Usage and precautions of yeast culture and yeast selenium in animal husbandry

      In animal husbandry, the use of yeast culture and yeast selenium should be scientifically configured based on the animal species, growth stage, and breeding objectives. The following provides a detailed analysis from two aspects: usage methods and precautions:

1、 Usage and precautions of yeast culture

（1） Usage method

Add form and dosage

Feed mixing:

Livestock and poultry breeding:
Piglets/chicks: Adding 500-1000 g/ton of feed during weaning can reduce diarrhea rates by 30% -40% (Data source: Chinese Journal of Animal Husbandry, 2021).
Breeding poultry/fattening pigs: 300-500 g/ton of feed, increasing feed conversion rate by 5% -8%.
Ruminant animals (cattle, sheep): 1000-2000 g/ton concentrate promotes rumen microbial proliferation and increases milk production by 8% -12%.

Aquaculture:
Fish fry/shrimp fry: Adding 1000-1500 g/ton to feed can increase survival rate by 25% -30%.
Adult fish/shrimp: 500-800 g/ton feed, combined with probiotics, can improve intestinal health.
Drinking water additives: During the stress period (such as conversion and high temperature), it can be dissolved in drinking water at a concentration of 0.1% -0.3% and used continuously for 3-5 days.

Applicable stages and scenarios

Young animals: Key use during weaning and seedling period to repair intestinal villus damage (such as a 30% increase in villus height/crypt depth ratio in piglets after weaning).
High stress environment: Relieve immune suppression (serum IgG levels increase by 15% -20%) during intensive farming, transportation, and seasonal changes.
Toxic contamination scenario: When the risk of feed mold is high, β - glucan adsorbs fungal toxins (such as aflatoxin adsorption rate of 85%).

（2） Precautions

quality control
Choose products that are dry, mold free, and have a natural odor, and the testing indicators should include:
Active ingredients: β - glucan ≥ 3%, small peptides ≥ 5%, organic acids (calculated as lactic acid) ≥ 2%.
Health indicators: mycotoxins (aflatoxin B ₁<10 μ g/kg), heavy metals (lead<10 mg/kg, arsenic<2 mg/kg).
Avoid simultaneous use with antibiotics (especially live yeast cultures), and feed every 2-3 hours.

Storage and compatibility
Store in a cool and dry place, with a shelf life of usually 12-18 months. After opening, seal and prevent moisture.
Can be used in conjunction with probiotics (such as Bacillus subtilis) and enzyme preparations (such as amylase), but should avoid direct mixing with strong acid/alkali additives.

Dose gradient adjustment
When used for the first time or when the animal's health condition is poor, it can be added according to the recommended dosage limit and gradually reduced to the regular dose after 2-4 weeks.
In aquaculture, water temperature adjustment is necessary: when the water temperature is below 20 ℃, metabolic efficiency decreases, and the dosage can be appropriately reduced by 20% -30%.

2、 Usage and precautions of yeast selenium

（1） Usage method
Add form and dosage

Feed premix:
Livestock and poultry breeding:
Breeding livestock (pigs, cows, sheep): 0.3-0.5 mg/kg selenium (calculated as yeast selenium), to improve reproductive performance (increase sow litter size by 1-2 and increase bull sperm motility by 15%).
Egg poultry: 0.2-0.3 mg/kg selenium, the selenium content in egg yolk can reach 200-300 μ g/piece (ordinary eggs are about 20 μ g/piece).
Meat and poultry/fattening pigs: 0.1-0.2 mg/kg selenium, improves the antioxidant properties of meat products (extends shelf life by 3-5 days).

Aquaculture:
Fish: 0.2-0.4 mg/kg selenium reduces the incidence of fatty liver (liver to body ratio decreases by 12% -18%).
Crustaceans (shrimp, crab): 0.3-0.5 mg/kg selenium, enhances stress resistance (ammonia nitrogen tolerance threshold increased by 20%).
Pre mixed carrier: As a selenium source for composite pre mixed materials, it is necessary to ensure the uniformity of mixing (coefficient of variation<5%).

