Testicular development and its relationship to semen production in Murrah buffalo bulls.

The objectives of this study were to determine the relationship of age and body weight to testicular development and to establish norms for breeding soundness evaluations of Murrah buffalo bulls. Testicular measurements of 133 Murrah buffalo bulls of various ages were recorded with a caliper and a tape. Semen was collected twice a week for 5 weeks from groups of bulls which were 25-36 (n=17), 37-48 (n=16), 49-60 (n=14), of >60 (n=10) months of age. After examining volume, sperm concentration, and progressive motility semen was diluted in Tris-citric acid-egg yolk-fructose extender and frozen in 0.5 ml French straws. Testicular measurements of buffalo bulls were lower than those recorded for European breeds of cattle bulls. Nevertheless, like cattle bulls, scrotal circumference was highly correlated with other testicular measurements. Also, it had a significant positive relationship with semen volume and sperm concentration per ejaculate. Average sperm output per week in order of increasing age group was 15.3, 18.2, 19.8 and 23.6 x 10(9). Corresponding values for sperm output per week per gram of testis were 59.1, 45.8, 41.1, 36.2 x 10(6) indicating a reduction in spermatogenesis per unit of testis with advancing age. Compared to European breeds, daily sperm output in Murrah bulls was nearly 45% lower, presumably due to their nearly 40% lower scrotal circumference than Holstein bulls of the same age. These results indicate that in buffalo, as in cattle, scrotal circumference is a useful indicator of potential sperm output and may serve as an important criterion for selecting young bulls as AI sires.

Bull-specific effect on fertilization rate and viable embryo recovery in the superovulated buffalo (Bubalus bubalis).

This study was conducted to compare fertilization rate and viable embryo recovery rate in superovulated buffalo (n = 64) following insemination with semen from buffalo bulls (n = 5) having different fertility rates as determined by AI. Frozen-thawed semen from fertile bulls with similar post-thaw progressive motility and sperm morphology was used to inseminate buffalo at superovulatory estrus. Fertilization and viable embryo recovery rates differed among bulls, but this bull-specific effect was not related to the overall herd fertility rate as determined by AI in normal cyclic animals. These results indicate that individual bulls differ in their contribution to fertilization of superovulated donors and also to embryonic development, as determined by viable embryo recovery. Moreover, the results also suggest that buffalo bulls can be screened for optimal fertility and embryo recovery rates in superovulated donors. Further studies are warranted to ascertain the factors which contribute to such bull-specific effects.

Factors affecting pregnancy rate following nonsurgical embryo transfer in buffalo (Bubalus bubalis): a retrospective study.

The objectives of this study were to determine the pregnancy rate and factors affecting it following nonsurgical embryo transfer in buffalo. Donor buffalo were superovulated with FSH, and embryos collected nonsurgically were evaluated for stage of development and quality. They were transferred nonsurgically to 91 recipients on Days 5 to 7 of the natural (n = 52) or induced (n = 39) estrus (estrus = Day 0). The overall pregnancy rate of 24/91(26.4%) was higher than in earlier reports for buffalo but was much lower than in cattle. Pregnancy rates were not affected by season (autumn vs winter), side of transfer (right vs left uterine horn), or type of estrus (spontaneous vs induced). The pregnancy rate was high 11/27(40.7%) when donors and recipients were closely synchronized, while it was compromised when recipients were in estrus at +12 h (1/7, 14.3%) and at -12 h (5/27, 18.5%). Asynchrony beyond 12 h on either side resulted into conception failure. The pregnancy rate tended to increase with the increase in CL size of recipients, while stage of embryonic development had no effect. The transfer of an 8-cell embryo with a 16-cell embryo led to the birth of heterosexual twins, indicating that the uterine milieu of Day 5 to 6 recipients may be tolerated by the out-of-phase 8-cell embryo, at least in the presence of a more mature embryo. Embryo quality had the greatest effect on pregnancy rate as it was higher (P < 0.005) after the transfer of Grade I than Grade III embryos (6/10, 60.0% vs 3/36, 13.9%). Assessment of returns to estrus indicated that among nonpregnant recipients, 17/67 (25.4%) embryos never matured sufficiently to prevent luteolysis through maternal recognition of pregnancy (MRP), while 14/67 (20.8%) embryos probably died following MRP. These results indicate that efforts to increase pregnancy rate following embryo transfer in buffalo should include prevention of luteolysis during the first week of transfer and a reduction in the incidence of embryonic mortality.

Rate of transport and development of preimplantation embryo in the superovulated buffalo (Bubalus bubalis).

