Environmental assessment of Ronozyme<Superscript>®</Superscript> P5000 CT phytase as an alternative to inorganic phosphate supplementation to pig feed used in intensive pig production

Goal, Scope and Background

Ronozyme^® P5000 CT is an industrially produced enzyme product (phytase) which is able to degrade naturally occurring phytate in animal feed and release the phytate’s content of phosphorus for pig’s growth. Ronozyme P5000 CT (hereafter called Ronozyme Phytase) can be used as an alternative to inorganic phosphorus supplementation to feed and the study addresses the environmental implications of substituting inorganic phosphorus with Ronozyme Phytase in intensive pig production in Denmark.

Methods

Life cycle assessment is used as an analytical tool, and modelling of the two considered systems is facilitated in SimaPro 6.0 software. The study addresses changes induced by switching from the one alternative to the other, and all significant processes influenced by the change are included in the study.

Results and Conclusions

Application of Ronozyme Phytase in intensive pig production is justified by major advantages in terms of avoided contributions to global warming, acidification, photochemical ozone formation and particularly nutrient enrichment and by significant energy savings and particularly phosphate savings. A single trade-off in terms of agricultural land use for enzyme production is small and unimportant unless use of agricultural land is given very large relative weight.

Recommendations and Perspectives

Hundreds of enzyme products are commercially available on the market today, each with a range of different applications. There are several indications that enzymes like Ronozyme Phytase can play an important role in a transition to a more sustainable society, and more focus should be addressed to the evolving enzyme technology in environmental research.

     

Implications of high animal by-product feed inputs in life cycle assessments of farmed Atlantic salmon

Purpose

Animal by-products may be increasingly relied upon to satisfy nutritional requirements of salmonids and other fed aquaculture species as demand for fish meal outpaces supply. Previous studies of aquaculture supply chains have included either no animal by-product inputs or small inputs of poultry by-products. Australian Atlantic salmon production includes high use of feed inputs derived from poultry and mammalian by-products and provides a case study to explore the environmental implications and methodological challenges associated with these inputs.

Methods

Life cycle assessment was carried out on a vertically integrated salmon production system in Tasmania, representing approximately 40% of Australian Atlantic salmon production. The system included feed production, smolt/juvenile production, farm grow-out, processing and packaging, and distribution of head-on gutted salmon to market. Impacts from animal production were allocated to by-products on a gross chemical energy basis. Scenario analyses were conducted to determine the extent to which changes in feed conversion ratio, feed composition, and other variables affect results. Sensitivity analysis was carried out on the allocation method for fishery and animal by-products.

Results and discussion

Environmental impacts associated with Tasmanian salmon fed high quantities of animal by-products were markedly higher than those of previously assessed systems. All impacts were driven by feed production with the exception of eutrophication potential, which was driven equally by feed production and nutrient loss during grow-out. Animal by-products accounted for the majority of all impacts from feed production. Adopting a feed composition without animal by-products would result in dramatic improvements, including a 70% decrease in greenhouse gas emissions. Allocation choice had a clear effect on results, with biophysical allocation methods placing much more burden from animal production on fed systems than economic or no-impact allocation methods.

Conclusions

The use of animal by-product inputs in aquaculture feeds has a substantial effect on the environmental profile of farmed salmon products. The magnitude of this effect is dependent on the allocation method chosen for the treatment of products and by-products in upstream systems. The high impact of such systems recognizes the environmental cost of future aquaculture production that may rely more on intensive and high-impact animal production inputs as more efficient fishery inputs become increasingly limited relative to demand.

     

Environmental assessment of yield improvements obtained by the use of the enzyme phospholipase in mozzarella cheese production

