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.

Buffalo bull spermatozoa are rich in polyunsaturated fatty acids and are prone to lipid peroxidation. We hypothesised that lipid peroxidation in buffalo bull semen will increase with age and will affect the semen quality. The objective was to compare malondialdehyde (MDA) concentration and the quality of fresh and frozen-thawed semen between aged (13.6 ± 1.0 years; n = 3) and young (3.4 ± 0.3 years; n = 3) Nili-Ravi bulls. The concentration of MDA did not differ (p >.05) between aged vs. young bulls in fresh (2.3 ± 0.2 vs. 2.9 ± 0.7 nmol mL⁻¹), frozen-thawed (53.1 ± 2.8 vs. 48.4 ± 2.6 nmol mL⁻¹) semen and seminal plasma (5.71 ± 0.97 vs. 5.19 ± 1.36 nmol mL⁻¹), respectively. In fresh semen, sperm motility and total concentration did not differ (p > .05) between aged and young bulls. The volume of fresh semen increased (p > .05) while sperm viability and DNA integrity decreased (p < .05) in aged vs. young bulls. In frozen-thawed semen, sperm motility, viability and DNA integrity decreased (p < .05) in aged vs. young bulls. In frozen-thawed vs. fresh semen, MDA level increased within young (48.4 ± 2.6 vs. 2.3 ± 0.2 nmol mL⁻¹) and aged bulls (53.1 ± 2.8 vs. 2.9 ± 0.7 nmol mL⁻¹). Conversely, sperm motility and viability decreased (p < .05) within the age groups between fresh and frozen-thawed semen. In conclusion, (1) lipid peroxidation (MDA) does not increase due to age; however, it is negatively associated with semen quality and (2) cryopreservation steps up lipid peroxidation irrespective of age and deteriorates semen quality of Nili-Ravi bulls.

Assessing undiluted, diluted and frozen-thawed Nili-Ravi buffalo bull sperm by using standard semen assays

Estimating genetic parameters for growth traits is crucial to plan breeding strategies for improving meat production in indigenous sheep breeds. The study first tested the effects of environmental and maternal effects on five growth traits, including birth weight (BWT), weight at 120 days (WT120), weight at 180 days (WT180), weight at 270 days (WT270) and weight at 365 days of age (WT365) and then estimated genetic parameters for these traits using data obtained in 1215 Lohi sheep. The effects of factors, including year (YOB), season (SOB) and type of birth (TOB), age of dam (AOD) and sex on growth traits of Lohi sheep, were examined using analysis of variance (ANOVA) in R software. Sex, TOB and YOB significantly affected all studied traits. The estimates of direct and maternal heritability for BWT and WT120 were 0.15 ± 0.08 and 0.20 ± 0.06, and 0.45 ± 0.16, 0.21 ± 0.08, respectively. The direct heritability estimates for WT180, WT270 and WT365 were 0.20 ± 0.07, 0.21 ± 0.07 and 0.19 ± 0.08, respectively. Due to the high heritability estimate obtained for WT120 compared to other studied traits, and its strong genetic correlation (>0.9) with post-weaning growth traits, it is recommended that selection must be practiced on WT120 to improve the growth performance of Lohi sheep. The results could be used for the development of genetic/genomic selection programs aiming to improve the production performance of the Lohi sheep.