Effect of the number of blind mounts and lateral deviation to the quality of semen

The semen samples collected from the 1^st mount (a) show the best results of total motility (3h) compared to all the other mounts and differ significantly (P < 0.05) from the results from the 4^th mount (c). The total motility after 24h shows the best results in an analysis of the samples from the 1^st mount (A) which differ significantly (P < 0.05) from all the other mounts (B). The frozen/thawed semen had the best motility-values in the semen samples of

Values with different letters differ significantly (P < 0.05). Following the specifications of the schedule the 1^st mounts always occured without any manual deflection of the penis (mount 1

 0 deflection).

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The DFI values did not differ significantly (P > 0.05) and all the values were lower than 15% and show normal sperm-morphology. The mean values of SCSA-parameters are represented in Table 2.2. The total DFI parameter in per cent (± SD) ranged between 10,0 ± 2.9 and 10.8 ± 3.2. Concerning %-DFI parameters, values did not differ significantly from each other.

The membrane intact sperms (3h) differ significantly (P < 0.05) in the 1^st (74.7% ± 4.4) and 2^nd (66.9% ± 6.7) mount. The values after 24h differ significantly in the 3^rd (71.5% ± 1.9) and the 4^th (68.2% ± 3.6). All values are represented in the following Table 2.2.

Table 2.2

The table shows the effect of number of mounts on the sperm characteristics of stallions 3h after collection and after 24h of storage at 5°C (± SD). The flow cytometric evaluation of the semen was able to detect membrane (PM) and acrosome (AM) damages. Results were described as mean ± standard deviation (±SD).

1 2 3 4

Defragmentation Index (%) 10.0 ± 2.9 10.4 ± 2.8 10.8 ± 3.2 10.7 ± 3.4

motility 3h (%) 87.2 ± 6.7 a 86.2 ± 6.3 a 83.3 ± 8.5 b 80.7 ± 6.1 b progressive motility 3h (%) 52.3 ± 9.6 51.7 ± 7.4 a 51.0 ± 7.9 49.2 ± 6.1 b

membrane intact 3h (%) 74.7 ± 4.4 a 66.9 ± 6.7 b 72.8 ± 5.6 70.3 ± 4.9

stained acrosome 3h (%) 10.1 ± 2.3 10.5 ± 3.41 9.2 ± 3.7 9.4 ± 2.1

motility 24h (%) 76.5 ± 12.4 a 72.0 ± 13.0 b 65.5 ± 6.3 b 69.2 ± 11.1 b progressive motility 24h (%) 41.6 ± 10.3 a 39.3 ± 11.1 ab 36.2 ± 8.0 b 41.6 ± 7.7 a

membrane intact 24h (%) 67.4 ± 1.4 65.4 ± 5.0 71.5 ± 1.9 a 68.2 ± 3.6 b stained acrosome 24h (%) 14.2 ± 0.1 14.9 ± 0.1 a 10.9 ± 0.2 12.5 ± 0.1 b

Number of mounts (n = 48)

75 6.5 Discussion

In the present study, it has been demonstrated that volume shows an enhancement but it does not increase significantly with the number of blind mounts. The first ejaculate in the majority of the examined semen samples shows the best results compared to all the other semen samples.

Deviating from the results of the present study, ECHTE (2001) detected that there was a significant (P < 0.05) correlation between volume and the number of mounts before ejaculation and mating behaviour. He noted a significant increase of the volume in correlation with the number of mounts. SIEME et al. (2004) also found an increase of volume when stallions mounted more than three times prior to ejaculation. Otherwise GAMBOA et al.

(2009) detected that the ejaculates did not differ significantly with an increasing number of mounts when evaluating semen from Pure Sangue Lusitano. Studies from SOFIKITIS and MIYAGAWA (1993) found an improvement of quantity after precoital sexual stimulation.

Further studies from CANISSO et al. (2010) described that sexual behaviour (except copulation duration) was not significantly correlated with semen characteristics. The perception that copulatory behaviour barely had influence on semen characteristics was detected by CAMARON (1985) and was contrary to the present results. In the present study there could not be found any significant (P > 0.05) relation between number of mounts and volume.

ECHTE (2001) described a decrease in sperm concentration with every mount whereas volume increased. A highly significant correlation was found between sperm concentration and total sperm in the ejaculate (CAMARON 1985). This could not be detected in the present study. Sperm concentration decreased on the average with every mount whereas total sperm count on the average increased, caused by higher volume.

Motility showed a statistically significant decrease between the 1^st and 4^th mount.

Progressive motility showed a significant decrease between the 2^nd and 4^th mount. Otherwise ECHTE (2001) detected that initial progressive motility and motility of equine semen were

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not influenced by the number of mounts. Sperm motility (24h) from the ejaculates of the first mount was significantly higher than from the mounts with a higher number of attempts.

Contrariwise HAFS et al. (1962) described for bovine semen that restraining or false mounts prior to semen collection significantly increased the number of motile spermatozoa.

Quality in the most of the studied parameters decreased with the number of mounts. The obtained results are close to the observations of other authors. Concentration and sperm viability after 24 hours of storage at +5°C showed a significant inverse correlation to the number of mounts (ECHTE 2001). This also could be shown in the present study. Generally a decrease of motility and progressive motile sperms with the number of mounts could be observed. SIEME et al. (2004) described that the number of false mounts and time to ejaculation was related to poor semen quality. A decrease of sperm concentration and total sperm count was observed compared to an increasing volume. SOFIKITIS and MIYAGAWA (1993) described a better quality of collected spermatozoa when pre-coital stimulation occurred. This could not be verified in the present study.

Reduced sperm concentration, sperm motility (both fresh and post-thaw), and sperm membrane integrity were produced after a several number of false mounts was reported by SIEME et al. (2004). In the present study AM and PM integrity (3h) showed a significant reduction from the 1^st to the 2^nd mount whereas the other mounts did not differ significantly from the first mount. After 24 h AM/PM-integrity resulting from the 1^st and the 2^nd mount differed significantly from the 3^rd and 4^th mount. Even if the values did not differ significantly they constantly decreased with each mount and from 3h to 24h. The DFI values did not differ significantly and all the values were lower than 15% and showed a normal non-damaged structure.

SIEME et al. (2000) concluded that there is a great importance in the preparation of the stallion before the mount to obtain high-quality semen with the first mount and to avoid higher numbers of mounts because of the decrease of the quality parameters. This also could be verified with the present study.

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The results show, that the ejaculate from the first mount is the best one in quality parameters. Even if quantity parameters like volume and total sperm count increased with the number of mounts and lateral deviations the quality decreased with every mount and after storage. The number of mounts and lateral deviations had a negative influence on the quality of semen.

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