BOARD-INVITED REVIEW: Opportunities and challenges in using exogenous enzymes to improve nonruminant animal production

Abstract

Diets fed to nonruminant animals are composed mainly of feed ingredients of plant origin. A variety of antinutritional factors such as phytin, nonstarch polysaccharides, and protease inhibitors may be present in these feed ingredients, which could limit nutrients that may be utilized by animals fed such diets. The primary nutrient utilization-limiting effect of phytin arises from the binding of 6 phosphate groups, thus making the P unavailable to the animal. The negative charges allow for formation of insoluble phytin-metal complexes with many divalent cations. Furthermore, phytin and protein can form binary complexes through electrostatic links of its charged phosphate groups with either the free amino group on AA on proteins or via formation of ternary complexes of phytin, Ca(2+), and protein. The form and extent of de novo formation of binary and ternary complexes of phytin and protein are likely to be important variables that influence the effectiveness of nutrient hydrolysis in plant-based diets. Nonstarch polysacharides reduce effective energy and nutrient utilization by nonruminant animals because of a lack of the enzymes needed for breaking down the complex cell wall structure that encapsulate other nutrients. Enzymes are used in nonruminant animal production to promote growth and efficiency of nutrient utilization and reduce nutrient excretion. The enzymes used include those that target phytin and nonstarch polysaccharides. Phytase improves growth and enhances P utilization, but positive effects on other nutrients are not always observed. Nonstarch polysaccharide-hydrolyzing enzymes are less consistent in their effects on growth and nutrient utilization, although they show promise and it is imperative to closely match both types and amounts of nonstarch polysaccharides with appropriate enzyme for beneficial effects. When used together with phytase, nonstarch polysaccharide-hydrolyzing enzymes may increase the accessibility of phytase to phytin encapsulated in cell walls. The future of enzymes in nonruminant animal production is promising and will likely include an understanding of the role of enzyme supplementation in promoting health as well as how enzymes may modulate gene functions. This review is an attempt to summarize current thinking in this area, provide some clarity in nomenclature and mechanisms, and suggest opportunities for expanded exploitation of this unique biotechnology.

Effects of mannan level and β-mannanase supplementation on growth performance, apparent total tract digestibility and blood metabolites of growing pigs

“…The positive effects of exogenous enzymes are quite variable and seem to depend on physiological status of the pigs and the content of NSP (Ji et al, 2008;Li et al, 2010;Adeola and Cowieson, 2011). Therefore, exogenous enzymes should be selected on the basis of type and amount of the NSP in the pig diets.…”

“…The beneficial effects of the exogenous enzymes depend upon the type of the substrate, physiological status of pigs and the amount of the NSP content in the diet (Ji et al, 2008;Li et al, 2010;Adeola and Cowieson, 2011). Therefore, identification of type and amount of NSP content in pig diets is essential for selection on the exogenous enzyme and dose of dietary supplementation.…”

Animal production for efficient phosphate utilization: from optimized feed to high efficiency livestock

“…It is expected that the continued development of phytase through improved understanding of its ability to breakdown organic P will produce more effective classes of phytases. Commercially, phytase in swine and poultry diets is used at a dose of 500-750 FTU/kg (FTU = the amount of enzyme that liberates 1 mmol inorganic PO 4 per minute from 1.5 mmol/L of sodium phytate at pH 5.5 and 37 8C) [4 ]. Superdosing with up to 12 000 FTU/kg has been tested [4 ,27,32] and in one study with broilers [32], an increase of phytase from 93 to 12 000 FTU/kg increased the phytate-P digestibility from 42 to 95%.…”

“…Phosphorus is an essential macromineral for all animals, which should be supplied in sufficient quantities because it plays a major role in bone development, growth and productivity of livestock. The need to use inorganic P in livestock diet arises because feedstuffs may contain organic P, which may not be fully available for absorption by animals [4 ]. Livestock excrete large amount of P [5] because less than 40% of P consumed may be utilized depending on P availability, efficiency of feed conversion and the amount of P consumed in excess of the animal's requirement [6 ].…”

The effect of serine protease on broiler growth and carcass quality

“…Enzyme supplementation should allow a reduction in CP level in fed but Zanella et al (1999) pointed out that individually amino acids were not improved equally by supplementation and should be balanced. In recent years, proteases have grown in profile, there are currently several stand-alone proteases available, and new mechanisms of action have been proposed (Adeola and Cowieson, 2011). Exogenous serine protease enzymes enhance protein and energy digestibility and thus improve the performance parameters (Fru-Nji et al, 2011).…”