The least squares means (LSMs) for semen production traits i.e. semen volume, sperm concentration, initial sperm motility, post-thaw sperm motility and number of semen doses per ejaculate with the random effect of bull and fixed effects of non-genetic factors such as farm, ejaculate number, season of birth, period of birth, season of semen collection and period of semen collection are given in Table 2. The results of type-3 tests of non-genetic factors and their interactions are given in Table 3.
Table 2
Least-squares means of semen production traits for non-genetic factors in Mehsana buffalo bulls
Non-genetic factors | n | Semen production traits |
Semen volume (ml) | Sperm concentration (millions per ml) | Initial Sperm motility (per cent) | Post-thaw motility (per cent) | Number of semen doses per ejaculate |
Overall | 55071 | 3.34 ± 0.18 | 1238.19 ± 75.57 | 70.55 ± 0.12 | 60.82 ± 0.16 | 181.61 ± 11.82 |
Farm | | ** | ** | ** | ** | ns |
F1 | 18235 | 3.07 ± 0.20b | 1394.10 ± 83.89a | 70.96 ± 0.14a | 51.48 ± 0.18b | 190.46 ± 13.19 |
F2 | 36836 | 3.61 ± 0.19a | 1082.29 ± 77.64b | 70.14 ± 0.12b | 70.17 ± 0.16a | 172.75 ± 12.13 |
Ejaculate number | | ** | ** | ** | ** | ** |
EJ1 | 31875 | 3.91 ± 0.18a | 1473.28 ± 75.62a | 70.53 ± 0.12b | 60.75 ± 0.16b | 248.15 ± 11.83a |
EJ2 | 23196 | 2.77 ± 0.18b | 1003.11 ± 75.65b | 70.58 ± 0.12a | 60.89 ± 0.16a | 115.06 ± 11.84b |
Season of birth | | ns | ns | * | * | ns |
SB1 (Winter) | 17947 | 3.29 ± 0.19 | 1199.78 ± 77.70 | 70.41 ± 0.13b | 60.73 ± 0.16a | 173.12 ± 12.14 |
SB2 (Summer) | 5295 | 3.34 ± 0.24 | 1280.58 ± 100.44 | 70.63 ± 0.16ab | 60.77 ± 0.21ab | 187.26 ± 15.69 |
SB3 (Monsoon) | 31829 | 3.38 ± 0.18 | 1234.23 ± 74.08 | 70.61 ± 0.12a | 60.96 ± 0.16b | 184.44 ± 11.60 |
Period of birth | | ** | ** | ** | ** | ns |
PB1 (2004-05) | 684 | 4.22 ± 0.37ab | 1060.12 ± 152.22bc | 70.86 ± 0.25ab | 60.86 ± 0.32abc | 199.05 ± 23.93 |
PB2 (2006-07) | 10669 | 4.09 ± 0.21a | 1040.54 ± 86.74c | 70.36 ± 0.14ab | 60.51 ± 0.18bc | 186.04 ± 13.63 |
PB3 (2008-09) | 5798 | 3.49 ± 0.24abc | 1130.05 ± 100.26bc | 70.22 ± 0.16b | 60.34 ± 0.21c | 163.98 ± 15.66 |
PB4 (2010-11) | 20775 | 3.06 ± 0.18bcd | 1286.26 ± 74.62b | 70.42 ± 0.12b | 60.56 ± 0.16c | 176.75 ± 11.70 |
PB5 (2012-13) | 5993 | 2.95 ± 0.22bcd | 1244.72 ± 93.12bc | 70.56 ± 0.15ab | 60.37 ± 0.20c | 169.96 ± 14.67 |
PB6 (2014-15) | 9722 | 2.98 ± 0.20cd | 1266.51 ± 81.92bc | 70.52 ± 0.14ab | 61.07 ± 0.18b | 175.56 ± 13.04 |
PB7 (2016-17) | 1430 | 2.59 ± 0.25d | 1639.16 ± 102.75a | 70.92 ± 0.17a | 62.02 ± 0.22a | 199.90 ± 16.41 |
Season of semen collection | | ** | ** | ns | ns | ** |
SSC1 (Winter) | 19384 | 3.28 ± 0.18c | 1195.98 ± 75.67b | 70.55 ± 0.12 | 60.82 ± 0.16 | 172.69 ± 11.85b |
SSC2 (Summer) | 17081 | 3.34 ± 0.18b | 1265.08 ± 75.77a | 70.54 ± 0.12 | 60.83 ± 0.16 | 185.23 ± 11.87a |
SSC3 (Monsoon) | 18606 | 3.40 ± 0.18a | 1253.52 ± 75.69a | 70.56 ± 0.12 | 60.82 ± 0.16 | 186.89 ± 11.85a |
