Table 3.
Nitrogen and total amino acid (AA) content (g kg−1 DM), individual AA content (g (100 g−1) of total AA) and N to protein conversion factor of Ulva Lactuca and extract fraction, compared to literature and soybean meal
| Amino acids | U. lactuca | Extracted fraction | U. lactuca, literaturea | Soybean meala |
|---|---|---|---|---|
| Lysine | 4.6 | 3.3 | 4.7–7.4 | 6.3 |
| Methionine | 2.2 | 2.2 | 1.1–5.5 | 1.4 |
| Cysteine | 1.1 | 1.0 | 0.5–2.2 | 1.5 |
| Threonine | 4.7 | 5.9 | 4.6–6.5 | 3.9 |
| Tryptophan | 0.7 | 1.0 | – | 1.3 |
| Leucine | 7.4 | 8.6 | 7.5–9.2 | 7.8 |
| Isoleucine | 4.0 | 4.6 | 4.0–6.1 | 4.7 |
| Histidine | 1.0 | 1.1 | 0.5–2.8 | 2.7 |
| Phenylalanine | 5.4 | 6.4 | 2.5–10.2 | 5.3 |
| Tyrosine | 3.6 | 4.6 | 3.6–5.5 | 3.7 |
| Arginine | 7.6 | 5.4 | 4.0–9.5 | 7.6 |
| Asparagine + aspartic acid | 13.8 | 11.8 | 9.2–12.2 | 11.7 |
| Serine | 4.9 | 5.9 | 4.0–6.8 | 5.2 |
| Glutamic + glutamic acid | 13.2 | 11.6 | 9.8–13.0 | 18.0 |
| Glycine | 5.9 | 6.3 | 6.1–7.5 | 4.4 |
| Alanine | 7.8 | 8.2 | 8.0–9.0 | 4.5 |
| Valine | 5.8 | 6.6 | 2.8–8.5 | 4.9 |
| Hydroxyproline | 0.7 | 0.4 | – | – |
| Proline | 5.5 | 4.9 | 3.8–7.0 | 5.2 |
| Essential AAb | 40.5 | 45.5 | 42.7–50.9 | 43.5 |
| Total AA (g kg−1 DM) | 262.7 | 401.3 | – | 459.9 |
| AA-N (g kg−1 DM)c | 39.5 | 57.6 | – | – |
| Total N (g kg−1 DM) | 48.7 | 72.7 | 11.3–43.5 | – |
| Non-protein N, % of total N | 18.8 | 20.7 | – | – |
| N-Protein factor, K P d | 4.62 | 4.72 | – | - |
| N-Protein factor, K A d | 5.69 | 5.95 | – | – |
aMai et al. (Mai et al. 1994) (Ireland, no time of harvest indicated), Wong et al. (Wong and Cheung 2000) (Hong Kong, December harvest), Ortiz et al. (Ortiz et al. 2006) (Chile, November harvest), Yaich et al. (Yaich et al. 2011) (Tunisia, July harvest) and Tabarsa et al. (Tabarsa et al. 2012) (Persian Gulf, April harvest). Soybean meal based on CVB (2007)
bEssential amino acids for monogastric species: lysine, methionine + cysteine, threonine, tryptophan, leucine, isoleucine, histidine, phenylalanine + tyrosine and valine
cBased on N content of each individual amino acid (Sosulski and Imafidon 1990)
dN to protein conversion factor, K P as ratio between sum of anhydrous AA residues and total N, K A as ratio between sum of anhydrous AA residues and N recovered from AA residues (AA-N) as described by Mariotti et al. (2008)