Effect of guanidinoacetic acid and betaine supplementation in soybean meal-based diets on growth performance, muscle energy metabolism and methionine utilization in the bullfrog Lithobates catesbeianus

Abstract

This study was carried out to evaluate the impacts and interactions of guanidinoacetic acid (GAA) and betaine (BT) supplementation of soybean-meal-based diets on the growth, meat quality, and methionine utilization in the bullfrog Lithobates catesbeianus. A basal diet was supplemented with 0 or 4 g/kg of BT and/or 0, 0.4, or 4 g/kg GAA to formulate six experimental diets, designated Control (BT/GAA: 0/0), B0G0.4 (0/0.4), B0G4 (0/4), B4G0 (4/0), B4G0.4 (4/0.4) and B4G4 (4/4). Each diet was fed to three individual bullfrogs (initially weighing 51.70 ± 0.33 g) for 8 weeks. As a result, bullfrogs fed diets with GAA showed greater weight gain than the control group (P < 0.05). The addition of GAA or BT to the diets increased whole-body protein deposition and the hind leg index (P < 0.05). Diets supplemented with GAA led to reduced muscle glycolysis, which increased the muscle pH value 24 h after euthanasia (P < 0.05). However, a combination of BT and GAA had an insignificant effect on the expression of betaine homocysteine methyltransferase mRNA compared with the diets supplemented with GAA-only (P > 0.05). The findings of this study suggest that dietary GAA supplementation improves bullfrog growth performance and muscle energy metabolism after slaughter, but GAA combined BT supplementation does not improve methionine utilization for bullfrog.