Figure 1. Monthly average temperature and relative humidity during the study
| Livestock Research for Rural Development 31 (2) 2019 | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
This study evaluated the effects of rainy and dry seasons on semen quality of bulls at Ungaran artificial insemination center. The semen was collected twice a week from one Ongole crossbred and one Simmental bulls, both at 5 years old, totaling 198 semen collections (99 of each bull). The results showed that the sperm concentration of Ongole crossbred bull was higher in the rainy season, however, the sperm motility before-freezing was higher in the dry season. On the other hand, Simmental bull showed no seasonal variation on all semen quality traits. The comparison of semen quality between these two breeds showed that the Ongole crossbred bull had a higher semen volume, however, the sperm concentration, total sperm count, total motile sperm count, and frozen semen dose were higher in the Simmental bull. The approved fresh semen was tended to be higher in the Simmental bull than the Ongole crossbred bull (98% vs 90.9%), but the discarded frozen semen was relatively higher in the Simmental bull than Ongole crossbred bull (8.25% vs 4.44%). This study suggests that the semen collection of Ongole crossbred and Simmental bulls could be done both in the rainy and the dry seasons. Simmental bull has superior semen concentration and the number of approved fresh semen than Ongole crossbred bull. However, the susceptibility of Simmental bull to the tropical environment resulting in a lower semen freezability compared to Ongole crossbred bull.
Keywords: artificial insemination, freezability, frozen semen, semen characteristics, tropical area
The increase in the human population, together with the increase in the income and urbanization, have driven the rapid increase in the demand for animal-origin protein such as beef. According to Henchion et al (2014), there was a 60% increase in meat consumption from 1990 to 2009, and it was expected that this trend will be continued, particularly in Asian countries. In another study, it was expected the meat consumption in 2050 will increase by 76% (WRAP 2017). This situation makes the improvement in beef production efficiency becomes a necessity.
To face this challenge, enhancing reproductive performance seems to be the most essential efforts due to the birth of a calf is a key to generate meat production (Thundathil et al 2016). Artificial insemination has been widely used to facilitate more effective and efficient animal production (Morrell 2011). By using this technique, one superior bull could breed thousands of cows, thus producing the calf with high genetic potential. However, the fertility of the bulls becomes a crucial factor determining the success of this technique.
The seasonal variation throughout the year could influence the semen quality. Snoj et al (2013) reported that the season affected the fresh semen characteristics in Bos taurus breed. In another study, Koivisto et al (2009) also observed the seasonal variation in semen freezability of Bos indicus and Bos taurus bulls. Moreover, the studies of the seasonal effect on semen quality of the bulls are mostly conducted in the area with 4 different seasons, while in the area with 2 seasons such as Indonesia is still very limited. For these reasons, this study was performed to evaluate the effects of rainy and dry seasons on semen quality of Ongole crossbred (Bos indicus) and Simmental bulls (Bos taurus) used for artificial insemination.
This study was carried out at the Ungaran Artificial Insemination Center, Semarang 50514, Indonesia. This location is situated in a tropical zone at 316 m above sea level, 7°07’45” S latitude and 110°24’49” E longitude. The data of climatic condition were taken from Meteorology, Climatology, and Geophysics Council of Semarang. The average temperature and humidity during the rainy season (from October 2017 to March 2018) were 26.6°C and 82.3%, respectively, while during the dry season (from April to September 2018) were 26.9°C and 81.5%, respectively. Figure 1 shows the monthly climatic condition during the study.
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Figure 1. Monthly average temperature and relative humidity during the study |
The forages used in this study were elephant grass and maize forage. The elephant grass was obtained from the farm owned by Ungaran Artificial Insemination Center. The elephant grass was planted in the 3 hectares area with the total forage production between 400 to 450 tons per year. Meanwhile, the maize forage was supplied by the local farmers around the study location. Both of the forages were available throughout the year during this study.
One Ongole crossbred and one Simmental bulls, aged at 5 years old, were used in this study. Both of the bulls were reared with similar management under the standard procedure in the Ungaran Artificial Insemination Center. The bulls were fed 30 kg of forage (consisted of elephant grass and maize forage with the ratio of 1:1), 5 kg concentrate ration (contained 17% crude protein and 67.5% total digestible nutrient), 100 g Starbio probiotic, and 100 g mineral premix per day throughout the study. The semen collection was done twice a week by using an artificial vagina (Kruuse, model 340284, Denmark) (Fiaz et al 2009) resulting in a total of 198 ejaculate semen (99 of each bull). The semen volume was directly measured by using a scaled vial (Eidan 2016). The semen pH was analyzed by using a pH indicator paper (Patel and Siddiquee 2013). Sperm concentration was evaluated by using a spectrophotometer. Total sperm count was calculated by a formulation = volume x sperm concentration (Bhakat et al 2011). Sperm motility of fresh semen, before-freezing, and post-thawing was assessed under a light microscope (400x magnification) (Nichi et al 2006). Total motile sperm count was calculated by a formulation = volume x sperm concentration x sperm motility (Arikawa et al 2016). Recovery rate was calculated by a formulation = (sperm motility post-thawing / sperm motility of fresh semen) x 100% (Abbas and Andrabi 2002). Frozen semen dose was calculated by a formulation = (volume x sperm concentration) / 25 x 106 (Indonesian National Standard, SNI 4869-1:2017). The fresh semen which had concentration below 0.5 x 109 (Ax et al 2000) or sperm motility below 70% as well as the frozen semen which had sperm motility post-thawing below 40% (Indonesian National Standard, SNI 4869-1:2017) were discarded.
