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Amino Acids for Animal Health

Posted January 30, 2019

Amino acids are the building blocks of proteins and polypeptides that are the major component of animals’ muscles and tissues. Amino acids also form an important component in some fluids such as milk. In addition to being building blocks of body proteins, amino acids play a significant role in various important biochemical and metabolic processes in the cells of animals. So, from growth to production and reproduction, amino acids play a large part in the productivity of farm animals and can contribute significantly to the profitability of a farm.

The composition of amino acids in feeds is very variable, so it is important to closely monitor feed quality to ensure that animals are consuming appropriate amounts of amino acids to maintain their health and productivity while maximizing profitability. Here we've compiled the basic information you need to know about amino acids and their benefits in animal nutrition.

What Are Essential Amino Acids?

There are 20 unique amino acids1 that have been genetically coded each containing carbon, nitrogen, oxygen, hydrogen and sometimes sulfur in different quantities and configurations. These amino acids combine in different chain configurations of 50 or more to create a single protein within the animal body. These proteins then operate within the body to sustain life functions. Amino acids are classified into two categories as essential and non-essential and these will be described below.

To synthesize proteins within the body, animals need raw amino acids as building blocks. In feedstuffs, amino acids are present within the protein chains, which are then broken down during digestion by enzymes in the gastrointestinal tract. Once processed down to individual amino acids, the amino acids are absorbed into the bloodstream to be used to form new proteins.

Essential amino acids: These are amino acids that the animal cannot make by itself and must be provided through dietary intake to ensure normal function of the animal. They include phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, histidine, arginine (sometimes considered to be non-essential), leucine and lysine.

02 - Essential Amino Acids

Non-essential amino acids: These are amino acids that can be synthesized within the animal’s body, usually from other amino acids or other compounds. They include alanine, aspartic acid, cysteine, cystine, glutamic acid, glycine, hydroxyproline, proline, serine and tyrosine.

While "non-essential" amino acids can be synthesized by the animal’s body and do not need to be provided in the diet, they still play important roles in the body. The term “non-essential” does not relate to their biological significance. They have historically been treated as unimportantfrom a dietary standpoint, but recent scientific studies have proved this viewpoint to be false. Despite their name, non-essential amino acids are important for producing proteins that fuel metabolism and digestion, regulate gene expression, signal cells, produce antioxidative responses, manage fertility, support neurotransmission and provide immune responses.

Regardless of whether an amino acid is termed essential or non-essential, animals need sufficient amounts of all amino acids to meet their metabolic needs, whether they need to produce milk, build muscle and tissues or reproduce. Depending on what each animal needs, it may produce different proteins in varying amounts, which may require a different number of specific amino acids. As such, an animal's amino acid intake requirement may change based on its stage of life. For example, a pregnant cow has different amino acid needs compared to a milk-producing cow because the protein quantities they require are slightly different.

The protein-producing potential of an animal is limited by the quantities of amino acids in its body. Since certain proteins require specific amino acids, if the body cannot synthesize enough of a single amino acid or it is not supplied in adequate amount in the diet, it will not be able to produce certain types of proteins required for certain processes. The amino acid in shortest supply is referred to as the "first-limiting" amino acid in the diet. The requirement for certain amino acids will vary depending on the species, gender, diet and stage of life of the animal. For example, lysine and methionine are typical first-limiting amino acids in dairy cows.

Identifying this first-limiting amino acid is extremely important for production purposes since animals cannot reach production levels of protein synthesis without sufficient quantities of first-limiting amino acids; no matter how much lysine you feed a dairy cow, if methionine is the first-limiting amino acid, the animal may not synthesize enough proteins to produce the desired quantities of milk. For this reason, providing sufficient amounts of all essential amino acids in the diets of production animals is paramount.

Problems Associated With Lack of Amino Acids in Farm Animal Diets

If an animal is not provided sufficient quantities of certain essential amino acids in its diet, the animal cannot produce enough proteins to support certain metabolic functions. From a production standpoint, failing to provide enough amino acids in an animal's diet will result in reduced overall performance, which can significantly reduce profitability. Here are just a few problems associated with inadequate supply of amino acids for livestock:

1. Changes in Intake

One of the first and most important signs of an amino acid imbalance in the feed of a herd is a reduction in feed intake. Although most animals will initially eat more food to try to compensate for the deficiency, after a few days the animals will decrease their food intake substantially. This decrease in intake occurs because amino acid imbalances in food result in reduced hunger in many species. This can contribute to further nutritional deficiencies and subsequently lead to low performance and health problems.

2. Low Body Weight

In both young and adult animals, amino acid deficiencies contribute to low body weight and a general reduction in muscle development. For younger animals, this can have long-lasting effects, including a reduced growth rate, a prolonged time to reach maturity and reduced size at maturity. This low body weight cannot be fixed through force-feeding3. Studies have shown that even when animals are forced to eat sufficient calories if the diet is missing amino acids, the animal will still experience morphological problems and will often continue to lose weight.

