This study aimed to investigate the relationship between increases in luteinizing hormone (LH) profiles induced by gonadotropin-releasing hormone (GnRH) in the serum and vaginal mucus of Japanese Black beef cows. A peak serum LH concentration was identified at 2.5 h post-GnRH administration, with serum concentrations returning to near-pre-GnRH-administration values after 6.5 h, whereas the peak LH concentration of vaginal mucus was identified 4.5 h after GnRH administration.

We evaluated the effects of supplementing cattle feed with difructose anhydride III (DFA III) by measuring urinary sterigmatocystin (STC) concentrations. DFA III was supplemented for 2 weeks to 10 animals, and non-treated animals served as controls. Our findings demonstrate the effect of DFA III on reducing the urinary concentration of STC in Japanese Black cattle.

This study aimed to compare the quality of frozen–thawed spermatozoa from microminipig boars. We also evaluated the effects of caffeine and heparin as well as the sperm–oocyte co-incubation length on the fertilization and embryonic development. We found that the presence of caffeine in the in vitro fertilization (IVF) medium and the appropriate length of sperm–oocyte co-incubation may have beneficial effects for improving IVF results when using microminipig spermatozoa with low quality.

Our studies evaluated the effects of parity and season on pregnancy rates of repeat-breeder (RB) Japanese black beef cattle after embryo transfer. Our findings indicate that the parity of the recipients does not have an apparent effect on the pregnancy rates following the transfer of fresh and frozen embryos. However, season may affect reproductive performance in RB multiparous cows.