Effect of feeding Aspergillus niger-fermented Ginkgo biloba-leaves on growth, small intestinal structure and function of broiler chicks

Abstract

Aspergillus niger-fermented Ginkgo biloba leaves (FR) and its comparative effect with non-fermented G. biloba leaves (NF) were investigated on growth performance, small intestinal structure and function of broiler chicks. A total of 300 d-old Arbor Acress broilers were randomly allocated into 5 dietary treatments, which were then denoted as the control group (basal diet), and the NF group (containing 0.35% and 0.7% NF in the starter and grower diets, respectively), FR1, FR2 and FR3 groups containing 0.2%, 0.35% and 0.5% FR in the starter diets and 0.4%, 0.7% and 1.0% FR in the grower diets, respectively. The results showed that, compared with the control and NF groups, reduced (P<0.05) feed/gain ratio of FR2 group and higher (P<0.05) mucosal alkaline phosphatase (AKP) activities in duodenum and jejunum of groups FR2 and FR3 were observed. Villous height of duodenum and jejunum was improved (P<0.05) as increased FR levels, while crypt depth of jejunum was decreased (P<0.05). FR supplementation led to an increase in the protease activities in pancreas, duodenum and jejunum, as well as amylase activity in the duodenum and jejunum (P<0.05 or P<0.01, respectively). In addition, the sodium glucose co-transporter 1 (SGLT1) mRNA level in duodenum was increased in birds fed with FR2 and FR3 diets. Furthermore, birds supplemented with FRs had increased (P<0.05) plasma d-xylose levels. Whereas compared with the control, broilers had lower (P<0.05) serum urea nitrogen (SUN) levels when they were provided with the FR2 and FR3 diets. The present study may indicate that the improved feed efficiency and intestinal functions in the group supplemented with FR are directly connected with physiological mechanisms such as the regulation of the SGLT1 mRNA expression.

Introduction

Over the last decade, the importance of gastrointestinal tract health in broiler chicks has been increasingly recognized due to its contribution to their overall health and performance (Mount-zouris et al., 2007, Rehman et al., 2007a, Rehman et al., 2007b). The use of antibiotics at subtherapeutic levels has been a cornerstone of the poultry industry for the control of subclinical diseases, maintenance of gut health and growth promotion for decades. However, antibiotic use tends to produce antibiotic resistance and residues in animal products. Since 2006, antibiotics have been banned for use as feed additives in the European Union. Probiotics have therefore become important as alternative means for enhancing growth performance and improving intestinal health and function common to poultry (Steiner, 2006). Aspergillus niger is a fungus that has the capacity to produce enzymes such as hemicellulases, hydrolases, pectinases, protease, amylase, lipases, and tannases (Mathivanan et al., 2006, Pinto et al., 2001), and is one of the major probiotic strains applied in broilers (Tannock, 2001).

Natural medicinal products originating from fungi or herbs have been used as feed supplements for centuries in ethnoveterinary medicine (Guo, 2003). Ginkgo biloba L. (Family: Ginkgoaceae) is a traditional herb in China, which has been used in some areas of the world, showing high physiological activities in therapies for inflammations, vascular and cardiac diseases and cancers (Chen et al., 2011, Lu et al., 2006, Puebla-Pérez et al., 2003, Sochocka et al., 2010, Ye et al., 2007). Leaves of G. biloba are well known for its high content of flavonoids. Chemically, the active components of G. biloba leaf are flavonoids (flavone glycosides, primarily composed of quercetin), polysaccharides (polymers of glucose, rhamnose, arabinose, mannose, galactose and xylose) and terpenoids (ginkolides and bilobalides) (Li et al., 2012, van Beek and Montoro, 2009). There were numerous reports in animals indicated that flavonoids posses some beneficial effects (Feng et al., 2011, Jenkins and Atwal, 1995). Most recently, Ginkgo flavonoids attracted much attention for their antimicrobial, neuroprotector, anti-mutational, improved cardiovascular well-being, and anticancer activity (Cao et al., 2002, Ding et al., 2009).

In recent years, fermentation is a useful tool for producing biological materials with health promoting properties and is an optimal way to solve overproduction and stimulate processing use of various fruits and vegetables (Dei et al., 2008, Ng et al., 2011). Studies have demonstrated that fermentation not only alters the original bioactivities of Chinese herbs, resulting in new treatment effects, but also enhances the original treatment efficacy (Lin and Chiang, 2008, Miyake et al., 2005). Probiotics are often used to preserve feed stuffs or ferment feeds with obvious effects such as silage for ruminants and liquid fermented feed applied in pigs for many years (Boguhn et al., 2006, Cumby, 1986), with beneficial effects (Besong et al., 1996). However, there is limited information on the use of fermented feeds in chickens (Feng et al., 2007). China has a large scale production of ginkgo leaves for years, about forty thousand tons every year, and mainly distributes in Jiangsu, Shandong, Sichuan, Zhejiang provinces. In the last few years, large-scale cultivation of ginkgo has been initiated. Therefore, it is important to find out a way to utilize this herbal resource as feed ingredient and unveil its potential economic value in feed industry. To promote processing of ginkgo leaves, we have developed a process for A. niger fermentation wherein the functionality of this resources is preserved and enhanced. Our previous researches confirmed that the use of up to 0.5% (in the starter phase) and 1.0% (in the grower phase) A. niger-fermented-G. biloba leaves (FR) products had a positive influence on growth performance, lipid metabolism, antioxidant capacity, breast meat quality, and fatty acid composition. Dietary total flavonoids and polysaccharides were most likely the key compounds responsible for the health-improving effect of the fermentation products (Cao et al., 2012). Despite these findings, there has been a dearth of information on the possible intestinal protective effect of FR. The aim in this study was to investigate the effect of FR on the growth performance and small intestinal structure and function of broiler chicks, and its comparison with non-fermented (NF) products.