Motion characteristics of Murrah buffalo bull spermatozoa in various seasons and its relationship with functional integrity of the plasmallema

Increased quality of in natura and cryopreserved semen of water buffaloes supplemented with saturated and unsaturated fatty acids from the palm oil industry

Ruminant energy supplementation with vegetable oils or fats has been standing out worldwide and oil palm processing has been receiving growing interest. This study assessed the effect of supplementation with saturated and unsaturated fatty acids from the palm oil industry on the lipid profile of seminal plasma and of the sperm membrane, as well as on the morphological and functional characteristics of raw and cryopreserved buffalo semen. Twelve purebred Murrah bulls (Bubalus bubalis) were assigned to the experimental groups and fed diets for 120 days with no added lipids (CONT, four bulls), or with an extra amount of 3% lipids from crude palm oil (PALM, four bulls), or from palm oil deodorizer distillate (PODD, four bulls). Semen was collected and cryopreserved every 15 days. The lipid composition of membranes and semen quality were determined after collections. Lipid supplementation did not impact feed intake (P>0.05). Diet enrichment with PALM increased the linoleic acid (C18:2,ω6) in seminal plasma. Lipid supplementation did not increase the polyunsaturated fatty acids in the sperm membrane composition, but significantly increased the lignoceric acid (C24:0). Cryopreserved semen of the supplemented bulls presented higher progressive motility (60.2 vs. 67.9 vs. 65.2%; P<0.05) and sperm viability detected by eosin-nigrosin staining (61.1 vs. 69.4 vs. 67.8%; P<0.05). Palm oil reduced major sperm defects in both raw (12.2 vs. 9.3 vs. 13.2%; P<0.0001) and cryopreserved semen (12.4 vs. 9.4 vs. 11.2%; P<0.0001). The lipids added to the diet did not impact the population of spermatozoa with intact plasma and acrosomal membranes (PI-/PSA-), but significantly increased the percentage of spermatozoa with high mitochondrial potential (25.6 vs. 31.5 vs. 32.0%; P=0.008). The results suggest that lipid supplementation based on crude palm oil or palm oil deodorizer distillate can be safely used to feed buffalo bulls and may increase sperm attributes related to male fertility.

Effect of season on semen quality parameters in Murrah buffalo

Seasonal influence on frozen semen quality in Murrah buffalo breeding bulls was determined. Frozen semen samples of 6 Murrah buffalo bulls were collected and semen frozen in 4 different seasons, viz. winter (Dec-Feb), spring (mid Feb-Apr), summer (May-Jun) and rainy (Jul-Aug) were assessed. Samples (12) of each bull, in a season, were evaluated for sperm motility, viability and acrosome integrity. Motility and other kinematics of spermatozoa during incubation (37°C) at 0, 30, 60, 90 and 120 min of thawing were assessed with computer assisted semen analyzer. Post-thaw sperm total motility and viability differed significantly among the seasons, the highest was in winter. Sperm plasma membrane integrity, acrosome integrity, progressive motility, rapid motility and other CASA evaluated parameters did not differ significantly among the seasons. Higher values of plasma membrane integrity (PMI), progressive motility, rapid motility, average path velocity (VAP), straight line velocity (VSL), curvilinear velocity (VCL), beat cross frequency (BCF), linearity (LIN) and straightness (STR) were obtained in winter season as compared to other seasons. Post-thaw motility at 0 min and 60 min of post-thaw incubation varied significantly between seasons and higher sperm motility was sustained for a longer period in semen cryopreserved in winter followed by rainy season, summer and spring. It can be concluded from this study that buffalo bull semen produced and frozen during winter season resulted in higher sperm motility, viability and postthaw longer survivability in comparison to other seasons.