Period of semen collection | | ** | ** | ** | ** | ** |
PC1 (2011-12) | 4465 | 2.57 ± 0.19c | 1284.82 ± 77.39a | 70.54 ± 0.13ab | 60.71 ± 0.17b | 151.51 ± 12.32d |
PC2 (2013-14) | 11115 | 3.50 ± 0.18b | 1236.22 ± 76.29bc | 70.44 ± 0.12c | 60.75 ± 0.16b | 189.35 ± 12.02b |
PC3 (2015-16) | 12341 | 3.68 ± 0.18a | 1222.29 ± 75.71c | 70.52 ± 0.12b | 60.76 ± 0.16b | 196.26 ± 11.86a |
PC4 (2017-18) | 17996 | 3.45 ± 0.18b | 1180.34 ± 75.63d | 70.56 ± 0.12b | 60.85 ± 0.16b | 177.29 ± 11.84c |
PC5 (2019-20) | 9154 | 3.51 ± 0.18b | 1267.30 ± 76.02ab | 70.69 ± 0.12a | 61.04 ± 0.16a | 193.62 ± 11.95ab |
Table 3
Type-3 tests for effects of non-genetic factors and their interactions on semen production traits in Mehsana buffalo bulls
Source of variation | Degree of freedom | Semen production traits |
Semen volume | Sperm concentration | Initial Sperm motility | Post-thaw motility | Number of semen doses per ejaculate |
F Value | P Value | F Value | P Value | F Value | P Value | F Value | P Value | F Value | P Value |
Farm | 1 | 14.77 | 0.0001 | 29.59 | < .0001 | 74.29 | < .0001 | 23037.7 | < .0001 | 3.77 | 0.0523 |
Ejaculate number | 1 | 5802.66 | < .0001 | 5908.64 | < .0001 | 11.44 | 0.0007 | 51.89 | < .0001 | 10756.6 | < .0001 |
Season of birth | 2 | 0.34 | 0.7132 | 0.6 | 0.5468 | 3.92 | 0.0198 | 3.07 | 0.0466 | 1.41 | 0.2432 |
Period of birth | 6 | 11.77 | < .0001 | 7.99 | < .0001 | 4.03 | 0.0005 | 16.45 | < .0001 | 1.46 | 0.1874 |
Season of semen collection | 2 | 20.91 | < .0001 | 44.15 | < .0001 | 0.4 | 0.6673 | 0.2 | 0.8199 | 45.38 | < .0001 |
Period of semen collection | 4 | 399.5 | < .0001 | 44.97 | < .0001 | 17.38 | < .0001 | 14.17 | < .0001 | 142.14 | < .0001 |
Overall LSMs of semen volume per ejaculate was found to be 3.34 ± 0.18 ml in the present study, which was higher as compared to semen volume reports of 2.66 and 2.71 ml by Bhakat et al. (2015) and Shakya et al. (2018) in Murrah buffalo respectively. Similarly, semen volume per ejaculate in other buffalo breeds reported to be 3.04, 3.34 and 3.12 ml in Surti buffalo by Dhami et al. (2016), Chaudhary et al. (2017) and Pathak et al. (2018); 2.31 ± 0.46 ml in Tarai buffalo by Tiwari et al. (2009); 2.10 (In young bulls) and 2.60 ml in Nili-Ravi buffalo by Ahmed et al. (2018) and Hameed et al. (2017) respectively were also lower as compared to the finding of the present study.
Semen volume per ejaculate found in the present study was lower than reported value of 3.67 ml (Saini et al., 2017) and 4.48 ml (Bhave et al., 2020) in the Murrah buffalo; 4.68 ml (Bhave et al., 2020) in the Surti buffalo; 5.11 ml (Ghodasara et al., 2016), 5.13 ml (Parmar et al., 2020) and 5.10 ml (Bhave et al., 2020) in the Jaffarabadi buffalo; 4.63 ml (Hameed et al., 2017) and 4.7 ml (Ahmed et al., 2018) in the Nili-Ravi buffalo; 4.09 ml (Bhave et al., 2020) in the Banni buffalo; 4.11 ml (Bhave et al., 2020) in the Bhadawari buffalo and 4.79 ml (Bhave et al., 2020) in the Pandharpuri buffalo.
