Through the explanation of the previous several articles, I believe that you have a relatively in-depth understanding of the use and effect of 5-ALA on crops. The previous article only mentioned the effect of 5-ALA on plants as a precursor of chlorophyll, in fact, it can also be used as an additive in agricultural products such as feed and pesticides. This issue will focus on the principle and application of 5-ALA in the regulation of iron metabolism in animals.

　　Note: Due to the content of the copy is more, this issue only tells the content of the first half, the next issue updates the second half

　　To talk about the regulation of iron, we first need to understand the role of iron in animals

　　So, what is the role of iron?

　　Iron is one of the essential nutrients in animal body, and plays an important role in oxidative metabolism, cell growth and proliferation, oxygen transport and storage. Iron is involved in the synthesis of hemoglobin and myoglobin, and serves as oxygen carrier to ensure the normal transport of oxygen in body tissues. Iron ion is involved in the synthesis of cytochrome, cytochrome oxidase, peroxidase and contactase as A cofactor, and is closely related to the activities of acetyl-CoA, succinate dehydrogenase, xanthine oxidase and cytochrome reductase. Closely related to energy metabolism, more than half of the enzymes and factors in the tricarboxylic acid cycle contain iron or can play biochemical roles in the presence of iron; Iron also affects protein synthesis and immune function in animals.

　　How was the concept of iron metabolism regulation discovered and taken seriously?

　　In the natural growth environment, the iron in grain feed and soil is enough to meet the iron needs of livestock and poultry. In recent decades, the rapid development of animal husbandry, animal breeding intensification degree and production level have been greatly improved. In an intensive farming environment, livestock and poultry have little access to soil. Iron must be added to the diet to meet the maintenance, growth and reproduction needs of livestock and poultry.

　　Taking piglets as an example, from birth to weaning, the iron content in breast milk is difficult to meet its rapid growth needs, and the intensive feeding environment greatly reduces the opportunity to obtain iron nutrition from the soil environment. In pig production, iron injection or iron dextrin injection within 3 days of birth has become a routine means to prevent iron deficiency anemia in piglets, but this method causes greater stress to piglets and increases the breeding cost. It is one of the challenges in animal nutrition field that how to improve the iron storage of sows during pregnancy and the iron content of breast milk and ensure the iron nutrition supply of piglets through nutritional control measures.

　　Therefore, in the past ten years, the high copper and high zinc diet has become a common technology for the preparation of domestic pig feed. Due to the antagonism between iron and copper and zinc, the amount of iron added in the high copper and high zinc diet has also been greatly increased. For adult livestock and poultry, more than 50% of iron added in the diet is excreted in feces. Therefore, it is of great significance to explore the regulation of iron metabolism and improve its absorption and utilization efficiency for livestock and poultry production.

　　How is the regulation of iron metabolism related to 5-ALA?

　　In the mitochondria, ALA is produced by glycine and succinyl-CoA under the action of 5-aminolulinic acid synthetase, which is the initial reaction of heme synthesis. ALA enters into the cellular fluid, and under the action of 5-aminolevulinate dehydratase, 2 molecules of ALA are dehydrated and condensed into 1 molecule of porphyrobilinogen, which is then converted into protoporphyrin IX through a series of enzyme reactions, and finally combined with Fe2+ to form heme under the catalysis of ferrous chelatase. In this series of enzyme reactions, 5-ALA synthetase produces the least rate-limiting enzyme for heme synthesis, and ALA synthesis is the rate-limiting reaction for heme synthesis.

　　It is inferred that additional ALA will promote more heme production. In this process, iron ions can be directly converted into heme iron, which has higher conversion efficiency and utilization effect on animal body. In vitro experiments with African toad kidney cells and mouse liver cells have confirmed that the synthesis of heme is affected by the amount of available ALA.

　　Since 5-ALA has an effect on the regulation of iron metabolism, is there any research progress in feed?

　　The efficiency of iron absorption is critical to the iron nutritional status of animals, "he said, adding that the two most important factors affecting iron absorption are iron storage and erythropoiesis. Animals only absorb the amount they need, and increasing the level of dietary iron will increase the total amount of iron absorption, and the nutritional status of iron is the factor that determines the conversion and utilization of iron absorption in animals. Too much iron absorbed into the intestinal mucosa cells, if not used by the body in time, will only be excreted by the shed intestinal mucosa cells after the formation of ferritin. The results show that organic iron supplementation can improve the iron nutritional status of weaned piglets, but has no significant effect on growth performance. According to expert experiments, when the iron content in the diet is 20 to 60mg/kg, the growth performance of broilers increases to the peak, but further supplementation of iron will inhibit its growth. Therefore, in terms of the impact on animal growth performance, it can be considered that improving the efficiency of intracellular iron utilization is more important than increasing the amount of intestinal iron absorption.

　　ALA does not have a direct effect on the animal body, but plays a catalytic and regulatory role in the cell by participating in the synthesis of heme, and then in the form of hemoglobin or myoglobin. The addition of ALA can promote the conversion of absorbed iron ions from non-heme iron to heme iron with higher biological titer, thus improving the utilization of iron.