Fermented soy products gaining 
popularity in poultry diets

Fermented soybean meal (FSBM) is a product obtained by fermentation of conventional soybean meal (SBM) in the presence of fungal and bacterial strains (Aspergillus oryzae and Lactobacillus subtilis, respectively). Several studies (Zhi-yong et al., 2012; Yuan et al., 2012; Hong et al., 2004; Hirabayashi et al., 1998) have reported the benefit of FSBM supplementation by confirming the degradation of soybean allergens in feed-grade soybean meal during fermentation by microbial proteolytic enzymes.

Availability of Phosphorous

Apart from eliminating anti-nutritive compounds like trypsin inhibitor, oligosaccharides and phytate (Chen et al., 2010; Hong et al., 2004), the bioavailability of phosphorous in FSBM is expected to be greater than in conventional SBM (Ilyas et al., 1995). The beneficial effects of using FSBM as poultry feed have been assessed by a number of studies. Hirabayashi et al. (1998) investigated phosphorus (P) excretion in chicks fed with a FSBM-based diet. For four weeks, they fed chicks with control SBM-based diet (TP= 5.2 g/kg; non-phytate P = 2.3 g/kg), a control SBM-based diet with added inorganic P (TP =7.1 g/kg; nonphytate P= 4.0 g/kg) and finally a FSBM-based diet without supplemental inorganic P (TP = 5.8 g/kg; nonphytate P = 3.9 g/kg). The control group exhibited a lower body weight gain, lesser amount of retained phosphorus and femoral phosphorus content than in the P-supplied and the fermented soybean meal group, while the latter two groups showed similarity in body weight gain and femoral phosphorus content. As expected, the phosphorous excretion was markedly more in the P-supplied group and as a result, the percentage retention (intake) was lower, in comparison with the FSBM-fed group.

Effect on feed conversion

Mathivanan et al (2006) fed 200 day-old Vencobb broilers with FSBM (fermented with Aspergillus niger) supplemented in broiler diet at 0.5, 1 and 1.5 % for six weeks and compared with control diet and diet supplemented with commercially available fungal hemicellulases, hydrolases, pectinolytic and lipolytic enzymes. The result showed that there was no difference in body weight for treatments up to four weeks of age. However, it was significantly higher than control at 5^th and 6^th weeks for 0.5 % FSBM-fed group. During 3^rd and 4^th weeks, 0.5 % FSBM-fed group recorded better feed conversion ratio than other groups. The pH of intestinal content was significantly lower while the ileum villi length and width was significantly higher in 0.5 and 1% FSBM as compared to control. The activities of digestive enzymes did not differ significantly between treatments, except lipase activity where it was significantly higher in 0.5 and 1% FSBM-fed group. They concluded that FSBM could be supplemented in broiler diet at 0.5%, eliminating the need for expensive microbial enzyme supplementation to improve the nutrient utilisation and production performance of broilers.

Chicks fed a diet with FSBM had higher daily gain

Feng et al. (2007) compared the effects of FSBM (fermented with Aspergillus oryzae) and SBM on growth performance in broilers. They used one-day-old broiler chicks for a six-week feeding trial. Results indicated that chicks fed a diet with FSBM had a greater average daily gain, average daily feed intake than chicks with soybean meal in both periods, but feed conversion improved only in the growing period. Phosphorus and IgM content in serum of FSBM-fed group also improved although IgA level increased only in the growing period, while urea nitrogen content of serum reduced dramatically. All these findings establish FSBM as a better alternative compared to SBM as a protein source in poultry feed.

Different FSBM-based products on market for poultry feed

Commercially available FSBM-based products are regularly evaluated for their applicability as poultry feed. Among the leading products, PepSoyGen (Nutraferma, USA) is frequently used in for poultry feed (Silva et al., 2014). The manufacturer claims that the fermentation process increases the protein content while significantly reduces most of the anti-nutritional factors traditionally found in soy. The finished product thus contains not only beneficial microbes such as Aspergillus oryzae and Bacillus subtilis but also valuable metabolites. Bio-Pro 480, ESP 500 and ESP 430 (Evershining Ingredient, Thailand) are produced through fermentation to break down antigens (allergens) which are contained in soy. The fermentation of de-hulled soybean meal is achieved by Lactobacillus acidophilus to produce these products. P 3 Dash (PIC BIO, Japan) is a protein feed produced from FSBM by utilising solid state fermentation using Bacillus subtilis and enzyme (protease) as catalyst. The manufacturer claims an increase in livability and average hatchability in poultry birds. DaBomb-P (DaBomb Protein, Taiwan) is another product using Lactobacillus acidophilus to hydrolyse soy antigenic proteins thereby reducing health problems arising from immunogenicity of SBM-based diet. AgroKorn from Denmark has developed AlphaSoy for all animal species, claiming the soy protein has been processed in such a way (and enriched with enzymes) that it is particularly good for young chickens, due to its improved digestibility.

FSBM-based products as livestock feed gaining popularity

As can be understood in terms of increase in daily feed intake, daily gain, IgM content in serum and phosphorous bioavailability, FSBM-based products are gaining increasing popularity as feed for livestock worldwide for its source of vegetal protein. Apart from these factors, decreases in phosphorus excretion and pH of intestinal content also significantly improve health and growth potentials causing an increase in the acceptability of such products. However, the efficacy and reliability of fermented soybean meal-based feed need to be thoroughly evaluated in a variety of animals, both young and adult, in order to fully realise the potential of this feed.

References are available on request.

This article was featured in AllAboutFeed magazine no. 3, 2015 – to read more published articles go to AllAboutFeed digital magazine.