Bacteriospermia and Sperm Quality of Cryopreserved Bull Semen Used in Artificial Insemination of Cows in South Wollo Zone, Ethiopia

Abstract

The objectives of this trial were to estimate prevalence of bacteriospermia, to determine the bacterial load, and to isolate the types of bacteria as well as to assess the association between bacterial load and sperm quality traits in cryopreserved bull semen in field conditions in the South Wollo Zone. A total of 309 cryopreserved straws of semen from the Holstein Friesian (HF)-cross bull (n = 180 straws) and pure Jersey bull (n = 129 straws) were investigated. Bacteriological assessments of the presence of aerobic bacteria, estimation of bacterial count and bacterial isolation, as well as semen quality were performed. Aerobic bacterial contamination was prevalent in 38.8% of the semen straws. No significant difference in the prevalence of bacteriospermia was observed among bulls although the HF-cross bull had a higher prevalence (40.0%). But, significant difference in prevalence of bacteriospermia was found among semen ejaculates of the same bull. The risk of bacteriospermia in the HF-cross bull was higher (Odds ratio = 1.86, 95% CI = 0.168–20.26) compared to Jersey although not significant. Overall average bacterial load of 50.38 ± 16.29 colony-forming units (CFU)/ml (from nil to 1318.20 CFU/ml) was found. No significant difference in bacterial count among bulls and their ejaculates was observed. Moreover, correlation analysis revealed that the proportions of motility, live, and normal morphology were negatively influenced by an increase in the bacterial contamination of semen. In this study, three isolates of coagualse-negative Staphylococcus species and one isolate of Corynebacterium species were found. Average percentages of sperm motility (48.35 ± 1.23), live (66.08 ± 1.0), and normal morphology (80.62 ± 1.24) were observed. It was concluded that cryopreservation does not guarantee the quality of semen from bacterial contamination. Hence, meticulous care should be adopted to prevent contamination of semen by bacteria during collection, transportation, processing, and storage times.

Effects of Extender Type, Storage Time, and Temperature on Bull Semen Parameters

“…The relatively high load in our field ejaculates may explain why our semen samples showed lower seminal parameters than in other studies [9][10][11][12][13]. CFU correlates negatively with sperm motility, viability, and morphology [60]. Similarly, we observed a negative timedependent correlation between CFU and viability.…”

“…Semen collected at Semen Stations inevitably contains ambient microorganisms, up to 2.36 × 104 ± 1943 CFU/mL in fresh semen [57] and 1.00 × 10 ± 90 CFU/mL in frozen semen after thawing [58]. Other authors found 103-106 CFU/mL in five bulls analysed after collection at an insemination centre [59] and 50.38 ± 16.29 CFU/mL in thawed cryopreserved bull semen collected under field conditions [60]. A recent study [61] isolated 135 microorganisms from 25 genera from 174 frozen-thawed semen collected from artificial vaginas and analysed at different periods of the conservation process.…”

Semen quality and total microbial load: An association study in important Indian Goat breeds during different seasons

“…Production and dissemination of microbe‐free quality semen are the major objectives of semen collection centres throughout the world, and the success of artificial insemination (AI) depends on the quality semen production and logistics (Reda et al., 2020). It is also envisaged that bacterial load in semen is considered as one of the major concerns, which affects the semen quality, and further fertility.…”

“…Decreased sperm concentration (Bezold et al., 2007), loss of motility (Moretti et al., 2014), sperm morphological alterations (Diemer et al., 2000), sperm viability (Domes et al., 2012) and impairment of acrosome reaction are the most frequent alterations seen in spermatozoa attributable to bacteria in both in vivo and in vitro conditions. Other mechanisms by which bacterial contamination in semen affects fertility is the altered mitochondrial function, which leads to formation of reactive oxygen species hereby provoking DNA damage (Reda et al., 2020). On the other hand, the resultant infiltration of leucocytes into the site of infection may be associated with the additional risk factor and is also responsible for alteration of sperm fertilising capability, due to oxidative, apoptotic and immune processes (Moretti et al., 2014).…”

“…On the other hand, the resultant infiltration of leucocytes into the site of infection may be associated with the additional risk factor and is also responsible for alteration of sperm fertilising capability, due to oxidative, apoptotic and immune processes (Moretti et al., 2014). Thus, the important reason contributing to failure of AI is the contamination of the semen with microbes, which eventually cause loss of fertility (Reda et al., 2020; Thibier & Guerin, 2000). Given the limited number of studies, it is still unclear whether the presence of specific bacterial groups has the potential to influence buck sperm function.…”