With the widespread and often inappropriate use of antibiotics, their negative consequences have become increasingly evident. These include the disruption of normal microbial populations in animals, leading to an imbalance in the microecological system; the promotion of antibiotic-resistant strains; increased sensitivity of susceptible habitats, and a higher risk of both exogenous and endogenous infections. Additionally, antibiotics can impair the immune function of animals, reducing their ability to fight off diseases. Residues of these drugs in animal products—such as meat, eggs, and milk—pose serious threats to human health. In some cases, they may even cause teratogenic effects or lead to poisoning and death in humans and animals.
Since the 1981 "three-in-one" injection incident in the UK, which was linked to the outbreak of bovine spongiform encephalopathy (BSE), many countries, especially in Europe, the US, and Japan, have implemented strict regulations on the use of antibiotics in animal feed. The European Union banned the addition of any antibiotics to animal feed after 2005. At the same time, there has been a strong push toward developing and promoting alternatives to antibiotics, such as microbial feed additives that support sustainable and safe livestock production.
This article reviews one of the research areas focused on the application of microbiological additives in dairy cow feed, which is considered a green alternative to traditional antibiotics.
**1. Microbial Agents Used in Dairy Cow Production**
Microbiological agents for dairy cows primarily consist of bacterial and fungal preparations and their active cultures. Ideal strains for these preparations should be non-pathogenic to both humans and animals, not capable of forming hybrid species with pathogenic microbes, and able to grow easily in both in vivo and in vitro environments. They should also maintain high viability and stability after processing, and ideally originate from the natural gut flora of the animal.
**1.1 Bacteria**
Common bacteria used in microbial additives for dairy cows include *Bacillus*, *Lactobacillus*, and *Streptococcus* (including *Enterococcus*). Among them, *Bacillus* species such as *B. subtilis*, *B. cereus*, and *B. licheniformis* are widely used. These bacteria are spore-forming, highly resistant to stress, and stable during feed processing. They produce various enzymes like cellulase and glucanase, which aid in digestion and improve feed conversion rates. As aerobic bacteria, they help create an oxygen-rich environment that supports the growth of beneficial anaerobic bacteria, thus maintaining a balanced gut microbiome.
**1.1.2 Lactic Acid Bacteria**
Lactic acid bacteria, including *Lactobacillus*, *Bifidobacterium*, and *Pediococcus*, are naturally present in the gut and are known for producing lactic acid, vitamins, and antimicrobial substances. While they are effective in improving gut health and immunity, they are less stable than *Bacillus* and require microencapsulation to enhance their shelf life. This increases production costs, limiting their widespread use.
**1.2 Fungi**
Fungal probiotics used in dairy cattle include *Saccharomyces* (yeast) and *Aspergillus*. Yeast helps improve rumen fermentation by increasing the population of cellulolytic bacteria, enhancing nutrient absorption, and promoting better feed utilization. *Aspergillus* species, particularly *A. niger* and *A. oryzae*, produce cellulases and other enzymes that break down plant cell walls, aiding in the digestion of fibrous feed and improving nutrient availability.
**2. Mechanism of Action of Microbial Feed Additives**
Microbial additives work by stabilizing the gut microbiome, competing with harmful pathogens, and supporting the growth of beneficial bacteria. They also contribute essential nutrients, enzymes, and metabolic byproducts that enhance digestion, immune function, and overall health. In the rumen, these additives stimulate the growth of cellulose-degrading microbes, regulate pH levels, and promote efficient nutrient utilization. This leads to improved milk yield, better feed conversion, and enhanced resistance to diseases.
**3. Application in Dairy Production**
Studies have shown that microbial additives significantly improve milk production. For example, feeding yeast cultures or *Aspergillus* supplements to dairy cows has led to increased milk yields, improved fat and protein content, and better reproductive performance. Some research also indicates that these additives help reduce the impact of heat stress, maintaining milk production during hot seasons. Overall, the use of microbial feed additives offers a sustainable and effective alternative to antibiotics, contributing to healthier livestock and safer food products.
Tumeric, Garlic Powder, Ginger Powder, Kaempferia Powder, Chilli Powder
Jiangsu Tiankang Food Co., Ltd. , https://www.tiankangfood.com