Feed Formula Design Experience Sharing: My Formula Insights, Part Two
Feed Formula Design Insights: My Formula Insights, Part Two
Feed formula design is a very interesting and highly logical task, and it also contains a lot of dialectical elements. A formula is not simply mixing several ingredients together; it requires not only a deep understanding of animal physiology, biochemistry, and organic chemistry, but also a thorough command of feeding standards, the types and usage characteristics of feed ingredients, and nutrient composition, while being able to flexibly apply feeding standards according to actual conditions. Below are some insights I gained while making formulas at a feed mill, for the reference of fellow professionals.
1 Must pay attention to feed palatability and raw material quality
Some formulators, when making feed formulas, merely mechanically enter various feed ingredients into formula software, then click "linear programming." As long as the resulting formula's nutrient composition meets the target, they print the formula and hand it to production, and consider everything done. In fact, doing so is extremely irresponsible. Although the formula's nutrition meets the target, whether the animal "customer" likes the feed is what matters most. Because if the feed's palatability is very poor, animals will eat very little or simply refuse it. Therefore, when selecting raw materials, one must choose ingredients with good palatability, fresh and not deteriorated. Formulators should not just sit in the office facing a computer making formulas every day. Before making each batch of feed, they must personally go to inspect the quality of the raw materials, and when necessary, personally taste the palatability of the raw materials. Also, after the feed is made, they should check whether the feed's color and smell meet the standard. Some feed mills often like to make special small-package premixes for anti-stress, increasing lean meat percentage, and promoting animal growth, because relatively speaking such small-package premixes have obvious effects and higher profits. For example, once I made a small-package premix for controlling mosquitoes and flies on farms. The main component of this premix is called cyromazine, whose main function is to kill the eggs of mosquitoes and flies. When making this premix, I did not notice that cyromazine has a rather unpleasant smell, and I only added some carriers and antibiotics to the formula. As a result, customers reported that pigs refused feed containing this premix. Later, when adjusting the formula, I added flavoring agents and sweeteners, and afterward this premix always had a very good market response. Another similar incident was that some customers complained that one of our company's premixes (main components were sulfonamides and sulfonamide potentiators) did not have a very good growth-promoting effect, so the dosage of sulfonamides and sulfonamide potentiators was increased twofold. The result was the same as in the previous example: the animals still refused this premix. The reason is actually very simple, because these medicinal additives inherently have poor taste and palatability, and when the dosage is increased, the unpleasant smell inevitably increases. So the dosage of sulfonamides and sulfonamide potentiators was changed to 1.5 times the original dosage, and some flavoring agents were also added. In this way, the formula's effect became much better.
One point to emphasize is that attention must be paid to the quality of feed raw materials, such as rice bran, wheat bran, and other ingredients. Fresh rice bran smells slightly fragrant, tastes sweet when held in the mouth, and generally contains green husk fragments, which indicates fresh rice bran. This kind of rice bran can be used at up to 50% in duck feed. However, because rice bran has a very high fat content, especially in the summer in the south, it easily becomes rancid (in about 5 days), so when using it in pig feed, special care must be taken, because pigs have a very sensitive sense of smell. Avoid using it if possible, and cassava can be used instead. Wheat bran and wheat middlings are actually also a type of raw material that easily becomes rancid, but many formulators overlook this point. Therefore, when using wheat bran, attention must also be paid to its freshness, otherwise animals may refuse to eat. Fishmeal is a very good raw material, but fishmeal adulteration (urea, protein powder) is the most serious problem. Once, our company's suckling pig feed caused severe diarrhea. Methods such as reducing protein, adding zinc oxide, and citric acid could not solve it. Later, we had no choice but to send various raw materials for testing. Other raw materials were all normal, and only fishmeal was found upon testing to contain ammonium salts. At that time, the fishmeal was removed from the formula, and the diarrhea problem was immediately solved. Because the quality of fishmeal is difficult to control, some companies can buy dried fish themselves and then process it into fishmeal. The price of dried fish is 3400 yuan/ton, and the processing cost is 50 yuan/ton, which is even cheaper than soybean meal. This kind of fishmeal not only reduces cost but also ensures quality.
