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This work was planned to study the effect of dog breeds on the physical and chemical properties of semen. A total number of 53 dogs of Caucasian (n=3), German shepherd (n=37), Malinois (n=8) and Rottweiler (n=5) breeds and mixed ages were used for semen collection along a year from 2016 to 2017. Semen was collected using an artificial vagina and examined for color, density, volume, pH, sperm individual motility, livability rate, cell concentration (SCC) and morphology. Seminal plasma was harvested after centrifugation and examined for testosterone hormone levels, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and total antioxidant capacity. Results indicated that dog breeds markedly (p<0.05) affect pH and SCC values. Seminal plasma testosterone, ALT and ALP significantly (p< 0.001, 0.001 and 0.05, respectively) differed between dog breeds. Semen pH and ALT values of Caucasian breed was the lowest among the examined breeds. SCC were substantially (p<0.05) higher in Malinois breed than in Rottweiler breed. Testosterone hormone was higher in Caucasian and Malinois than German Shepherd and Rottweiler breeds. The ALP enzyme activity was higher in Rottweiler than German shepherd and Malinois breeds. It conclusion, dog breeds markedly affect the fertility potential of semen though its influence on testosterone-dependent libido intensity, sperm count per ejaculate and seminal plasma enzymatic activity.

Ram sperm have a higher ratio of polyunsaturated/saturated fatty acids and a lower ratio of cholesterol/phospholipids molar than other species, which renders the sperm much more vulnerable to oxidative damage caused by reactive oxygen species (ROS) .The aim of the current study was to evaluate the effects of cysteine, glutathione and taurine on the freezability of ram spermatozoa and biochemical parameters. Semen samples from ten mature mixed Barki rams were used in this study. Pooled semen samples were divided randomly into 7 aliquots one was diluted with a Shotor extender as a control basal diluent while others in addition to basal extender L-Cysteine, L-reduced glutathione and taurine were added by two levels for each to present seven experimental groups. Diluted semen cooled to 5 o C then frozen by liquid nitrogen in 0.25 ml French straws. After 48 hr frozen, straws were then thawed individually at 37 o C for 30 sec. in a water bath then subjected to evaluation.The obtained results showed that, addition of glutathione by a rate of 5mM was significantly increases motility than control group. Similarly, addition of taurine by a rate of 50mM significantly increased the viability index of cryopreserved semen samples.Percentages of acrosomal defects were dramatically decreased (P < 0.05) with glutathione (10 mM) addition compared to control (9.00 ± 1.16 % and 21.00 ± 0.58 % respectively)In regards to sperm membrane integrity, cysteine (5 mM) provided a greater protective effect (47.00 ±1.16) compared to control (%, 35.33 ± 0.88 %).Antioxidant addition showed decreased enzyme leakage and significantly (P < 0.05) improved total antioxidant capacity (TAC) especially taurine (50Mm) compared to control group.In regards to DNA integrity, taurine (50mM) provided a significant protective effect (98.51± 0.42 %) compared to control.Findings of this study showed that addition of cysteine, glutathione and taurine to semen extenders, of greater benefit to quality of frozen-thawed ram sperm. However further investigation on their effect on fertilizing capacity and pregnancy rate still needed.