levels of riboflavin (0, 4, 8mg/kg). At the end of week 2 and week 5, the data of feed intake, weight gain, feed conversion rate and paralysis morbility were analyzed; the riboflavin content in liver and EGRAC (erythron glutathi one reductase activity coefficient) were tested. The results showed (1) The supplementation of different antibiotics had no significant effect on the performance of 14-day broilers, but both aureotnycin 50mg/kg and colistin 20mg/kg decreased feed conversion rate of broilers at day 35. (2) The supplementation of aureomycin 50mg/kg and colistin 20mg/kg significantly improved the riboflavin content in liver of broilers at day 21 fed diets added 4 mg/kg riboflavin and without addition of riboflavin at day 35. (3) The supplementation of different antibiotics made no effect on EGRAC in broilers aged at day 14 and day 35 (p>0.05). Experiment 3. Effect of different levels of aurcomycin and colistin on the structure of intestinal wall and its relationship with absorption of riboflavin in broilers At the ends of week 3 and week 5, all those broilers fed diets supplemented riboflavin 0~ 4mg/kg were conducted with the structure of intestinal wall. The result...