Reproductive conditioning of matrinxã Brycon amazonicus (Spix & Agassiz, 1829) submitted to prolonged fasting
Author: Vivianne da Silva Fonseca (Currículo Lattes)
Supervisor: Dr Ricardo Berteaux Robaldo
Co-supervisor: Dra Marle Angélica Villacorte Correa
The matrinxã Brycon amazonicus is highly appreciated for the quality of its meat and is the second most produced species by fish farming in the Northern Region of Brazil. It is a reophilic species, and in its reproductive migration it experiences reduction of the ingestion for three continuous months. Studies carried out with the species under study indicated that pre-reproductive feed restriction improves the response of captive breeders, as did an increase in the eggs of restricted females. The objective of this work was to evaluate the reproductive performance of matrinxã when exposed to prolonged fasting, similar to that suffered by the species in the natural environment. For this, an experiment was carried out from Oct/2010 to Jan/2011 at the Aquaculture Station at UFAM-AM (2 ° 39'39.27 ”S 60 ° 03'04.07” W), when 100 breeders were stocked in 4 600m2 ponds (n = 25/nursery), distributed in 2 control groups fed daily and two groups fasted for 3 months in the period prior to spawning At the end of the experimental period, coinciding with the spawning period of the species, hormonal induction tests were carried out with pituitary carp extract and tissue collection for biochemical analysis (blood, liver and muscle) and calculation of biometric indices: hepatosomatic, gonadosomatic, cavity fat and condition factor index. In inductions, fasting promoted an improvement in reproductive performance with higher values in success rates in induction, fertility, fertilization and hatching, proving the hypothesis tested. In females, fasting also decreased plasma glucose levels, fraction of very low density lipoproteins and triglycerides,indicating a greater mobilization of the 11 nutrients for ovarian development. In males, only plasma cholesterol levels were high. The biochemical parameters of the liver and muscle showed a slight effect of fasting, with reduced levels of triglycerides in the liver and increased muscle glycogen in males. The IGS, IHS and IGC indices showed no difference for females, and only K was reduced during fasting. In males, IGS and IGC were high and K reduced in the same condition. Greater mobilization of energy was found for the reproductive period in males. The main source of energy used appears to have been lipids and proteins. In view of the results obtained in this study and in line with those carried out previously, it was possible to conclude that the maintenance of matrinxã breeders in an extended fast during the three months preceding the natural spawning period of the species, promotes the optimization of the reproductive response.