EFFECT OF DIFFERENT GLYCEROL CONCENTRATIONS ON MOTILITY BEFORE AND AFTER FREEZING, RECOVERY RATE, LONGEVITY AND PLASMA MEMBRANE INTEGRITY OF NILI-RAVI BUFFALO BULL SPERMATOZOA

The present study has designed to observe the effects of different concentrations of glycerol on sperm motility before after freezing and thawing, recovery rate, longevity and plasma membrane integrity in Nili- Ravi buffalo bull spermatozoa. Semen was collected and evaluated from four Nili-Ravi buffalo bulls in a standardized procedure. The ejaculates possessing more than 65% visual motility were selected and pooled at 37°C. Pooled samples were divided into eight aliquots of 0.5 ml each and extended (50 x 106 sperm/mi) in Tris-citric acid extenders (pH=7.0. OP=320 mOsmol/kg) at 37°C with different (2. 4. 5, 6. 7. 8. 10 or 12%) concentrations of glycerol. Semen was cooled to 4ºC in 2 hours, equilibrated for 4 hours, packed in 0.5 ml French straws and frozen from +4°C to -15°C at the rate of 3°C per minute and from -15°C to -80°C @ 10°C/ minute in a programmable cell freezer. Semen straws were thawed at 37° (for 30 seconds after 24 hours of storage in liquid nitrogen at -196°C. The motility before freezing did not differ due to the treatments. The motility after freezing did not differ among the extenders containing glycerol (%) concentrations either 5, 6, or 7. This was higher than that in extender containing glycerol (%) concentrations either 4, 8 or 10. Post thaw motility in extenders having glycerol (%) concentrations either 2 or 12 compared to all other treatments was the lowest. The recovery rate of spermatozoa (%) after freezing and thawing did not differ among the extenders containing glycerol (%) concentrations either 4.5.6. 7 or 8. This was higher (P<0.05) than that in extenders containing glycerol (%) concentrations either 2 or 10 and was lowest (P<0.05) in extender containing 12% glycerol. The mean sperm longevity (37 ºC) at 2 hours was highest (32.6 ± 5.2, P<0.05) for 6. 7 or 8% glycerol, intermediate (13.9 ± 4.4, P<0.05) for 4.5 or 10% and lowest (3.3 ± 2.5 P<0.05) For 2 or 12%. Plasma membrane integrity (%) of spermatozoa frozen in 7% glycerol (42.0 ± 1.3) was superior (P<0.05) to 5.6. 8. 10 or 12% glycerol (29.6 ± 2.9). Plasma membrane integrity of Nili-Ravi buffalo bull spermatozoa was least protected (P<0.05) when frozen in 2 or 4% glycerol (10.4 ± 1.8). It is concluded that glycerol (%) concentrations of 6 or 7 in the extender may be suitable for crypreservation of Nili-Ravi buffalo bull spermatozoa

EFFECT OF TWO DIFFERENT ANTIBIOTIC COMBINATIONS ON FERTILITY OF FROZEN BUFFALO AND SAHIW AL BULL SEMEN

This study was carried out to identify the suitable antibiotic combinations in semen extender for improvement in fertility of frozen semen of buffalo and cow (Sahiwal) bulls to obtain better pregnancy rate through artificial insemination (AI). For this study eight first ejaculates, four each from a buffalo and a cow (Sahiwal) bull were used. The ejaculates were split-sampled and diluted with Tris-citric acid extender (at 37°C; 50x 106 spermatozoa/mI), containing either SP (streptomycin 1000 ~g/ml and penicillin 1000 IU/ml) or GTLS (gentamycin 500 µg/ml, Tylosin 100 µg/ml and linco-spectin 300/600 µg/ml). There was no difference in post-thaw motility for these samples. Fertility test based on 75-days first service pregnancy rate was determined under field conditions. A total of 400 inseminations were recorded, 200 for each buffalo and cow (Sahiwal) with J 00 of each antibiotic combination, respectively. Fertility rates for SP-based frozen semen of buffalo bull were 41.66% and were 55.2% for GTLS-containing frozen semen, respectively. The results for GTLS were higher (P<0.0001) than SP. Similarly, fertility rates were higher (P<0.0001) for GTLS-based frozen semen of Sahiwal bull (78.78%) than SP-containing frozen semen (69.6%) of the same specie. Fertility rates also differed due to species of donor bulls. They were better (P<0.0001 ) for the frozen Sahiwal bull semen than that of the buffalo bull in both SP and GTLS- based frozen semen samples, respectively. In conclusion. seminal quality measured by field fertility trial indicated GTLS combination of antibiotics added to the semen extender was better for improvement in the fertility of frozen buffalo) and Sahiwal bull semen, by yielding better pregnancy rates through AI

POSTPARTUM ANOESTRUS IN NILI-RAVI BUFFALOES MAINTAINED UNDER RURAL AND PERI-URBAN MANAGEMENT

The trial was conducted to assess anoestrous problem in Nili Ravi buffaloes kept under rural and peri-urban management around Islamabad, during the months of October to December. One hundred and three buffaloes under peri-urban management and 40 buffaloes under rural management belonging to six and 21 farmers, respectively, were included in this study. Buffaloes that did not show heat signs for 6-12 months postpartum were considered anoestrus in this study. For inducing heat, two injections of cloprostenol were administered in silent oestrous buffaloes, whereas gonadotropin releasing hormone followed by cloprostenol was administered in true anoestrous buffaloes. A higher proportion of buffaloes (35%) was noted in anoestrus under rural than under peri-urban management (17.5%, P=0.02). All the buffaloes diagnosed as silent oestrus responded to cloprostenol therapy by showing heat signs under both management systems. However 71% rural buffaloes diagnosed in true anoestrus showed heat symptoms compared to 100% peri-urban buffaloes followed by GnRH+cloprostenol therapy. Fixed time insemination (72 and 96 hours after 2nd cloprostenol injection) resulted in a conception rate of 58% and 67% in rural and peri-urban buffaloes, respectively. An overall 33% conception rate was observed in true anoestrous compared to 83% in silent oestrous buffaloes. It is concluded that cloprostenol could be used successfully to induce heat and achieve an optimum conception rate in silent oestrous buffaloes during peak breeding season