The semen volume per ejaculate was significantly (P ≤ 0.01) higher in farm-2 (3.61 ± 0.19 ml) as compare to farm-1 (3.07 ± 0.20 ml). Hameed et al. (2017) reported significant effect of districts on the semen volume per ejaculate in Nili-Ravi buffalo which was in accordance to the finding of the present study that effect of two farms at different locations was significant.
The finding of the present study revealed that effect of seasons was not found on semen volume per ejaculate. The hypothesis behind the study on effect of season of birth on semen volume per ejaculate was to find the effect of environment of particular season on growth of the bull which lead to development of reproductive organs to achieve pubertal age and ultimately it reflect to the semen volume per ejaculate.
Bulls born during period-1 (2004 to 2005) produced higher semen volume per ejaculate of 4.22 ± 0.37 ml, thereafter it did not differ significantly up to period-3 (2008 to 2009) however semen volume per ejaculate was found to be lower (2.59 ± 0.25 ml) in the period-7 (2016 to 2017) born bulls. Effect of period of birth on the semen volume per ejaculate was found significant (P ≤ 0.01) in the present study which might be due to changes in the environmental condition and managemental practices over the periods.
Monsoon season of semen collection was found favorable and significantly (P ≤ 0.01) highest semen volume per ejaculate (3.40 ± 0.18 ml) was recorded, which was followed by summer (3.34 ± 0.18 ml) and winter (3.28 ± 0.18 ml) seasons of semen collection. Present findings were at par with those of Ravimurugan et al. (2003) and Bhat et al. (2004) in Murrah; Bhave et al. (2020) in Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes pooled data reported significant effect of season of semen collection on semen volume per ejaculate. Whereas, Bhakat et al. (2015) in Murrah; Koonjaenak et al. (2007) in Swamp and Hameed et al. (2017) in Nili-Ravi buffalo reported non-significant effect of season of semen collection on semen volume per ejaculate. Highest semen volume per ejaculate was produced during monsoon followed by summer and winter seasons in present study. The higher semen volume was reported in monsoon season of semen collection was due to physiological effect of breeding season of buffalo. Monsoon season of semen collection was reported as favorable season of semen collection by Ravimurugan et al. (2003) and Bhat et al. (2004).
Semen collected during the ten years’ time span was considered for the present study. During the period of semen collection 1 to 3 (years 2011 to 2016), semen volume per ejaculate increased significantly (P ≤ 0.01) from 2.57 ± 0.19 ml to 3.68 ± 0.18 ml. Thereafter, during the remaining periods of semen collection 4 to 5 (2017 to 2020), semen volume per ejaculate decreased significantly (P ≤ 0.01) as compared to production during period-3 (2015 and 2016). Significant effect of period of semen collection on the semen volume per ejaculate was found in the present study. Similar to the present study Mir et al. (2016) and Bhave et al. (2020) also reported significant effect of period of semen collection on semen volume per ejaculate in Murrah and pooled data of Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes respectively.
The semen collected in the first ejaculate number gave significantly (P ≤ 0.01) higher semen volume (3.91 ± 0.18 ml) compared to second ejaculate number (2.77 ± 0.18 ml). Significantly higher semen volume was produced in the first ejaculate collection in the present study. Lower semen volume in the second ejaculation was due to physiological effect which was always bound to occur in subsequent collection after first collection. Similar findings were also reported by Ramajayan (2016) in Murrah and Bhave et al. (2020) in pooled data of Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes.
