The authors, writing in BioMed Research International, said broiler feed containing both probiotic, Aspergillus awamori and prebiotic, fructooligosaccharide, can boost FCR and weight gain most probably by stimulation of skeletal muscle protein metabolism.
They say some of the reported benefits of Aspergillus probiotic include the reduction of gut pH, production of some digestive enzymes and vitamins and antibacterial substances as well as the stimulation of immune system, and the improvement of calcium absorption.
And fructooligosaccharides have been shown, added the team, to enhance the growth of Bifidobacterium and Lactobacillus but inhibit Escherichia coli and Salmonella in the large intestine.
There have been very few studies conducted on synbiotics - the combination of prebiotic and probiotics – in broilers, said the researchers, who are based at Kafrelsheikh University and the Animal Health Research Institute in Giza.
Their theory was that synbiotics could strategically benefit the birds by improving the survival rate and colonization of the introduced probiotic microorganisms in the gastrointestinal tract as prebiotics provide a readily available substrate for probiotic growth and may promote the metabolism of the beneficial bacteria.
To test this, they evaluated the effects of dietary Aspergillus awamori (AA) and fructooligosaccharide (FOS) separately and in combination (AA + FOS) on growth performance, some blood parameters, and digestibility.
They also investigated the rate of expression of some growth related-genes of broiler chicks as a result of the probiotic and prebiotic inclusion in the diet.
The authors report that the growth hormone secretagogue receptor (GHSR), insulin-like growth factor 1 (IGF1), and insulin-like growth factor 1 receptor (IGF1R) have a significant role in muscles development and growth in such birds.
“Mitchell et al. reported that overexpression of the IGF1 gene in the muscle tissue leads to enhanced muscle growth in chicks. On the other hand, Sun et al. found that GHSR plays an essential role in energy expenditure, food intake, and food conversion rate,” they said.
A total of 60 broiler chicks at 15 days of age were divided into a control group and three different treatment groups.
The control group was fed a basal diet, and the treatment groups were fed the same diet but it was supplemented with 0.05% AA, 0.05% FOS, and a blend of 0.05% AA and 0.05% FOS.
Synbiotics on broiler performance
Results from measurement of growth performance and digestibility revealed a significant increase in the body weight gain with improved feed conversion rate in the treatment groups, particularly in the diets involving the blend of probiotic and prebiotic.
“The combined feeding AA and FOS synergistically promoted the broiler performance. Either feeding AA or FOS tended to increase body weight gain.
And feeding the combination of AA and FOS maximally increased the body weight gain,” found the team.
The researchers said feeding AA, FOS, and AA + FOS improved dry matter digestibility and crude protein utilization, while plasma total cholesterol and low density lipoprotein-cholesterol were decreased, and plasma high density lipoprotein-cholesterol increased.
They found that expressions of the growth hormone secretagogue receptor (GHSR), insulin-like growth factor 1 (IGF-1), and insulin-like growth factor 1 receptor (IGF1R) were higher in the treatment groups.
Promotion of skeletal muscle protein metabolism
The authors note that body weight and breast muscle weight were increased by AA and FOS and the authors say this seems to be due to a growth promoting factor produced by Aspergillus:
“Guobin et al. noted that the IGF1 is one of the main growth factors that stimulate protein synthesis in muscle tissue.
The IGF1 gene exerts anabolic actions on skeletal muscle tissue. Therefore, it is likely that feeding on AA and FOS would have a positive effect on expression of IGF1 and its receptor IGF1R. This indicates the activation of pathways related to the skeletal muscle protein synthesis.”
The scientists say the results support their notion that feeding on AA stimulates skeletal muscle growth through decreasing breakdown of their protein.
They also noted a remarkable high expression level of GHSR after diet supplementation with AA and FOS. “This elevation is therefore likely to be responsible for, or associated with, improved digestibility and food conversion rate.”
They call for additional research to validate this theory.
Publication: BioMed Research International Volume 2014 (2014), Article ID 946859
Title: Integrative Effects of Feeding Aspergillus awamori and fructooligosaccharide on Growth Performance and Digestibility in Broilers: Promotion Muscle Protein Metabolism
Authors: A. A. Saleh, K. Amber, M. A. El-Magd, et al