2 Pay attention to distortion of the formula
A good finished feed is determined by many factors, including: a good feed formula, good raw materials, and a good processing technology, among others. An excellent formula is not difficult to make, but due to factors such as the actual quality of raw materials and actual processing, the product cannot faithfully reflect the quality of the formula. The reasons are roughly as follows: ① Variation in the nutrient composition of raw materials. The reason for variation is that even for the same raw material, due to differences in place of origin, environment, harvest timing, processing, storage and transportation methods, moisture, degree of mold contamination, and so on, its nutrient composition will vary greatly. Therefore, the quality control department must provide the formulator with accurate nutrient composition data for various raw materials. Do not assume that soybean meal protein is necessarily 43% or 46%; it may also be 44% or 40%. Also, take corn: generally speaking, Northeast corn protein is relatively low, while Henan and Hebei corn protein is relatively high. Do not assume that because corn is an energy feed, its protein does not need to be tested, because corn is used at a very large proportion in feed formulas. If its protein is one percentage point lower or higher, it will have a great impact on the formula's nutrient composition and cost. If corn's actual protein is 8%, and it is treated as 8.7% when calculating the formula, then the formula made in this way will inevitably have a protein level that does not meet the animal's actual nutritional needs. Conversely, if corn's actual protein is 8.7% and it is treated as 8.0% when calculating the formula, such a formula not only wastes protein raw materials but also invisibly increases formula cost. ② The influence of various factors in the feed processing process. Because many formulators come purely from an animal nutrition background, they consider feed processing relatively little, only thinking about completing the formula and not considering much the impact of processing on the formula. The factors causing formula distortion due to feed processing are also many-sided, including the effects of grinding particle size, mixing uniformity, and batching accuracy. Because different animals have different requirements for feed particle size, only when the particle size meets the requirement can animals achieve optimal digestibility. Also, there is the issue of mixing uniformity, especially the uniformity of premixes. If mixing is not uniform, animals may suffer from trace element deficiency, and even more seriously, poisoning. This is especially true for certain medicinal additives, such as maduramicin, whose normal dosage is 5 ppm, but if it exceeds 6 ppm, it will cause poisoning in chickens. Therefore, even more attention must be paid to the effects of mixing uniformity and batching accuracy. Use large scales for large dosages and small scales for small dosages, and when necessary use stepwise dilution, so as to ensure that medicinal additives are uniformly mixed. The feed processing process can also affect nutrient composition. Some formulators say that during processing raw materials will be lost, causing the formula's actual nutrient content to be lower than the formula's intended content, so when designing the formula they add a safety margin. But some formulators lower certain standards when making formulas, because during feed processing the moisture in raw materials will be lost, resulting in the feed's nutrient composition being higher than the formula's nutrient composition. Each of these two practices has its own rationality, but I think the best method is to send the finished feed to the laboratory to check the nutrient composition and see whether the formula has been distorted.
3 Use scientific methods to formulate feed
With the continuous progress of animal nutrition, new diet technologies are becoming increasingly mature. These technologies include: low-protein diets, the application of net energy in monogastric animals, and formulating diets using digestible amino acids and protein, among others. The application of these technologies not only reduces formula cost and lowers nitrogen excretion, but also makes the formula's nutrient composition closer to the animal's nutritional needs. In particular, low-protein diet technology has already become very mature in its application to pig feed. The protein level of pig feed can now be reduced by 3-4% while achieving the same growth performance as high-protein diets, but when reducing protein, the following points must be noted: (1) The energy and lysine levels of the low-protein diet must remain consistent with those of the high-protein diet; (2) Formulate the diet using an amino acid balance model; (3) Add individual amino acids to the diet; (4) For the essential amino acid levels of diets based on miscellaneous meals, correction should be made using amino acid true ileal digestibility (pigs) or amino acid true digestibility (chickens). However, for broiler feed, even reducing by 1-2 percentage points is relatively difficult, because threonine is the third limiting amino acid for broilers and cannot enter the feed formula. But experiments have also shown that reducing protein in the diet of medium broilers by 7% (with glutamine added to the diet) did not cause a significant decline in broiler growth performance. Therefore, low-protein broiler diets should be a hot spot and key focus of future animal nutrition research. Once successful, their economic value will be inestimable.
