Bacterial pigment for Nile tilapia feeding

The aim of this study was to evaluate the effects of different carotenoids sources in tilapia fish diets on the animals' performance and fillets characteristics. Nine hundred and sixty tilapias, Oreochromis niloticus, averaging 15 g were distributed into 24 tanks to receive one of the six treatments (four repetitions) for 80 days: basal diet with no pigment (control group), basal diet with 350 mg/kg astaxanthin 10 % and basal diets added of four different concentrations of Rubrivivax gelatinosus biomass (175, 350, 700 and 1400 mg/kg). Variables analyzed included feed consumption, weight gain, feed conversion and specific growth rate for the animals and pH, proximate composition, carotenoids, polyunsaturated fatty acids and color for the fillets. Productive parameters did not differ statistically. Moisture content was lower on the fillets of treatments with pigments. The protein contents on the fillets of diets supplemented with the bacterial biomass were higher than in control group, while pH, minerals and lipids did not vary among treatments. Lightness and yellowness did not differ among the treatments, but redness and carotenoids contents were higher for all the groups that received the pigments than for the control group. The ratio of polyunsaturated fatty acids n-6/n-3 was improved with the dietary biomass. So, it was concluded that the use of the pigmenting ingredients did not alter productive parameters but increased redness and carotenoids contents in the fillets. Moreover, the use of R. gelatinosus biomass also increased the protein contents and improved the fatty acids profile in the fillets.