Rashad Nasrullah

Eeffect Of Cryopreservation And Equilibration Time On Characterstics Of Buck Semen - 2011

The objectives of present study were a) to determine the effect of stages of cryopreservation on motility, plasma membrane integrity and acrosome and sperm morphology of buck spermatozoa (exp. 1) and b) to find out the effect of different equilibration periods on post thaw semen characteristics (exp. 2). In the first experiment semen ejaculates from three Beetal bucks were collected (n= 15) and diluted in Tris-citric acid extender, cooled to 4ºC in 90 min., equilibrated at 4ºC for 2 hr, filled in straws and frozen in liquid nitrogen. Semen assays (motility, plasma membrane integrity, acrosome and sperm morphology) were examined at different stages of cryopreservation i.e., (after extension (AE), at cooling (AC), before freezing (BF) and after freezing (AF). In experiment two, semen samples (n=4) were cryopreserved with different equilibration periods (0 hr, 2 hr, 4 hr, 8 hr). Frozen semen was thawed at 37ºC for 30 s. In exp. 1 mean percent motility of after extension (86±1.4) was reduced (P<0.05) at cooling (77.6±1.3) or before freezing (74.6±1.45) but dropped significantly (P<0.05) after freezing and thawing (42.3±2.47). Mean percentage of swollen spermatozoa after extension (82.2±1.14) was reduced (P<0.05) at cooling (75±1.71) or before freezing (72.6±1.96), however, it decreased greatly (P<0.05) after freezing and thawing (50.1±2.97). The mean percentage of normal acrosome of fresh semen sample (87.7±1.3) was reduced (P<0.05) significantly before freezing (81.7±1.8). It did not differ from mean percentage at extension (85.8±1.7) and at cooling (83.2±1.58) but it declined (P<0.05) significantly after freezing and thawing (45.2±2.8). Mean percentage of live spermatozoa of fresh semen samples (92.6±0.68) and after extension (89.3±1.4) did not differ but it reduced (P<0.05) at cooling (84.8±1.78) and before freezing (80.2±2.51). Mean percentage of live spermatozoa declined (P<0.05) significantly after freezing and thawing (56±3.46). Mean percent morphology of after extension (96.4±0.27) was reduced (P<0.05) at cooling (88.8±1.28) or before freezing (87.6±2.14) dropped (P<0.05) after freezing and thawing (81±1.89). In experiment two mean percentage motility at 2 hr of equilibration time (57.5±6.3) significantly (P<0.05) improved compared to 0 hr (10.75±1.5). However, this motility did not differ (P<0.05) significantly due to 4 hr (53.75±4.7) and 8 hr (45±3.53) equilibration. Mean percentage of swollen spermatozoa at 2 hr (55.75±6.24) significantly (P<0.05) improved compared to 0 hr (28±8.9). However, this percentage of swollen spermatozoa did not differ (P<0.05) significantly due to 4 hr (53.25±4.42) and 8 hr (54.25±7.33) equilibration. Mean percentage of normal acrosome at 2 hr (62.75±2.9) significantly (P<0.05) improved compared to 0 hr (33.5±7.4). However, normal percentage of acrosome did not differ (P<0.05) significantly due to 4 hr (52.25±6) and 8 hr (56±6.5) equilibration. Mean percentage of live spermatozoa at 2 hr (53±6) significantly (P<0.05) improved compared to 0 hr (26.25±9.43). However, Mean percentage of live spermatozoa did not differ (P<0.05) significantly due to 4 hr (55.25±5.02) and 8 hr (50.5±3.92) equilibration. Mean percentage of live spermatozoa at 2 hr (53±6) significantly (P<0.05) improved compared to 0 hr (26.25±9.43). However, this percentage of live spermatozoa did not differ (P<0.05) significantly due to 4 hr (55.25±5.02) and 8 hr (50.5±3.92) equilibration. Mean percentage of morphology at 0 hr
(80.5±4.29), 2hr (84±2 ), 4h ( 82.5±7.1) and 8 hr( 69±4.6) did not differ significantly. In conclusion, maximum changes to motility, plasma membrane integrity, acrosome integrity and morphology occur during freezing and thawing. Furthermore, equilibration period from 2hr to 8hr seem to be optimal for cryopreservation of goat semen.



Department of Theriogenology

1259,T


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