Applicable stages and scenarios
Selenium deficient areas: 70% of soil in China is selenium deficient and requires yeast selenium fortified feed (such as in some farms in Northeast and Southwest China where additional supplementation is needed).
Antioxidant requirements: In high temperature and high humidity seasons (such as summer poultry farming), the addition amount can be increased to 0.3 mg/kg to alleviate the decrease in egg production rate caused by heat stress (a 50% reduction).
High value-added product production: selenium rich meat, egg, and milk farming require the addition of yeast selenium throughout the entire process (continuous use 4-6 weeks before slaughter).

（2） Precautions
Dose safety control
Selenium poisoning threshold: The amount of selenium added to livestock and poultry feed must not exceed 0.5 mg/kg (ruminants can tolerate 1-2 mg/kg). Excessive amounts can cause liver damage, hair loss, and even death in animals.
Regulatory compliance: It is required to comply with the "Safety Use Regulations for Feed Additives", and the label must clearly indicate the "organic selenium content" and "inorganic selenium residue" (usually requiring inorganic selenium to be less than 10%).

Interaction with other nutrients
Vitamin E: It has a synergistic antioxidant effect with yeast selenium, and the content of vitamin E in feed needs to be synchronized to meet the requirements (such as the recommended amount of 10-20 IU/kg of vitamin E for poultry).
Heavy metals: Avoid simultaneous use with high-dose heavy metals such as cadmium and mercury, as they may competitively inhibit selenium absorption.

Detection and residual control
Regularly monitor the selenium content in animal blood/tissues (such as the normal range of 0.1-0.4 μ g/mL for pig serum selenium) to ensure that the selenium residue in the product meets food safety standards (such as Chinese meat selenium residue ≤ 0.5 mg/kg).
Attention should be paid to selenium accumulation in aquatic aquaculture, and the water change cycle should be shortened to 7-10 days to avoid environmental pollution.

Storage and compatibility
Store in a cool place, away from light and sealed to prevent selenium from evaporating at high temperatures (>35 ℃). The shelf life is usually 12 months.
Cannot be directly mixed with strong oxidants (such as potassium permanganate) or acidic additives (such as phosphoric acid), and must be pre mixed separately.

3、 Key points of collaborative use

In some aquaculture scenarios, yeast culture and yeast selenium can be used in combination to enhance the effect, but it should be noted that:

Dose optimization:
Yeast culture should be used at regular doses (such as 800 g/ton for piglets), and yeast selenium should be used at the recommended lower limit (such as 0.2 mg/kg) to avoid metabolic burden.
Example: Adding 500 g/ton yeast culture+0.2 mg/kg yeast selenium to the feed of laying hens can increase egg production by 6% compared to using yeast selenium alone, while reducing egg breakage rate by 10% (Data source: Feed Industry, 2023).

Complementary mechanism of action:
Yeast culture improves the intestinal absorption environment and enhances the bioavailability of yeast selenium (an 18% -22% increase in selenium absorption rate compared to using yeast alone).
The antioxidant function of yeast selenium can protect the active ingredients in yeast culture (such as small peptides that are not resistant to oxidation) and reduce processing losses.

Applicable scenarios:
High end organic farming and export animal product production (such as supplying pigs to Hong Kong) need to meet both the needs of "health regulation" and "selenium enrichment".
Young animals (such as chicks before 21 days of age), when used in combination, can reduce early mortality to less than 5% (the mortality rate of yeast culture alone is about 8%).                                                

Summary: Principles of Scientific Use

      The rational application of both should be based on the physiological characteristics of the breeding objects, environmental conditions, and the standards of target products. It is recommended to verify the effect through preliminary tests before large-scale promotion, so as to achieve a balance between economic benefits and safety.