Discover how the integration of Holstein cow genomics and rumen microbiome can unlock feed efficiency in dairy production. Can this be the future of cost-effective farming?
Picture this: you’re a dairy farmer, constantly striving for a boost in your cows’ feed efficiency. However, the rising cost of feed presents a significant hurdle that impedes your path to achieving this goal. But what if we told you that the solution could lie in something as common as the rumen microbiome found in cows?
Welcome to an exploration of an exciting field of research – the joint effect of host genome and rumen microbiome, also known as the holobiont effect, on feed efficiency in Holstein cows. Here, we will delve into the core concepts, the findings of our recent study, and the potential implications for practicing dairy farmers like you.
Immense strides have been made in genetics, and genomic selection in livestock is proving to be a successful method for enhancing traits that are difficult to measure. Not to mention that this significantly reduces the waste generated during production.
However, as nature would have it, there’s more to this story than genetics alone. Enter the rumen microbiome, an invaluable partner in crime. This set of microorganisms residing in the bovine gut lends a helping hand by breaking down the feed, a pivotal interaction that affects the cow’s overall efficiency in digestion and nutrient absorption.
So, the question that arises is, what if we could tweak this alliance between the cow’s genome and its rumen microbiome to optimize feed efficiency? And that, dear reader, is exactly the question that our study set out to answer.
Armed with a dataset comprising both genetic and microbiome information, we put various models to the test. From purely genomic-based models to others considering the rumen microbiome, and finally, the intriguing holobiont model that takes into account the interactions between the two.
Are you ready to delve into this scientific rendezvous between genetics and microbiology and possibly discover ways to optimize your dairy production? Let’s dive in!
Understanding Heritability and Microbiability
The contributions of the genome and the microbiome are quantified by heritability (h2) and microbiability (m2), respectively. When both genome and microbiome are included in the model, the h2 reflects only the contribution of the direct genetic effects, known as direct heritability (ℎ2𝑑). So, when we’re talking about heritability, it’s important to remember it’s no longer straightforward; it’s actually mediated by the genome-microbiome interaction.
The Holobiont Effect: A Joint Action
But what happens when the genome and microbiome work together? This is illustrated by the holobiont effect, quantified as the holobiability (ho2). Just like symphonies sound better when all the instruments play together, the combined influence of the genome and the microbiome produces a more robust and efficient cow.
Objectives of The Study
In this study, we aimed to estimate h2, ℎ2𝑑, m2, and ho2 for dry matter intake, milk energy, and residual feed intake. In addition, our goal was to evaluate the predictive ability of different models, including the genome, microbiome, and their interaction. The data consisted of feed efficiency records, SNP genotype data, and 16S rRNA rumen microbial abundances from 448 mid-lactation Holstein cows from 2 research farms.
Comparing Different Models
Three kernel models were fit to each trait: model G (the genome effect only), model GM (the genome and microbiome effects), and model GMO (the genome, microbiome, and interaction effects). The analysis showed that the GMO model, also known as the holobiont model, had the best goodness-of-fit.
When interpreting the results, it became apparent that the ℎ2𝑑 estimates were always 10% to 15% lower than h2 estimates for all traits, suggesting a genetic effect mediated through the rumen microbiome. Interestingly, m2 estimates were moderate for all traits, going up to 26% for milk energy. This indicates that the rumen microbiome contributes significantly to cow productivity.
Genome-Microbiome Interaction Influences Feed Efficiency
It’s quite surprising, but the ho2 was greater than the sum of ℎ2𝑑 and m2, suggesting that the interaction between the genome and the microbiome had a substantial effect on feed efficiency. So, when we look at feed efficiency, it’s not just one or the other — both genome and microbiome play crucial roles.
The kernel models fitting the rumen microbiome, i.e., models GM and GMO, showed larger predictive correlations and smaller prediction bias than the model G. This implies that models using both the genome and microbiome offer a more accurate prediction of feed efficiency and reaffirms the importance of considering both factors.
The Bottom Line
In conclusion, the findings reveal a moderate contribution of the rumen microbiome to feed efficiency traits in lactating Holstein cows and strongly suggest that the rumen microbiome mediates part of the host genetic effect. It’s clear that the interaction between the microbiome and the genome is a key determinant for dairy cow performance. Understanding this interaction better could potentially lead to more efficient dairy production, helping reduce costs and increase yields in the long run.
Read more : https://doi.org/10.3168/jds.2023-23869
