New Opportunities in Layer Feed Formulation

Bruce R. Behrends

Until recently, layer feed formulation in the Midwestern United States has been reasonably simple. Few ingredients were available that would compete with locally produced corn and soybean meal. In some areas, byproducts play a minor role but corn and soybean meal are considered the "gold standard".

Biotechnology is changing this picture. Manipulation and selection of organisms to produce specific biochemicals are making new ingredients available. This trend started in Europe where specific enzymes were identified and produced to make the nutrients in wheat and barley more utilizable. Currently, enzymes designed for corn–soy formulas are available in the U.S. Recombinant DNA technology has made specific metabolites, such as 25-OH vitamin D3 available at a cost that is acceptable to the egg production industry. It will be the objective of this report is to provide information and discuss opportunities to use these new products in feeding layers.

Until recently, enzymes used in the feed industry were byproducts of the food industry. Actual enzyme components, stability and activity were questionable making use of these products a hit or miss effort. Advances in biotechnology and biochemistry have allowed sophistication in enzyme design and production. Limiting factors in feedstuffs including cell wall components and anti-nutritional factors have been identified and characterized biochemically. Microbial enzymes with possible activity to these factors have been identified and tested. For an enzyme to be active in a live animal, it must be able to withstand the acidic conditions of the stomach and the proteolytic attack of enzymes in the small intestine. It must be effective at the pH of the small intestine and be stable to feed manufacturing processes. Potential enzymes are identified and screened for desirable characteristics in-vitro. In-vivo testing, field trials and production scale-up result in enzymes with specific characteristics being produced under controlled conditions. Enzymes available to the feed industry may be bacteria, fungal or a combination. They may be provided as liquid, dry powder or stabilized dry powder.

The possible effects of enzymes on digestion have been outlined by Bedford (1996). It was indicated that the enzymes in feed might improve ingredient digestibility by a) disruption of plant cell walls b) destruction of anti-nutritional factors c) supplementation of endogenous enzymes and d) manipulation of gut micro-flora populations.

Significant improvement in barley or wheat based diets have been accomplished by using beta glucanases and pentosanases. Phytases were developed in Europe to release phytin bound phosphorus and are currently being marketed in the United States. Newer enzymes available in the U.S. are hemicelluases, which break down the structural carbohydrates in soybean meal and enzyme mixtures that aid in the digestion of starch and protein.

Enzymes in Corn-Soybean Meal Rations
It has been assumed that enzymes are of limited value in corn-soybean meal rations. Corn is highly digestible and low in non-starch polysaccharides. Soybean meal is less digestible due to the galacto-oligasaccharides in the cell walls and other anti-nutritional factors. Because the laying hen has a mature digestive system, potential enzyme responses may be less than in rapidly growing animals with less mature systems.

Despite these concerns, a number of enzymes are being marketed in the U.S. for the use in corn-soy diets. Incorporation of enzymes into mash layer feeds is less complex as destruction by the pelleting process is not a concern. Also, the layer’s mature digestive system may benefit from lower levels of enzyme than in younger birds resulting in a lower enzyme cost. Table 1 gives a partial listing of enzymes available in the U.S. This table outlines the product name, the manufacturer, the active enzymes and the targeted feed component. These products can be grouped into three major categories based on enzyme components:

Hemicellulases- These enzymes are designed to breakdown the hemicellulose component of soybean meal. Hemicelluloses are structural carbohydrates of the soybean seed and include galactomannans and galacto-oligosaccharides. Enzymes include A-galactosidase, B-mannanase and cellulases.

Phytases - These enzymes are designed to break down phytin that binds phosphorus in plant materials. These enzymes may release other nutrients complexed by phytin.

Enzyme Blends- These products may contain xylanases, proteases, amylases, cellulases and galactosidases. These enzymes are designed to break down non-starch polysaccharides, proteins and increase digestibility of starches. An advantage of enzyme blends are their ability to break down several components of plant structural materials rather than a specific polysaccharide.

The hemicellulases and the enzyme blends may increase metabolizable energy and protein digestibility through breakdown of cell wall materials and anti-nutritional factors. Ingesta viscosity may be reduced allowing slower passage through the gut and better nutrient absorption. Less waste material reaching the hindgut may decrease population of unfavorable microbes. Phytases release the phosphorus portion of the phytin molecule and make other phytin complexed nutrients more available.

