Better microbes, better calves

Work by scientists at AgResearch is providing a better understanding of the complexities of the digestive tract of ruminants and could help lead to more productive, efficient and healthy animals.

Ruminants have evolved an efficient digestive system which relies on a complex microbial community to break down and ferment plant fibre and provide products and nutrients for growth.

However, Dr Sinead Leahy from the Rumen Microbiology Team at Grasslands, in Palmerston North, says little is still known about how the complex relationship between the microbes and the gastro-intestinal tract (GIT) in young ruminants develop.

The result of the latest step in this work has just been published in the journal Scientific Reports.

The paper looked at a subset of microbes – Bifidobacterium, a microbe which dominates the GIT when a neonate is fed a milk diet.

These microbes are considered highly beneficial and the paper looked in detail at how these microbes may be adapting and interacting with the calf GIT.

“Current rearing strategies for dairy and dairy-beef calves typically disrupt ‘mother nature’s’ co-ordinated functional co-development of the microbial community and the calf because it is removed from its mother at a very early age”, Dr Leahy says.

“Of course, it’s not possible to keep the calves with the mum under a dairying system, but it’s certainly different to what is recommended for humans, from a nutritional point of view.”

Researchers were interested in seeing what the impact to microbes would be, under those calf rearing systems, and one of the first things they wanted to look at was Bifidobacterium.

“In humans, these microbes have a versatile and important role in infant gut development. They do a lot of useful things, including preventing the establishment of pathogens and production of a range of beneficial metabolic substrates,” Dr Leahy says.

“Just like their human counterparts, young ruminants are often susceptible to a number of microbial pathogens which can cause diarrheal disease (often referred to as scouring in animals) during their first months of life which can severely affect growth. The idea that Bifidobacterium could be used to provide beneficial effects for young livestock during a time when the risks of morbidity and mortality are high is attractive.”

The research showed that Bifidobacterium can be easily isolated from young calves and three species of Bifidobacterium had their genomes sequenced to get a clearer idea of what they are and what they do in the GIT.

Alongside collaborators at the U.S. Department of Energy Joint Genome Institute in the United States, the genomes were sequenced through the Hungate1000 project, a New Zealand-led initiative to generate a reference set of rumen microbial genome sequences. Using the genomes the researchers were able to predict the genetic strategies these microbes use for carbohydrate metabolism and host colonisation and persistence.

For the first time, this provides insight into how these important group of microbes have adapted to the calf GIT.

Dr Leahy says this raises more questions.

“In instances where young animals can’t be fed their mothers’ milk is there a way we can replenish their digestive tract with these beneficial microbes? For example could they be used with calf replacement formulas?”

The long-term purpose of the research is to identify beneficial microbes that are important to have as a neonate for protection against disease and which are important for normal metabolic and immune development, normal maturation of which, are likely to be key to the long-term productivity of the animal.