Restrição alimentar no manejo de juvenis de tambaqui (Colossoma macropomum)

Abstract

Spending on food reaches around 70% of production costs in fish farming. One of the alternatives to alleviate this cost is the adoption of feeding strategies, including food restriction, which consists of leaving the fish in a short period of fasting, providing feed savings. The aim of this study was to evaluate the different number of days of food restriction of tambaqui juveniles in order to reduce feed costs without compromising performance, as well as to evaluate the existence of compensatory growth. The study was conducted at the Fish Nutrition and Health Laboratory at Embrapa Western Amazon, Manaus, Amazonas, Brazil. The trial was conducted in a completely randomized design (DIC), using 6 treatments (T0 - Daily food, T1 - One fasting day a week, T2 - Two fasting days a week, T3 - Three fasting days a week, T4 - Four fasting days a week and T5 – Five fasting days a week) with 5 repetitions. Juveniles with an average initial weight of 25.89 ± 3.57 g and average length of 11.69 ± 0.65 cm were used, housed in 70 L basins, with constant water renewal and artificial aeration fed for a period of 45 days. At the end of the experiment, zootechnical performance indices were evaluated such as final weight (FP), weight gain (GP), feed intake (CR), apparent feed conversion (CAA) and survival, hepatosomatic, liposomal and viscerosomatic index, blood parameters in addition to a simple food cost analysis. There was a significant difference for PF, GP, CR and CAA. The best CAA were found on two and three days of fasting, as well as the best GP that was found on a weekly fasting day, in addition to the control treatment (daily feeding). In the somatic relationships, there was a statistical difference for all variables and the values of the treatments that were closest to the daily diet were one and two days of weekly fasting. In hematological parameters, glucose showed a statistical difference between the control treatment and the others, with the exception of treatment 4 which did not differ significantly from the control and hemoglobin also showed a statistical difference between treatments, however there was no significant difference between treatments of one and three days of weekly fasting in relation to the control treatment. With regard to cost, the treatment with two days of weekly restriction provided greater reduction in the cost of feed. It was concluded with this study that tambaqui juveniles submitted to up to two days of food restriction may present partial compensatory growth, in addition to reducing the costs with feed supply by up to 36.8%. Submitting tambaqui juveniles to more than two days of food restriction compromises zootechnical performance, somatic relationships, in addition to causing changes in glucose and hemoglobin.