Effects Of Dietary CS On Growth Performance Of AA Broilers And Approach To The Mechanism

Two experiments were conducted to determine the effects of different dietary cysteamine(CS) on growth performance of AA broilers and discuss the mechanism of CS through determining serum parameters,enzyme activities in duodenal contents and anatomy experiments. In experiment I,A total of 600 AA broilers,1-day-old,were selected and randomly assigned to one of 5 dietary treatments,with three replicates per treatment and 40 broilers per replicate. Birds in different group were fed a basal com-soy-fishmeal diet added 0,60,90,120 and 150 mg/kg CS,respectively. The whole feeding trail was divided into two periods:0-21 days period(phase I ) and 22-42 days period (phase II). The metabolic trail was performed during the feeding trail,serum and duodenal content were collected and analyzed when phase I and II ended. Two broilers (1 male and 1 female) were randomly selected from each treatment and slaughtered to evaluate the damage of CS on viscera in broilers at the end of this trail. A total of 600 AA broilers with 1-day-old were used in experiment II and randomly assigned to 5 dietary treatments,with 3 replicates per treatment and 40 broilers per replicate. During phase I and II,birds in different group were fed a basal corn-soy-fish meal diet supplemented with 0,30,60,90 and 120 mg/kg CS,respectively.The results of feeding trail showed that appropriate dietary CS improved ADG to some extent,but high dosage of supplemental CS suppressed the growth of broilers. In experiment I,from 0 to 2Id,ADG was increased by 4.99% (p<0.05) in broiler chicks administered CS at 60 mg/kg of the diet compared to the control (0 mg/kg). ADG of broiler fed diets added 120 and 150 mg/kg CS were lower than the other treatments (P<0.01). Broilers fed diets added 120mg/kg CShad a lower ADFI than that of the control. Birds in the group received 150 mg/kg CS had a significant lowest ADFI and highest F/G compared to the other groups (PO.01).From 22 to 42d,adding 90 mg/kg CS to the diets improved ADG by 7.82% (p<0.05),compared to the control. The broilers fed diets added 150 mg/kg CS had a significant and lowest ADFI among these treatments (P<0.01).The results from experiment II were the same to the experiment I .From 0-2Id,the ADG of broilers fed diets added 60 mg/kg CS were 6.41% (p<0.05) higher than the control.Supplementing 120 mg/kg CS to the diets depressed the ADG by 12.45% (p<0.01) compared to the control. F/G of broilers fed diets added 120 mg/kg CS was higher than the other treatments.From 22 to 42 d,the ADG of broilers fed diets added 60,and 90 mg/kg CS were 4.65% (p<0.05) and 6.29% (p<0.05) higher than the control,respectively. These results is the same as experiment II.The metabolic trail showed at phase I,the CP utilization(CPU) of broilers fed diets added 60,90 and 120 mg/kg CS were higher than the control respectively. The broilers fed diets added 150 mg/kg CS had the lowest CPU compared to the other treatments (P<0.01). At phase II,adding 60,90and 120 mg/kg CS to the basal diets increased CPU by 1.98% (p>0.05 ) 2.35% (p>0.05) and 1.25% (p>0.05 ) compared to the control,respectively. The broilers fed diets added 150 mg/kg CS had the lowest CPU compared to the other treatments (PO.05).The results from anatomy trail indicated that with increasing dosage of supplemental CS the broilers had a significant increased incidence of damage in viscera. With increasing dosage of supplemental CS,there was a high incidence of liver hyperemia,hemorrhage or intumescences;the duodenum and jejunum hyperemia or hemorrhage;splenic organ incumescence;muscular stomach and glandular stomach ulcer.The datum obtained from serum analysis showed that addition of the CS at 60 mg/kg of the diet increased the level of GLU,GPT,TG,and AKP (P>0.05) and decreased the content of SUN in serum (P>0.05) compared to the control. Addition of the CS at 60 and 90 mg/kg of the diet increased the TP content by 59.58% (p<0.05) and 38.26% (p<0.05) compared to the control,respectively. Addition of the CS at 150 mg/kg of the diet decreased serum TP...