Where do enzymes function? Enzymes are proteins and subject to the rigors of the digestive system, and are themselves digested. Prior to inactivation they must accomplish the degradation of the target substrate. A critical component is pH; enzymes will not function outside their preferred range, and will be progressively denatured outside this range. Food entering the anterior digestive tract (crop/proventricus/ventriculus in chickens; stomach in pigs) will initially be mildly acidic and near optimum for fungal enzymes (5.0-5.5). The pH will drop as the feed is acidified with gastric secretion, with activity declining and ultimately reaching a point where they activity is irreversibly lost. Only a fraction of the enzyme will escape to the small intestine. Which enzymes are preferred, fungal or bacterial? Most enzyme products offered by enzyme manufacturers for feed purposes are produced by fungi rather than bacteria. An exception is amylase which in many products is bacterial in origin. Fungi prefer a lower pH than bacteria, and produce an enzyme spectrum with the desired lower pH preference. Fungal enzymes are compatible with a lower feed pH induced by the use of organic acids in starter diets, whereas the activity of bacterial enzymes in such applications is questionable. All GNC Bioferm enzyme products are derived from fungi. What are the benefits of Genetically Modified Organisms (GMO's) in Production of Feed Enzymes? Unlike many competitor products, all GNC Bioferm enzymes are based on traditional microbial selection systems. GNC Bioferm has been successful in achieving very high activity levels without reliance of GMO's. The advantage of GMO's as applied to feed enzymes has been the capacity to achieve higher production levels of specific enzymes. One disadvantage is that GMO products lack the ancillary enzymes and other factors that assist in the breakdown of complex substrates as occur in feed ingredients. A second disadvantage is that there is only a single isozyme (form) which will function in only a narrow band of the pH spectrum; unlike natural products which contain many isozymes (forms) of the same enzyme and a broader pH range.
What are the Limitations of Feed Enzymes in Relation to Pelleting Temperature? Feed enzymes are proteins and, like all proteins, are heat labile. With very few exceptions, fully hydrated enzymes are rapidly denatured at temperatures well below routine pelleting temperatures. However, in a dry state they are remarkably stable. Thus the extent of enzyme loss associated with steam conditioning relates to the extent of hydration, and efforts to reduce hydration confer stability. Naturally it is impossible to ‘protect’ against heat per se. Powdered enzymes are somewhat less stable than granulated enzymes, because they hydrate more easily. Granulated enzymes incorporate hydrophobic elements (eg saturated fat) which coat the granule and prevent water uptake. Powdered enzymes achieve some coating protection from feed fat during feed mixing, which is adsorbed by the enzyme particulates. In practice the difference in conditioning conditions each will tolerate is approximately 5-7°C, with granulated enzymes clearly preferred when the conditioning temperature exceeds 85°C. Granulated enzymes have two important disadvantages that should be considered. Firstly, the particulate size is much larger than powdered products, which introduces mixing concerns. Proper mixing is more critical for enzymes than micronutrients, since they must have immediate, intimate contact with their substrate to function. Secondly, the coating process of granulates also reduces water uptake and enzyme solubility in the intestinal tract, which reduces the exposure time of the enzyme to its substrate. The pelleting process may be required to damage the granules for adequate enzyme release, which has caused concern in mash diets. What Nutrient Levels Should be Specified with Enzymes? The effect of enzymes is to increase nutrient digestibility, which must be accommodated in diet formulation. One popular solution is to increase the stipulated energy level for wheat (5%) and barley (10%). The shortcoming of this approach is that the response is not uniform; poorer samples tend to benefit more than good samples. Normally existing feeding values have been established with high quality samples. Other concerns are that the offending soluble fiber attacked by the feed enzyme affects the digestibility of other ingredients in the diet. In the case of low energy density diets, enzymes increase the rate of digestion which in turn allows increases consumption. An alternative approach that is theoretically preferable is to ndicate a much more modest increase in energy (barley, 2%; wheat, 1%) allow lower energy densities, particularly in the finisher feeds. In practice, the diet formulations using the two systems are similar. However, wheat and barley will tend to be overvalued in least cost formulations when energy values are increased. At What Levels of Wheat and Barley Are Enzymes No Longer Necessary? When least cost formulations stipulate only low levels of wheat or barley in the diet, the potential economic benefit is greatly reduced. An important advantage of GNC Bioferm products is the ancillary enzymes, which are active on other ingredients in the diet. This is not a major effect, but does offset the enzyme being weighed totally against the barley/wheat constituent. Generally it is considered that fifteen per cent or less in the finisher diets do not warrant enzyme addition, or the enzyme is added at a partial dose. One pitfall of which formulators should be aware concerns the common practice of stipulating a separate energy value for wheat and barley with enzyme added. In almost all cases the formula would call for the grain with the enzyme. However, the formula is assuming that the addition rate varies according to the level of grain, which is normally not the case. |
Tel: 1-250-743-7850 Fax: 1-250-743-7860
Plant: PO Box 6, Bradwell, SK. Canada S0K 0P0
Tel: 1-306-257-3244 Fax: 1-306-257-3528
Email: gnc.bioferm@shaw.ca