With increasing prices of key raw materials, there is now a great deal of pressure on feed manufacturers to maximise the efficiency of nutrient utilisation. Much of the cost pressure has been on two nutrients in particular, namely energy and phosphorus (P).

1. Digital Re-print - January| February 2011
The impact of feed enzymes on diet digestibility
and animal profitability
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2. FEATURE FEATURE
wall material are produced. At some point the breakdown, to the extent that the contents a poor sample of corn is utilised, the enzyme
fragments become small enough (i.e. oligosac- of the cells are better exposed to gastric and significantly enhances its digestibility such that
charides) and numerous enough to act as a small intestinal digestion. Ironically this may well the elevated matrix energy value used in the
substrate (pre-biotic) for bacterial fermenta- explain the so called cell wall effect of NSP LCF is justified. The net result is consistent cost
tion. Xylanases, mannanases and cellulases enzymes, since the amount of time that the savings. There is also the added advantage of
produce xylo-, manno- or gluco- oligosaccha- diet spends in the stomach of chickens and to reduced variability in animal performance as a
rides, respectively. The benefit of such end a lesser extent pigs, coupled with the extremes result of the enzyme reducing the differences
products depends upon the type and quantity in pH, means that it is unlikely that significant in digestible energy content between good and
of the oligosaccharides produced, with different cell wall damage will take place through direct bad samples of corn.
enzymes producing different oligosaccharides. exogenous enzyme attack. Thus, the use of an There are many different NSP enzymes
Many beneficial species of bacteria are able to NSP enzyme may well result in significant cell on the market today, many of which dif-
utilise such products to varying degrees and in wall destruction, but perhaps more through fer markedly from one another. Even within
doing so produce volatile fatty acids (VFAs), its effects on hind gut fermentation and the xylanases, there are enormous differences in
which provide a source of energy and patho- consequent hormonal responses rather than pH profiles, end products produced and their
gen control for the chick (Choct et al., 1999; a direct destruction of cell walls in the gastric ability to attach soluble and/or insoluble xylan
The impact of feed Bedford & Apajalahti, 2001; Sohail et al., 2003).
Care must be taken in selection of the enzyme,
however, as some can, if overdosed, reduce
environment.
Value in practice
structures. It is important when making a choice
of enzyme that the decision is based on the
biological performance of the product and not
enzymes on diet digestibility the size of the oligosaccharides down to mon-
osaccharides. If sufficient monosaccharide is
produced, this may result in osmotic diarrhoea
In principal, corn-soy enzymes offer an
improvement in the average digestible energy
content of the diet by markedly improving
simple in vitro assays, none of which bear much
relationship to the environment in which these
products act.
and animal profitability and/or poor performance (Schutte, 1990).
Such a problem is most likely to occur with
digestibility of the poorest quality corn samples
whilst having minimal value on the best sam- Phytases
endo-xylanases, which is an issue with crude ples. Unfortunately, with no method available Phytases were originally employed in the
preparations which contain substantial amounts to allow rapid determination of the quality of 1990s in response to financial penalties for P
by Dr Michael Bedford, AB Vista Feed Ingredients, Marlborough, Wiltshire, United Kingdom of exo- rather than endo-xylanase activity. corn prior to diet manufacture, the only option pollution imposed on pig and poultry produc-
A consequence of increased production is to use such an enzyme in all cases. Since use ers, particularly in Benelux. Phytases degrade
W
ith increasing prices of key Recently, however, the dramatic increase studies have shown improvements in starch and of VFAs in the large intestine is that butyric of the enzyme effectively increases the matrix plant phytate P which would otherwise pass
raw materials, there is now a in the price of dietary energy has meant to a lesser extent protein digestibility, which is and propionic acids may play a role in stimu- value of corn, the result is that even when a through to the manure intact. Without the
great deal of pressure on feed that many feed manufacturers have taken a indicative of activity of the enzyme towards corn lating hormonal responses which encourage good quality, un-responsive sample of corn economic penalties for waste disposal at that