Research Information
Initial research on enzymes in poultry was conducted with broilers because of low cost, quick response and large sales potential. To support use by the egg industry, research information is being generated with layers. Results from field trials and supplier sponsored university research are available. Because of the difficulty of conducting research with layers (expense, lack of facilities and variability), less information exists than for meat species. In general, variable, positive responses in egg production, egg weight and feed conversion have been demonstrated. In some cases, statistical significance is achieved and in other cases not. Research by Jackson (1999) found significant responses in egg production in both low and high energy diets from B-mannanase (Table 2). In a trial with molted hens (Table 3) comparing three enzyme products, egg production was increased significantly with a enzyme blend (protease, cellulase, A-galactosidase, xylanse, B-glucananse). In this trial, B-Mannanase increased egg weight but had an opposite effect in a third trial (Table 4). Scheideler (1998) found non-significant improvements in egg production and feed conversion with a xylanase, protease, amylase blend (Table 5). Phytase has been extensively researched and has been found to be effective in releasing phosphorus and other nutrients bound by phytin (Gordon, 1997). Field trials with various enzymes have shown positive results but lack of adequate controls make this information very difficult to use in making sound, scientific decisions.

Feed Formulation with Enzymes
The improvements in nutrient digestibility must be considered to effectively use enzymes in formulation. The nutrients affected and the actual improvements in digestibility may be based on research or expected results for the enzyme in use. A summary of estimated changes to specifications of corn-soy layer diets is given in Table 6. This table was compiled from available information and provides a range for each enzyme class. More specific information is available from enzyme suppliers.

Two techniques to use enzymes in formulation involve a) altering the formula nutrient specifications or b) assigning nutrient specifications to the enzyme in the ingredient matrix.

Examples of these techniques are given in Tables 7 and 8. A theoretical "Enzyme A" which improves digestibility of protein, energy, calcium and phosphorus is used for this example. The changes to the specifications and the ingredient matrix values for theoretical "Enzyme A" are shown in Table 7. These values would be supplied by the enzyme manufacturer and verified by research. Table 8 shows composition of high-density layer formulas with and without the enzyme. The standard formula was set to contain a minimum of 1320 Kcal ME/lb. and utilized 47 lbs. of fat to meet this requirement. In the second formula the enzyme was forced in at 1 lb. /ton and the formula specifications were decreased by the amount suggested on Table 7. Minimum specifications for metabolizable energy, protein, amino acids, calcium and phosphorus were decreased because of the enzyme’s effects in making these nutrients more available. The least cost formula used less soybean meal, limestone, dical and fat resulting in a lower formula cost. In the last column, the enzyme was given the nutrient specifications in Table 7. The formula and cost savings are the same but the nutrient levels assigned to the enzyme inflate the reported nutrient levels. The actual nutrient values in the last column are those that would be measured by analysis. A possible solution is to add additional nutrients and update ingredients to reflect these changes.

Cost Benefit Ratios of Enzymes and Layer Formulas
Practical experience in evaluating enzymes in layer formulas finds greater potential in nutrient dense formulas were energy is limiting. Enzymes that make metabolizable energy more available result in formulas with less fat and lower cost. Enzymes that made calcium and phosphorus more available result in less non-energy containing ingredients (limestone, dicalcium phosphate). In higher consumption formulas with lower nutrient density enzymes won’t usually "come in" to the formula unless there are low cost ingredients (wheat midds, soy hulls) available. In parts of the United States where meat and bone is low in cost relative to soy, it is difficult to economically use the phytase enzymes because it is less expensive to get phosphorus from meat and bone meal than to pay for the enzyme to release it from plant material. In some situations, adding enzymes as a separate ingredient provides more flexibility than incorporating in a premix that must be used in all formulas.

Additional Applications of Enzymes in Layer Feeds
In addition to decreasing ration cost, enzymes have other applications in pullet and layer feeds. The energy sparing effect allows formulation of high metabolizable energy feeds without excess fat. This may be beneficial in times of heat stress for both layers and pullets. Enzymes may provide more uniform performance by increasing digestibility of low quality, or variable ingredients. The effects of the phytase enzymes in decreasing manure phosphorus have been well documented.

Osteoporosis and poor eggshell quality are on going problems to the nutritionist and egg producer. Many times these problems persist even when calcium, phosphorus and vitamin D supplementation is adequate. Vitamin D3, which is necessary for calcium transport across the intestine and uterine walls, must be converted to 25-OH-D3 in the liver and to 1,25-OH D3 in the kidney before it is biologically active. If one of these metabolic processes is not functioning, vitamin D3 deficiency symptoms may result.

