A Study On The Effectiveness Of Virginiamycin In Broiler Diet

Two experiments were carried out to 1) investigate the effects of virginiamycin on performance,intestinal morphology,cecal microflora,slaughter performance,meat quality, and tissue mineral elements concentrations in broiler;2) to determine the optimal dosage of virginiamycin in the diet,and 3) to study the nutrient-sparing effect of virginiamycin. Exp.1 was to evaluate the effects of virginiamycin,enramycin,and flavamycin on growth performance,nutrient utilization,intestinal morphology,cecal microflora,slaughter performance,meat quality,and tissue mineral elements in broilers.A complete randomized experimental design was used.Two hundred and sixteenl-day-old Arbor Acres broilers were randomly assigned to one of six treatments,each consisting of 6 replicate cages with 6 birds(3 male and 3 female) per cage.The basal diet served as the control group,and the other 5 treatment diets were formulated by adding virginiamycin(5,10,20 mg/kg of diet), enramycin(5 mg/kg of diet from 1d to 21d,3 mg/kg of diet from 22d to 42d) or flavomycin(5 mg/kg of diet) to the basal diet.The average daily gain(ADG) of 1d to 21d and the average daily feed intake(ADFI),ADG of 22d to 42d were significantly(P＜0.10) improved by virginiamycin and enramycin when compared with the control group.The ADG of 22d to 42d was significantly(P＜0.10) improved when the diet supplemented with flavomycin,and the drip loss of pectoral muscle of broilers feeding flavomycin significantly(P＜0.10) lower than that of broilers feeding virginiamycin.The slaughter performance and meat quality were not significantly(P＞0.10) changed by virginiamycin, flavomycin or enramycin when compared with the control group.The apparent utilizations of energy and dry matter were significantly(P＜0.10) improved by virginiamycin and enramycin,but the apparent utilizations of crude protein,calcium,and phosphorus were not significantly(P＞0.10) affected by virginiamycin,enramycin,or flavomycin.Although the weight of intestine was significantly(P＜0.10) reduced by virginiamycin,enramycin, and flavomycin,there were some differences of effects of the antibiotics between the locations of intestine.The numbers of cecal E.coli and Salmonella were significantly (P＜0.10) reduced by antibiotics.The villi height of jejunum,crypt depth of duodenum,and villi height-to-crypt depth ratio of duodenum were significantly(P＜0.10) reduced.The crypt depth of ileum was also significantly(P＜0.10) increased.Exp.2 was conducted to investigate the energy,crude protein,and non-phytate phosphorus sparing effect of virginiamycin supplemented in broiler diet at an optimal level.A complete randomized experimental design was used.Forty hundred and fifty 1-day-old Arbor Acres broilers were randomly assigned to one of five treatments,each consisting of 15 replicate cages with 6 birds(3 male and 3 female) per cage.The dietary treatment including 1) positive control group(feeding basal diet without antibiotics);2) negative control group 1(decreasing the ME,crude protein(CP),and non-phytate phosphorus levels on the basis of basal diet by 104.6 kJ/kg,1 percentage points,and 0.04 percentage points,respectively);3) negative control group 2(decreasing the ME,crude protein(CP),and non-phytate phosphorus levels on the basis of basal diet by 209.2 kJ/kg,2 percentage points,and 0.04 percentage points, respectively);4) negative control group 1 supplemented with virginiamycin at the level of 15 mg/kg of diet;5) negative control group 2 supplemented with virginiamycin at the level of 15 mg/kg of diet.The ADFI and ADG of 1d to 21 and 22d to 49d and ADFI of 22d to 49d were significantly(P＜0.01) reduced by reducing the nutrient levels compared with the control group.The performance of negative control group 1 of 22d to 49d and 1d to 49d had no significant(P＞0.10) differences with the positive control group,and the performances of negative control group 1 supplemented with virginiamycin and positive control group were numerically similar.In conclusion,the growth performance and nutrient utilization were improved by virginiamycin,enramycin,and flavomycin,but the slaughter performance was not affected.There were some differences of effects of virginiamycin,enramycin,and flavomyicn on growth performance,meat quality,and tissue mineral elements concentrations.The suitable dietary level of virginiamycin was 10 mg/kg to 20 mg/kg.There were nutrient spareing effects of virginiamycin.With the addition of virginiamycin 15 mg/kg,the dietary nutrients level could be lowere with ME 104.6 kJ/kg, CP 1 percentage points and non-phytate phosphorus 0.04 percentage points.