Feed enzyme application: challenges in bird's physiological perspective
Published:August 4, 2021
By:Aminul Islam; DVM, MS.
No common feedstuff is 100% digested. In practice, 10-15% are excreted in faeces without bringing any means to bird requirement and in addition cause potential anti-nutritional effects. Thus, there is no doubt poultry benefits the most from use of exogenous enzymes and is becoming a norm to utilize the undigested parts and to overcome the adverse effects as well. However, the biological reality is that there are some limits, imposed by different physiological conditions in the digestive tract, to enzyme responses. The dilemma faced by the users of exogenous enzymes is that bird responses to feed enzyme applications are variable and not entirely predictable. The large variations in the bird's physiological parameters is an important factor behind this.
Underdeveloped digestive capacity brings potential benefits for exogenous enzyme usages, such as protease, lipase, and amylases. This is scientifically proven the benefits of such enzymes generally diminish with age and responses are usually greater during early life. As the bird becomes mature, the digestibility increases in general and lowers the efficacy of feed enzymes.
As per enzyme kinetics, product concentration, [P] is inversely proportional to enzyme reactions and there is a thumb rule, for each 1% improvement in the digestibility, there is a 5% decrease in enzyme effectiveness. Thus in most cases, the use of exogenous enzymes can bring more positive response only if the dietary nutrient concentration is marginal and enzymes can get space to contribute. This is best described by the law of diminishing return theory of xylanase use described by several scientists. Another simple example is dietary phosphorus level and microbial phytases; if the diets contain excess amounts of phosphorus, then the chance of response to phytase addition will be low.
The passage of feed in the GIT of poultry is relatively rapid and the average retention time in the functional area is probably around 3 to 4 h. On the other hand, practices of ad libitum feeding and use of finely ground pellet feeds hamper the normal functions of crop and gizzard, leading to reduced retention time. Less time for action is a potential threat for optimum effects by enzymes. For example, digesta possibly spends only 60 to 90 min in the anterior digestive tract (crop, proventriculus and gizzard), giving limited opportunity for the enzyme action that are considered as best performers at this segment, such as phytase. Manipulation of retention time by feeding coarse feed and practicing intermittent feeding systems can be a potential strategy to overcome this physiological limitation. Superdosing can benefit by quick dephosphorylation of phytate at early phase of digestion. Moisture content is an essential factor for the initiation of enzyme activity. Rapid passage of finely grinded pellet feed gets less time in the crop. This may cause delay in moisturizing the feed with sufficient water and delaying the enzyme activation.
Enzymes are sensitive to pH and each enzyme has an optimal pH point for its optimum performance. Changing the pH of its surroundings will also change the shape of the active site of an enzyme. Therefore, wide varieties of pH changes in different parts of the poultry digestive system are great limitations for consistent enzyme efficacy. For example, Phytic acid phosphate groups are protonated at low pH, allowing their effective hydrolysis by phytases. Therefore, phytase should be active in the crop and proventriculus of birds as the optimal pH for phytase activity typically varies over a range of 2.5 to 5.5. On the other hand, at high pH phytase becomes more complex with positive metal ions in the lower segment of gut favoring them merely hydrolysis by the enzymes.
Therefore, to secure benefits in poultry by using of exogenous enzyme there are some physiological aspects you must keep in mind. Enzyme of your interest must be compliance with the physiological condition of bird.
References
1) V. Ravindran, Feed enzymes: The science, practice, and metabolic realities, 2013 J. Appl. Poult. Res. 22 :628–636.
2) Nutrition of the Chicken, 4th edition b Steeve Leeson.
Karnataka Veterinary, Animal and Fisheries Sciences University
5 de agosto de 2021
Use of exogenous enzymes and is becoming a norm to utilize the undigested parts and to overcome the adverse effects as well. It depends on the selection of feed ingredients to be incorporated in the feed .Underdeveloped digestive capacity brings potential benefits for exogenous enzyme usages, such as protease, lipase, and amylases. The birds physiology varies with the age This is scientifically proven the benefits of such enzymes generally diminish with age and responses are usually greater during early life. Therefore selection of enzymes are important as per age and the type of ingredients used in the feed. However it is beneficial and cost saving if properly designed by a nutritionist.
The basic nutrients that poultry birds require for maintenance, growth and reproduction include carbohydrates, proteins, minerals and vitamins. The energy and protein are the most important as well as expensive nutrients in poultry diet. Maize and soyabean meal are the conventional feed ingredients commonly used in poultry industry because of its nutrients composition and digestibility. In recent year skyrocketing prices of conventional protein sources like soyabean meal, has leads to increase in feed cost and production cost of chicken. Today's biggest challenge in poultry industry is optimising feed cost by using alternative non-conventional protein sources like DDGS, Maize Gluten, Rapeseed Meal, Groundnut Cake, Cotton Seed Cake, Guar Meal, Sunflower Meal, etc. There are some limitations in using such alternative ingredients due to poor nutrient digestibility and presence of anti-nutritional factors like non starch polysaccharides (NSP's), phytate and protease inhibitors. Anti-nutritional factors are inhibiting normal feed digestion, & thereby bird's health results to compromised performance.
Use of exogenous enzymes like protease, xylanase, mannanase, phytase, etc. gives flexibility in using alternative ingredients without compromising bird's performance by reducing anti-nutritional effects and improving nutrients availability.
PROMAXYL-a is a comprehensive solution designed through extensive research and substrate consideration over the lifetime of the birds. It is combination of Protease (Acid, Alkaline and neutral), endo 1,4-ß- Xylanase, endo 1,4-ßMannanase, a Amylase and 6 Phytase for more nutrient release. PROMAXYL-a targets the major anti-nutritional factors increases the digestibility and utilization of nutrients in poultry by improved utilization of phytate phosphorous, non-starch polysaccharides, starch, proteins and amino acids. It gives flexibility for using non-conventional feed ingredients. It will provide up to 115 Kcal/ kg energy and 3 % protein of total CP present in feed. It enables producers to naturally enhance the growth of their birds, lower feed cost and maximize profits.
The passage of feed in the GIT of poultry is relatively rapid and the average retention time in the functional area is probably around 3 to 4 h. On the other hand, practices of ad libitum feeding and use of finely ground pellet feeds hamper the normal functions of crop and gizzard, leading to reduced retention time. Less time for action is a potential threat for optimum effects by enzymes. For example, digesta possibly spends only 60 to 90 min in the anterior digestive tract (crop, proventriculus and gizzard), giving limited opportunity for the enzyme action that are considered as best performers at this segment, such as phytase. Manipulation of retention time by feeding coarse feed and practicing intermittent feeding systems can be a potential strategy to overcome this physiological limitation. Superdosing can benefit by quick dephosphorylation of phytate at early phase of digestion. Moisture content is an essential factor for the initiation of enzyme activity. Rapid passage of finely grinded pellet feed gets less time in the crop. This may cause delay in moisturizing the feed with sufficient water and delaying the enzyme activation.
