Seminal cryopreservation of Tambaqui, Colossoma macropomum
Author: Antônio Sérgio Varela Júnior (Currículo Lattes)
Supervisor: Dr Mario Roberto Chim Figueiredo
The reproductive biotechnology applied to aquaculture has been increased with works of seminal cryopreservation, genetic improvement and production of germplasm banks. During the cryopreservation of sperm cells, different internal and external cryoprotectants, cooling curves, or freezing forms can be used to minimize the deleterious effect of this biotechnology. The objective of this thesis was to evaluate the effect of different cryoprotectants on characteristics of sperm cells from tambaqui Colossoma macropomum observed in vitro and in vivo. The experiments evaluated Dimethylsulfoxide (DMSO) (5, 10, 15 and 20%); Dimethylformamide (DMF), dimethylacetamide (DMA) and Methylformamide (MF) (all amides in 2, 5, 8 and 11%); Chicken egg yolk low density lipoprotein (LDL) (4, 8,12 and 16%) as well as Trealose (50, 100, 150 and 200 mM), for sperm cryoprotection of tambaqui. After the semen was frozen and thawed, its quality was assessed for rates of sperm motility, fertilization, hatching, mitochondrial functionality, membrane integrity, DNA integrity and latency time. Fertilization and hatching rates with 10% DMSO did not differ from fresh semen. Due to the results obtained with 10% DMSO, this was compared with the amides, LDL and Trealose. The highest rates of fertilization and hatching occurred when amides were used in concentrations of 5% DMA, 8% DMF and 8% MF, which did not differ between them. In these treatments, fertilization and hatching rates were similar to those observed with fresh semen.Higher LDL concentrations ensured the maintenance of membrane and mitochondria integrity and promoted greater cell viability. On the other hand, it was observed that the higher the LDL concentrations, the lower the latency time, motility, fertilization and hatching rates. The fertilization and hatching rates did not differ between DMSO and the treatments that used trehalose, and the fertilization rate with 150 mM trehalose did not differ from the treatment with fresh semen. With these results it is concluded that the amides (5% DMA, 8% DMF and 8% MF) and 150 mM trehalose efficiently preserved sperm cells from Colossoma macropomum.