manufacturers to maximise the efficiency of renewed interest in such enzymes due to the endosperm cell walls. enhanced gastric motility. In the pig and espe- is used in diet manufacture, value has been time, the use of phytase would not have
nutrient utilisation. Much of the cost pressure huge potential savings they offer. The second mechanism relevant for NSP- cially the chicken, this may result in enhanced extracted through the savings created by the been established since the cost savings in
has been on two nutrients in particular, enzymes is that of viscosity reduction. A por- particle size reduction and endosperm cell wall higher energy values used in the LCF. When inorganic phosphate were offset by the cost of
namely energy and phosphorus (P). Mode of action tion of the hemicellulose may be soluble and
It is thought that NSP enzymes function of sufficient chain length to create a gel in the
This is likely a result of the surge in through a composite of three separate actions, intestinal aqueous phase. The greater the chain
S
requirements for cereals for biofuels and the contribution of each action varying with length and quantity of this material, the more Ha ee
in requirements for phosphates for fertiliz- ingredients and individual birds. These activi- viscous the gel created in the gut (Bedford & ll us
3, at
ers, respectively. The net result is that the ties include plant (cereal) cell wall destruction, Classen, 1992). Viscous gels reduce the rate of st V
increase in shadow prices in least cost reduction of digesta viscosity and stimulation of diffusion of all solutes (and thus with it the rate an IV
d As
formulations (LCF) for energy and P has beneficial bacteria in the animal gut (Bedford & of digestion) with the effect being proportional E0 ia
71
driven feed manufacturers to consider use Schulze, 1998b). to the viscosity of the solution. In the case of
of enzymes for releasing more energy from The cell walls of the starchy endosperm of digestion, fat micelles are the largest solutes in
corn. They may also consider using phytase maize are constructed of a small amount of the gut and would be most influenced by a
at considerably higher dosages than cur- cellulose encrusted with hemicellulose, the bulk viscous intestinal tract (Danicke et al., 2000).
rently employed. Not only does this increase of which is arabinoxylan with minor ß-glucan Viscosity, however, is most relevant for rye and
P release from phytate, but it also spares components and lesser contents of mannans barley based diets for poultry, to a lesser extent
energy as a result. The principal issues aris- (Stone, 2004). Since monogastrics do not pos- wheat, and to a minor extent to corn (Bedford
ing from use of each of these enzymes is sess the necessary enzymes to degrade plant & Schulze, 1998a). This is due to the fact that
discussed below. cell walls, the contents of any cells which remain the content and chain length of the soluble
intact following milling, processing and the grind- viscous fibres is much lower in corn than in
NSP enzymes for corn based diets ing action of the teeth or gizzard effectively other grains, and for this reason viscosity is not
Non-starch polysaccharide- (NSP) or bypass digestion. Microscopy has shown that so relevant in corn-soy diets. Nevertheless,
fibre-degrading enzymes were first devel- there can be an appreciable amount of such viscosity varies with variety, climatic conditions
oped in the 1980s for use in barley and then material and thus an opportunity for cell wall during cereal growth, postharvest handling (e.g.
subsequently wheat-based diets. Their use degrading enzymes to improve on the digestive drying) and pelleting/extrusion. It is possible,
coincided with an almost immediate and process (Tervila-Wilo et al., 1996; Parkkonen therefore, under the right set of circumstances,
visible improvement in litter quality and an et al., 1997). Effective cell wall degradation for viscosity to play a role even in a corn-soy
equally evident improvement in perform- requires the addition of sufficient amounts of the diet, but the frequency of such events is
ance (Elwinger & Teglof, 1991). Use of appropriate enzyme activity such that “holes” probably low. Provided an enzyme is used
such enzymes in corn-based diets is not are created in the cell wall which are large which can attack the soluble fibres, the rate of
associated with improved litter quality, sim- enough to allow entry of pancreatic proteases viscosity reduction can be rapid as only a few,
ply because there are few such problems and amylases. Xylanases, and to a lesser extent well-targeted attacks towards the middle of
associated with corn. In addition, the scale of cellulases (ß 1-4 glucanases), have proven most the chain are required to dramatically reduce
animal performance response is somewhat effective in the field (Zanella et al., 1999; Zanella average chain length and hence viscosity.
