Abstract
1. A study was undertaken to compare the effect on fertility in the fowl of aqueous medium, natural homologous seminal plasma, heterologous turkey seminal plasma and whole turkey semen when whole fowl semen was excessively diluted with these media and inseminated fresh. 2. High dilution with fowl seminal plasma resulted in the best fertility. 3. Dilution with the turkey semen components produced fertility no different from that with aqueous diluent when the dose of spermatozoa was 5.5 or 10 × 106. 4. The results of this study confirm that 5.5 to 10 × 106 good quality spermatozoa are sufficient to produce acceptable fertility in weekly inseminations of fresh semen. This enables good quality semen to be highly diluted. However, at high dilution rates there is a need to reconsider the composition of semen diluents, with respect to simulating as yet unknown properties provided by factor(s) in homologous ductus deferens seminal plasma.