Foot and Mouth Disease Circulating and Vaccine-Induced Antibodies and Evaluation of Coconut Water As A Potential Extender on Bull Semen
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Date
2024-01
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Kenyatta University
Abstract
Artificial Insemination (AI) is the single most important technique that employs genetic improvement of cattle for producing quality livestock breeds. Bulls farmed for AI in Kenya are vaccinated against the Foot and Mouth Disease (FMD). It is however, not clear if all FMD vaccinated bulls develop immunity against the vaccines. There have been no studies to establish if vaccinated bulls produce semen in parameters within the normal range (as assumed that vaccinated bulls have good semen). In addition, although the FMD in Kenya is known to occur in certain endemic regions while other regions remain nonendemic, there have been no studies carried out to establish if animals in endemic areas develop natural immunity or if animals in the disease- free regions could be seropositive. The present study was aimed at determining the impact of foot and mouth circulating and vaccine-induced antibodies and evaluation of coconut water as a potential extender of bull semen for artificial insemination. The cross-sectional study used bulls specifically farmed for production of semen for AI and therefore, vaccinated against FMD. For a pilot study to establish natural protection against FMD, bulls in both endemic and none endemic regions were used. Antibodies were quantified using virus neutralization test. Semen samples were obtained from FMD vaccinated bulls and analyzed for parameters. Coconut water was evaluated alongside a commercial semen extender to establish its potential for use in semen processing. Data were analyzed using the GraphPad InStat software utilizing one way analysis of variance (ANOVA) and Kruskal-Wallis test with Tukey and Dunn post-tests respectively. In addition, t-test was used to analyze for intergroup differences while Spearman test was used for correlation analysis. A P value < 0.05 was considered statistically significant. Results indicated that in FMD non-endemic region, 23%, 10.3%, 2.6% and 7.7% of the animals had protective levels of antibodies against the FMD virus strains O, A, SAT 1, and SAT 2 respectively with a significantly higher protection conferred by induced by the O strain virus as compared to SAT 1 (P = 0.0124). In the FMD endemic area, all sampled animals showed protection levels at 100%, 100%, 100% and 29% for virus strains O, A, SAT 1, and SAT 2 respectively with the antibody titres showing significant differences (P <
0.05) for all the intergroup analysis except between strains O vs SAT 1 and A vs SAT 1 (P > 0.05). Analysis of semen parameters in FMD vaccinated bulls showed at least two animals from each of the bulls that developed immunity and those that failed to develop immunity to have light creamy or watery semen instead of the normal cream-colored semen. In addition, while most of the semen parameters were within normal values, bulls that failed to develop immunity following vaccination were associated with significantly higher sperm recovery post thawing as compared to animals that seroconverted (P < 0.0001). Comparable sperm recovery rate was obtained from semen processed with coconut water and commercial extender post thawing (P > 0.05). In conclusion, the present findings point to a possible emergence of FMD in disease non-endemic region while most animals in disease prevalent regions have protective levels of virus specific antibodies. In addition, there appears to be some negating effect of FMDV specific antibodies on recovery of sperms post thawing. Furthermore, coconut water appears to perform similarly to commercial semen extender and shows potential as a medium for semen processing. The study recommends surveillance of FMD in disease non-endemic regions and the confirmation of the present findings using large sample sizes in order to make more informed conclusive decisions
Description
Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science (Immunology) in the School of Pure and Applied Sciences of Kenyatta University, January 2024
Supervisors;
1.Michael Gicheru
2.Jemimah Simbauni