Solid-State Hydrolysis (SSH) Improves the Nutritional Value of Plant Ingredients in the Diet of Mugil cephalus

Abstract

The possibility of improving the nutritional quality of plant byproducts (brewers’ spentgrain and rice bran) through an enzyme treatment was tested in a formulated feed for grey mullet(Mugil cephalus). The enzyme treatment was carried out by Solid-State Hydrolysis (SSH) using acommercial preparation including carbohydrases and phytase. A feed prepared without the treatmentand a commercial feed for carp were used as controls. In a preliminary short-term trial carried out atlaboratory facilities, fish receiving the enzyme-treated feed showed significant improvement in bothFCR and SGR when compared to those obtained with the untreated diet, although both experimentaldiets presented worse values than those obtained with the commercial feed. Different metabolicindicators including higher values of muscle glycogen and plasmatic triglycerides supported thepositive effect of the enzyme treatment on the nutritional condition of the fish over those fed on thediet containing non-treated ingredients. Results of growth and feed efficiency that were obtainedin a second long-term trial developed for 148 days under real production conditions evidenced theequivalence among the experimental and commercial diets and confirmed that enzyme pretreatmentof plant ingredients by SSH may be a useful procedure to improve the nutritive value of highfiber plant byproducts when included in practical diets for this species and others with similarnutritional features.