03 - Lack of Amino Acids

3. Reduced Production

In dairy cows, an inadequate supply of amino acids will result in reduced milk production. In poultry, an overall reduction in the size and quantity of eggs produced has been reported. Amino acids are the building blocks of tissues and milk proteins, so that any deficiency will reduce production.

4. Disease

Amino acids are essential for animal health, contributing to the maintenance of numerous metabolic functions, including maintenance and immune responses. If certain amino acids are missing from an animal's diet, it may experience reduced immune and metabolic responses, leaving its body more vulnerable to diseases, and, in severe cases, mortality.

Although amino acid deficiencies can result in low performance and health problems, they can be prevented through dietary manipulations, such as adjusting the types and quantities of the various common feeds. However, these adjustments have limitations because the traditional feeds vary in amino acid composition, and their combination may not always achieve the correct proportion of amino acids required to maintain production and health of the animal. The use of specific proteins or amino acids offers a more flexible and targeted solution for manipulating animal diets to achieve the required level and ratios of amino acids. 

04 - Feed Mechanisms

Challenges With Feeding Amino Acids to Ruminates

One of the biggest challenges with supplementing amino acids to ruminants (cows, goats and sheep) is the rumen, or first stomach. The rumen is the habitat to many microbes that ferment almost any feed or compound that is not protected. So, if unprotected amino acids are fed to ruminants, they will be degraded by the rumen microbes, which may be a waste.

To manage this problem and ensure that ruminants get the amino acids they need in adequate quantities, animal health and nutrition companies have found ways to feed amino acids directly to the small intestine. This is often accomplished by employing two mechanisms:

Rumen Protection: Rumen-protected amino acids are protected from the environment of the rumen so that they can reach the small intestine more consistently while avoiding degradation. Note that 100% protection may not be possible or ideal as this may lead to complete protection even in the small intestine, and the amino acids will be passed out through the feces.

Intestinal Availability: Amino acids are useless if the intestine can't absorb them after passing through the rumen. Some amino acid products fail to release the amino acid at this point, and the amino acid is excreted in the feces. To avoid this, feed producers have developed products that release the rumen-protected amino acid after passing through the rumen so that it can be absorbed in the intestine.

A great example of a product that exhibits these features is LysiPEARL™ by Kemin. LysiPEARL™ is a highly efficient, concentrated, consistent, and rumen-protected lysine source. Historically, blood meal has been used to get lysine through the rumen and into the bloodstream, but this product tended to be unreliable and often resulted in the excretion of excess nitrogen into the environment. LysiPEARL™ delivers more consistent performance without the same level of nitrogen excretion.

Benefits of Amino Acids for Animal Production

Numerous feeding trials over the past several decades have shown that protein supplements can increase production for milk and eggs in livestock and poultry, respectively. While the exact mechanism and amino acid balances differ based on the species and type of feed being used, cows, sheep and chickens all exhibited increased production when fed increased amounts of amino acids in their respective diets.

 1. Amino Acids for Ruminates

For cattle and sheep specifically, introducing more dietary protein and a better amino acid makeup to cows can increase milk production substantially. Depending on diet, the limiting amino acids for milk production can be methionine, lysine or any other amino acid. However, research suggests that increasing overall amino acid availability to the small intestine results in an increase in production attributed to the increased availability of disposable non-essential amino acids. In cows specifically, the delivery of high-quality protein with a well-balanced spread of amino acids was seen to produce a curvilinear increase in milk production4, leveling out as the cows reached their genetic limits.

2. Amino Acids for Poultry

Studies of egg-laying hens found similar results when fed more amino acids. Hens consistently produced more eggs of larger sizes. Unlike cows and sheep, hens do not have a rumen to consider, so unprotected amino acids can be added directly to the diet. Typically, methionine tends to be the limiting amino acid in the diets of laying hens, and ideally they each should be fed around 415 mg of methionine per dayto achieve maximum production. Lysine and arginine are also highly significant in their diet, though it is equally important for hens to be fed enough pure caloric energy to produce since egg-laying is energetically expensive. 

06 - Animal Production

Benefits of Amino Acids for Animal Growth

During the early phases of growth, all animals need access to as many essential amino acids as possible, as they need to produce sufficient proteins to support their growing bodies. Studies have shown that an increase in protein intake directly corresponds to an increase in protein deposition6 within the bodies of growing animals, resulting in stronger, healthier mature animals. Some amino acids are slightly more important than others, however.

1. Amino Acids for Ruminates: For calves, the most important amino acids are methionine, lysine, isoleucine, threonine and leucine. A deficiency in any of these amino acids results in a slowing of growth and delayed onset of maturity. The most important of these, methionine, is an essential amino acid. Though used inefficiently from a biological standpoint, methionine is important in cattle and sheep as a methyl group donor and a precursor for cysteine synthesis.

