From Farmland to Pasture: Urea Phosphate and Zinc Sulfate as Feed Additives for Livestock and Poultry

In agricultural production, fertilizers are usually regarded as key inputs that support crop growth. However, less attention is paid to the fact that some fertilizers, thanks to their unique nutritional composition and physicochemical properties, can also be applied across sectors as feed additives for livestock and poultry—helping safeguard animal health and improve farming efficiency. Among them, urea phosphate and zinc sulfate are two representative examples. The former, as a nitrogen–phosphorus compound fertilizer, provides efficient nutritional supplementation specifically for ruminants; the latter, as a trace element fertilizer, fulfills the zinc requirements of all categories of livestock and poultry. Although they belong to different categories of fertilizers, both demonstrate significant value in feed applications, provided that they are used in line with scientific standards to ensure safety and effectiveness.

I. Urea Phosphate: From Nitrogen–Phosphorus Fertilizer to Specialized Feed Additive for Ruminants

Urea phosphate (chemical formula: CO(NH₂)₂·H₃PO₄) is a highly efficient nitrogen–phosphorus compound fertilizer in agriculture, supplying crops simultaneously with nitrogen and phosphorus. In animal feed, it has become a specialized nutritional additive for ruminants (such as cattle, sheep, and deer), thanks to its “dual N–P supplementation + safe slow release” advantages. It effectively solves the common problem of imbalanced nitrogen–phosphorus supply in conventional feed, which often leads to metabolic disorders.

1. Core logic in feed use: Matching ruminant physiology

Ruminants host a large microbial population in their rumen. These microbes can convert non-protein nitrogen into microbial protein, which the animals can absorb. This feature underpins the feed application of urea phosphate:

• Slow-release nitrogen source, reduced risk: The urea component in urea phosphate slowly releases ammoniacal nitrogen. This provides microbes with a substrate for protein synthesis while avoiding rumen ammonia toxicity commonly caused by rapid release from ordinary urea. Research shows that in simulated rumen conditions, regular urea releases 60%–70% of its total nitrogen as ammoniacal nitrogen within one hour, while urea phosphate releases only 20%–30%, greatly reducing toxicity risks.

  
  

• Direct phosphorus supply: The phosphate group in the molecule can be directly absorbed, supporting bone development, energy metabolism (e.g., ATP synthesis), and cell membrane construction. This is especially beneficial for young ruminants (e.g., lambs aged 3–6 months) and lactating females, where phosphorus intake is often insufficient. For example, skeletal mineralization in fast-growing young ruminants directly depends on phosphorus supply; supplementing urea phosphate helps improve bone quality.

  
  

• Rumen regulation, improved digestion: Urea phosphate can slightly adjust rumen pH to 6.5–7.0, the optimal range for microbial activity, promoting cellulolytic bacteria growth. This enhances roughage digestibility by 10%–15%. In trials, the number of cellulolytic bacteria increased by 30%–40% in urea phosphate groups, while cellulose degradation improved by ~12%.

2. Application scenarios and effects

• Fattening cattle/sheep: Adding 1%–2% urea phosphate to rations can replace 5%–10% of protein feed (e.g., soybean meal), reducing costs. Experiments showed lambs receiving 1% replacement had the highest average daily gain, with overall gains improved by 15%–20%. Cattle fattening cycles were shortened by 7–10 days.

  
  

• Lactating cows/goats: Adding 0.8%–1.2% (cows) or 0.5%–1% (goats) can reduce phosphorus loss during lactation, increase milk yield by 5%–12%, and improve milk fat by 0.2–0.3 percentage points.

  
  

• Grazing ruminants: During winter forage shortages, feeding concentrate containing 1%–1.5% urea phosphate prevents weight loss (average 0.5–1 kg/month reduction in loss) and reduces nutritional disease incidence (e.g., rickets).

3. Application standards

• Grade requirements: Only feed-grade urea phosphate (purity ≥98%) may be used. Fertilizer-grade products may contain excessive heavy metals or fluorides, causing toxicity.

  
  

• Dosage control: Typical inclusion rate is 1%–3% of dry matter. For young/pregnant animals, 0.5%–1%. Overuse may cause bloating.

  
  

• Compatibility: Avoid concurrent large amounts with raw soybeans or fresh legumes (high urease activity), which may accelerate ammonia release. Mixing with corn, bran, or straw is recommended.

II. Zinc Sulfate: From Trace Element Fertilizer to Universal “Zinc Supplement” for Livestock and Poultry

Zinc sulfate (ZnSO₄) is a common trace element fertilizer used to correct zinc-deficient soils and prevent crop diseases. In feed, due to its high solubility and bioavailability (>80%), it is widely applied as a zinc source for pigs, poultry, ruminants, and aquaculture animals. It addresses growth retardation and immune suppression caused by zinc deficiency.

1. Core logic in feed use: Supplying essential trace elements

• Growth promotion, anti-deformity: In young animals (e.g., piglets, chicks), zinc supports protein synthesis and cell division, preventing growth retardation and skeletal issues. Supplementation improves piglet growth rate by 15%–20%.

  
  

• Skin and gut health: Zinc is vital for keratinization. Supplementation prevents dermatitis and reduces post-weaning diarrhea in piglets by 20%–30%.

  
  

• Immunity and reproduction: Zinc activates immune cells, reducing infectious disease incidence by 15%–20%. It also improves boar sperm vitality (by 10%–15%) and increases laying and hatching rates in poultry (by 3%–8%).

2. Species-specific use

• Pigs: 80–120 mg/kg for weaned piglets; 60–80 mg/kg for fatteners. Prevents diarrhea and improves feed conversion.

  
  

• Poultry: 60–80 mg/kg for broilers; 70–90 mg/kg for layers. Reduces cracked eggs and prolongs laying peaks.

  
  

• Ruminants: 40–60 mg/kg for fattening cattle/sheep; 50–70 mg/kg for pregnant females. Reduces lameness and abortion rates.

  
  

• Aquaculture: 30–50 mg/kg for fish/shrimp feed. Supports scale/shell development and stress resistance.

3. Application standards

• Purity and impurities: Feed-grade zinc sulfate must meet minimum zinc content (≥35% for monohydrate, ≥28% for heptahydrate) and strict limits on heavy metals and arsenic.

  
  

• Mixing method: Pre-mixing with carriers (e.g., bran, limestone powder) is required to ensure even distribution.

  
  

• Compatibility: Can be combined with other trace minerals, but avoid high-calcium feeds that reduce zinc absorption.

III. Common Principles for Fertilizer-to-Feed Transition

Whether urea phosphate or zinc sulfate, safe and effective application in feed requires adherence to common principles:

1. Differentiate feed-grade vs. fertilizer-grade: Standards differ sharply in purity and impurity limits. Only certified feed-grade products should be used.

2. Precise dosage control: Benefits are dose-dependent; both deficiency and excess cause harm.

3. Uniform mixing: Use pre-mixing and proper equipment to prevent localized overdosing.

4. Match physiological stages: Adjust dosage for young, pregnant, lactating, or laying animals to prevent negative effects.

Conclusion

The cross-sector application of urea phosphate and zinc sulfate—from fertilizer to feed additive—challenges the traditional view that fertilizers serve only crops. Their successful use in livestock demonstrates efficient resource recycling and integrated agricultural development. Yet, their value depends on selecting the correct grade, controlling dosage, and ensuring scientific formulation. Only then can these fertilizers fully realize their potential in animal husbandry—achieving cost reduction, efficiency gains, safety, and quality improvement. Their “crossover journey” vividly illustrates modern concepts of resource efficiency and the synergy between crop farming and animal husbandry.