Abstract: The present project was designed to study the effect of substitution of buffalo bull seminal plasma with that of cow bull on liveability and fertility of buffalo bull spermatozoa. After collection, semen was divided into three fractions. a) Half of the seminal plasma of buffalo bull was substituted with equal amount of cow bull seminal plasma, b) The seminal plasma of buffalo bull was completely substituted with that of cow bull, c) No substitution was made (control group). The liveability (hrs) of buffalo bull spermatozoa stored at 37°C was significantly higher (p<0.05) in half substituted seminal plasma (21.3) as compared to that in full substituted (8.4) and control groups (13.7). Significantly higher conception rate was observed with half substituted seminal plasma semen samples (65.58) as compared to inseminations with control group (54.4) semen samples.
Introduction
Low conception rate is one of the serious reproductive problems affecting the dairy industry. Among various factors influencing the conception rate, high concentration of seminal plasma has been shown to be deleterious to bovine spermatozoa (Pickett et al., 1975; Baas et al., 1983). The seminal plasma of both cattle (Avenell, 1982) and buffalo bulls (Ahmad et al., 1994) has been shown to reduce the motility percentage, liveability and absolute index of liveability of spermatozoa. Buffalo bull semen contains higher contents of inhibitory factors compared to cattle semen (Ganguii, 1978; Sahni, 1990). Cockrrll (1974) postulated that the poor keeping quality of buffalo bull semen may be due to higher seminal plasma concentrations of calcium, esterified phosphate and various phosphate splitting enzymes.
Substitution of buffalo bull seminal plasma with that of cattle seminal plasma has been shown to have beneficial effect on liveability and preservation of buffalo bull spermatozoa (Ibrahim et al., 1981; Sahni, 1990). However, the possible beneficial effect of this treatment on the fertility has not yet been established. Therefore, the objective of this study was to investigate the effect of substitution of buffalo bull seminal plasma with that of cattle on liveability (hrs) and fertility of buffalo bull spermatozoa under local conditions.
Materials and Methods
For this study, semen of one buffalo and one cow bull (cross bred), maintained under identical conditions of feeding and management at Semen Product ion Unit, Department of Animal Reproduction, University of Agriculture, Faisalabad, was used. A total of 10 ejaculates of each buffalo and cow bull were collected. After collection, each ejaculate was divided into three fractions A, B and C. In fraction A half of the seminal plasma of buffalo bull was substituted with equal amount of cow bull seminal plasma. In fraction B, the seminal plasma of buffalo bull was completely substituted with that of cow bull. The fraction C was kept as untreated control. For substitution, the seminal plasma from fraction A and B was removed by centrifuging the ejaculates at 3000 rpm for 15 minutes (Ahmad et al., 1994).
All semen fractions were diluted in whole milk egg yolk glycerol extender at the rate of 1:10 and stored at 37°C For determination of liveability, the motility percentage of each sample was recorded at hourly interval till the death of all spermatozoa (Milavenof, 1962).
On the basis of liveability results, inseminations were done only with fractions A and C semen. A total of 150 buffaloes each of control and half substituted seminal plasma samples, were inseminated at the clinic of the Department of Animal Reproduction. University of Agriculture, Faisalabad. Buffaloes of both the groups were checked for pregnancy through rectal palpation at least eight weeks following insemination.
Statistical analysis: The data on liveability (hrs) of all experimental groups were subjected to completely randomized design (Steel and Torrie, 1980) and the means were compared by Duncan's Multiple Range Test (Duncan, 1955). To see any statistical difference in conception rate of two groups the "Chi-Square" test was applied.
Results
The mean values (±S.E) for liveability of spermatozoa in control, full substituted and half substituted seminal plasma semen samples are shown in Table 1. Statistical analysis revealed that liveability (hrs) was significantly higher (p<0.05) in half substituted seminal plasma semen samples as compared to rest of the two groups, whereas liveability (hrs) was significantly higher (p<0.05) in the control group as compared to the one in which complete substitution of seminal plasma was performed (Table 2).
| Table 1: | Liveability of buffalo bull spermatozoa (hrs) at 37°C in half, full substituted seminal plasma and control semen samples. |
| Table 2: | Analysis of vriance showing the effect of substitution of seminal plasma on liveability (hrs) of buffalo bull spermatozoa |
Statistical analysis regarding effect of substitution of seminal plasma on conception rate showed significantly higher (p<0.1) conception rate in half substituted seminal plasma 65.38 per cent semen samples as compared to 54.4 per cent in control group (Table 3).
| Table 3: | Effect of substitution of buffalo bull seminal plasma with that of cow bull on fertility of buffalo bull spermatozoa. |
| Values with different superscripts differed significantly (p<0.05). | |
Discussion
High concentrations of seminal plasma have been shown to be deleterious to storage of buffalo bull semen (Sahni, 1990; Sahni and Mohan, 1990; Ahmad et al., 1994). Centrifugation has been used as an approach for reducing concentration of seminal plasma (Pickett et al., 1975; Clay et al., 1984).
It is obvious from results of the present study that the preserving ability of buffalo bull spermatozoa is dependent someway on the presence of seminal plasma (Table 1). These findings are in agreement with previous results recorded by Albright et al. (1958) and Ibrahim et al. (1981), who reported that preserving ability of buffalo bull spermatozoa was improved with the substitution of half the volume of seminal plasma of cow bull. This improvement may be attributed to the dilution of the inhibitory factor(s) believed to be present in higher concentration in the seminal plasma of buffalo bull (Sengupta et al., 1976). Cockrrll (1974) reported that the poor keeping quality of buffalo bull semen may be due to higher concentrations of calcium, esterified phosphatase and the phosphate splitting enzyme in buffalo semen. The observed improvement in spermatozoa viability following the withdrawal of 50 per cent of the volume of the seminal plasma in buffalo semen in the present study was indirectly supported by these views. However, the possibility of presence of some other unknown factor (s) cannot be excluded. The improvement in sperm viability in half seminal plasma substituted semen samples suggests that the molarity of the mixed seminal plasma is more suitable than complete and un-substituted seminal plasma semen samples. However, the complete replacement of seminal plasma resulted in significant reduction (p<0.05) in the viability of buffalo bull spermatozoa over the control, indicating that the permissible change in the molarity was achieved when the substitution was done to only 50 percent of the volume. These findings are in agreement with those reported earlier by Bora and Rao (1969), since they showed that the half combination of buffalo seminal plasma with zebu cattle improved significantly the keeping quality, while complete substitution of seminal plasma resulted in significant decrease in liveability of spermatozoa of either species.
In this study 50 percent substitution of buffalo bull seminal plasma with that of cow bull significantly improved the conception rate over the control group samples. This could be due to higher liveability of spermatozoa in half substituted seminal plasma semen samples. Verma and Mohan (1982) and Fadeev et al. (1983) reported significantly higher conception rate with semen samples having longer liveability (hrs) compared to samples having shorter sperm liveability.
Results of the present study clearly indicate that liveability and conception rate of buffalo bull spermatozoa can be improved by substituting the half of seminal plasma with that of cow bull prior to extension of the semen. However, its effect on freezing quality and fertility status of frozen buffalo bull spermatozoa needs further investigations.