Significant effect of NSP‐ase enzyme supplementation in sunflower meal‐based diet on the growth and nutrient digestibility in broilers

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The non‐feed additives as part of the poultry diets have been extensively studied. They are not important for the biological functions of the birds but are reported to exert positive effect on growth, health and immunity of the animals. These non‐feed additives include antibiotics, prebiotics, probiotics, enzymes and coccidiostats (Saegusa et al., 2004). Soya bean meal (SBM) has been the main protein ingredient in poultry diets as its nutritional value is understood globally. The poultry feed‐manufacturing industry is not finding any alternative to the high‐quality SBM which seems to be the ultimate protein ingredient for meat‐type birds. The indigenous protein ingredients such as oilseed meals have been proposed to substitute SBM but have not been thoroughly investigated. Among these, sunflower meal (SFM) has been a promising vegetable protein source. Sunflower (Helianthus annuus) is a relatively inexpensive source of protein. When the extraction of oil from seeds of sunflower is undertaken, SFM is obtained as a by‐product. Its use in poultry feed as a source of protein is constrained due to high fibre (Villamide and San Juan, 1998; Senkoylu and Dale, 2006) that can partially be reduced through the decortication process (Niazi et al., 1991; McDonald et al., 2011; Alagawany et al., 2015). Crude protein content of SFM has an inverse relation with its crude fibre contents (14–32%) (Mushtaq et al., 2006).
The digestion of nutrients (sugars, proteins and fats) mainly takes place through endogenous enzymes secreted by the gastrointestinal tract of birds. However, non‐starch polysaccharides (NSPs) that include cellulose, β‐glucans, arabinoxylans and pectins (Dalibard and Geraert, 2004) make up a substantial proportion of the poultry feed and are not digested by the endogenous enzyme system of the bird (Lee et al., 2003) unless supplemented with exogenous NSP‐ase.
The presence of NSPs in the diet has been reported to increase intestinal viscosity of the broilers (Burnett, 1966; Almirall et al., 1995; Austin et al., 1999; Naqvi and Nadeem, 2004) that results in reduced enzymes–substrate interaction (Danicke et al., 2000) leading to compromised nutrient breakdown. Disruption of cell matrix of SFM can be achieved by the addition of exogenous enzymes leading to easy access to the entrapped proteins (Choct and Kocher, 2000). Supplementation of exogenous enzymes to improve performance of birds has been extensively studied and reviewed (Selle et al., 2000; Acamovic, 2001; Cowieson and Adeola, 2005). Adding NSP‐ase enzyme in sunflower–corn‐based diet in broiler chicks has been reported to improve weight gain, FCR and digestibility (Khan et al., 2006). Glamocic et al. (2011) reported that supplementation of exogenous enzyme (Roxazyme) with different levels of ME and SFM in broiler chicks increased the digestibility of CP, NDF, hemicellulose and ash, but the effects were most evident in diets with the reduced level of ME. A commercial multienzyme product (Zympex 008®) is reported to contain α‐galactosidase, β‐glucanase, amylase, xylanase, β‐mannanase, protease and cellulose. A project was envisaged to evaluate this NSP‐ase in sunflower meal‐based diets using broiler for 42 days of trial. The response of birds in terms of growth, FCR, carcass characteristics and nutrient digestibility was examined.
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