Carboxylated poly-l-lysine (CPLL), an ampholytic polymer, has remarkable cryoprotective properties. It was hypothesized that CPLL will reduce/replace glycerol in extender and improve the freezability of buffalo semen. The objective was to evaluate various combinations of CPLL and glycerol in extenders for any synergism toward cryosurvivability of Nili-Ravi buffalo sperm. Semen collected from four Nili-Ravi buffalo bulls (ejaculates = 40; replicates = 5) was diluted in tris-citric acid based extenders, Control: (0% CPLL +7% Glycerol); E1: (1% CPLL +6% Glycerol); E2: (2% CPLL +5% Glycerol); E3: (3% CPLL +4% Glycerol); E4: (4% CPLL +3% Glycerol); E5: (5% CPLL +2% Glycerol); E6: (6% CPLL +1% Glycerol), and E7: (7% CPLL +0% Glycerol), and cryopreserved using a programmable cell freezer. Percentages of post-thaw sperm motility, plasma membrane integrity, and acrosomal integrity were found to be higher (p < 0.05) in extenders E1, E2, E3, E4, and E5 compared to E6 and the control. Sperm livability (%; live/dead ratio) and viability (%; live sperm with intact acrosome) were higher (p < 0.05) in extender E4 compared to all the other extenders. Sperm DNA integrity was higher (p < 0.05) in extender E2, E3, E4, and E5 compared to control, E1, and E6 extenders. Sperm lipid peroxidation levels were lower (p < 0.05) in E3, E4, E5, and E6 compared to control, E1, E2, and E7 extenders. Total antioxidant capacity of seminal plasma was higher (p < 0.05) in extenders E5, E6, and E7 than control, E1, E2, E3, and E4 extenders. It is concluded that synergism between CPLL and glycerol (4% CPPL and 3% Glycerol) seems to improve the freezability of Nili-Ravi buffalo semen by reducing oxidative stress.

This study reports the first evaluation of sperm hyaluronan binding assay (HBA) for predicting the fertility of Nili‐Ravi buffalo bulls in relation to standard parameters of sperm quality. Cryopreserved semen doses of low (n = 6), medium (n = 3) and high fertility (n = 8) bulls based on their respective return rates were used. Significantly, more spermatozoa bound to hyaluronan from the most fertile bulls (57.15% ± 1.44) compared with medium (42.46% ± 1.08) and low fertility bulls (29.70% ± 0.78). A strongly positive correlation (r = .824, p < .01) was found between HBA and fertility that predicts a 67.9% variability (r2 = .679, p < .01) in fertility. HBA was also strongly positively correlated with sperm viability (r = .679, p < .01) followed by their live/dead ratio (r = .637, p < .01), uncapacitated spermatozoa (r = .631, p < .01), normal apical ridge (r = .459, p < .01), motility (r = .434, p < .01), mature spermatozoa with low residual histones (r = .364, p < .01), high plasma membrane integrity (r = .316, p < .01) and nonfragmented DNA levels (r = .236, p < .05). It was negatively correlated with spermatozoa having reacted acrosome (r = −.654, p < .01). A fertility model built using a combination of sperm HBA and either sperm livability or viability predicts, respectively, 86.1% (r2 = .861, p < .01) and 85.9% (r2 = .859, p < .01) variability in buffalo bull fertility. In conclusion, sperm HBA may prove to be a single robust predictor of Nili‐Ravi buffalo bull fertility.

The present study was designed to determine physico‐chemical characteristics and best extender for refrigerated preservation of Labeo rohita milt. In experiment I, milt was collected from mature and healthy brooders (n = 5) of L. rohita reared at fish seed hatchery, Rawal Town, Islamabad, Pakistan. After collection, milt was maintained at 4°C and physico‐chemical characteristics were studied. The mean volume of Labeo rohita milt was 8.02 ± 0.12 ml, pH 7.60 ± 0.17, sperm count 2.77 ± 0.19 1010/ml, osmolality 267.6 ± 7.4 mOsmol/kg, sodium 95.43 ± 6.7 (mM/L), potassium 34.41 ± 1.2 (mM/L), total lipids 178.94 ± 5.0 mg/dl and motility 83.5 ± 5.0%. In experiment II, nine male brooders (3 brooders/replicate) maintained in three different ponds were used. In each replicate, milt from three brooders was pooled, kept at 4°C and divided into 4 aliquots. An aliquot was kept undiluted (control), while other aliquots were diluted in Alsever's solution, sugar‐based extender and modified Kurokura extender (KE) in 1:9 ratio at 4°C and stored up to 7 days. Sperm motility and viability were assessed for up to 7 days. Total antioxidant capacity was measured on Day 4. Sperm motility was higher (p < 0.05) in milt diluted with KE compared with control and other diluents from Day 5 to Day 7. However, highest sperm viability was observed on Day 6 and Day 7 in sperm diluted with KE. Total antioxidant capacity of milt diluted with KE and control was higher than other diluents on Day 4. In conclusion, viability of Labeo rohita sperm can be increased by diluting it in KE.

This study was conducted with cysts of Streptocephalus proboscideus obtained from the University of Gent-Belgium. The cysts were hatched in Environmental Protection Agency (EPA) medium. The nauplii were reared at the Sturgeon Research Institute using a pure culture of Scenedesmus obliquus alga supplied at a density of 5 Â 10 3 cell mL À 1 that gradually increased to 1 Â 10 4 , 5 Â 10 4 and 1 Â 10 5 cell mL À1 with the growth of the nauplii. The nauplii attained sexual maturity and started producing cysts in 8 days and yielded a mean cyst number of 220 AE 40 female À1 brood À1 cysts. These cysts were used in the larviculture of Persian sturgeon, Acipenser persicus (Borodin). Forty-three larvae of Persian sturgeon (mean weight: 15.4 AE 1.1mg; mean length: 27.1 AE 2.7 mm) with roughly absorbed yolk sacs were stocked in three aquaria and fed S. proboscideus nauplii at 8-h intervals. By the end of the experiment (day 5), the mean weight and length of Persian sturgeon larvae were 51.4 AE 13.3 mg and 20.7 AE 1.4 mm respectively.

No abstract