Lysine is the second most limiting amino acid for growing calves, especially in maize-based diets because maize is relatively low in lysine. So, if maize is a major component in a cow’s diet, it may be necessary to consider supplementing the diet.

2. Amino Acids for Pigs: Pigs have similar needs to calves, with the notable exception being arginine. While arginine is not an essential amino acid since it can be synthesized from glutamate and glutamine, it is essential to younger piglets in the neonatal and immediate postweaning phases. Forty percent of pigs' arginine requirements7 must be supplied through their diet, primarily due to their rapid growth rates and the fact that most arginine is used in the urea cycle of the liver.

3. Amino Acids for Poultry: Growing poultry require similar amino acid balances as other growing animals, but they require arginine in their diets because they do not have a urea cycle and therefore cannot synthesize it on their own. A deficiency of arginine often results in feather deformation in chickens8. Lysine deficiencies can negatively affect feather growth in turkeys as well.

07 - Animal Growth

Benefits of Amino Acids for Animal Reproduction

Nutrition has a significant effect on the quality of eggs in all animals. From the emergence of ovarian follicles through embryonic development, undernutrition can have a devastating effect on reproductive health for farm animals. By feeding animals sufficient amounts of amino acids to support egg production and embryonic health, you can ensure that your animals are producing healthy offspring at an optimal rate.

1. Amino Acids for Ruminates

In ruminants, under-nutrition of amino acids can have a negative effect on fertility, especially during early ovulation. Most prominently, the intake of methionine and lysine have a strong effect throughout the fertility cycle. These two amino acids are particularly important for embryonic development and consuming too little of either nutrient can negatively impact fertility.

In one study, feeding rumen-protected methionine during the peripartum period of a cow's cycle significantly improved postpartum performance. Additionally, studies have found that pregnancies are healthier when cows are fed sufficient amounts of methionine and lysine through the pregnancy, especially on days nine through 19, during which the cow's body determines whether to continue with a pregnancy.

2. Amino Acids for Pigs

Pigs require a balanced diet that contains plenty of essential and non-essential amino acids. While essential amino acids are important to support a pregnancy, sows also require dietary glutamine and arginine9 to support mucosal integrity and neonatal growth, respectively.

08 - Animal Reproduction

How Amino Acids Improve Performance and Profitability

In summary, amino acids play varying importance roles based on the species of farm animal, its age and its production purpose. Across all factors, however, protein supplements for cattle, pigs and poultry can deliver promising results and improve the performance and profitability of an animal. Here are just a few ways that essential amino acids for animal health can benefit your bottom line:

 1. Better Feed Efficiency

When you raise the protein level in farm animal feed, farm animals will eat more food and digest it more efficiently, in turn increasing the amounts of amino acids and nutrients available to the animal. This also improves feed efficiency, so there is less waste.

 2. Healthy Growth Rate

Appropriate amino acid balances support improved growth rate so that animals will wean and reach mature weight early. Additionally, well-fed calves, piglets and chicks tend to be healthier and larger as adults, producing more and experiencing disease at a lower rate.

 3. Improved Fertility

The most prominent reason for culling cows is reproduction — if a cow doesn't calve, it doesn't produce milk. Conversely, the higher an animal's production potential, the higher the value of the pregnancy. By increasing the amount and the quality of amino acids in feed, especially methionine and lysine, studies have shown an improvement in pregnancy rates10, which not only contribute to herd numbers but also improve milk production, increasing profitability. One study showed that using Kemin’s USA Lysine® (sold in USA, equivalent in Asia is LysiGEM™) and MetiPEARL™ delivered a return on investment of $56.35 per cow per year.

4. Increased Production

Regardless of how much a cow is producing, it costs the same to keep it in the herd due to operating costs, fixed overhead costs, maintenance requirements and dry matter. To make the most of that cow, it is important that she produces enough milk to offset any costs of increasing feed quality. By improving the ratio of amino acids in the diet, you can increase cow's milk production cost-effectively and achieve a positive return on investment.

 5. Reduced Incidence of Disease

Higher incidence of disease leads to diminished production and higher maintenance costs, reducing the profitability of your farm. Additionally, a disease can impact the future production potential of a segment of your herd, negatively affecting production in the long-term. By ensuring that your herd's diet is complete with balanced amino acid levels to support the animals’ metabolism and immune response, you can protect the health of your farm animals and minimize costly diseases.

09 - Performance and Profitability

Learn More About Kemin Amino Acid Products

Are you interested in learning more about amino acid products and how they can help you achieve more with your livestock? Learn about the products that might be best for you, as well as their benefits and potential for improving your animals' performance and profitability. Learn about your options11 or contact us with questions about our products today