Statistical analysis was performed by using SPSS 13 for Windows. Effects of season on semen quality of both Ongole crossbred and Simmental bulls, as well the comparison of semen quality of these two breeds were evaluated by using analysis of variance. Data were expressed as a mean ± standard error. The significance was set at p<0.05. Only qualified semen which included in the statistical analysis (86 ejaculate semen of Ongole crossbred bull and 89 ejaculate semen of Simmental bull), while the discarded semen was calculated separately and analyzed descriptively.
Figure 2 shows the semen quality of Ongole crossbred and Simmental bull throughout the year. The overall mean semen volume, semen pH, sperm concentration, total sperm count, sperm motility of fresh semen, total motile sperm count, sperm motility before-freezing, sperm motility post-thawing, recovery rate, and frozen semen production of Ongole crossbred bull were 6.5 ml, 6.29, 1.3 x 109, 8.43 x 109, 70.5%, 5.94 x 109, 55.6%, 40.9%, 73.5%, and 337 straw, respectively. On the other hand, the overall mean semen volume, semen pH, sperm concentration, total sperm count, sperm motility fresh semen, total motile sperm count, sperm motility before-freezing, sperm motility post-thawing, recovery rate, and frozen semen production of Simmental bull were 5.5 ml, 6.3, 1.7 x 109, 9.35 x 109, 70.2%, 6.57 x 109, 56%, 41.1%, 73.4%, and 374 straw, respectively.
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Figure 2. Monthly variations of the semen quality of Ongole crossbred and Simmental bulls |
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In general, the semen quality of Ongole crossbred and Simmental bull had met the standard semen quality of the bulls. According to the Indonesian National Standard (SNI 4869-1:2017), the bovine semen used for artificial insemination should have sperm motility of fresh semen and post-thawing of at least 70% and 40%, respectively. In addition, Ax et al (2000) noted that the minimum standard for bull semen should have the sperm concentration of at least 0.5 x 109.
Table 1 shows the seasonal effects on semen quality of Ongole crossbred bull. The sperm concentration was higher in the rainy season, however, the sperm motility before-freezing was higher in the dry season. The semen volume, semen pH, total sperm count, sperm motility of fresh semen, total motile sperm count, sperm motility post-thawing, recovery rate, and frozen semen dose were similar between two different seasons.
| Table 1. Effects of rainy and dry seasons on semen quality (mean ± SE) of Ongole crossbred bull | |||
| Items | Rainy | Dry (n=45) | P value |
| Semen volume (ml) | 6.39 ± 0.2 | 6.53 ± 0.19 | 0.593 |
| Semen pH | 6.3 ± 0.02 | 6.29 ± 0.02 | 0.853 |
| Sperm concentration (x109) | 1.34 ± 0.04b | 1.24 ± 0.03a | 0.043 |
| Total sperm count (x109) | 8.52 ± 0.33 | 8.2 ± 0.36 | 0.524 |
| Sperm motility of fresh semen (%) | 70.6 ± 0.26 | 70.2 ± 0.16 | 0.194 |
| Total motile sperm count (x109) | 6.02 ± 0.24 | 5.76 ± 0.25 | 0.459 |
| Sperm motility before-freezing (%) | 55 ± 0.17a | 56.3 ± 0.33b | 0.001 |
| Sperm motility post-thawing (%) | 41 ± 0.31 | 40.8 ± 0.27 | 0.634 |
| Recovery rate (%) | 58.1 ± 0.52 | 58.1 ± 0.38 | 0.998 |
| Frozen semen dose (straw) | 341 ± 13.2 | 328 ± 14.4 | 0.526 |
| a,b Different superscript within a row show a difference (p<0.05) | |||
In this study, there was no consistent seasonal effect on semen quality of Ongole crossbred bull. In agreement with this finding, Mallick et al (2016) also observed that there was no well-defined seasonal pattern in semen characteristics of Karan Fries crossbred bulls during winter and summer. Brito et al (2002) also found that there was no seasonal trend on semen quality of Bos indicus bulls. Previously, Snoj et al (2013) explained that in the area which closed to the equator, there is a small variation of day length between the seasons so that the obvious seasonal effect is not detected on semen quality of bull. Moreover, the small variation in the temperature and relative humidity throughout the year (Figure 1) may also partly explained the inconsistent seasonal effect on the sperm quality.