Another point is the application of net energy in monogastric animals. When using digestible energy or net energy, the energy of protein or fiber is overestimated, while the energy of carbohydrates is underestimated. For example, corn and soybean meal have similar ME and DE, but if their NE is compared, corn NE is 2650 and soybean meal NE is 1940. Therefore, when DE is used to design formulas, the formula is unreasonable and uneconomical. However, NE data for various raw materials are relatively lacking, and we can refer to Ajinomoto's net energy calculator. When using net energy to make formulas, the cost per ton of feed can be reduced by 5-7 yuan. The last technology is to formulate diets using digestible amino acids. A very simple example: some formulators use 13% soybean meal when making laying duck feed, while some formulators do not use any soybean meal at all, yet also achieve the same production level as diets with high soybean meal usage. What is the reason? The answer is to use digestible amino acids to formulate diets based on miscellaneous meals. Of course, purely corn-soybean meal diets are very easy to formulate into nutritionally balanced diets, but now corn and soybean meal have reached sky-high prices. A formulator who uses corn-soybean meal diets all day long will inevitably lead to the decline of a feed enterprise. It can be said that being able to use digestible amino acid values is now the key to success in least-cost feed formulation. Because pigs have relatively high requirements for feed palatability, it is unlikely that purely miscellaneous meal diets can be applied to pig diets. Because poultry have an underdeveloped sense of taste, we can boldly use the digestible amino acid model, and we should abandon the formula mindset of using large amounts of soybean meal for laying ducks and chicks (ducks). There is already a lot of information on true amino acid digestibility for chicken feed, but there is very little information on ducks, and generally chicken values are referenced, but this method often underestimates the nutritional value of various raw materials for ducks, because ducks have greater digestive capacity than chickens. Even formulas made using such reference values usually perform better than formulas using total amino acid values.
4 Formulate duck feed according to the growth characteristics of ducks
Meat ducks have the characteristics of fast growth and high feed conversion efficiency, and duck farming has developed rapidly in recent years. However, nutritional research on ducks has not kept up with the development of the meat duck farming industry. In particular, many formulators feel uncertain when making duck feed formulas, because there is very little data on ducks. Take the metabolizable energy of soybean meal alone: for ducks it is 2856 Mcal/KG, while for chickens it is 2467 Mcal/KG. So if chicken feed metabolizable energy values are still referenced in the formula, it is unscientific. NRC already has sufficient data on digestible amino acids for pigs and chickens, while reports on digestible amino acids for ducks are still rare. Therefore, if one wants to use digestible amino acids to formulate duck feed, one must still refer to chicken data. Ducks have far greater digestive capacity than chickens, especially medium and large ducks, whose daily feed intake is about 0.2 kg, while that of medium and large chickens is only 0.1 kg. Therefore, when formulating duck feed, the factor of duck feed intake must be considered. If the protein for medium and large chickens is set at 17 and energy at 3000 Mcal/KG, then the protein for medium and large ducks can be set between 12.5-16%, and energy can be set between 2350-2600 Mcal/KG, because when formulating feed we must consider the protein-to-energy ratio and daily feed intake. As long as the protein-to-energy ratio of medium and large ducks is maintained above 45, good production performance can be achieved. Since ducks have relatively large feed intake, when setting the energy and protein levels for ducks, there can be a relatively large range of variation compared with the nutritional levels for broilers. For laying ducks, because the energy requirement is not high, keeping energy at 2400-2600 Mcal/KG and protein above 16.5, with a minimum energy-to-protein ratio of 70, can achieve maximum egg production rate and egg weight.
In short, feed formula design is a highly technical and artistic task. It requires advanced theoretical knowledge as guidance, requires experience accumulated over time, and only by studying and thinking more and practicing more can we make a formula with very high cost performance.
This is an article I wrote in 2007, but I never dared to publish it. Looking at it now, some views are very naive. Please forgive me, Dr. Wang.
--------------------------------------
Hey, buddy, I waited so long. I opened your post, but you deleted it again.
--------------------------------------
Aren't you just messing with people? Is there anything or not?
--------------------------------------
Typical teasing, an ad post.
--------------------------------------
Could you?
[email protected]
Thanks
--------------------------------------
What are you coughing about? So tiring.
--------------------------------------
Can you let me learn from it?
[email protected]
Thanks
--------------------------------------
Could you let me take a look? [email protected] Reply to give me some comfort, haha.
--------------------------------------
Already re-edited. Sorry, everyone.
--------------------------------------
Well written, I learned something.
