Tryptophan

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The tryptophan requirement values for fish are presented in Table 23.11. The requirement appears to be about 5-10 g kg-1 of dietary protein for the various species studied.

Table 23.10. Threonine requirements (g kg-1 of protein) for various fish species.

Fish

Requirement

Type of diet

Reference

Catla

50

Purified

Ravi and Devaraj (1991)

Channel catfish

20

Purified

Wilson et al. (1978)

Chinook salmon

22

Purified

DeLong et al. (1962)

Chum salmon

30

Purified

Akiyama et al. (1985a)

Coho salmon

20

Purified

Arai and Ogata (1993)

Common carp

39

Purified

Nose (1979)

European sea bass

26-30

Semipurified

Tibaldi and Tulli (1999)

Hybrid striped bass

26

Semipurified

Keembiyehetty and Gatlin (1997)

Japanese eel

40

Purified

Arai (in Nose, 1979)

Milkfish

45

Purified

Borlongan (1991)

Nile tilapia

38

Purified

Santiago and Lovell (1988)

Rainbow trout

32-37

Semipurified

Rodehutscord etal. (1995)

Red drum

23

Semipurified

Boren and Gatlin (1995)

Rohu

43

Murthy and Varghese (1996)

Striped bass

25

Practical

Small and Soares (1999)

Table 23.11. Tryptophan requirements (g kg-1 of p rote in) for various fish species.

Fish

Requirement

Type of diet

Reference

African catfish

11

Purified

Fagbenro and Nwanna (1999)

Catia

10

Purified

Ravi and Devaraj (1991)

Channel catfish

5

Purified

Wilson et al. (1978)

Chinook salmon

5

Purified

Halver (1965)

Chum salmon

7

Purified

Akiyama et al. (1985b)

Coho salmon

5

Purified

Halver (1965)

5

Purified

Arai and Ogata (1993)

Common carp

8

Purified

Nose (1979)

Gilthead sea bream

6

Semipurified

Luquet and Sabaut (1974)

Japanese eel

11

Purified

Arai (in Nose, 1979)

Milkfish

6

Semipurfied

Coloso et al. (1992)

Nile tilapia

10

Purified

Santiago and Lovell (1988)

Rainbow trout

5

Semipurified

Walton etal. (1984b)

6

Purified

Kim etal. (1987)

14

Purified

Poston and Rumsey (1983)

Rohu

6

Purified

Khan and Jafri (1993)

Sockeye salmon

5

Purified

Halver (1965)

The high value of 14 g kg-1 of dietary protein for rainbow trout may have been overestimated because no dietary levels between 2.5 and 5.0 g kg-1 of diet were fed (Poston and Rumsey, 1983).

Tryptophan deficiency results in several deficiency signs in salmonids that have not been observed in other fish species. Halver and Shanks (1960) observed scoliosis and lordosis in sockeye salmon but not in Chinook salmon fed tryptophan-deficient diets. Scoliosis and lordosis have also been observed in tryptophan-deficient rainbow trout (Shanks et al., 1962; Kloppel and Post, 1975; Poston and Rumsey, 1983; Walton et al., 1984b) and chum salmon (Akiyama et al., 1985b). These deformities were found to be reversible in rainbow trout when the fish were fed adequate dietary tryptophan (Shanks et ah, 1962; Kloppel and Post, 1975) and appear to be related to a depletion of 5-hydroxytryptophan in the body or brain (Akiyama et al., 1986). Other tryptophan deficiency signs in rainbow trout include renal calcinosis (Kloppel and Post, 1975), caudal fin erosion, cataracts and short gill opercula (Poston and Rumsey, 1983), and increased liver and kidney levels of calcium, magnesium, sodium and potassium (Walton et al., 1984b).

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