Evaluation of sperm quality: Identification of the subfertile male and courses of action

Use of semen analysis to predict fertility in animal agriculture has yielded a vast literature but no test yielding accurate predictions. Reasons for this disappointing conclusion are complex, but include: (a) unrealistic goals; (b) incomplete inclusion of emerging information on the steps in fertilization into design of an assay; (c) erratic assay technique; and (d) difficulty in explicitly defining success. Each topic is treated in this presentation. Three possible goals for an assay are to: (a) identify subfertile males (can be achieved); (b) estimate current fertility of a male of previously known fertility (may be possible) and (c) identify males who will have superior fertility (impossible). Steps in the fertilization process are analyzed in terms of identifying potential assay methods with maximum predictive power. Sources of assay error are considered, with their effects on assay conclusions listed. If assays are considered in terms of end application, established techniques for developing decision matrices can be used to optimize use of assay output information, Will the information be used as a basis for the culling of otherwise valuable animals or to identify all animals likely to benefit from therapeutic treatments to enhance probability of fertilization? Examples of the latter case are provided.