Background, aim and scope  Phospholipase is an enzyme which is able to increase the yield of cheese in, for instance, mozzarella production. Milk production is the most important source of environmental impacts in cheese production and it is obvious to assume that the milk saving that comes with the use of phospholipase reduces the overall environmental impacts of the final product. Production of industrial phospholipase is, however, also associated with environmental burdens and it is not known whether and to what extent the use of phospholipase is justified by overall environmental improvements. The aim of the present study is therefore to assess the environmental impacts that come with the use of industrial phospholipase in mozzarella production and compare with the savings that come with the avoided milk production. The study addresses mozzarella production in Denmark. Methods  LCA is used as analytical tool and environmental modelling is facilitated in SimaPro 7.1.8 LCA software. Yield improvements refer to full scale industrial application of phospholipase in cheese industry. The study is a comparative analysis and a marginal and market-oriented approach is taken. The study addresses contribution to global warming, acidification, nutrient enrichment, photochemical smog formation, energy consumption and use of agricultural land. Estimation of environmental impact potentials is based on Eco-indicator 95 v.2.1 equivalency factors. Toxicity is addressed by qualitative means. Results  The environmental impacts induced by phospholipase production are small compared with the savings obtained by reduced milk consumption for mozzarella production when all impact indicators are considered. Sensitivity analyses and data quality assessments indicate that this general outcome of the study is robust, although results at the more detailed level are the subject of much variation and uncertainty. Discussion  Transport of the enzyme from producer to mozzarella producer is insignificant and the general outcome of the study is considered applicable to other regions of the world where milk is produced in modern milk production systems. Conclusions  Use of phospholipase as a yield improvement factor is a means of reducing environmental impact of mozzarella production. Recommendations and perspectives  The total annual global warming mitigation potential of phospholipase used in production of mozzarella and other pasta filata products is in the order of 7 × 10⁸ kg CO₂ equivalents. The use of phospholipase is driven by overall cost savings and it is therefore recommended that the enzyme should be given attention as a cost-efficient means of reducing greenhouse gas emissions.     

Cradle-to-gate environmental assessment of enzyme products produced industrially in denmark by novozymes A/S

Goal, Scope and Background  

Enzymes are biological catalysts with an enormous capacity to increase the speed of a huge variety biochemical reactions. Industrially produced enzymes are used in a broad variety of sectors to increase quality, speed and yield of processes, and reduce energy consumption and use of hazardous chemicals. The present paper provides a methodological framework for analysing environmental impacts of enzyme products and environmental data for five characteristic enzyme products.     

A new process for simultaneous production of tannase and phytase by <Emphasis Type="Italic">Paecilomyces variotii</Emphasis> in solid-state fermentation of orange pomace

The production of enzymes such as tannases and phytases by solid-state fermentation and their use in animal feed have become a subject of great interest. In the present work, Paecilomyces variotii was used to produce tannase and phytase simultaneously. Solid-state fermentation, a process initially designed for tannase production, was implemented here using orange pomace as substrate. Orange pomace is the waste product of the large orange juice industry in Brazil, and it has also been used as an ingredient in animal feed. In addition to enzymatic production, biotransformation of the phenolic content and antioxidant capacity of the orange pomace were analyzed after fermentation. Fermentation conditions, namely moisture level and tannic acid concentration rate, were studied using CCD methodology. The response surface obtained indicated that the highest tannase activity was 5,000 U/gds after 96 h at 59% (v/w) and 3% (w/w) and that of phytase was 350 U/gds after 72 h at 66% (v/w) and 5.8% (w/w) of moisture level and tannic acid concentration, respectively. The amount of tannase production was similar to the levels achieved in previous studies, but this was accomplished with a 7% (w/w) reduction in the amount of supplemental tannic acid required. These results are the first to show that P. variotii is capable of producing phytase at significant levels. Moreover, the antioxidant capacity of orange pomace when tested against the free radical ABTS was increased by approximately tenfold as a result of the fermentation process.     

Sustainability assessment of salmonid feed using energy,classical exergy and eco-exergy analysis

Reduction of the environmental impact of feed products is of paramount importance for salmon farming. This article explores the potential to compare three thermodynamically based ecological indicators. The environmental impact of partial replacement of fish meal (FM) and fish oil with alternative ingredients was investigated using energy, classical exergy and eco-exergy analysis. Seven hypothetical feeds were formulated: one with high levels of FM and fish oil, four feeds based on plant ingredients, one containing krill meal, and one based on algae-derived products. Analysis included cultivation of crops and algae, fishing for fish and krill, industrial processing of these ingredients and production of complete fish feed. Because most harvested products are refined in multiple product outputs that have good value to society, two scenarios were compared. In the base case scenario, no allocation of co-products was used and all the environmental costs were ascribed to one specific co-product. Co-product allocation by mass was used in the second scenario; this is considered to be the preferred scenario because it accurately reflects the individual contributions of the co-products to the environmental impact of the feed products. For this scenario, the total energy consumption for a fish-based diet was 14,500 MJ, which was similar to a krill diet (15,600 MJ), about 15–31% higher than plant-based diets, and 9% higher than an algae diet. Substituting FM and fish oil with alternative ingredients resulted in minor changes in total classical exergy degradation (2–16% difference). The calculations based on energy only consider the energy conservation based on the First Law of Thermodynamics, whereas those based on classical exergy also takes the Second Law of Thermodynamics into account; energy that can do work is distinguished from energy that is lost as heat to the environment. The calculations based on eco-exergy consider the total loss of work energy in the environment including the work energy associated with the information embodied in the genomes of organisms. The diet based on fishery-derived ingredients was the highest total work energy consumer compared with plant-based diets (24–30% greater), the diet containing krill meal (25% greater), and the algae diet (four times higher). Thus, reducing FM and fish oil levels in fish feed can contribute significantly to more sustainable aquaculture. In particular, algae-derived products in aquafeeds could drastically decrease environmental costs in the future.     

