The patterns of plasma free amino acids after force-feeding in rainbow trout Oncorhynchus mykiss (Walbaum) with and without dorsal aorta cannulation

Abstract

Two experiments were conducted to compare the patterns of plasma free amino acid concentrations after force‐feeding in rainbow trout Oncorhynchus mykiss (Walbaum) with and without dorsal aorta cannulation. In the first experiment, 35 rainbow trout averaging 504 ± 7.8 g (mean ± SD) were divided into seven groups of five fish each. After 48 h starvation, a group of fish was anaesthetized and blood samples were taken at one of the following time periods: 0, 4, 8, 12, 24, 36 and 48 h after feeding. In the second experiment, five dorsal aorta cannulated rainbow trout averaging 511 ± 6.2 g (mean ± SD) were kept in a cage. After 48 h starvation, the fish were anaesthetized and blood samples were taken from the same fish at 0, 4, 8, 12, 24, 36 and 48 h after feeding. In the first experiment, the concentration of all plasma free amino acids except histidine and glycine peaked at 4 h and returned to the basal level 24 h after feeding. In the second experiment, the concentration of all plasma free amino acids except isoleucine, leucine, phenylalanine and tryptophan also peaked at 4 h and returned to the basal level 24 h after feeding. These results showed that the pattern of plasma free amino acid concentrations from fish with and without dorsal aorta cannulation were similar.

Postprandial changes in plasma free amino acid levels obtained simultaneously from the hepatic portal vein and the dorsal aorta in rainbow trout (Oncorhynchus mykiss)

“…The free AA concentrations reported here for DA samples are comparable to earlier studies where only the DA was cannulated (Ok et al, 2001;Sunde et al, 2003). In general, our data also agree with the earlier study of Ash et al , who measured the postprandial concentrations of free AA in both the DA and HPV of lightly anaesthetized rainbow trout, but only at 3·h.…”

“…Ok et al found that postprandial plasma free AA concentrations in the DA peaked at 4·h, except for glycine (Ok et al, 2001). Here, the total free AA concentration peaked at 6·h, a time frame that agrees with the results reported after serial sampling of slaughtered fish (see Sunde et al, 2003;Espe et al, 1993).…”

“…This slight delay in the peak of free AA compared with those found by Ok et al may be related to the warmer temperature (~17°C) used in the experiments of Ok et al compared with the two subsequent studies (~10°C), although an effect of dietary differences cannot be excluded. Ok et al used a combination of crystalline amino acids and casein and gelatine (Ok et al, 2001), and crystalline AAs are known to be absorbed quickly (Cowey and Walton, 1988). A more rapid uptake should result in higher and sharper peaks of plasma free AAs.…”

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

“…A 3 mL syringe with a 23-gauge needle was used to remove air and blood clot, and the cannula was flushed with the heparinized saline solution. The cannula was sutured behind the bubble on the roof of the mouth, led out from the right nostrum, plugged with a colour head pin, and sutured at the dorsal fin (Ok et al 2001;Bai et al 2003;Park et al 2005). Thirty five dorsal aorta cannulated rainbow trout were randomly distributed into seven groups of five fish per group and fed one of the seven experimental diets per group.…”

“…Although the effects of dietary protein or amino acid mixtures on PFAA concentrations in rainbow trout, O. mykiss (Murai et al 1987;Schuhmacher et al 1997;Vermeirssen et al 1997), and sea bass, Dicentrarchus labrax (Thebault et al 1985), have been reported, the complete dose response relationships for amino acids have not been investigated. In our previous studies, requirements for dietary essential amino acids such as arginine, methionine, lysine and threonine were obtained in rainbow trout, O. mykiss, by using surgically modified methods in our laboratory (Ok et al 2001;Ok 2002;Park et al 2005).…”