The results showed that the approval rate of fresh semen in the rainy and dry seasons were 89.8% and 92%, respectively (Table 2). In the rainy season, 10.2% of fresh ejaculates were discarded due to the low sperm motility. On the other hand, in the dry season, 2% of fresh ejaculate were discarded because of low sperm motility and the rest (6%) due to the low sperm concentration. The percentage of frozen semen which was suitable to be used for artificial insemination were 93.2% and 97.8% in the rainy and dry seasons, respectively.
The rainy season was relatively had a higher ejaculate with sperm motility post-thawing below 40% than the dry season. In agreement with this finding, Srinivas et al (2016) also found that the discarded semen in Ongole bulls was mainly due to the low volume, low sperm motility, and low sperm concentration of fresh semen.
| Table 2. Effects of
rainy and dry seasons on the approved and discarded
ejaculate number of Ongole crossbred bull |
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| Items | Rainy | Dry |
| Fresh semen | ||
| Total ejaculate | 49 | 50 |
| Approved ejaculate | 44 | 46 |
| Discarded ejaculate | 5 | 4 |
| Sperm motility <70% | 5 | 1 |
| Sperm concentration <0.5 x 109 | - | 3 |
| Frozen semen | ||
| Total ejaculate | 44 | 46 |
| Approved ejaculate | 41 | 45 |
| Discarded ejaculate (sperm motility post-thawing <40%) | 3 | 1 |
Table 3 summarizes the seasonal effects on semen quality of Simmental bull. No seasonal effects were recorded on all semen quality traits of Simmental bull. This finding was in accordance with Brito et al (2002) who noted that there was no seasonal variation in semen quality of Bos taurus bulls. This result may be due to the bull was normally considered as a non-seasonal breeder species (Gonzalez-Arto et al 2016) so that the seasonal change did not affect the semen quality. No extreme temperature change between different periods and between the day and night in the tropical area may be could also explain why the seasonal effect on semen quality was not pronounced in this study.
| Table 3. Effects of rainy and dry seasons on semen quality (mean ± SE) of Simmental bull | |||
| Items | Rainy (n=47) | Dry (n=42) | P value |
| Semen volume (ml) | 5.7 ± 0.15 | 5.32 ± 0.2 | 0.131 |
| Semen pH | 6.3 ± 0.02 | 6.29 ± 0.02 | 0.631 |
| Sperm concentration (x109) | 1.69 ± 0.04 | 1.69 ± 0.03 | 0.968 |
| Total sperm count (x109) | 9.68 ± 0.34 | 9 ± 0.39 | 0.199 |
| Sperm motility of fresh semen (%) | 70.3 ± 0.18 | 70 ± 0 | 0.098 |
| Total motile sperm count (x109) | 6.8 ± 0.24 | 6.3 ± 0.27 | 0.172 |
| Sperm motility before-freezing (%) | 56 ± 0.29 | 56.2 ± 0.33 | 0.597 |
| Sperm motility post-thawing (%) | 41.1 ± 0.3 | 41.2 ± 0.33 | 0.778 |
| Recovery rate (%) | 58.4 ± 0.47 | 58.8 ± 0.48 | 0.529 |
| Frozen semen dose (straw) | 387 ± 13.8 | 360 ± 15.6 | 0.198 |
Both in the rainy and dry seasons, 98% of fresh semen were met Indonesian National Standard (SNI 4869-1:2017) and only 2% of the fresh semen were discarded due to the low sperm motility (Table 4). The assessment of sperm motility post-thawing revealed that the discarded semen of Simmental bull was tended to be higher in the dry season than in the rainy season (14.2% vs 2%). This result probably due to the heat stress during the dry season which may impair semen freezing ability of Simmental bull. As previously noted by Perumal et al (2017), during the summer season, Mithun breeding bulls had higher malondialdehyde production followed by lower sperm motility in their post-thawed semen compared to the other seasons.