--------------------------------------
I've wanted to read about this for a long time. Thanks!!! Just in time!!!
--------------------------------------
But for broiler feed, even reducing by 1-2 percentage points is relatively difficult, because threonine is the third limiting amino acid for broilers and cannot enter the feed formula.
------------------I don't understand this sentence? Please enlighten me.
1 Must pay attention to feed palatability and raw material quality
Some formulators, when making feed formulas, merely mechanically enter various feed ingredients into formula software, then click "linear programming." As long as the resulting formula's nutrient composition meets the target, they print the formula and hand it to production, and consider everything done. In fact, doing so is extremely irresponsible. Although the formula's nutrition meets the target, whether the animal "customer" likes the feed is what matters most. Because if the feed's palatability is very poor, animals will eat very little or simply refuse it. Therefore, when selecting raw materials, one must choose ingredients with good palatability, fresh and not deteriorated. Formulators should not just sit in the office facing a computer making formulas every day. Before making each batch of feed, they must personally go to inspect the quality of the raw materials, and when necessary, personally taste the palatability of the raw materials. Also, after the feed is made, they should check whether the feed's color and smell meet the standard. Some feed mills often like to make special small-package premixes for anti-stress, increasing lean meat percentage, and promoting animal growth, because relatively speaking such small-package premixes have obvious effects and higher profits. For example, once I made a small-package premix for controlling mosquitoes and flies on farms. The main component of this premix is called cyromazine, whose main function is to kill the eggs of mosquitoes and flies. When making this premix, I did not notice that cyromazine has a rather unpleasant smell, and I only added some carriers and antibiotics to the formula. As a result, customers reported that pigs refused feed containing this premix. Later, when adjusting the formula, I added flavoring agents and sweeteners, and afterward this premix always had a very good market response. Another similar incident was that some customers complained that one of our company's premixes (main components were sulfonamides and sulfonamide potentiators) did not have a very good growth-promoting effect, so the dosage of sulfonamides and sulfonamide potentiators was increased twofold. The result was the same as in the previous example: the animals still refused this premix. The reason is actually very simple, because these medicinal additives inherently have poor taste and palatability, and when the dosage is increased, the unpleasant smell inevitably increases. So the dosage of sulfonamides and sulfonamide potentiators was changed to 1.5 times the original dosage, and some flavoring agents were also added. In this way, the formula's effect became much better.
One point to emphasize is that attention must be paid to the quality of feed raw materials, such as rice bran, wheat bran, and other ingredients. Fresh rice bran smells slightly fragrant, tastes sweet when held in the mouth, and generally contains green husk fragments, which indicates fresh rice bran. This kind of rice bran can be used at up to 50% in duck feed. However, because rice bran has a very high fat content, especially in the summer in the south, it easily becomes rancid (in about 5 days), so when using it in pig feed, special care must be taken, because pigs have a very sensitive sense of smell. Avoid using it if possible, and cassava can be used instead. Wheat bran and wheat middlings are actually also a type of raw material that easily becomes rancid, but many formulators overlook this point. Therefore, when using wheat bran, attention must also be paid to its freshness, otherwise animals may refuse to eat. Fishmeal is a very good raw material, but fishmeal adulteration (urea, protein powder) is the most serious problem. Once, our company's suckling pig feed caused severe diarrhea. Methods such as reducing protein, adding zinc oxide, and citric acid could not solve it. Later, we had no choice but to send various raw materials for testing. Other raw materials were all normal, and only fishmeal was found upon testing to contain ammonium salts. At that time, the fishmeal was removed from the formula, and the diarrhea problem was immediately solved. Because the quality of fishmeal is difficult to control, some companies can buy dried fish themselves and then process it into fishmeal. The price of dried fish is 3400 yuan/ton, and the processing cost is 50 yuan/ton, which is even cheaper than soybean meal. This kind of fishmeal not only reduces cost but also ensures quality.