Overall LSMs of sperm concentration was found as 1238.19 ± 75.57 million per ml in the present study, which was higher as compare to reported values of 766.69 ± 5.50, 1016.68, 1164 and 978.9 million per ml by Bhakat et al. (2011), Bhakat et al. (2015), Saini et al. (2017) and Shakya et al. (2018) respectively in Murrah buffalo. Finding of the present study was also higher than the sperm concentration reports of 838.30, 1219.98 and 1180 million per ml in Jaffarabadi buffalo by Ghodasara et al. (2016), Parmar et al. (2020) and Bhave et al. (2020); 1100 to 1200 million per ml in Swamp buffalo by Koonjaenak et al. (2006); 990 and 854.27 to 1023 million per ml in Nili-Ravi buffalo by Sajjad et al. (2007) and Hameed et al. (2017); 920.0 ± 71.09 million per ml in Tarai buffalo by Tiwari et al. (2009); 930 million per ml in Pandharpuri by Bhave et al. (2020); 963.05 and 846.30 million per ml in Surti buffalo by Dhami et al. (2016) and Chaudhary et al. (2017) respectively and 1160 million per ml in Bhadawari by Bhave et al. (2020).
The LSM of sperm concentration found in the present study was lower than the earlier reports of 1610.23 ± 142.07 million per ml (Selvaraju et al., 2008), 1343 million per ml (Pathak et al., 2018) and 1310 million per ml (Bhave et al., 2020) for the Murrah buffalo; 1365.15 ± 120.23 million per ml (Dhami and Sahni, 1994) for the Jaffarabadi buffalo; 2335.7 to 3550.5 million per ml (Ahmed et al., 2018) for the Nili-Ravi buffalo; 1246 million per ml (Pathak et al., 2018) and 1270 million per ml (Bhave et al., 2020) for Surti buffalo and1310 million per ml (Bhave et al., 2020) for Banni buffalo.
The sperm concentration was significantly (P ≤ 0.01) higher in farm-1 (1394.10 ± 83.89 million per ml) as compare to farm-2 (1082.29 ± 77.64 million per ml). The finding of the present study on sperm concentration was in accordance with study conducted by Hameed et al. (2017) in Nili-Ravi buffalo who reported significant effect of districts on the sperm concentration.
The finding of the present study revealed no significant (P > 0.05) effects of season of birth on sperm concentration. Similar to the semen volume, the hypothesis behind the study of effect of season of birth on sperm concentration was to find the effect of environment of particular season on growth of the bull which lead to development of reproductive organs to achieve pubertal age and ultimately it reflect in the sperm concentration.
Sperm concentration was significantly low in the semen produced by 2004 and 2005 born bulls (1060.12 ± 152.22 million per ml) compared to 2016 and 2017 born bulls (1639.16 ± 102.75 million per ml) but sperm concentration in semen was at par in the bulls born during 2004 to 2015. Effect of period of birth on the sperm concentration was found significant (P ≤ 0.01) in the present study which might be due to changes in the environmental conditions and managemental practices over the periods. As the semen volume reported in the present study was gradually decreased over the period of birth of the bulls from 2004–05 to 2016–17, contrary increase in the sperm concentration was evident. As the semen volume decreases sperm concentration is likely to increase, which might be the reason behind increasing trend in the sperm concentration of the bulls born during 2004–05 to 2016–17.
Summer and Monsoon seasons of semen collection were found favorable with significantly (P ≤ 0.01) higher sperm concentration of 1265.08 ± 75.75 and 1253.52 ± 75.69 million per ml respectively as compared to winter season (1195.98 ± 75.67 million per ml). Higher sperm concentration found during summer season of semen collection which did not differ with sperm concentration of monsoon season of semen collection in the present study. Similar to the present study Bhakat et al. (2015), Hameed et al. (2017) and Bhave et al. (2020) also reported significant effect of season of semen collection on sperm concentration, Whereas non-significant effect of season of semen collection reported by Koonjaenak et al. (2007). In accordance to the present study Bhat et al (2004) also reported higher sperm concentration during the summer season of semen collection. Contrary to this, Ravimurugan et al. (2003) has reported higher sperm concentration during winter season of semen collection.
During 2011 and 2012 to 2017 and 2018 sperm concentration decreased significantly (P ≤ 0.01) from 1284.82 ± 77.39 to 1180.34 ± 75.63 million per ml but during the years 2019 to 2020 significant (P ≤ 0.01) rise was found in sperm concentration (1267.30 ± 76.02 million per ml). Significant effect of period of semen collection on the sperm concentration was found in the present study. Bhave et al. (2020) also reported significant effect of period of semen collection on sperm concentration during the study based on pooled data of Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes.
