The effectiveness of ferrous fumarate in feed is influenced by multiple factors, which directly or indirectly affect its iron supplementation efficiency and its impact on animal growth and health by altering its stability, absorption rate, or interactions with other components. Here is a detailed analysis of the key influencing factors:
I. Feed Raw Materials and Formula Composition
Interference from anti-nutritional factors: Components in feed such as phytic acid, tannins, and dietary fiber easily bind to ferrous fumarate, forming complexes that are difficult for animal intestines to absorb, thereby reducing its bioavailability. For example, phytic acid, which is abundant in plant-based feeds (such as soybean meal and wheat bran), binds iron ions through chelation, leading to a 10%-20% decrease in the absorption efficiency of ferrous fumarate.
Competition from other minerals: Minerals in feed such as calcium, zinc, and copper compete with iron for absorption. High-calcium feeds (e.g., excessive addition of high-calcium bone meal) can inhibit intestinal iron absorption, so the ratio of calcium to iron must be controlled (usually recommended to not exceed 10:1); excessive zinc, copper, and other elements also reduce the utilization of ferrous fumarate by competing for transporters.
Synergistic or antagonistic effects of proteins and amino acids: Small peptides produced by protein hydrolysis can form soluble complexes with iron to promote absorption (e.g., chelation of iron by casein peptides); however, excessive amounts of certain amino acids (such as histidine and cysteine) may bind to iron to form precipitates, which in turn affect absorption.
II. Intrinsic Properties of Ferrous Fumarate
Chemical stability: Although ferrous fumarate is more stable than inorganic iron, it may still oxidize in high-temperature and high-humidity environments, forming poorly absorbable ferric oxides. Therefore, the pelleting temperature during feed processing (recommended to not exceed 80°C) and the humidity of the storage environment (relative humidity must be below 60%) directly affect the retention rate of its activity.
Particle size and dispersibility: Coarse-grained ferrous fumarate may disperse unevenly in feed, leading to local over-concentration or deficiency; ultra-fine grinding (e.g., particle size less than 50μm) can increase its specific surface area, improve contact efficiency with intestinal mucosa, and promote absorption. However, excessive grinding may increase oxidation risk, requiring coating technology to balance dispersibility and stability.
III. Animal Physiological Status
Species and growth stage: Different aquatic animals or livestock/poultry have varying iron requirements and absorption mechanisms. For example, young animals with underdeveloped intestines have lower absorption efficiency of ferrous fumarate (about 60%-70% of adult animals), requiring a moderate increase in addition amount; herbivores, with a higher intestinal pH (weakly alkaline), are prone to iron ion precipitation, requiring acidifiers (such as citric acid) to improve the absorption environment.
Health status: When animals suffer from intestinal diseases (e.g., enteritis), intestinal mucosa damage reduces iron absorption and transport capacity; parasitic infections (e.g., hookworm disease) cause chronic blood loss, and even with ferrous fumarate supplementation, the effect may be poor due to rapid iron loss, requiring improvement of health status before intensive iron supplementation.
Body iron reserves: When iron reserves in animals are sufficient, intestinal iron absorption is inhibited through negative feedback mechanisms. Excessive addition of ferrous fumarate at this stage is not only wasteful but may also increase metabolic burden; in contrast, under iron deficiency, the body's absorption efficiency of ferrous fumarate can increase by 2-3 times.
IV. Processing and Storage Conditions
Feed processing technology: High temperature and pressure during pelleting may destroy the chemical structure of ferrous fumarate, especially when mixed with heat-sensitive components such as vitamins and enzyme preparations. Stepwise addition (e.g., late-stage spraying) or microcapsule coating technology is required to reduce losses.
Storage time and environment: Long-term storage (exceeding 3 months) causes gradual oxidation and inactivation of ferrous fumarate, especially under light, high temperature, and high humidity, which accelerate inactivation. Therefore, feed must be stored in sealed containers in a cool, dry place, and the storage period must be controlled.
V. Synergistic or Antagonistic Effects with Other Additives
Absorption-promoting additives: Vitamin C (ascorbic acid) can reduce ferric iron to more absorbable ferrous iron; when used in synergy with ferrous fumarate, iron absorption rate can increase by 30%-50%. Organic acids (e.g., lactic acid, propionic acid) lower intestinal pH, enhance iron ion solubility, and improve absorption efficiency.
Absorption-inhibiting additives: Certain antibiotics (e.g., tetracyclines) form stable chelates with iron, reducing the biological activity of both. Therefore, ferrous fumarate should not be added simultaneously with such antibiotics in the same feed, and separate administration is recommended.
Optimizing the effectiveness of ferrous fumarate in feed requires comprehensive consideration of feed formula design, its own physicochemical properties, animal physiological needs, and processing/storage conditions. By reasonably controlling the addition amount, improving synergistic effects, and reducing antagonistic factors, its iron supplementation efficiency and application value can be maximized.
