1208
COOLING OF EQUINE SEMEN AT 16ºC FOR 36h WITH THE ADDITION OF CYSTEINE IN DIFFERENT CONCENTRATIONS
Equine semen manipulation during the cooling process reduces sperm viability and fertility in consequence to, among others, membrane lipid peroxidation, because of the high content of polyunsaturated fatty acids, which makes cells highly susceptible to free radicals and reactive oxygen species. The objective of the present study was to evaluate the effect of in vitro addition of cysteine in four concentrations (0, 1, 1.5, and 2.5mM) for cooling spermatozoa of 12 stallions at 16ºC for 36h. Evaluated variables were motility, vigor, viability and plasmatic and acrosomal membrane integrity in four different moments (0, 12, 24 and 36h). With the exception of acrosomal integrity, it was verified a reduction in motility, vigor and plasmatic membrane integrity in all samples, during cooling. In the evaluations at 36h of cold storage, motility (mot) and viability (viab) were greater in groups treated with 1mM (mot:46,5±6,1/viab:76,5±6,9) and 1.5mM (mot:46,0±4,6/viab:76,9±3,7) cysteine, respectively, compared to control (mot:35,5±18,4/viab:68,1±13,4) and 2.5mM (mot:39,7±12,4/viab:66,0±17,2) (P<0.05). As for vigor (vig) and plasmatic membrane integrity (plasm), 1mM cysteine (vig:3.6±0.5/plasm: 57.2±9.5) showed greater results compared to control (vig:3.2± 1.1/plasm:54.1±11.8), 1.5mM (vig:3.5±0.6/plasm:52.2±13.3) and 2.5mM (vig:3.2±1.1/plasm:55.8±12.5) (P<0.05). Regarding acrosomal membrane integrity, in general, there was no loss of integrity (70.5±10.4; 69.4±4.4; 68.0±7.2 and 70.3±0.5), control, 1mM, 1.5mM and 2.5mM respectively. The concentration of 1mM cysteine was more effective for the protection of sperm cells in the commercial system of passive cooling at 16ºC for 36h, with greater values for motility, vigor, viability and plasmatic membrane integrity.
Keywords:
antioxidant, cooled semen,
stallion