June 28, 2018

Interpretive Summary: Investigation of maternal breed and rearing type on calf rumen microbiome from day 28 through weaning

Interpretive Summary: Investigation of maternal breed and rearing type on calf rumen microbiome from day 28 through weaning

Presented at the 2018 WSASAS Annual Meeting

By: Lindsay Tretter

As there is an increase in population, feed cost, and urbanization, it is becoming increasingly difficult to meet consumer demands. This study explored how feed efficiency can be improved through alterations in the rumen microbiome. The rumen is effected by many aspects including nutrition, environment, and maternal factors. Early profiles are important for proper development of the rumen, as well as, during the transitional stage to a functional rumen. Evidence suggests association of sire breed effects, and host genetics influence microbial activity. It is important when thinking about the microbiome to also think of host physiology for genetic selection.

In the beef industry, it is uncommon to remove a calf from its dam, but this technique can be utilized to investigate how the rearing effect influences the microbiome. For example, raising without the presence of mature animals can adversely influence the developing rumen microbiome. It has been noted in the literature that there is a difference between formula fed versus breast fed infants.

This study isolated maternal factors that influence the young microbiome, looked at host genetics (maternal breed), and milk delivery system. Prior to parturition, cows were separated by breed, and then broken into either the control group, nursing, or an experimental treatment group, bottle fed. The cows were separated by breed until parturition then by treatment group after that. Calves that were bottle fed were removed after 24 hours and put on milk replacer until 180 days of age. Hay and water were available and creep feed was introduced at 1 ½ months of age.

Milk and rumen fluid samples were collected at day 28 to represent the transition of the rumen, and at weaning to show stabilization of the rumen microbiome. The rumen fluids DNA was extracted, sequenced and analyzed.

The day effect was found to be the strongest. At day 28 there was increased richness in rumen fluid compared to richness at weaning. The data from the weaning collection displayed tightly clustered data points representing the stability of the rumen microbiome.

The breed effect showed a significant difference between Angus and Charolais rumen microbiome. Charolais had increased richness when compared to the Angus which warrants further investigation regarding which taxa are influencing this difference.

The rearing type effect showed no diversity, and overall differences aren’t evident between bottle reared and control in this sample.

Rearing type by day effect only showed non significance between the post weaning sample in the bottle and control groups. The breed by day effect, showed that Angus post weaning had increased richness most likely due to day effect. As the animals approached weaning the microbiome was stabilized.

Rumen microbiome can be effected by rearing type, and difference in richness were evident with each breed.

The study concluded that in the beef industry, maternal influence along with the rumen transition phase are both critical to the end rumen microbiome which influences host performance.