Effects of osmotic pressure on motility, plasma membrane integrity and viability in fresh and frozen-thawed buffalo spermatozoa

In the first experiment, osmotic pressure of semen and seminal plasma in a semen sample from each of the 20 mature Nili-Ravi buffalo bulls was determined. In the second experiment, effects of osmotic pressure on motility (%), plasma membrane integrity (%) and viability (%) in fresh and frozen-thawed semen samples from each of the seven mature Nili-Ravi buffalo bulls was determined. In the first experiment, seminal plasma was harvested by centrifuging semen at 400 × g for 10 min at 37°C and osmotic pressure was determined using an osmometer. In the second experiment, motility (%) was assessed in fresh and frozen-thawed (37°C for 30 s) semen samples using a phase-contrast microscope (×400). Plasma membrane integrity (%) was determined by mixing 50 μl each of fresh and frozen-thawed semen with 500 μl of solution having an osmotic pressure of 50, 100, 150, 190 or 250 mOsm/l (hypotonic treatments of fructose + sodium citrate) and incubating at 37°C for 1 h. Viability (%) of fresh and frozen-thawed spermatozoa before and after challenging them to osmotic pressure (hypotonic treatments) was assessed using supravital stain under a phase-contrast microscope (×400). In the first experiment, the mean ± s.e. osmotic pressures of the buffalo semen and seminal plasma were 268.8 ± 1.17 and 256.0 ± 1.53 mOsm/l, respectively. In the second experiment, motility (%) decreased (P < 0.05) in frozen-thawed semen samples as compared with fresh semen (60.1 ± 1.34 v. 81 ± 1.57, respectively). The plasma membrane integrity (%) and magnitude of osmotic stress in fresh and frozen-thawed semen samples was higher (P < 0.05) at 50, 100, 150 and 190 mOsm/l as compared with 250 mOsm/l. Loss of viability (%) in fresh and frozen-thawed semen samples was higher (P < 0.05) at 50 mOsm/l (59% in fresh, 70% frozen thawed) as compared with other osmotic pressures, while it was lowest at 250 mOsm/l (4.1% for fresh, 9.7% frozen thawed). In conclusion, osmotic pressure of Nili-Ravi buffalo semen and seminal plasma is determined. Furthermore, variation in osmotic pressure below 250 mOsm/l is not favorable to fresh and frozen-thawed buffalo spermatozoa.

Reproduction in the Water Buffalo

In this paper, an account of various aspects related to buffalo reproduction are given. Fundamental concepts of the reproductive physiology as well as manipulation of the reproductive function will be presented. This will include an overview of the most recent developments of the oestrous cycle and the ovulation control, new strategies of reproductive management for the improvement of genetic gain and the application of newly developed reproductive technologies, such as in vitro embryo production, embryo and sperm sexing and cloning.

Seasonality affects post-thaw plasma membrane intactness and sperm velocities in spermatozoa from Thai AI swamp buffaloes (Bubalus bubalis)

Altogether 218 frozen semen AI doses, prepared between 1980 and 1989 and also between 2003 and 2005 from 18 AI Thai swamp buffalo sires, were examined to determine whether seasonality affects post-thaw viability, as plasma membrane integrity (PMI, using SYBR-14/PI), plasma membrane stability (PMS, using Annexin-V/PI), or motility (Mot, using CASA). A thermoresistance test (38 degrees C for 60 min) was used to further analyze sperm survivability in vitro. All variables were compared over 3 seasons of the year (rainy: July-October; winter: November-February; and summer: March-June), with distinct ambient temperature and humidity. PMI (% of alive spermatozoa) was higher in winter (54.6%, P<0.001) than in the rainy (43.5%) or summer (46.7%) seasons. Outcomes of PMS (Annexin-V/PI assay) confirmed those of PMI, the highest PMS in spermatozoa processed in winter (55.7%, P<0.001). Spermatozoa depicting linear Mot post-thaw ranged from 48.2% to 48.8% across seasons (ns), proportions that decreased during incubation (33.5-37.9%), albeit without seasonal differences. The mean percentages of straight linear velocity (VSL), average path velocity (VAP), or curvilinear velocity (VCL) were higher (P<0.05-0.001) in the rainy season than in winter or summer, while average lateral head displacement (ALH) was higher (P<0.05) in summer, differences maintained after incubation. In conclusion, post-thaw PMS and PMI, assessed by flow cytometry, were significantly better in sperm samples processed during winter than in samples processed during the other seasons of the year, a seasonal difference not picked up by CASA, probably due to the larger number of spermatozoa assessed.