Dietary guanidinoacetic acid response on digestibility, growth performance, feed utilization and carcass quality in Nile Tilapia ( Oreochromis niloticus )

Abstract

Creatine plays a vital part in the energy metabolism and physiological roles. It is exclusively found in ingredients of animal origin, so using all‐plant protein‐based diets increases the risk of creatine deficiency. The objectives of this current study were to determine the optimal level of dietary guanidinoacetic acid (GAA) with regard to the nutrient digestibility, growth performance, feed utilization and carcass quality of Nile tilapia (Oreochromis niloticus). The fish (27.33 ± 0.70 g) were fed with five different isonitrogenous and isoenergetic diets for 60 days: T1 was the positive control diet (HF; 6% fish meal inclusion); T2 was the negative control formulated to contain no GAA (NC, free fish meal); and T3, T4 and T5 were NC supplemented with 0.06%, 0.12% and 0.18% of GAA respectively. At the end of the experiment, it was found that growth performance and feed utilization were not significantly different (p > .05) among the groups. However, fish from the T3 and T4 groups had slightly better weight gain and growth rate, as well as improved digestibility of protein, methionine, lysine and histidine (p < .05). Fish fed the dietary GAA at 0.06 or 0.12% had clearly larger width increment than the other groups. This is important as consumers prefer large dorsal muscles. This result from this study showed no adverse effect on haematological parameters, serum biochemistry parameters, fillet texture quality and histopathological change in the liver of Nile tilapia. Therefore, these results indicate that GAA supplementation at 0.06%–0.12% in Nile tilapia diet can potentially improve fish growth and feed utilization without setback on health.

Creatine: A valuable supplement in aquafeeds?

“…In Nile tilapia ( Oreochromis niloticus [Linnaeus]), GAA increased growth rates at 0.6–1.8 g kg −1 after 60 days of supplementation 38 . Nevertheless, in a similar study at the same concentrations, GAA did not increase growth performance or feed efficiency in this species 39 . Stites et al 33 even reported decreased weight gain, increased whole body lipid and protein as well as feed efficiency at much higher concentrations (5–20 g kg −1 ) in Red drum ( Sciaenops ocellatus [Linnaeus]).…”

“…Other studies found creatine to enhance growth when used to supplement in plant‐based diets 25,26 . Still, some reports do not reflect such effects, 26,34 others are controversial 39 . In hybrid Striped bass ( Morone chrysops × Morone saxatilis ) reared in freshwater, no growth promotion or improved feed efficiency was observed, but, in fish transferred to brackish water, Burns and Gatlin reported slightly increased weight gain but no effect on feed efficiency or fillet ratio 28 .…”

“…25,26 Still, some reports do not reflect such effects, 26,34 others are controversial. 39 In hybrid Striped bass (Morone chrysops  Morone saxatilis) reared in freshwater, no growth promotion or improved feed efficiency was observed, but, in fish transferred to brackish water, Burns and Gatlin reported slightly increased weight gain but no effect on feed efficiency or fillet ratio. 28 When Red drum was reared in hypoosmotic and isosmotic water, creatine supplementation improved weight gain.…”

“…38 Nevertheless, in a similar study at the same concentrations, GAA did not increase growth performance or feed efficiency in this species. 39 Stites et al 33 even reported decreased weight gain, increased whole body lipid and protein as well as feed efficiency at much higher concentrations (5-20 g kg À1 ) in Red drum (Sciaenops ocellatus [Linnaeus]). Still, GAA supplementation increased weight gain, feed intake and feed efficiency already at concentrations between 0.15 and 0.6 g kg À1 in Grass carp (Ctenopharygodon Idella [Valenciennes]) over a 60-day period.…”