Life cycle emissions and energy study of biodiesel derived from waste cooking oil and diesel in Singapore

Background, aim and scope  

Biodiesel derived from Waste Cooking Oil (WCO) is considered highly environmentally sustainable since WCO is a waste product from domestic and commercial cooking processes and then recycled to a transportation fuel in Singapore. In addition, it avoids the conversion of land use for crop production. This is a strong advantage for Singapore which has relatively smaller land space than other countries. The import of virgin oil as feedstock into Singapore is also avoided. Therefore, the more appropriate feedstock to produce biodiesel in Singapore context is WCO. According to the National Environment Agency, diesel vehicles in Singapore contribute 50% of the total particulate matter smaller than 2.5 μm (PM_0.25) emissions to air ambient. Hence, the aim of this life cycle assessment study was to compare the environmental performances of biodiesel derived from WCO and low sulphur diesel in terms of global warming potential, life cycle energy efficiency (LCEE) and fossil energy ratio (FER) using the life cycle inventory. The results of this study would serve as a reference for energy policy makers and environmental agencies.     

Ethylene based on woody biomass—what are environmental key issues of a possible future Swedish production on industrial scale

Purpose

In order to reduce its environmental impact, the chemical industry no longer produces base chemicals such as ethylene, solely from fossil, but also from biomass-based feedstocks. However, a biomass option suitable for one region might not be as suitable for another region due to, e.g., long transport and the related environmental. Therefore, local biomass alternatives and the environmental impact related to the production of chemicals from these alternatives need to be investigated. This study assesses the environmental impact of producing ethylene from Swedish wood ethanol.

Methods

The study was conducted following the methodology of life cycle assessment. The life cycle was assessed using a cradle-to-gate perspective for the production of 50,000 tonnes ethylene/year for the impact categories global warming, acidification (ACP), photochemical ozone creation, and eutrophication (EP).

Results and discussion

The production of enzymes used during the life cycle had a significant effect on all investigated impacts. However, reduced consumption of enzyme product, which could possibly be realized considering the rapid development of enzymes, lowered the overall environmental impact of the ethylene. Another approach could be to use alternative hydrolyzing agents. However, little information on their environmental impact is available. An additional key contributor, with regard to ACP, EP, and POCP, was the ethanol production. Therefore, further improvements with regard to the process’ design may have beneficial effects on its environmental impact.

Conclusions

The study assessed the environmental impact of wood ethylene and pointed to several directions for improvements, such as improved enzyme production and reduced consumption of enzyme products. Moreover, the analysis showed that further investigations into other process options and increase of ethylene production from biomass are worth continued research.     

The cloning and expression of chymosin (rennin) genes in microorganisms

Chymosin, also known as rennin, a milk-clotting enzyme obtained from the stomach of calves, is used in the manufacture of cheese. The production of this enzyme by recombinant DNA technology is now becoming possible. A new source of this enzyme to replace or supplement the animal product or similar, naturally occurring fungal enzymes will be of great economic value.     

