A long-time ambient temperature diluent for boar semen

ABSTRACT Semen was collected from boars of proven fertility and diluted with Zorpva base using the antibiotic treatments: benzylpenicillin and streptomycin; polymixin B; tylosin; neomycin; gentamycin; kanamycin or lincomycin and spectinomycin. The last combination provided an economical treatment with enhanced quality and preservation of motility. The addition of trehalose (1 g/1) and potassium chloride (0·25 g/1) improved the preservation of acrosomes. The resulting ‘Reading’ variant was compared with Zorpva at days 4 to 6 of storage in a split ejaculate trial using 40 sows slaughtered 9/10 weeks after insemination. Conception rates were significantly higher using Reading (16/20) compared with Zorpva (8/20; P < 0·05) and the effect was particularly marked at days 5 and 6. The mean number of embryos per pregnant sow was 11·6 (Reading) v. 9·4 (Zorpva), representing 51% and 42%, respectively, of ova shed, as measured by counting corpora lutea.