Evaluation of commercial rations in the growing and finishing phases of the post metamorphic stage of bullfrog

Abstract

The work was carried out with the objective of to evaluate four commercial rations in the feeding of bullfrog in the growing and finishing phases (post metamorphic: 50 to 200 g). The rations were recommended for different species or phases of development: ration 1=for bullfrogs (initial); ration 2=for omnivorous fish (initial); ration 3=for trout (growing); ration 4=for trout (initial). The first trial, for evaluation of the apparent metabolizable energy (AME) and the apparent metabolizable dry matter (AMDM) of the rations, was carried out with 128 bullfrogs, in a completely randomized blocks design, with four repetitions of eight animals for each experimental unit. The ration 4 showed the largest average value of AME (3,440 kcal/kg) and the ration 2, the lowest (2,930 kcal/kg). It was not observed any effect of the ration on the AMDM value. In the second trial, for analysis of the performance and economic viability, that lasted for 56 days, 320 bullfrogs with initial average weight of 51.75 g, were distributed in a completely randomized blocks design, with eight repetitions of ten animals for experimental unit. The rations 1 and 4, which had higher levels of protein and energy, provided the best results of performance and economic viability. The greatest numerical value of EE, AME and AMDM in the ration 4 resulted, probably, of its ingredients, that may have influenced the better values of food conversion obtained with the use of that ration. The use of antibiotic in the rations for bullfrogs should be studied and that substance may have influenced the worst results presented by the ration 3.