muted compared with wheat and particularly et al., 2004; Leslie et al., 2007). Mannanases and The third mechanism relates to the fact
barley based diets, and as a result the rate of pectinases target the soybean fraction of the that as a result of the NSP enzymes breaking
uptake of such products in the market has feed more so than the corn, but with the same down cell walls or reducing chain length of
been relatively slow. endpoint in mind (Jackson et al., 2004). Many viscous polymers, smaller fragments of cell
Untitled-1 1 17/01/2011 08:53
20 | January - february 2011 Grain &feed millinG technoloGy Grain &feed millinG technoloGy January - february 2011 | 21

3. FEATURE FEATURE
the enzyme. With time, however, the cost of the above has significantly improved the ability if the 500 unit product had an AvP value of
the enzyme reduced and that of the nutrients of such products to reduce feed costs. 0.1 percent AvP and the 1000 unit product a
spared by use of this enzyme increased (for value of 0.13 percent, then the 500 to 1000
Heat Recovery Dryer
30%
various reasons, e.g. the ban on meat and Value in practice unit product would have a value of 0.03 per-
bone meal in EU countries), such that its use Phytase is quite unlike the NSP enzymes cent AvP. Since the cost of the two products
spread through much of the EU in the mid for corn soy diets in that the dosage used in is exactly the same per gram, the second
practice, even product with the lower matrix value would
that of the E. not be pulled into the LCF until the full 500
coli phytases, is units of the former had been used. The error
well below that in the LCF for solutions between 500 and 1000 Up to
of the biologi- units of use would be markedly reduced as is
cal optimum. In
fact the benefit
of this enzyme
evident from the proximity of the logarithmic
curve to that of the 500 to 1000 units matrix
line represented in red. Such approaches will
Energy Savings
is linearly relat- help maximise the value that a feed producer With our Heat Recovery Dryer you get the
ed to logarith- can extract from this enzyme, particularly when
lowest energy consumption on the market.
mic increments high ingredient prices justify much greater inclu-
in dose – i.e. sion levels of phytase. TORNUM Grain Coolers – The eco-friendly
improvement way of preserving grain quality.
Figure 1: Relationship between dose of in P digestibility Enzyme delivery to the animal
phytase and expected response is doubled with One source of variability which must be
a 10 fold incre- addressed by the enzyme manufacturer is that
and late 1990s. As understanding of its mode ment in dose. Despite the extension of the of consistent delivery of the enzyme to the bird.
of action improved, and with the realisation nutritional matrices of most phytases into This means that the enzyme must be able to
that this enzyme may spare more than P, its energy and amino acids, the economic incen- survive or bypass the thermal stresses of the
use spread further, and at the present day it is tive for feed manufacturers to increase the dos- feed manufacturing process, act under the rigours
now the most commonly used feed enzyme age of phytase has not been sufficiently obvi- of the intestinal tract, and be simple to assay in
in the world. ous. Clearly, with increasing ingredient costs, premix, mash and pelleted feed for quality control
phytase dose rate should be reconsidered. A purposes. Various solutions to this are offered,
Mode of action clear problem in use of phytase in LCF is that ranging from truly thermostable enzymes with TORNUM AB Box 100, SE-535 22 Kvänum, SwEdEn
Phytases release P from phytate, and as the benefit of the enzyme increases in logarith- no susceptibility to problems associated with the Phone +46 (0)512–291 00 E-mail: info@tornum.com
a result enable the feed producer to reduce mic fashion while the LCF linearly relates dose assay (binding to fibres of the feed; inhibition by www.tornum.com
the use of inorganic phosphates in the ration. to benefit. For example, if a phytase is included xylanase inhibitors found in wheat, barley and
As more P is released from phytate, the less as an ingredient with a nutrient matrix for 500 triticale, for example), to use of coated enzymes Wenger_Ad_2010_210x147mm 5/24/10 9:37 AM Page 1
able it is to bind or chelate minerals, starch units and the LCF selects only 250 units of and post-pelleting liquid application. Intrinsically
or proteins either directly or via ionic bridges phytase, it will assume that the phytase has thermostable enzymes are clearly the best solu-
(Selle & Ravindran, 2007). As a result, use of provided only 50 percent of the given matrix, tion, with compromises arising from the use of
phytase may directly improve the digestibil- whereas in reality the actual value is closer to either coating or post-pelleting application which
ity of P, divalent cations such as calcium (Ca), 75 percent for such a dose. This relationship is vary with each product.