2 Pay attention to distortion of the formula
A good finished feed is determined by many factors, including: a good feed formula, good raw materials, and a good processing technology, among others. An excellent formula is not difficult to make, but due to factors such as the actual quality of raw materials and actual processing, the product cannot faithfully reflect the quality of the formula. The reasons are roughly as follows: ① Variation in the nutrient composition of raw materials. The reason for variation is that even for the same raw material, due to differences in place of origin, environment, harvest timing, processing, storage and transportation methods, moisture, degree of mold contamination, and so on, its nutrient composition will vary greatly. Therefore, the quality control department must provide the formulator with accurate nutrient composition data for various raw materials. Do not assume that soybean meal protein is necessarily 43% or 46%; it may also be 44% or 40%. Also, take corn: generally speaking, Northeast corn protein is relatively low, while Henan and Hebei corn protein is relatively high. Do not assume that because corn is an energy feed, its protein does not need to be tested, because corn is used at a very large proportion in feed formulas. If its protein is one percentage point lower or higher, it will have a great impact on the formula's nutrient composition and cost. If corn's actual protein is 8%, and it is treated as 8.7% when calculating the formula, then the formula made in this way will inevitably have a protein level that does not meet the animal's actual nutritional needs. Conversely, if corn's actual protein is 8.7% and it is treated as 8.0% when calculating the formula, such a formula not only wastes protein raw materials but also invisibly increases formula cost. ② The influence of various factors in the feed processing process. Because many formulators come purely from an animal nutrition background, they consider feed processing relatively little, only thinking about completing the formula and not considering much the impact of processing on the formula. The factors causing formula distortion due to feed processing are also many-sided, including the effects of grinding particle size, mixing uniformity, and batching accuracy. Because different animals have different requirements for feed particle size, only when the particle size meets the requirement can animals achieve optimal digestibility. Also, there is the issue of mixing uniformity, especially the uniformity of premixes. If mixing is not uniform, animals may suffer from trace element deficiency, and even more seriously, poisoning. This is especially true for certain medicinal additives, such as maduramicin, whose normal dosage is 5 ppm, but if it exceeds 6 ppm, it will cause poisoning in chickens. Therefore, even more attention must be paid to the effects of mixing uniformity and batching accuracy. Use large scales for large dosages and small scales for small dosages, and when necessary use stepwise dilution, so as to ensure that medicinal additives are uniformly mixed. The feed processing process can also affect nutrient composition. Some formulators say that during processing raw materials will be lost, causing the formula's actual nutrient content to be lower than the formula's intended content, so when designing the formula they add a safety margin. But some formulators lower certain standards when making formulas, because during feed processing the moisture in raw materials will be lost, resulting in the feed's nutrient composition being higher than the formula's nutrient composition. Each of these two practices has its own rationality, but I think the best method is to send the finished feed to the laboratory to check the nutrient composition and see whether the formula has been distorted.
3 Use scientific methods to formulate feed
With the continuous progress of animal nutrition, new diet technologies are becoming increasingly mature. These technologies include: low-protein diets, the application of net energy in monogastric animals, and formulating diets using digestible amino acids and protein, among others. The application of these technologies not only reduces formula cost and lowers nitrogen excretion, but also makes the formula's nutrient composition closer to the animal's nutritional needs. In particular, low-protein diet technology has already become very mature in its application to pig feed. The protein level of pig feed can now be reduced by 3-4% while achieving the same growth performance as high-protein diets, but when reducing protein, the following points must be noted: (1) The energy and lysine levels of the low-protein diet must remain consistent with those of the high-protein diet; (2) Formulate the diet using an amino acid balance model; (3) Add individual amino acids to the diet; (4) For the essential amino acid levels of diets based on miscellaneous meals, correction should be made using amino acid true ileal digestibility (pigs) or amino acid true digestibility (chickens). However, for broiler feed, even reducing by 1-2 percentage points is relatively difficult, because threonine is the third limiting amino acid for broilers and cannot enter the feed formula. But experiments have also shown that reducing protein in the diet of medium broilers by 7% (with glutamine added to the diet) did not cause a significant decline in broiler growth performance. Therefore, low-protein broiler diets should be a hot spot and key focus of future animal nutrition research. Once successful, their economic value will be inestimable.