This study was designed to ascertain the rate of transport and development of preimplantation embryo in the superovulated buffalo in order to determine the optimum time for their nonsurgical collection. Eighteen Murrah-type buffalo were superovulated with 600 mg NIH-FSH-P1. Luteolysis was induced by administration of PGF2 alpha at 72 (PG + 72) and 84 h (PG + 84) after initiating gonadotrophin treatment and fixed-time AI was done beginning at 36 h post PG + 72 administration and at 12-h intervals thereafter, upto 72 h. Six control buffalo received treatment similar to experimental group except that in place of FSH they received normal saline. For embryo collection, experimental animals were humanely killed at 6-h intervals corresponding to 156 (n = 2), 162 (n = 2), 168 (n = 2), 174 (n = 3), 180 (n = 3), 186 (n = 3) and 192 h(n = 3) after PG + 72 treatment, whereas the control animals were humanely killed at 156 (n = 2), 174 (n = 2) and 192 h (n = 2). Superovulated buffalo had higher number of ovulations than untreated controls (8.78 +/- 5.00 vs 0.67 +/- 0.51) and total ova/embryos recovered was 4.11 +/- 2.46 and 0.67 +/- 0.51, respectively. The high estradiol-17 beta (E2) levels with its prolonged rise may, by leading to reverse peristalsis in the oviduct with a consequent loss of some embryos in the peritoneal cavity, be one of the reasons for our inability to recover nearly 84/158 ova/embryos in the superovulated buffalo. In superovulated animals, nearly all the ova/embryos reached the uterus between 168 and 174 h post PG + 72 treatment or about 134 h (circa 5.5 d) after the onset of superovulatory estrus, suggesting that the ideal time for non-surgical embryo collection in the buffalo is between Days 7 to 8 after PG + 72 treatment or Days 5.5 to 6.0 of the superovulated cycle (estrus = Day 0). Embryo development of superovulated buffalo showed considerable variation as various stages of embryos (8 cell to expanded blastocyst) were recovered from the same donor buffalo, and the rate of development appeared to be 24 to 36 h faster than in cattle.

Successful culmination of pregnancy and live birth following the transfer of frozen-thawed buffalo embryos.

A total of 141 embryos was recovered by nonsurgical flushing of the uterus of 31 superovulated buffalo. A total of 66 good quality embryos (Grade I and Grade II) was frozen using 1.4 M glycerol. Forty-two of the frozen embryos were thawed randomly over a 1-year period, and a total of 39 embryos (Grades I, II or III post thaw) were transferred into an equal number of estrus synchronized recipients. Of 11 confirmed pregnancies, 9 calves were born live.

Multiple ovulation and embryo transfer in Indian buffalo (Bubalus buoalis ).

This study was undertaken to identify the most effective dosage level of folltrooin for superovulation in buffalo. In addition, the effect of the day of estrus on superovulation and the use of exogenous GnRH were also studied. Eighty-three buffalo were treated with prostaglandin. A functional Corous luteum (CL) was palpated in only 73 buffalo 1 d before the superovulation treatment was initiated. One of eight treatments was used on the buffalo: Protocol I(n 8) 9 mg folltropin (PPFE) on Days 9 to 12 of the cycle; Protocol II(n 10) 18 mg PPFE on Days 9 to 12 of the cycle; Protocol III(n 9) 18 mg PPFE on Days 13 to 15 of the cycle; Protocol IV(n 9) 21.6 mg PPFE on Days 9 to 12 of the cycle; Protocol V(n 9) 21.6 mg PPFE with GnRH on Days 9 to 12 of the cycle; Protocol-VI(n 10) 25.2 mg PPFE on Days 9 to 12 of the cycle; Protocol VII(n 9) 28.8 mg PPFE on Days 9 to 12 of the cycle; Protocol VIII (n 9) 36 mg PPFE on Days 9 to 12 of the cycle. The highest ovulation rate was observed in Protocol VI (x 5.3+/-0.79) which is significantly higher (P < 0.01) than other Protocols. Maxium embryos (x 3.7) were recovered using Protocol III. Whereas, highest number of transferable embryos (x 2.2) were recovered from Protocol V. Use of GnRH and superovulation treatment on Days 13 to 15 has no advantageous effect on ovulation rate. In all, 41 embryos were transferred to 35 recioients: nine buffalo became pregnant; 59 embryos were frozen; 12 were thawed; nine good frozen-thawed embryos were transferred to eight recidients, three of which were diagnosed pregnant.