Life cycle assessment of pasture-based suckler steer weanling-to-beef production systems: Effect of breed and slaughter age

Demand for beef produced from pasture-based diets is rising as it is perceived to be healthier, animal friendly and good for the environment. Animals reared on a solely grass forage diet, however, have a lower growth rate than cereal-fed animals and consequently are slaughtered at an older age. This study focused on the former by conducting life cycle assessments of beef production systems offering only fresh or conserved grass, and comparing them to a conventional pasture-based beef production system offering concentrate feeding during housing. The four suckler weanling-to-beef production systems simulated were: (i) Steers produced to slaughter entirely on a grass forage diet at 20 months (GO-20); (ii) Steers produced to slaughter entirely on a grass forage diet at 24 months (GO-24); (iii) Steers produced to slaughter on a grass forage diet with concentrate supplementation during housing (GC-24), and (iv) Steers produced to slaughter entirely on a grass forage diet at 28 months (GO-28). Two breed types were evaluated: early-maturing and late-maturing (LM). The environmental impacts assessed were global warming potential (GWP), non-renewable energy (NRE), acidification potential (AP), eutrophication potential (marine (MEP) and freshwater) were expressed per animal, per kg live weight gain (LWG), kg carcass weight gain, and kg meat weight gain (MWG). The GO-20 production system had the lowest environmental impact across all categories and functional units for both breeds. Extending age at slaughter increased environmental impact across all categories per animal. The LWG response of EM steers to concentrate feed supplementation in GC-24 was greater than the increase in total environmental impact resulting in GC-24 having a lower environmental impact across categories per kg product than GO-24. Concentrate feed supplementation had a similar effect on LM steers with the exception of NRE and AP. The increase in daily LWG in the third grazing season in comparison to the second grazing and housing resulted in GO-28 having lower GWP, NRE, AP, and MEP per kg product than GO-24. Early-maturing steers had lower environmental impact than LM when expressed per kg LWG. However the opposite occurred when impacts were expressed per kg MWG, despite LM steers producing the least LWG. The LM steers compensated for poor LWG performance by having superior carcass traits, which caused the breed to have the lowest environmental impact per kg MWG. The results reaffirms the importance of functional unit and suggests reducing the environmental impact of LWG does not always translate into improvements in the environmental performance of meat.     

Wax production from renewable feedstock using biocatalysts instead of fossil feedstock and conventional methods

Background, aim, and scope

Using renewable feedstock and introducing biocatalysts in the chemical industry have been suggested as the key strategies to reduce the environmental impact of chemicals. The Swedish interdisciplinary research program “Speciality Chemicals from Renewable Resources—Greenchem” is aiming to develop these strategies. One target group of chemicals for Greenchem are wax esters which can be used in wood coatings to replace paraffin wax made from fossil crude oil. The aim of this study was to conduct a life cycle assessment of wax esters based on rapeseed oil produced by biocatalysts (enzymes). The scope was to compare the environmental performance of wax esters with paraffin wax produced by conventional methods.

Materials and methods

The study has a cradle-to-gate perspective and the functional unit is “1-kg wax product ready to use in a wood coating product.” Extensive data collection and calculations have been performed for the wax esters, whereas existing life cycle inventory data have been used for the paraffin wax.

Results

The energy input into the wax ester production is about one third of the energy input in paraffin wax production. However, the wax ester has a higher contribution to the global warming potential (GWP) due to high emissions of nitrous oxide from rapeseed cultivation. Referring to a cradle-to-grave perspective, including waste incineration, the contribution to the GWP will, however, be 3.5 times higher from paraffin wax. Wax ester makes a higher contribution to the acidification and eutrophication potential, due to emissions from soil from rapeseed cultivation, but five times lower contribution to the photochemical ozone creation potential. From a land-use perspective and a global warming point of view, it is more efficient to produce paraffin wax and grow high-yielding, short-rotation coppice (Salix) to replace fuel oil than it is to grow rapeseed for wax ester production.

Discussion

Overall, this study shows the importance of studying the environmental performance of a product not only from a gate-to-gate perspective but, instead, considering the environmental performance from cradle-to-gate. The biocatalytic production of the wax ester consumes less energy than the conventional chemical method, but the raw material step, cultivation of rapeseed contributes much to both acidification and eutrophication. When the waste treatment step is included, the contribution to GWP, however, for paraffin wax will be 3.5 times higher than for the wax ester.

Conclusions

From a gate-to-gate perspective, replacing conventional chemical processes by biocatalysts using enzymes leads to energy savings and reduces emissions. However, from a cradle-to-gate perspective, the use of renewable feedstock, such as rapeseed oil, may counteract some of these benefits. Concerning the GWP benefit from using renewable feedstock instead of fossil feedstock, the final waste treatment step must be included, thereby applying a cradle-to-grave perspective.

