Reproduction Abstracts

Seedstock bulls in Australia are commonly fed high-energy supplements prior to sale. These supplements contain readily fermentable carbohydrates, which may precipitate ruminal acidosis. We hypothesise that a single transient acidotic SARA event would decrease semen production sufficient to preclude bulls from BBSE thresholds and thereby sale.Santa Gertrudis bulls (n=10, age 20±6 months) were fed in yards on ad lib hay with daily in...

Introduction: This study investigates the effect of dietary crude protein on conception in range beef heifers and uses circulating progesterone as a measure of early embryonic loss known to be a major cause of reproductive inefficiency.Methods: Primaparous 14 month old Bos indicus cross heifers (n=350) were selected from a range population. 60 days prior to artificial insemination they were randomly assigned to two equal groups and indi...

Sex specific expression occurs in 20–30% of all hepatic genes in the adult animal (1). We have shown that there is an interaction between gender and the level of maternal dietary protein intake on bovine fetal development as early as 36–39 days post conception (dpc) We hypothesise that exposure to different levels of maternal protein intake in the periconceptional period (60d preconception to 23dpc) and in the postconceptional period (23–98dpc) will result in a ...

Introduction: Neonatal and fetal mortality is increased in male fetuses. Evidence is emerging of sex specific differences in fetal and placental perfusion1. This study investigates effects of dietary intervention at specific time points upon blood flow and fetal growth trajectory in cattle.Materials and methods: Primiparous heifers were either individually- (Australia, Au; n=360) or group-fed (UK; n=188) diets containing diff...

Introduction: This study investigates the effect of dietary crude protein on the cellular composition of the 98 days bovine placenta.Materials and methods: Primiparous 14-month-old Bos. indicus cross heifers in Australia (n=350) were individually fed isocalorific high (H; 14%) or low (L; 7%) CP from day −60 prior to conception to 23 days post conception (dpc). At 23 days post-conception the two groups were further split into high ...