Demonstrating the effect of live weight on heifer pregnancy rates in northern Queensland

A group of beef producers north of Charters Towers identified low heifer pregnancy rates as a consistent and significant problem, aligning with the regional median from the Cash Cow project of 67%. Results from their Producer Demonstration Site (PDS) over three years monitoring >1,300 heifers clearly demonstrated a highly significant (p<0.001) relationship between proportion pregnant and weight. To achieve rates of more than 75% in high-percentage Brahman type heifers, live weights of at least 400 kg at pregnancy diagnosis (end of mating) was required. Ovarian scanning demonstrated a pre-mating live weight of approximately 340 kg was required for 80% of heifers to be at or near puberty. Neither pestivirus nor vibriosis were shown to be contributing factors in this study. Use of fewer, better bulls (