Author Description

Efficiency of livestock production is critically important due to the growing demand for high quality animal products paralleled by shrinking available resources. Rumen fermentation accounts for 70% of dietary energy for the host ruminant, and the microbes responsible for that fermentation, collectively referred to as the rumen microbiome, likely play an important role in feed conversion efficiency. Non-ruminant research suggests maternal factors have a large impact on microbial colonization of the gut with implications for long-term health. In beef cattle, factors that influence the initial microbial colonization of the rumen are relatively unexplored but have potential to impact host performance later in life. We hypothesized that the rumen microbiome is affected by maternal influences and may have implications for calf performance later in life. Our goal was to determine the effects of gestational nutrition, maternal breed, mode of delivery, and rearing type on the calf rumen microbiome. Three separate studies were conducted; the first two studies utilized 24 mature, late-gestating Angus cows. Two objectives were investigated using the same negative control group for each objective; 1) determine if nutrient restriction during late gestation alters the calf rumen microbiome, and 2) determine if ruminal microbiome composition differs in calves born vaginally versus caesarean. For objective 1, control (CON; n= 8) cows were fed to meet NRC requirements while nutrient restriction (NR; n = 8) were restricted to reduce BCS by 1.5-2 pts over the last trimester compared to CON. Cows calved naturally and rumen fluid was collected on calves at d 7. For the second objective, the same CON cows were used and the caesarean section (CS; n = 6) cows were fed the same as CON but calves were delivered via caesarean section instead of vaginally. Rumen fluid was collected at d 7 from the calves. Metagenomic shotgun sequencing on DNA extracted from rumen fluid was completed and analyz