<Tr> <Td> W Tryptophan </Td> <Td> </Td> <Td> 280 </Td> <Td> 5 </Td> </Tr> <Tr> <Td> V Valine </Td> <Td> 26 </Td> <Td> 1820 </Td> <Td> 24 </Td> </Tr> <P> The recommended daily intakes for children aged three years and older is 10% to 20% higher than adult levels and those for infants can be as much as 150% higher in the first year of life . Cysteine (or sulphur - containing amino acids), tyrosine (or aromatic amino acids), and arginine are always required by infants and growing children . </P> <P> Various attempts have been made to express the "quality" or "value" of various kinds of protein . Measures include the biological value, net protein utilization, protein efficiency ratio, protein digestibility - corrected amino acid score and complete proteins concept . These concepts are important in the livestock industry, because the relative lack of one or more of the essential amino acids in animal feeds would have a limiting effect on growth and thus on feed conversion ratio . Thus, various feedstuffs may be fed in combination to increase net protein utilization, or a supplement of an individual amino acid (methionine, lysine, threonine, or tryptophan) can be added to the feed . </P>

Essentail amino acids are more important to the human body than nonessential amino acids