JWSS - Journal of Water and Soil Science

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This experiment was conducted to compare the effect of probiotic thepax^® in diets with different quantities of protein on the performance of Cobb-500 broiler chickens and their serum antibody level against Newcastle disease vaccine (NDV). Two basal diets were formulated based on NRC (1994) recommendations which had NRC (sufficient protein diet) and 90% NRC (low protein diet) for protein. The basal diets were then supplemented with 0 and 0.1% probiotic, resulting in a 2×2 factorial arrangement with 2 levels of probiotic (0 and 0.1%) and 2 levels of protein (NRC and 90% NRC). Each of the 4 dietary treatments was fed to six replicate groups of 20 chicks. The results of experiment showed broilers fed low protein diet without supplementation of probiotic had lower performance than other treatments. Supplementing low protein diet with 0.1% probiotic significantly improved body weight gain and feed conversion ratio, as did those which were fed diets with sufficient quantities of protein. Reducing dietary protein level increased abdominal fat content, but had no significant effect on other carcass composition. Supplementing of probiotic significantly reduced abdominal fat percentage (P<0.05). The utilization of probiotic in low protein diet resulted in increasing serum antibody level against NDV, but sufficient protein diet produced no such effect. Also, the results of experiment indicated that probiotic added to low protein diet improved broilers performance and immune response. However, these effects were not observed in adding probiotic to diet with sufficient quantity of protein.

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This experiment was conducted in a completely randomized design with five treatments and four replications. There were 15 chicks in each replication during the first 30 days and 10 chicks from day 30 to the end of experiment. Diets were control (without probiotic and dry whey) and levels 500 and 750 gm/ton probiotic, and each level contained two diets with and without %2 dry whey. Daily weight gain, feed intake, feed conversion rate at the end of each experiment and carcass characteristics including weights of neck, Liver, wing, heart, and abdominal fat on the 49th day of experiment were measured. Chicks which received diets with 500 and 750 mg/ton probiotic +%2 dry whey were significantly heavier than other chicks (p<0/05) between 0-21 days. Feed intake significantly increased during 3 periods including 0-21, 21-42, and 42-49 days of experiment, when chicks used diets with dry whey, especially diets containing 750 gm/ton probiotic (P<0/05). Blood plasma cholesterol significantly decreased when chicks used diets with dry whey. Also an increase in white cells was observed in days 21 and 35. Treatments did not have any significant effect on feed conversion rate, mortality and carcass characteristics (P>0/05).

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The present experiment was carried out to determine the effect of feeding a diluted diet together with avilamycin or probiotics on catch-up growth of broiler chickens. Three hundred day-old chicks (Ross 308 hybrid) were assigned to 4 treatments with 5 replicates based on a completely randomized design. The control group, which met NRC requirements, fed a diet consisting of 2900 KCal/kg ME and 20.8%CP. A diluted diet included 2700 KCal/kg ME and 19.4%CP fed to the negative control group during 7 to 21 days of age. There were two additional treatments with 10ppm avilamycin and 100ppm probiotic, respectively. Feeding the diluted diet resulted in reduced body weight gain (P<0.05). Final body weight was higher in chickens having received avilamycin. Although this difference was insignificant compared with the control, it was significant in comparison with other groups. There was no significant difference in terms of feed intake among the treatments. However, birds which received avilamycin had superior feed conversion ratio to other groups. Birds in the control group had the highest abdominal fat content but the difference was not significant. In conclusion, avilamycin significantly increased body weight gain during catch-up growth though the probiotic caused no significant change.