Effect of choline and methionine as methyl group donors on juvenile kuruma shrimp, Marsupenaeus japonicus Bate

Choline and methionine are considered as methyl-group donors; therefore, their interaction may affect the growth of the aquatic animal. Thus, a 42-day feeding trial was conducted as a 2 × 3 factorial design to evaluate the effect and interaction of two methyl-group donors, choline chloride (CC) and methionine (Met), on juvenile kuruma shrimp of initial size 0.91 ± 0.04 g (mean ± S.D.). Six test-diets were formulated to contain 3 levels of CC (0%, 0.06% and 0.12%) and 2 levels of Met (0% and 1.5%). Soybean protein isolate (SPI) was utilized as the main source of protein because of its limited Met content. A significant (P < 0.05) interaction was determined between CC and Met on survival (%S), percent weight gain (%WG), specific growth rate (SGR% day− 1), feed efficiency ratio (FER), protein efficiency ratio (PER) and both choline and Met content of the whole body of the juvenile Marsupenaeus japonicus. The shrimp group with neither supplemental CC nor Met showed lower (P < 0.05) values of the above-mentioned parameters than other shrimp groups fed with 0.06% and 0.12% supplemented CC with or without Met supplementation. The present study showed that supplementation of 0.12% CC in the diets could compensate kuruma shrimp juveniles with the needed methyl-group when fed Met-deficient diets. Also, the supplementation of Met was needed in the case of rearing kuruma shrimp juveniles on choline-deficient diets to compensate methyl group deficiency.