The semen collected in the first ejaculation gave significantly (P ≤ 0.01) higher sperm concentration (1473.28 ± 75.62 million per ml) as compare to the second ejaculation (1003.11 ± 75.65 million per ml). Sperm concentration was significantly affected by ejaculate number and significantly higher sperm concentration was found in the first ejaculate number in the present study. Similar findings were also reported by Ramajayan (2016) in Murrah and Bhave et al. (2020) in pooled data of Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes.
Overall LSMs of initial sperm motility (70.55 ± 0.12 %) in the present study was higher as compared to initial sperm motility reports of 68.40 ± 1.30, 68.1, 60.64 and 68.4% by Shakya (2013), Khatun at el. (2013), Bhakat et al. (2015) and Shakya et al. (2018) in Murrah buffalo respectively. Finding of the present study was also higher than the initial sperm motility reports of 61.37 % in Mehsana buffalo (Patel and Dhami, 2016), 59.44 ± 3.05 and 61.80 % in Jaffarabadi buffalo by Shelke and Dhami (2001), Patel and Dhami (2016) respectively and 49.72 to 66.02 % in Nili-Ravi buffalo by Hameed et al. (2017).
Initial sperm motility found in the present study was lower than 76.58% (Shukla, 2002), 71.56 ± 0.37 % (Rana, 2012), 90 % (Saini et al., 2017), 84.38 % (Pathak et al., 2018) and 74.05 % (Bhave et al., 2020) reported for the Murrah buffalo; 78.90 ± 1.22 % (Patel et al., 2012), 79.41 % (Ghodasara et al., 2016), 79.53 % (Parmar et al., 2020) and 74.70 % (Bhave et al., 2020) for the Jaffarabadi buffalo; 79.00 ± 3.82 % (Tiwari et al., 2009) for Tarai buffalo; 75 % (Dhami et al., 2016), 80.76 % (Chaudhary et al., 2017), 84.58 % (Pathak et al., 2018) and 73.21 % (Bhave et al., 2020) for Surti buffalo; 72.1 to 72.2% (Ahmed et al., 2018) for the Nili-Ravi buffalo; 74.14 % (Bhave et al., 2020) for Banni buffalo; 71.57 % (Bhave et al., 2020) for Bhadawari buffalo and 73.22 % (Bhave et al., 2020) for Pandharpuri buffalo.
The initial sperm motility was significantly (P ≤ 0.01) higher in farm-1 (70.96 ± 0.16 %) as compare to farm-2 (70.14 ± 0.12 %). Hameed et al. (2017) reported significant effect of districts on the initial sperm motility in Nili-Ravi buffalo which supports present findings of significant effect of two farms at different locations.
Season of birth of bull significantly (P ≤ 0.05) affect initial sperm motility. Higher initial sperm motility was found in summer (70.63 ± 0.16 %) and monsoon (70.61 ± 0.12 %) season born bulls as compare to winter (70.41 ± 0.13 %) born bulls. The higher initial sperm motility of 70.92 ± 0.17 % was observed in the 2016 to 2017 born bulls, whereas it was the lower (70.22 ± 0.16 %) in 2008 to 2009 born bulls.
Effect of period of birth on the initial sperm motility was found highly significant (P ≤ 0.01) in the present study which might be due to changes in the environmental condition and managemental practices over the periods. Effect of age of bull at first semen collection on initial sperm motility was significant (P < 0.05) in the present study. Higher initial sperm motility of 70.61 ± 0.36 to 70.73 ± 0.07 % were found in the bulls with 1 to 3 years of age at first semen collection which was at par with initial sperm motility found in the semen of 5 to 7 years of age of bull at first semen collection.
Initial sperm motility was not affected significantly by season of semen collection in the present study. The present findings are similar to those of Koonjaenak et al. (2007) and Hameed et al. (2017). They reported non-significant effect of season of semen collection on Initial sperm motility. Contrarily significant effect of season of semen collection on initial sperm motility was reported by Ravimurugan et al. (2003), Bhakat et al. (2015) and Bhave et al. (2020).
Highly significant (P ≤ 0.01) effect of period of semen collection was found on initial sperm motility. Highest initial sperm motility of 70.69 ± 0.12 % was found in the semen collected during the period of 2019 to 2020 whereas lowest initial sperm motility of 70.44 ± 0.12 % was found in the semen collected during the 2013 to 2014. It revealed that change in managemental and environmental condition during semen collection may contribute to differential initial sperm motility.
