Use of glucose or BTS™ combined with DMSO or methylglycol under two differentfreezing protocols for the cryopreservation of sperm from the common curimatã(Prochilodus brevis)

ABSTRACT

This study evaluated the effect of glucose orBeltsville Thawing Solution (BTS™) combined withdimethyl sulfoxide (DMSO) or methylglycol (MG)under two different freezing protocols on the kineticsand morphology of cryopreserved Prochilodus brevissperm. The semen samples were diluted using one of fourdifferent treatments (glucose+DMSO, glucose+MG,BTS™+DMSO, and BTS™+MG), loaded into 0.25-mlstraws and subjected to two different freezing processes(programmed freezing machine and dry shipper). After10 days, the semen samples were thawed, and the spermmorphology and kinetics were evaluated. Thephysicochemical parameters of the semen in naturawere similar to those observed in other studies ofCharaciformes, indicating the feasibility of semencryopreservation. Glucose, when used as a diluentwith the cryoprotectant MG (glucose+MG), yieldedhigher percentages of mobile spermatozoa afterfreezing in a dry shipper (76.88 ± 4.84%) and in aprogrammed freezing machine (70.95 ± 1.76%)compared with the combination of glucose and DMSO.Moreover, the glucose+MG treatment yielded a highersperm velocity (curvilinear velocity 79.52 ± 2.88 µm s-1; straight-line velocity 45.46 ± 3.01 µm s-1; averagepath velocity 67.92 ± 3.08 µm s-1) than the otherstudied treatments, and a higher amount of normalsperm (74.56 ± 0.77%) was observed in the semensamples cryopreserved using a programmed freezingmachine. The sperm abnormalities observed included abent tail morphology. Therefore, the use ofglucose+MG in combination with either a dry shipper ora programmed freezing machine is recommended forthe cryopreservation of P. brevis sperm because thesemethods yielded high numbers of motile andmorphologically normal spermatozoa.