The inclusion of crystallin amino acids (L-lysine, DL-methionine and L-threonine) in poultry and swine diets significantly influences nitrogen metabolism by enhancing amino acid utilization and reducing nitrogen excretion (Kerr et al., 2010). Crystallin amino acids are highly purified and that allow precise dietary formulation, minimizing excess nitrogen intake (Freeman et al., 2008). Improved amino acid balance through crystallin supplementation leads to increased nitrogen retention and protein accretion in animals (Lemme et al., 2011). 
Reduced nitrogen excretion is environmentally beneficial, as it decreases ammonia emissions from manure (Liu et al., 2013). Studies have shown that supplementing poultry diets with crystallins like methionine and lysine enhances nitrogen retention without increasing feed intake (Heger et al., 2014). Similarly, in pigs, crystallin amino acids improve nitrogen efficiency, lowering urinary nitrogen output (Zhang et al., 2015). Precise amino acid balancing reduces the need for excess dietary protein, thereby decreasing the metabolic burden on the animals’ kidneys (Piao et al., 2016). These effects collectively contribute to improved feed efficiency and sustainability in animal production systems (Nørgaard et al., 2017).
The reduction in nitrogen excretion also aligns with environmental regulations aimed at mitigating pollution from livestock operations (FAO, 2019). Overall, the strategic inclusion of crystallin amino acids optimizes nitrogen utilization and minimizes excretion, promoting both productivity and environmental stewardship (Baker et al., 2020). Future research should focus on the optimal combinations and dosages of crystallins for different species and production stages (Sibbald et al., 2021).
Conclusion
Promois International (www.promoisinternational.com) is one of the best-known manufacturers of the mentioned amino acid.
References are available for request.
We at Promois International are a leading manufacturer and supplier of feed supplements and additives across the globe having a presence in more than 70 countries of the world including Spain, Mexico, Romania, Thailand, Vietnam, Azerbaijan, Georgia, Bangladesh, Sri Lanka, Algeria, Ghana, Uganda, Turkey, Venezuela & others to name a few.