The semen collected in the second ejaculation gave significantly (P ≤ 0.01) higher initial sperm motility of 70.58 ± 0.12 % as compare to the first ejaculation (70.53 ± 0.12 %). Lower initial sperm motility in the first ejaculation was due to physiological effect which was always bound to occur as the first ejaculation contains more non-viable sperms. Similar to the present study, Ramajayan (2016) in Murrah and Bhave et al. (2020) in pooled data of Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes also reported significant effect of ejaculate number on initial sperm motility.
Overall LSMs of post-thaw sperm motility was found to be 60.82 ± 0.16 % in the present study, which was higher as compare to post-thaw sperm motility reports of 59.58 and 48.45 % by Pathak at el. (2018) and Bhave et al. (2020) in Murrah buffalo respectively. Finding of the present study was also higher than the post-thaw sperm motility of 34.30 % in Mehsana buffalo (Patel and Dhami, 2019), 33.20, 58.71, 57.60 and 48.37 % reported in Jaffarabadi buffalo by Patel and Dhami (2016), Ghodasara et al. (2016), Parmar et al. (2020) and Bhave et al. (2020) respectively; 58.33 and 48.34 % reported in Surti buffalo by Pathak et al. (2018) and Bhave et al. (2020) respectively; 43.25 % reported in Kundhi buffalo by Kaka et al. (2012); 48.47 % reported in Banni buffalo by Bhave et al. (2020); 43.8 to 46.6 % reported in Nili-Ravi buffalo by Ahmed et al. (2018); 47.80 % in Bhadawari buffalo and 48.93 % in Pandharpuri buffalo reported by Bhave at el. (2020) respectively.
Post-thaw sperm motility found in the present study was lower than reported values of 72.45 ± 2.22 % (Purohit et al., 2000) and 61.75 % (Dhami et al., 2016) for Surti; 67.64 % (Samo et al., 2005) and 64.53 ± 0.76 % (Rehman et al., 2012) for Kundhi and 75.85 ± % (Alavi-Shoushtari and Babazadeh-habashi, 2006) for Azarbaijani buffalo.
The post-thaw sperm motility was significantly (P ≤ 0.01) higher in farm-2 (70.17 ± 0.16 %) as compare to farm-1 (51.48 ± 0.18 %).
Effect of season of birth was significant (P ≤ 0.05) on post-thaw sperm motility. Post-thaw sperm motility of 60.96 ± 0.16 % was observed in the winter born bulls which significantly differed with monsoon born bulls’ post-thaw sperm motility (60.73 ± 0.16 %).
Effect of period of birth was highly significant (P ≤ 0.01) on post-thaw sperm motility. Higher post-thaw sperm motility of 62.02 ± 0.22 % was observed in the 2016 to 2017 born bulls but it was lower (60.34 ± 0.21 %) in 2008 to 2009 born bulls which was at par with 2004 to 2007 and 2010 to 2013 born bulls. Effect of period of birth on the post-thaw sperm motility was found highly significant (P ≤ 0.01) in the present study which might be due to changes in the environmental conditions and managemental practices developed and adopted over the periods. Younger bulls produced semen with higher post-thaw sperm motility as compare to adult and older bulls in the present study.
Post-thaw sperm motility was not affected significantly by season of semen collection in the present study. Contrarily to the present study significant effect of season of semen collection on post-thaw sperm motility was reported by Bhave et al. (2020) in the pooled data of Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes.
Highly significant (P ≤ 0.01) effect of period of semen collection was found on post-thaw sperm motility. Post-thaw sperm motility of 61.04 ± 0.16 % was found to be significantly highest in the semen collected during the period of 2019 to 2020 as compare to post-thaw sperm motilities during periods 1 to 4. Post-thaw sperm motilities of semen collected during period 1 to 4 were at par with each other. As the period of semen collection advanced post-thaw sperm motility increased showing better handling practices adopted by the semen stations with time.