Another point is the application of net energy in monogastric animals. When using digestible energy or net energy, the energy of protein or fiber is overestimated, while the energy of carbohydrates is underestimated. For example, corn and soybean meal have similar ME and DE, but if their NE is compared, corn NE is 2650 and soybean meal NE is 1940. Therefore, when DE is used to design formulas, the formula is unreasonable and uneconomical. However, NE data for various raw materials are relatively lacking, and we can refer to Ajinomoto's net energy calculator. When using net energy to make formulas, the cost per ton of feed can be reduced by 5-7 yuan. The last technology is to formulate diets using digestible amino acids. A very simple example: some formulators use 13% soybean meal when making laying duck feed, while some formulators do not use any soybean meal at all, yet also achieve the same production level as diets with high soybean meal usage. What is the reason? The answer is to use digestible amino acids to formulate diets based on miscellaneous meals. Of course, purely corn-soybean meal diets are very easy to formulate into nutritionally balanced diets, but now corn and soybean meal have reached sky-high prices. A formulator who uses corn-soybean meal diets all day long will inevitably lead to the decline of a feed enterprise. It can be said that being able to use digestible amino acid values is now the key to success in least-cost feed formulation. Because pigs have relatively high requirements for feed palatability, it is unlikely that purely miscellaneous meal diets can be applied to pig diets. Because poultry have an underdeveloped sense of taste, we can boldly use the digestible amino acid model, and we should abandon the formula mindset of using large amounts of soybean meal for laying ducks and chicks (ducks). There is already a lot of information on true amino acid digestibility for chicken feed, but there is very little information on ducks, and generally chicken values are referenced, but this method often underestimates the nutritional value of various raw materials for ducks, because ducks have greater digestive capacity than chickens. Even formulas made using such reference values usually perform better than formulas using total amino acid values.
4 Formulate duck feed according to the growth characteristics of ducks
Meat ducks have the characteristics of fast growth and high feed conversion efficiency, and duck farming has developed rapidly in recent years. However, nutritional research on ducks has not kept up with the development of the meat duck farming industry. In particular, many formulators feel uncertain when making duck feed formulas, because there is very little data on ducks. Take the metabolizable energy of soybean meal alone: for ducks it is 2856 Mcal/KG, while for chickens it is 2467 Mcal/KG. So if chicken feed metabolizable energy values are still referenced in the formula, it is unscientific. NRC already has sufficient data on digestible amino acids for pigs and chickens, while reports on digestible amino acids for ducks are still rare. Therefore, if one wants to use digestible amino acids to formulate duck feed, one must still refer to chicken data. Ducks have far greater digestive capacity than chickens, especially medium and large ducks, whose daily feed intake is about 0.2 kg, while that of medium and large chickens is only 0.1 kg. Therefore, when formulating duck feed, the factor of duck feed intake must be considered. If the protein for medium and large chickens is set at 17 and energy at 3000 Mcal/KG, then the protein for medium and large ducks can be set between 12.5-16%, and energy can be set between 2350-2600 Mcal/KG, because when formulating feed we must consider the protein-to-energy ratio and daily feed intake. As long as the protein-to-energy ratio of medium and large ducks is maintained above 45, good production performance can be achieved. Since ducks have relatively large feed intake, when setting the energy and protein levels for ducks, there can be a relatively large range of variation compared with the nutritional levels for broilers. For laying ducks, because the energy requirement is not high, keeping energy at 2400-2600 Mcal/KG and protein above 16.5, with a minimum energy-to-protein ratio of 70, can achieve maximum egg production rate and egg weight.
In short, feed formula design is a highly technical and artistic task. It requires advanced theoretical knowledge as guidance, requires experience accumulated over time, and only by studying and thinking more and practicing more can we make a formula with very high cost performance.
This is an article I wrote in 2007, but I never dared to publish it. Looking at it now, some views are very naive. Please forgive me, Dr. Wang.
--------------------------------------
Hey, buddy, I waited so long. I opened your post, but you deleted it again.
--------------------------------------
Aren't you just messing with people? Is there anything or not?
--------------------------------------
Typical teasing, an ad post.
--------------------------------------
Could you?
[email protected]
Thanks
--------------------------------------
What are you coughing about? So tiring.
--------------------------------------
Can you let me learn from it?
[email protected]
Thanks
--------------------------------------
Could you let me take a look? [email protected] Reply to give me some comfort, haha.
--------------------------------------
Already re-edited. Sorry, everyone.
--------------------------------------
Well written, I learned something.
--------------------------------------
I've wanted to read about this for a long time. Thanks!!! Just in time!!!
--------------------------------------
But for broiler feed, even reducing by 1-2 percentage points is relatively difficult, because threonine is the third limiting amino acid for broilers and cannot enter the feed formula.
------------------I don't understand this sentence? Please enlighten me.