Abstract
The objective of this study was to investigate the impact of varying levels of synbiotic supplementation on the growth performance and intestinal physiology of broiler chickens. A total of 360-day-old broiler chicks were randomly assigned to six different treatments, with four replicates per treatment and 15 birds per replicate. The control treatment was not supplemented, while the remaining treatments were supplemented with four different levels (0.25, 0.5, 0.75 and 1 g/kg) of synbiotic to the basal diets. The treatments were as follows: (1) control (not any supplement), (2) zinc bacitracin 0.04 g/kg, and (3) the remaining four treatments, which were supplemented with four different levels of synbiotic. On days 10, 24 and 35, the feed remaining and the birds were weighed in order to measure the body weight, weight gain, feed intake and feed conversion ratio. On day 10 and throughout the experimental period, there was a significant increase (P<0.05) in both body weight and weight gain, as well as a significant improvement in feed conversion ratio (FCR) with rising level of synbiotic. The control group exhibited a poorer feed conversion ratio than the other experimental groups (P<0.05). Up to 10 days, there was a significant increase in feed intake in birds on diets supplemented with 0.25 and 0.75 g/kg synbiotic. However, when the data from the 35-day experimental period were analyzed, it was found that the birds that had received 0.75 g/kg of synbiotic had significantly (P<0.05) decreased feed intake compared to the other experimental groups. The relative weight of the internal organs was not affected by the dietary treatments. The carcass yield and breast meat were found to increase significantly (P<0.05) with rising levels of dietary synbiotic. The length of the villi was found to be significantly affected by the treatment, with the villi in birds on diets supplemented with 0.5 g/kg of synbiotic being longer than those in the control group. Significantly, the shortest villi were observed in birds that received the highest supplement level (1 g/kg) of synbiotic. The number of Escherichia coli in the ileum was not affected by the dietary treatments. It can be concluded that synbiotic dietary supplementation exerts beneficial effects on growth output at an early age and during the broiler development cycle. In terms of performance, synbiotics supplementation resulted in an improvement in performance and a positive effect on carcass yield and breast meat production. The current research has demonstrated that the administration of synbiotics at a dosage of 0.75 g/kg exerts beneficial effects on the efficiency and subsequent physiological processes of broilers during the course of their growth.