The semen collected in the second ejaculation gave significantly (P ≤ 0.01) higher post-thaw sperm motility of 60.89 ± 0.16 % as compare to the first ejaculation (60.75 ± 0.16 %). Post-thaw sperm motility was significantly affected by ejaculate number and significantly higher post-thaw sperm motility was found in the second ejaculation in the present study. Lower post-thaw sperm motility in the first ejaculation was due to physiological effect which was always bound to occur as the first ejaculation contains more non-motile sperms due to gap between semen collection days and sperm production cycle in the reproductive organ as sperms get produce, mature and become non-motile till next semen collection. Similarly significant effect of ejaculate number on post-thaw sperm motility were reported by Ramajayan (2016) in Murrah and Bhave et al. (2020) in pooled data of Banni, Bhadawari, Jaffarabadi, Murrah, Pandharpuri and Surti buffaloes.
The overall LSM of number of semen doses per ejaculate was 181.61 ± 11.82. Ejaculate number, season of semen collection and period of semen collection contributed significantly (P ≤ 0.01/0.05) to the variation in number of semen doses per ejaculate. Whereas, farm, season of birth and period of birth were non-significant sources of variation for number of semen doses per ejaculate.
Number of semen doses per ejaculate did not differ significantly between farm-1 and 2. Semen production traits like semen volume, sperm concentration, initial sperm motility and post-thaw sperm motility under present study were significantly differed between farm-1 and 2 but number of semen doses per ejaculate was not affected. Number of semen doses per ejaculate mainly depend on semen volume and sperm concentration. From the data of the present study it was observed that farm-1 has lower semen volume compared to farm-2 but sperm concentration was higher in farm-1 as compare to farm-2 which might have resulted in overall at par production of semen doses per ejaculate.
Effect of season of birth was non-significant (P > 0.05) on number of semen doses per ejaculate. This indicate overall adoption of bulls to the particular environment to achieve pubertal age and have well developed reproductive organs without influence of seasonal variation. Number of semen doses per ejaculate was not affected significantly by period of birth of bull.
Number of semen doses per ejaculate were significantly (P ≤ 0.01) affected by season of semen collection. Semen collected in the monsoon season has higher number of semen doses per ejaculate (186.89 ± 11.85) which was followed by 185.23 ± 11.87 in summer, however difference between both of them was non-significant. Significantly lower number of semen doses was observed in the winter season of semen collection (172.69 ± 11.85). Number of semen doses per ejaculate were significantly affected by season of semen collection in the present study. Significantly higher number of semen doses per ejaculate were produced from the semen collected during summer and monsoon seasons compared to winter season. Semen characteristics like semen volume and sperm concentration were higher during the summer and monsoon seasons’ collected semen. Hence, the higher number of semen doses per ejaculate were produced during summer and monsoon season of semen collection. Contrary to the present finding, Bhosrekar (1988) reported highest frozen semen doses in the winter season but he also narrated that rainy season seemed to be better for semen freezability and lower discard rate. Similar to the present study significant effect of season of semen collection on number of semen doses per ejaculate was also reported by Bhosrekar (1988) and Bhosrekar et al. (1992) in Surti buffalo.
Highly significant (P ≤ 0.01) effect of period of semen collection was found on number of semen doses per ejaculate. Higher number of semen doses per ejaculate (196.26 ± 11.86) was observed from the semen collected during 2015 to 2016 whereas lowest number of semen doses per ejaculate of 151.51 ± 12.32 was produced from the semen collected during 2011 to 2012. Significant (P ≤ 0.01) effect of period of semen collection on the number of semen doses per ejaculate was found in the present study. Relatively higher number of semen doses per ejaculate produced during 2015 to 2016 and 2019 to 2020 periods which might be due to better environmental and managemental practices during the periods.
The semen collected in the first ejaculation produced significantly (P ≤ 0.01) higher number of semen doses per ejaculate (248.15 ± 11.83) as compare to the second ejaculation (115.06 ± 11.84).
In conclusion, Monsoon and summer were favorable seasons for semen collection because of higher sperm concentration which resulted in to higher semen doses per ejaculate in Mehsana buffalo bull. Additionally, Monsoon collected semen had highest volume. Hence, monsoon followed by summer season would be the favorable season for semen collection. Mature Mehsana buffalo bulls of 3 to 5 years of age or bulls having more than 700 kg body weight or the bulls, where semen collection was done after 2012 produced higher semen volume leading to higher semen doses per ejaculate. This indicates that bulls maturing at the age of 3 years (approx.) or having body weight of 700 kg or more produced more semen. First ejaculation had higher semen volume irrespective of age and season of semen collection resulting in to more semen doses per ejaculate in Mehsana buffalo bulls.