Crescimento, primeira maturação, hematologia, bioquímica sanguínea e reprodução do tambaqui (Colossoma macropomum) em sistema de recirculação de água

Abstract

The objective of the present study was to evaluate the growth, first hematological maturation, blood biochemistry and reproduction of Colossoma macropomum under controlled conditions. In this way, two experiments were carried out. In the first experiment, growth, gonadal development, first maturation, quality of the first spermiation and reproduction were evaluated. Initially, C. macropomum larvae, acquired from a farm located in the state of Pará, were acclimatized and placed in a water recirculation system at the Laboratório de Aquacultura (LAQUA), until they reach the ideal size and weight to start the experiment. 150 animals 155 days after hatching (DAH) were transferred to a tank with a capacity of 3.0 m³ and a static system (27.6±0.5 °C, dissolved oxygen above 4.5 mg/L, total ammonia below 0.5 mg/L and pH between 6.5 and 7.8), fed twice a day with a commercial diet containing 32% crude protein (CP), 7% ethereal extract and 5% fiber, 4-6 mm pellets. Due to rapid growth, with 171 DAH, the animals were divided into two tanks of 3.0 m³ each and remained in this system for 60 days. At 231 DAH, the animals were transferred to a single 23 m³ tank, equipped with a water recirculation system, with temperature control (27.5±0.5 °C), oxygen (> 4.00 mg/L) and photoperiod (12/12), fed twice a day with a commercial diet (32% CP), until the end of the experiment (1080 DAH). Throughout the study, males and females showed gains in weight and length, with no significant difference (P>0.05) observed between the sexes for this parameter. At 590 DAH, the first males were observed in the process of initial maturation and the first females only reached this same stage at 710 DAH. There was a difference (P<0.05) between males and females in the hepatosomatic (HSI) and gonadosomatic índices (GSI). No difference (P>0.05) was observed in the sperm quality analyzed between males of different ages (890 and 990 DAH). At the end of the experiment, 50% of the females that were induced responded positively to the induction and spawned. In the second experiment carried out, we compared the hematological and blood biochemical profile of males and females during the first maturation process. Greater variation in hematological parameters was observed between females of different ages. In the hematological profile, there was a difference (P<0.05) between males and females, only in the erythrocyte count. In the blood biochemical profile, males and females showed differences (P<0.05) only in triglyceride concentrations during the study period. However, within the same sex, but when comparing ages, there was a difference (P<0.05) in the values of hematocrit, plasma protein, hemoglobin, leukocytes, erythrocytes, glucose, triglycerides and cholesterol in females, and in males it was observed difference in the values of leukocytes, erythrocytes, glucose, triglycerides and cholesterol. Regarding the concentration of FSH and LH in males and females at an advanced stage of maturation, no difference (P>0.05) was observed between the sexes. Therefore, with the results obtained in this study, we conclude that it is possible to carry out the complete cultivation cycle of C. macropmum, from larviculture to reproduction in a water recirculation system. We also observed that females present greater variations in hematological and biochemical parameters when compared to males. The hematological and biochemical results can assist future studies by serving as a comparative parameter, as the animals remained in optimal cultivation conditions throughout the experimental period.