magnesium (Mg) and zinc (Zn), and energy and shown in figure 1.
protein. Phytate has also been shown to be an The feed formulator is therefore faced Conclusions
innovation is our enduring legacy.
active antinutrient, interacting with the gut in with an economical problem. If shadow prices Recent changes in the cost-structure of the
such a way as to stimulate the small intestinal encourage greater use of phytase, then the feed industry have significantly altered the value Since 1935, we've been help-
immune system and increase production and traditional approach would be to replace the of P and energy. Enzymes which influence the ing customers solve problems
losses of mucin proteins (Cowieson et al., 500 units matrix with a 1000 units matrix. This utilisation of these nutrients are now being con- and capitalize on opportuni-
2004). Destruction of phytate reduces this 1000 unit matrix has a lesser nutrient value per sidered in situations which would have been ties faced by their businesses.
anti-nutritive effect in a directly proportional unit of activity but a maximum inclusion rate uneconomic in the past, and in some cases at
manner, and as a result energy and amino acids which is double that of the 500 units. At the inclusion levels which would previously never Seventy-five years ago, a key
that would have been used in a maintenance maximum inclusion rates, the 1000 units deliver have been contemplated. Such changes have answer was a molasses mixer.
activity (immune surveillance and intestinal 30 percent more nutrients than the 500 units. forced the feed enzyme industry to review Today, the solutions tend to
turnover) can instead be directed towards pro- These two matrices are represented by the how it should support such products, and be more technologically com-
ductive energy. It must be noted that this effect straight regression lines which pass through the to consider how to provide products better plex – but our founding
of phytase is mostly a post-adsorptive effect, origin in figure 1. The problem is that the actual suited to the task. The combination of better pledge remains unchanged.
and as a result the value of this activity is not value of the enzyme is represented by the log products and more considered application
captured in simple AME or even TME assays. curve in figure 1. Use of any dose below the advice should help mitigate at least some of At Wenger, we innovate to
The recent development of E. coli derived product maximum results in the LCF assum- the financial burden being placed on the feed solve customer challenges.
phytases has significantly improved the value of ing that the enzyme delivers less value than it industry by current world events.
this enzyme for broilers in particular. An equiva- actually does in vivo. This loss is represented as References available on request. And then we do it again.
lent 500 unit dose from a second-generation E. the difference between the curve and either of
coli source delivers 20-30 percent more nutri- the straight regression lines. As a result the true
ents than the same dose of a first-generation optimum will not be found and a large part of More inforMation:
Aspergillus phytase (Augspurger et al., 2003), the value of the enzyme is lost. AB Vista
and its effect is more consistent due to its more A solution under these circumstances is to Woodstock Court, Blenheim
suitable pH profile and greater stability towards have two ingredients in the LCF. One would Road Marlborough Business Inventing the new original since 1935.
pepsin digestion in the intestinal tract (Igbasan be the standard 500 unit product with its given Park, Marlborough, Wiltshire
et al., 2000). Some E. coli phytases have been matrix, the second would be a new 500 to SN8 4AN, United Kingdom
Tel:: +44 1672 517 650 SABETHA, KANSAS USA 785-284-2133 INFO@WENGER.COM WWW.WENGER.COM
further enhanced either by genetic modification 1000 unit product which would have a matrix
or coating to make them even more stable defined as the difference between the 500 Website: www.abvista.com USA BELGIUM TAIWAN BRASIL CHINA TURKEY
through the feed manufacturing process. All of and 1000 unit matrix products. For example,
22 | January - february 2011 Grain &feed millinG technoloGy Grain&feed millinG technoloGy January - february 2011 | 23

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Belting Half Page FLT.indd 1 20/01/2011 13:18:54

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