The dietary valine requirement for rainbow trout, Oncorhynchus mykiss, can be estimated by plasma free valine and ammonia concentrations after dorsal aorta cannulation

Figures & data

Table 1. Composition of the experimental diets (% of dry matter basis).^a

Ingredients	Experimental diet (graded valine level, % in diet)
	Diet 1	Diet 2	Diet 3	Diet 4	Diet 5	Diet 6	Diet 7
	(0.45)	(0.95)	(1.20)	(1.45)	(1.70)	(1.95)	(2.45)
EAA^b				15.27
NEAA^c				5.47
Casein^d				5.00
Gelatine^d				2.00
Dextrin^d				27.97
Dextrose^d				5.00
A-Cellulose^d				8.20
Fish oil^e				10.00
Other ingredients^f				12.20
L-valine^g	0.10	0.60	0.85	1.10	1.35	1.60	2.10
Aspartic acid^g	4.23	3.98	3.85	3.73	3.60	3.48	3.23
Glutamic acid^g	4.57	4.32	4.19	4.07	3.94	3.82	3.57
Total	100	100	100	100	100	100	100
^aDiets were neutralised with NaOH to give a final pH of 6.6.
^bEAA, essential amino acids (gram per 100 g diet): arginine, 1.924; histidine, 0.725; isoleucine, 1.674; leucine, 2.702; lysine, 1.904; methionine, 1.030; cystine, 0.172; phenylalanine, 1.742; tyrosine, 1.335; threonine, 1.601; tryptophan,0.462 (Ajinomoto, Tokyo, Japan).
^cNEEA, Non-essential amino acids (gram per 100 g diet): alanine, 1.741; glycine, 0.758; proline, 0.568; serine, 2.398 (Ajinomoto, Tokyo, Japan).
^dUnited States Biochemical (USB), Cleveland, OH, USA.
^eEwha Oil Company, Busan, Korea.
^fOther ingredients include: carboxymethyl cellulose, 1.00% (United States Biochemical); Ca(H2PO4)2H2O, 3.00%; choline bitartrate, 1.20% (United States Biochemical), vitamin mixture, 3.00% & mineral mixture, 4.00% (Bae et al. 2010).
^gAjinomoto, Tokyo, Japan.

Table 2. Amino acid composition of the experimental diet (% of dry matter basis).

Amino acids	From casein and gelatin	From crystalline amino acids	Total^a
EAA
Arginine	0.353	1.924	2.277
Histidine	0.194	0.725	0.919
Isoleucine	0.252	1.674	1.926
Leucine	0.493	2.702	3.195
Lysine	0.502	1.904	2.406
Methionine	0.152	1.030	1.182
Cystine	0.019	0.172	0.191
Phenylalanine	0.271	1.742	2.013
Tyrosine	0.270	1.335	1.605
Threonine	0.221	1.601	1.822
Tryptophan	0.065	0.462	0.527
Valine	0.350	0.000^b	0.350
NEAA
Alanine	0.345	1.741	2.086
Aspartic acid	0.483	4.280	4.763
Glycine	0.538	0.758	1.296
Glutamic acid	1.298	4.616	5.914
Proline	0.790	0.568	1.358
Serine	0.374	2.398	2.772
^aThe amino acid profile was simulated with that of 35% whole chicken egg protein (Robinson et al. 1981).
^bSeven experimental diets were formulated to have graded levels of valine (0.45, 0.95, 1.20, 1.45, 1.70, 1.95 or 2.45%) equal amount of aspartic acid and glutamic acid by weight were substituted for the proper amounts of valine in the basal diet.

Table 3. Plasma post-prandial (5 h after intubation) and post-absorptive (24 h after intubation) valine and ammonia concentrations (nmol mL⁻¹) of rainbow trout fed graded levels of dietary valine.*

Dietary valine level (%)	Plasma valine concentrations		Plasma ammonia concentrations
	Post-prandial values (PPval)	Post-absorptive values (PAval)	Post-prandial values (PPA)	Post-absorptive values (PAA)
0.45	123^d	141^e	121^e	105
0.95	357^c	163^d	148^d,e	114
1.20	487^b	186^c	162^d	120
1.45	608^a	256^a,b	172^d	107
1.70	617^a	250^a,b	222^c	122
1.95	593^a	243^b	284^b	110
2.45	649^a	271^a	312^a	116
Pooled SEM†	72.1	19.4	27.3	2.43
*Values are means from groups (n=5) of fish where the means in each column with different superscript letters are significantly different (P<0.05).
†Pooled standard error of mean: SD/√n.

Figure 1.  Broken line analysis of post-prandial plasma valine concentrations (nmol mL⁻¹) in rainbow trout fed graded levels of dietary valine. Values of the X-axis are the valine levels in the experimental diets. Values are means±SD of five replicates. Y=486.1x −98.383, Y′=616.75, R ²=0.9996.

Figure 2.  Broken line analysis of post-absorptive plasma valine concentrations (nmol mL⁻¹) in rainbow trout fed graded levels of dietary valine. Values of the X-axis are the valine levels in the experimental diets. Values are means±SD of five replicates. Y=104.9x −80.274, Y′=237.6, R ²=0.8077.

Figure 3.  Broken line analysis of post-prandial plasma ammonia concentrations (nmol mL⁻¹) in rainbow trout fed graded levels of dietary valine. Values of the X-axis are the valine levels in the experimental diets. Values are means±SD of five replicates. Y=139.66x −16.103, Y′=160.67, R ²=0.9006.