The biochemistry of vitamin D3 activation has been known for 20 years and recent advances in recombinant DNA technology have made 25-OH vitamin D3 available to the egg production industry at a competitive cost. As with enzymes, 25-OH vitamin D3 was first researched with broilers. A summary of 22 trials showed average improvements in both feed conversion and weight gain (IsoGen, 1998).

Current research on 25-OH vitamin D3 with layers is limited. Field trials and unpublished research supplied by the manufacturer (Calabotta, 1998) indicates 1-5% improvements in egg production, 1-3% improvement in cracks and 2-4% improvements in feed efficiency. A recent study (S. Newman and S. Leeson, 1999) studied the effect of 1,25-OH-D3 in 72 week old layers. The product, which is not commercially available, was fed to help improve bone characteristics. After a thirty-day study, no differences in mechanical or structural properties of the tibia of the leghorn hen were noted. The authors noted that they and others have observed that the older hen has little ability to form new bone.

Field use of 25-OH-D3 is usually limited to problem solving situations where osteoporosis has been diagnosed or eggshell quality problems exist. Biochemically, 25-OH- D3 would have the most benefit when liver damage prevents the conversion of D3 to 25-OH-D3. Long term inclusion of 25-OH D3 in the ration or replacement of Vitamin D3 in the premix with 25-OH-D3 may provide the greatest benefits but nutritionists and egg producers have been reluctant to add the cost with limited evidence on performance improvements.

Biotechnology is making new products available for use in layer feeds. These products are being produced and marketed by highly ethical companies and are designed to provide specific benefits. Acceptance and use by industry nutritionists and egg producers will depend on documentation of benefits by correctly conducted, unbiased research. As always, the probability of a product to improve bottom line financial performance will be the deciding factor.

Table 2. Effect of B-Mannanase Supplemetation on Laying Hen Performance

1 Low ME, 1266-1285 Kcal/lb.; High ME, 1311-1330 Kcal/lb.

Means within columns not sharing a common superscript are significantly different (p<.05)

Jackson, 1999

 

1 A - protease, amylase, xylanase
B – B-mannanase
C – protease, cellulase, A-galactosidase, xylanase, B-glucanase
Means within columns not sharing a common superscript are significantly different (p<.05)

Jackson, 1999

Table 4. Effect of B-Mannanase Supplementation on Laying Hen Performance at Four Amino Acid Densities, 17-37 Weeks of Age

Table 5. Effect of Enzyme¹ Supplementation on Performance of W-36 and B-300 Layers at Two Metabolizable Energy Levels

20-40 weeks of age

1 xylanase,protease and amylase enzymes

Scheideler, 1999

 

 

Table 6. Estimated Changes to Corn-Soy Layer Ration Specifications with Various Enzymes

Table 7. Feed Formulation with Theoretical "Enzyme A"

"Enzyme A" – Hemicellulose, phytase blend. Use rate 1lb/ton (0.05%). Cost - $1.50/lb

1 Based on expected improvements in nutrient digestibility, "Enzyme A" allows us to change our nutrient specifications by these amounts and achieve results similar to a ration without the enzyme.
² These values must be assigned to ‘Enzyme A" in the ingredient nutrient matrix based on expected improvements in nutrient digestibility. Enzyme use must be restricted to 1 lb./ton

 

Table 8. Comparison of Formulation Methods with Theoretical "Enzyme A"

1 Values reported on formula sheet based on values assigned to the enzyme
² Nutrient values that would be determined by analysis

 

References

Bedford, M., 1996. The Effect of Enzymes on Digestion. J. Appl. Poultry Res. 5:370-377.

Calabotta, D.F., 1998. An Update on the Effectiveness/Economics of 25-OH-D₃ In Layer Operations. Presented at the Arkansas Poultry Symposium.

Gordon, R.W., D.A. Roland., 1997. Performance of Commercial Laying Hens fed various Phosphorus Levels with and without Supplemental Phytase. Poultry Sci. 76:1172-1177.

IsoGen, 1998. Technical Information HyD. Available from IsoGen 150 W. Warrenville Road, Naperville, Ill.

Jackson, M., 1999. Enzymes in Corn-Soy Rations for Layers. Proceedings, Nutrition Symposium, Midwest Poultry Federation Convention. pp. 13-24.

Newman, S., S Leeson., 1999. The Effect of Dietary Supplementation with 1,25 Dihydroxycholecalciferol or Vitamin C on the Tibia of Older Laying Hens. Poultry Sci. 78:85-90.

Scheideler, S., A. Abudabos., 1998. Enzyme Supplementation in Corn/Soy Based Layer Diets. The Nebraska Poultry Report. pp. 12-13.