Recommendations and perspectives

The introduction of biocatalysts as a key strategy in reducing the environmental impact from the chemical industry is supported by the results in this study. On the other hand, it is not obvious that the key strategy of using renewable feedstock in chemical production per se leads to benefits concerning all environmental impact categories. Thus, much more attention needs to be paid to the choice of potential renewable feedstock options, the minimization of energy inputs, and the biological emissions from the soil in the cultivation of feedstock crops, improved gas cleaning in nitrogen fertilizer production plants, and the alternative use of the arable land, in optimizing the overall environmental benefits of an increased use of renewable feedstock in the chemical industry.     

Lupin as primary protein source in young broiler chicken diets: Effect of enzymes preparations catalyzing degradation of non-starch polysaccharides or phytates

This work examined the effects of three enzyme preparations (A,B,C) directed towards degradation of Non Starch Polysaccharides (NSP) and one targeting phytates (D) on performance traits in broilers fed maize meal basal diets containing 400 g/kg of yellow lupine seeds (LM). A soybean meal (SBM) based diet served as a reference control. Growth rate, coefficients of total tract apparent digestibility (CTTAD) of organic matter, protein and energy, as well as morphometric measurements of selected sections of gastrointestinal tract (GIT) were determined. In comparison to chickens fed the SBM diet, chickens fed the LM diet consumed less feed, had considerably lower body weight gain, as well as lower CTTAD of measured nutrients and energy. Also the GIT relative weight and length were increased within the group fed the LM diet. Addition of each NSP degrading enzymes (A,B,C) to the LM diet increased feed intake and decreased size of GIT organs (all p < 0.05). Addition of enzymes A or B increased (p < 0.05) growth rate of chicks, whereas only enzyme B increased fed efficiency (p < 0.05) and tended to slightly improve CTTAD of nutrients. The addition of enzyme D did not have any effect on feed intake, growth rate or CTTAD. This study indicates that a diet containing high levels of LM is detrimental to feed intake and condition of the digestive tract of young broilers, and thus affects their performance. However, when the LM diet is supplemented with suitable enzyme preparations, performance parameters are not different from those obtained with SBM.     

Biocatalysts: application and engineering for industrial purposes

Enzymes are widely applied in various industrial applications and processes, including the food and beverage, animal feed, textile, detergent and medical industries. Enzymes screened from natural origins are often engineered before entering the market place because their native forms do not meet the requirements for industrial application. Protein engineering is concerned with the design and construction of novel enzymes with tailored functional properties, including stability, catalytic activity, reaction product inhibition and substrate specificity. Two broad approaches have been used for enzyme engineering, namely, rational design and directed evolution. The powerful and revolutionary techniques so far developed for protein engineering provide excellent opportunities for the design of industrial enzymes with specific properties and production of high-value products at lower production costs. The present review seeks to highlight the major fields of enzyme application and to provide an updated overview on previous protein engineering studies wherein natural enzymes were modified to meet the operational conditions required for industrial application.     

Life Cycle Assessment of Frozen Tilapia Fillets From Indonesian Lake‐Based and Pond‐Based Intensive Aquaculture Systems

We used life cycle assessment to evaluate a subset of the cradle‐to‐destination‐port environmental impacts associated with the production, processing, and transportation of frozen, packaged Indonesian tilapia (Oreochromis niloticus) fillets to ports in Chicago and Rotterdam. Specifically, we evaluated the cumulative energy use; biotic resource use; and global warming, acidifying, and eutrophying emissions at each life cycle stage and in aggregate. We identify the importance of least environmental cost feed sourcing for reducing supply chain environmental impacts. We also highlight the need for more effective nutrient cycling in intensive aquaculture. The environmental trade‐offs inherent in substituting technological inputs for ecosystem services in intensive pond‐based versus lake‐based production systems are discussed. We further call for more nuanced considerations of comparative environmental advantage in the production and interregional trade of food commodities than has been characteristic of historic food miles discussions. Significant opportunities exist for improving environmental performance in tilapia aquaculture. This product compares favorably, however, with several other fishery, aquaculture, and animal husbandry products, according to the suite of impact categories considered in this study.     

Comparative life cycle assessment of a commercial algal multiproduct biorefinery and wild caught fishery for small pelagic fish

Purpose

The purpose of this study was to compare the environmental impacts of omega-3 fatty acid (n-3), high protein feed and biofuel production from algae to the impacts of the production of those products from fish.

