تاثیر واکسیناسیون بیماری تب‌برفکی بر پارامتر‌های کیفی و کمی مایع منی گاو‌ نژاد هلشتاین

Introduction: Many outbreaks of foot and mouth disease (FMD), an endemic disease of artiodactyl ruminants, occur all over the country every year. FMD is one of the diseases that cause a lot of economic damage to animals and is one of the main obstacles in ensuring health and production of livestock. Preventing the introduction of the disease into a country by controlling the imports of meats and meat products and other sources which might transmit the virus or use of vaccination are two major alternatives in respect to preventing and controlling FMD (Carpenter and Thieme, 1979). Vaccination, with currently available and tested vaccine must be undertaken at least three times annually to maintain immunity. The semen quality may be affected by vaccination due to vaccine stress and anaphylactic shock (Murugavel et al. 1997). The present investigation was carried out to study the effect of FMD vaccination on seminal traits of Holstein bulls.
Material and methods: Twenty Holstein bulls between three and five years old maintained at Nahadehaye Dami Jahed Artificial Insemination center were used in present study, which were housed in individual pens under identical feeding and management regimes. FMD vaccine polyvalent (inactivated, containing virus types O2016, A13, A15 and Asia1 strains) produced by Razi vaccine and serum research Institute was administered for vaccination purpose at 5 ml by SC injection route. Semen samples were collected by artificial vagina technique. Appropriate sexual preparation with two false mount on dummy cow was followed. A total of 571 semen ejaculates were collected at 15 days before, 15 days after and 15-30 days after FMD vaccination during autumn of 2018 and spring of 2019. Seminal traits like fresh and post thaw sperm motility, motility after incubation test, sperm concentration, semen volume and HOS test were evaluated. The ejaculate volume was measured in the divided semen collection tube in milliliters. The concentration of spermatozoa was calculated by photometer. Motility of spermatozoa was analyzed by Computer-assisted sperm analysis (CASA). The integrity of sperm membrane was evaluated using the hypo-osmotic swelling test (HOST). Extended semen was filled in medium straws and were frozen by programmable freezing device. Recorded data were analyzed using SPSS, oneway ANOVA. The differences at P<0.05 were considered to be statistically significant.
Results and discussion: However, the available reports on the effect of such vaccination on semen quality are conflicting, Vaccination is one of the major anaphylactic stress factors that affect the semen quality (Gahlot and Kohli, 1981; Venkatareddy et al. 1991 and Murugavel et al. 1997).
In this study There was no significant (P>0.05) effect of vaccination on the semen volume in Holstein bulls, but a slightly increasing trend was observed. The secondary activities of accessory sex glands remain unaffected following vaccination (Radhakrishnan et al. 1975). So, this can be considered as a possible cause for no change in the ejaculate volume. However, Venkatareddy et al. (1991) in Onqole, Jersey and Ongole × Jersey breeds reported an increase in the volume of semen. Significant decrease in sperm concentration following vaccination was observed by Venkataswamy and Rao (1970); Venkatareddy et al. (1991) and Singh et al. (2003). On the contrary, Kammar and Gnagadhar (1998) reported no adverse effect of vaccination on sperm concentration during post vaccination period, and in the current study there is no evidence of reduction in sperm concentration (p>0.05). The decreased sperm concentration may be due to the adverse effects of therapeutic agents on germinal cells resulting into increase in dead spermatozoa, which are absorbed by leucocytes through phagocytosis (Mann and Mann 1981). The negative effects of vaccination may be due to the adverse effects produced by therapeutic agents or degenerative changes in germinal epithelium. The increased resorption of abnormal spermatozoa leads to reduction in epididymal sperm reserves (Rao et al. 1980), thereby decreasing concentration. The motility of sperm cell develops during their passage through epididymis (Olson et al. 2002). However, vaccination transitory rise in body temperature as well as testes temperature causes derangement in spermatogenesis and epididymal function, and this leads to vaccination mediated declined sperm motility (Arthur 1989). When testicular temperature increases, metabolism increases at a greater rate than blood flow and hence the testes become hypoxic. Therefore, the testes are very susceptible to temperature increases due to endogenous or exogenous factors (e.g. fever, high ambient temperature). As testicular temperature increases, the proportion of defective spermatozoa increases; recovery is dependent upon the nature and duration of the thermal insult (Setchell 1978). Pankaj et al. (2007) reported significant reduction in the mass activity and motility of buffalo bull semen after vaccination. In this study a non-significant effect on initial progressive motility with decreasing trend was observed which is in agreement with observation of Gupta et al. (2017). Our results are in agreement with the findings of Bhakat et al. (2010) who reported a significant decline in post thaw motility during post vaccination. To be specific, there was a significant decrease in frozen semen samples progressive and slow motility, rate of plasma membrane integrity and significant increase in immotile spermatozoa in our study(p<0.05). Contrary to this Mangurkar et al. (2000) observed no significant effect on post freezing motility. Both physiological and structural status of sperm get severely affected during cryopreservation (Bailey et al. 2003). The chemical, osmotic, thermal and mechanical stresses during extension, cooling, freezing and thawing result in cryoinjuries of varying degree to the spermatozoa (Farooq et al. 2013). The significant variation in post thaw motility and motility after incubation test can be attributed to the effect of thermal stress developed following vaccination (Gupta et al. 2017).
Conclusion: The observations showed that vaccination changes the seminal characteristics of Holstein bulls. Thus, it is suggested that AI Centers consider sexual rest and prescribe supportive treatment in order to improve semen characteristics after vaccination.