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Table 4. Effects of rainy
and dry seasons on the approved and discarded ejaculate number of Simmental bull |
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| Items | Rainy | Dry |
| Fresh semen | ||
| Total ejaculate | 49 | 50 |
| Approved ejaculate | 48 | 49 |
| Discarded ejaculate | 1 | 1 |
| Sperm motility <70% | 1 | 1 |
| Sperm concentration <0.5 x 109 | - | - |
| Frozen semen | ||
| Total ejaculate | 48 | 49 |
| Approved ejaculate | 47 | 42 |
| Discarded ejaculate (sperm motility post-thawing <40%) | 1 | 7 |
Table 5 presents the comparison of semen quality between Ongole crossbred and Simmental bulls. Ongole crossbred bull had higher semen volume, however, the sperm concentration, total sperm count, total motile sperm count, and frozen semen dose was lower compared to Simmental bull. The semen pH, sperm motility of fresh semen, sperm motility before-freezing, sperm motility post-thawing, and recovery rate did not differ between these two breeds.
| Table 5. Comparison of semen quality (mean ± SE) between Ongole crossbred and Simmental bulls | |||
| Items |
Ongole crossbred (n=86) |
Simmental (n=89) |
P value |
| Semen volume (ml) | 6.46 ± 0.13b | 5.52 ± 0.12a | <0.001 |
| Semen pH | 6.3 ± 0.01 | 6.3 ± 0.01 | 0.938 |
| Sperm concentration (x109) | 1.29 ± 0.02a | 1.69 ± 0.02b | <0.001 |
| Total sperm count (x109) | 8.35 ± 0.24a | 9.36 ± 0.26b | 0.005 |
| Sperm motility of fresh semen (%) | 70.4 ± 0.15 | 70.2 ± 0.1 | 0.176 |
| Total motile sperm count (x109) | 5.88 ± 0.17a | 6.57 ± 0.18b | 0.007 |
| Sperm motility before-freezing (%) | 55.7 ± 0.21 | 56.1 ± 0.22 | 0.22 |
| Sperm motility post-thawing (%) | 40.9 ± 0.21 | 41.1 ± 0.22 | 0.409 |
| Recovery rate (%) | 58.1 ± 0.32 | 58.6 ± 0.33 | 0.237 |
| Frozen semen dose (straw) | 334 ± 9.76a | 374 ± 10.4b | 0.005 |
| a,b Different superscript within a row show a difference (p<0.05) | |||
In agreement with this finding, Anchieta et al (2005) also reported that Bos indicus bulls had higher semen volume, whereas, their sperm motility and concentration were lower than Bos taurus bulls. In another study, Chacur et al (2013) also reported that Simmental bulls had higher sperm concentration compared to Nelore bulls (Bos indicus). Moreover, the lower value of total sperm count, total motile sperm count, and frozen semen dose can be explained by the lower sperm concentration in Ongole crossbred bull than Simmental bull.
In this study, the Simmental bull tended to have a higher approved fresh semen than Ongole crossbred bull (98% vs 90.9%) (Table 6). However, the discarded frozen semen was relatively higher in Simmental bull than Ongole crossbred bull (8.25% vs 4.44%). It could be stated that Simmental bull had a superior genetic in terms of semen production and quality so that the suitable fresh semen for freezing process was higher than Ongole crossbred bull. Whereas, the environmental impact seemed to be take a more dominant role affecting the semen freezability of the breeding bulls compared to the genotype effect. It could be speculated that Simmental bull was more susceptible to the tropical environments than Ongole crossbred bull. The susceptibility of Simmental bull to the tropical environments could accumulate a higher lipid peroxidation concentration in the semen (Nichi et al 2006). As a result, lipid peroxidation could depress semen quality during the frezing process so that the discarded frozen semen was higher in Simmental bull. The result of this study partly supported by Koivisto et al (2009), who also found that the discarded frozen ejaculate was higher in the Bos taurus than Bos indicus bulls.
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Table 6. Comparison of the
approved and discarded ejaculate number between Ongole crossbred and Simmental bulls |
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| Items | Ongole crossbred |
Simmental |
| Fresh semen | ||
| Total ejaculate | 99 | 99 |
| Approved ejaculate | 90 | 97 |
| Discarded ejaculate | 9 | 2 |
| Sperm motility <70% | 6 | 2 |
| Sperm concentration <0.5 x 109 | 3 | - |
| Frozen semen | ||
| Total ejaculate | 90 | 97 |
| Approved ejaculate | 86 | 89 |
| Discarded ejaculate (sperm motility post-thawing <40%) | 4 | 8 |
In comparison with the previous studies, the discarded semen of both breeds in this study was relatively lower. Srinivas et al (2016) found that the discarded semen in breeding bulls was 34.97%. In another study, Koivisto et al (2009) found that the discarded semen in the bulls used for artificial insemination ranged from 48 to 59.4%. It could be stated that the semen quality of Ongole crossbred and Simmental bulls in this study were still acceptable to be used for artificial insemination.
The authors are grateful for the research facilities provided by Ungaran Artificial Insemination Center.
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Received 28 November 2018; Accepted 18 December 2018; Published 1 February 2019