Methods

The functional unit was the production of one metric ton of omega-3 fatty acids from algae (fish) and the accompanying co-products of biofuel and high protein feed. This was a cradle to gate LCA. Four scenarios were used in this model. The algae multiproduct model (MPM) scenario was the baseline using only unit operations currently in use at the reference facility (Cellana LLC). A low-energy centrifuge replaced the existing conventional centrifuge (MPM (LE)) to reduce energy consumption. The MPM was improved in a different manner, employing membrane filtration prior to centrifugation (MPM (MF)). These three scenarios were compared to the conventional production of the same products from fish (conventional product model: CPM). This life cycle assessment investigated the following impacts: ozone depletion potential, global warming potential, smog formation potential, acidification potential, and eutrophication potential.

Results and discussion

The environmental impacts of producing omega-3 fatty acids from algae were higher than producing omega-3 fatty acids from fish if membrane filtration was not used. Membrane filtration reduced most of the environmental impacts of the algae system by more than 50%. Fuel consumption was the only factor that caused the fish systems to change by greater than 10% from the baseline. Productivity, membrane filtration electricity, and annual operating days could each affect the environmental impacts of the algae system by greater than 10% from the baseline. Improvements to the algae system depend on improvements to cultivation and harvesting, with the impacts from processing being very small.

Conclusions

This study presented results comparing the environmental impacts from a multiproduct system from algae and from fish. The results of this study can serve as a benchmark for the environmental impacts of an algal multiproduct biorefinery compared to the conventional production of those same products from fish. Areas of improvement have been identified for the algae production system for dewatering and cultivation. The amount of n-3 had little impact on the n-3 market but had a significant effect on the existing algal n-3 market. The amount of fuel and feed produced had a negligible effect on both markets.

     

High performance microbiological transformation of L-tyrosine to L-dopa by <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis>NRRL-143

Background  

The 3,4-dihydroxy phenyl L-alanine (L-dopa) is a drug of choice for Parkinson's disease, controlling changes in energy metabolism enzymes of the myocardium following neurogenic injury. Aspergillus oryzae is commonly used for L-dopa production; however, potential improvements in ease of handling, growth rate and environmental impact have led to an interest in exploiting alternative yeasts. The two important elements required for L-dopa production are intracellular tyrosinases (thus pre-grown yeast cells are required for the transformation of L-tyrosine to L-dopa) and L-ascorbate, which acts as a reducing agent.     

Comparative secretome analyses of two <Emphasis Type="Italic">Trichoderma reesei</Emphasis> RUT-C30 and CL847 hypersecretory strains

Background  

Due to its capacity to produce large amounts of cellulases, Trichoderma reesei is increasingly been researched in various fields of white biotechnology, especially in biofuel production from lignocellulosic biomass. The commercial enzyme mixtures produced at industrial scales are not well characterized, and their proteinaceous components are poorly identified and quantified. The development of proteomic methods has made it possible to comprehensively overview the enzymes involved in lignocellulosic biomass degradation which are secreted under various environmental conditions.     

Micro ecosystems from feed industry surfaces: a survival and biofilm study of <Emphasis Type="Italic">Salmonella</Emphasis>versus host resident flora strains

Background  

The presence of Salmonella enterica serovars in feed ingredients, products and processing facilities is a well recognized problem worldwide. In Norwegian feed factories, strict control measures are implemented to avoid establishment and spreading of Salmonella throughout the processing chain. There is limited knowledge on the presence and survival of the resident microflora in feed production plants. Information on interactions between Salmonella and other bacteria in feed production plants and how they affect survival and biofilm formation of Salmonella is also limited. The aim of this study was to identify resident microbiota found in feed production environments, and to compare the survival of resident flora strains and Salmonella to stress factors typically found in feed processing environments. Moreover, the role of dominant resident flora strains in the biofilm development of Salmonella was determined.     

Influence of added microbial enzymes on energy and protein availability of selected feed ingredients

Addition of enzymes to feed ingredients results in an improved energy availability that reduces the difference between gross and metabolisable energy of the raw material. The level of improvement seen is related to enzyme type and to dosage, and correlates well with the substrate specificity of the various enzymes present. Thus the values found in this study are specific for the enzymes and dosages used. Nitrogen retention is also improved by enzyme addition but this did not show a clear dosage response with all materials. An improved nitrogen retention cannot be directly correlated with protein digestibility but an improved retention of protein may offer the possibility to reduce protein levels in the diet.