L-carnitine, also known as vitamin BT, is a vitamin-like nutrient naturally present in animals. In the feed industry, it has been widely used as a crucial feed additive for decades. Its primary function is to act as a "transport vehicle," delivering long-chain fatty acids to mitochondria for oxidation and decomposition, thereby generating energy.

The following are the main applications and roles of L-carnitine in various animal feed:

1. Application in livestock and poultry feed.

• Improvement of growth performance in pig feed: Adding L-carnitine to the diet of piglets and growing and fattening pigs can increase daily weight gain and feed conversion rate. It saves protein by promoting fat utilization, making animals grow thinner and have better meat quality. 
• Improving the reproductive performance of sows: Reserve sows: promoting estrus and increasing ovulation rate. Pregnant and lactating sows: help regulate body fat, reduce weight loss during lactation, increase milk production, thereby improving piglet weaning weight and survival rate. At the same time, it helps to shorten the estrus interval after weaning.
• Relieve stress: Under stress conditions such as weaning, weaning, and high temperatures, L-carnitine can help animals utilize energy more effectively, maintain health and productivity.

2. Poultry feed (chickens, ducks, etc.) for broiler/meat ducks:

• Improves weight gain and feed efficiency: promotes fat metabolism, reduces abdominal fat deposition, increases chest muscle percentage and leg muscle production.
• Improve meat quality: reduce fat content and increase protein content. Egg laying hens/poultry: increase egg production rate: provide more energy for follicle development.
• Improving egg quality: may increase egg weight and improve the fertilization and hatching rates of hatching eggs.

Ⅱ Aplication in aquatic feed:

The application effect of L-carnitine in aquaculture is particularly significant, as fish (especially carnivorous fish) mainly rely on fat and protein as energy sources.

Promote growth: significantly increase the growth rate and weight gain of fish and shrimp.

• Improving body shape and meat quality: promoting protein deposition, inhibiting excessive accumulation of fat in the body and liver, making fish have a better body shape, higher meat yield, and effectively preventing nutritional fatty liver.
• Saving protein: By efficiently utilizing fat for energy supply, reducing the use of protein for energy consumption, thereby lowering feed protein levels and saving costs.
• Improve reproductive performance: Improve the gonadal development and sperm quality of parent fish.

Ⅲ. Application in pet feed

• Weight management: For obese pets, L-carnitine can help them burn fat more effectively and is very common in weight loss diets.
• Improving heart function: Cardiomyocytes mainly rely on fatty acids for energy supply, and L-carnitine is crucial for maintaining heart health and is commonly used as an adjuvant therapy for dilated cardiomyopathy in dogs.
• Improving exercise endurance: For working dogs, racing dogs, or active pets, it can enhance their athletic performance and fatigue resistance.
• Support liver health: promote liver fat metabolism and prevent liver fat deposition.

Ⅳ. Summary of mechanism of action:

• The core of energy metabolism: as a carrier, it transports long-chain fatty acids from the cytoplasm to the mitochondrial matrix for beta oxidation, which is a key step in the conversion of fat into energy.

• Adjusting the ratio of CoA/acetyl CoA in mitochondria: helps to eliminate excess acetyl groups produced during metabolic processes and maintain normal mitochondrial metabolic function.

• Protein saving effect: When fat can be efficiently utilized, protein can be used more for muscle growth and tissue repair, rather than being broken down for energy.

Ⅴ. Add precautions:

• Addition amount: Accurate design is required based on animal species, growth stage, physiological status, and production goals, and not the more the better. The usual addition amount is between 50-500 grams per ton of feed.

• Cost effectiveness: L-carnitine is a relatively expensive additive, therefore its economic return in specific production systems needs to be evaluated.

• Synergy with other nutrients: It has a synergistic effect with betaine, choline, certain vitamins, etc., and can be considered together in formula design.

Ⅵ. Conclusion:

• L-carnitine is a safe and effective nutritional feed additive. It plays an irreplaceable role in improving animal growth performance, improving carcass quality, enhancing reproductive capacity, and maintaining health by optimizing energy metabolism.

• In modern intensive and efficient aquaculture, the rational use of L-carnitine is one of the important means to achieve precise nutrition and reduce costs while increasing efficiency.

Trimethylamine hydrochloride is mainly used as an alkaline reagent in the quaternization reaction of L-carnitine synthesis, to adjust the pH value of the reaction system, promote the separation of epichlorohydrin, and facilitate the subsequent cyanide reaction. ‌

The role in the synthesis process：
PH adjustment: During the quaternization reaction stage, trimethylamine hydrochloride releases ammonia molecules to neutralize the acidic substances produced by the reaction, maintaining the stability of the system pH and avoiding excessive alkaline substances from affecting reaction efficiency. ‌
Promoting Resolution: As an alkaline reagent, trimethylamine hydrochloride can accelerate the enantiomeric resolution of epichlorohydrin and increase the yield of the target product L-carnitine. ‌

By controlling by-products: By adjusting reaction conditions, the generation of by-products such as L-carnitine is reduced, simplifying subsequent refining steps. ‌