Effect of a second treatment of prostaglandin F during the Ovsynch program on fixed-time artificial insemination conception rates and luteolysis in split-calving, pasture-fed dairy cows.

Objective: To compare fixed-time artificial insemination (FTAI) conception rates and serum progesterone concentrations at the time of FTAI for cows treated with the original Ovsynch program (OV) with those treated with a modified Ovsynch (MO) program.

Design: This was a randomised clinical trial.

Methods: The study used five split-calving, pasture-based dairy herds in Southwest Victoria, Australia.

Comparison of effects of GnRH and prostaglandin in combination, and prostaglandin on conception rates and time to conception in dairy cows.

Objective: To assess the effectiveness of a gonadotrophin-releasing hormone (GnRH) / prostaglandin program (GnRH-PG-GnRH, Ovsynch) on conception rates and time to conception of lactating dairy cows compared with a PG program (double prostaglandin injection).

Design: A randomised multi-centre cohort study was conducted with 778 cows from nine dairy herds. Cows at different stages of lactation were randomly assigned, after matching for days open at the time of treatment, to either the PG or Ovsynch program.

Mastitis, polyarthritis and abortion caused by Mycoplasma species bovine group 7 in dairy cattle.

Objective: To report an outbreak of mastitis, polyarthritis and abortion caused by Mycoplasma sp bovine group 7 in three large, centrally-managed dairies and to review the relevant literature.

Design: Epidemiological, clinical and laboratory data were analysed, collated and reported. Multidisciplinary procedures were employed.