The importance of amino acids and the cost performance of livestock and poultry feed

There are many differences in protein nutrition in the aquaculture industry. Nutritionists are now paying more attention to the amino acid composition of animal feed formulations. In aquaculture production, amino acid balance can enable enterprises to reduce costs and increase efficiency.

01

What are amino acids?

Proteins are made up of about 20 amino acids combined in different ratios. During digestion, animals break down proteins into single amino acids, which are absorbed into the blood.

Amino acids in the diet are key factors for normal animal growth and development. Soy contains the five essential amino acids required to provide proper nutrition and is therefore a complete protein. The five amino acids are lysine, threonine, methionine, tryptophan, and cysteine. The growth of animals such as pigs does not have specific requirements for crude protein, but it does have specific requirements for amino acids, the constituent parts of protein.

02

Limiting amino acids in diets

Although soybean meal is able to provide complete protein and has desirable nutrient concentrations, different meal products are often mixed in feed formulations. Factors such as price and availability influence the formulation of animal feed.

The dietitian considers the balance of amino acids during feed formulation. Animal nutritionists often use protein complementation, combining protein sources to ensure that the full amino acid requirements of the animal are met. In all feed formulations, the use of limiting amino acids, namely lysine, threonine, methionine, and tryptophan, is required. If the diet is deficient in any of the essential amino acids, protein synthesis is limited. Therefore, the calculation of digestible and metabolizable amino acids must take into account the difference in protein source.

"For example, soybean meal is rich in lysine, but methionine is the first limiting amino acid." While maize is rich in methionine, lysine is the first limiting amino acid in maize. By mixing the two ingredients together, dietitians strive to ensure that the two protein sources are complementary. This means that if soybean meal does not provide sufficient methionine, corn will supply it.

However, the reality is more complex. Lysine is the first limiting amino acid in corn-soybean meal mixed feed. For feed formulators, threonine was more restrictive than tryptophan in the piglet mix, while tryptophan was more restrictive in the finishing pig feed. The combination of the source of the protein and the specific situation of the animal makes it more complex to meet amino acid requirements and highlights the importance of understanding the interaction of amino acids under different conditions.

The quality of the protein depends on meeting the primary limiting amino acid requirements associated with animal needs. If an imbalanced formula is formed in the feed due to the lack of a certain essential amino acid, it will reduce the performance of the animal. Amino acid imbalance may occur when a second limiting amino acid is added to the diet before the first limiting amino acid is met. This would lead to a reduction in animal feed intake and a decrease in performance.

The essential amino acids in soybean meal are very important. If birds are fed only soybean meal and the amino acid balance is not at its required level, some protein will be wasted. If soybean meal does not supply most of the digestible amino acids, it will cause poor feed conversion and the enterprise will suffer losses.

Chicken is the world's largest meat production and consumption product. About 70% of the world's chicken comes from white-feather broilers, which contribute about 45% to China's chicken production. In the case of white-feathered broilers, regardless of breed, feed specifications must be established based on digestible amino acids.

03

The cost of different feeds

Animal nutritional requirements vary by species, age, and stage of production. Although nutrient requirements can vary, digestible amino acids, metabolizable energy, and available phosphorus are the three most expensive nutrients that make up animal feed. Formulators can add these nutrients from multiple sources, but if the nutrients come from different sources and additional additions are required, the cost increases rapidly.

Certain amino acids, especially those contained in soy, are crucial and are the starting point for formulating animal feed. Lysine is one of the key amino acids in soybean meal. The advantage of US soybean meal is the high proportion of lysine in its protein.

The ideal amino acid pattern used in broiler rearing determines the importance of lysine. By calibrating the ratio of other amino acids relative to lysine against the requirement of lysine, the requirement of other amino acids can be calculated automatically. With a lysine dominant feed formulation, if there is a good level of digestible lysine with which all other amino acids are matched, an amino acid balanced formulation will be obtained.

Providing natural nutrients through raw materials such as soybean meal can also help reduce costs. For example, lysine and methionine in soybean meal can produce feed with higher nutrient concentrations even at lower addition ratios, further reducing the cost per kilogram of feed. However, due to market conditions and product availability, it is sometimes necessary to add additional complementary ingredients in feed production, usually synthetic raw materials.

According to the FAO, amino acids have been used in the feed industry for about 40 years. In the late 1950s and 1960s, DL-methionine produced by chemical synthesis began to be used in poultry feed production. Production of L-lysine by fermentation began in Japan in the 1960s. In addition to DL-methionine and L-lysine hydrochloride, L-threonine and L-tryptophan were introduced in the late 1980s.

With the advancement of biotechnology, the production cost of each amino acid has been greatly reduced, which is also a key factor in the expansion of amino acid addition in animal feed.

The general assumption is that if 0.15% lysine (0.192% lysine-hcl) is added, the protein content of a corn-soybean meal type diet for growing and finishing pigs can be reduced by 2%.

The quality of a protein can be defined as the amount of essential amino acid components contained in the protein and the extent to which the overall amino acid requirements of the animal are met. When a feed is formulated with common grain and protein sources, the crude protein levels that are commonly used as a measure of feed quality contain sufficient amounts of amino acids to meet the needs of the animal. Synthetic amino acids are added to the feed, which can maintain production efficiency and cost effectiveness. However, when synthetic amino acids, alternative products or by-products are used as feed ingredients, the level of crude protein does not always reflect whether the feed can meet the needs of the animal. The level of digestion of synthetic amino acids also needs to be considered.

In addition to cost, the overall economic value of incorporating US soybean meal into the feed should be considered when selecting a protein source. The United States Soybean Export Association (USSEC) funded a project to conduct 27 feeding studies on more than 234,400 brosters, layers and pigs in Asia, South America and Europe over an 8-year period, examining the performance of different batches of soybean meal in feeding animals from the United States, Argentina, Brazil, India, China, Thailand and Malaysia.

The results showed that the hulled soybean meal in the United States had higher protein content, amino acid content and digestibility, and therefore had better economic value. Using standardized feed ingredient prices in all studies, the results show the economic advantages offered by peeled soybean meal in the United States:

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$33.60 higher than non-hulled soybean meal from India, Brazil, Argentina and China;

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$8.74 per metric ton higher than similar peeled soybean meal from Argentina, Brazil, Paraguay and China.

The results showed that it was economically advantageous to continue using American peeled soybean meal even though the price of American soybean meal was higher than that of soybean meal from other sources.