Feed Efficiency, A Basic Metric for a Complex System

Introduction

Feed efficiency has become a growing topic in the dairy industry, driven by sustainability goals and desires to optimize farm profit. But what is feed efficiency, how can it be influenced, and should you use the measure on your farm? This article provides a basic overview of feed efficiency as a metric.

What is Feed Efficiency?

At its core, feed efficiency asks, “how well is my cow utilizing the feed I provide her?”  There are many ways to define feed efficiency depending on context, whether in research, genetic evaluation, or farm management.  The most common measure on dairy farms is pounds of energy corrected milk (ECM) divided by pounds of dry matter intake (DMI).  Throughout this article series, Feed Efficiency will refer to this metric (ECM/DMI), which gives a snapshot of how effectively a cow turns feed into milk. 

Feed efficiency values typically range from 1.3 to 1.8 depending on stage of lactation, milk production level, cow health, and other factors (1).  Low feed efficiency may indicate that a cow is not converting feed into milk efficiently, possibly due to poor digestion, health issues, or other competing biological demands.  On the flip side, extremely high feed efficiency could signal that a cow is mobilizing too much energy from body reserves (fat) to support milk production, which is not sustainable long-term. 

Limitations of Feed Efficiency (ECM/DMI)

While improving feed efficiency could help reduce costs or improve resource use, it’s important to recognize that ECM/DMI has limitations. 

Feed efficiency reflects just a snapshot of performance and is influenced by many variables: stage of lactation, animal health, feed quality, ration formulation, bunk management, environmental conditions, stress, and more (2, 3).  Feed efficiency calculated as ECM/DMI can be misleading, especially if cows are gaining or losing body condition. In those cases, the metric may over- or under-estimate true efficiency. Additionally, feed efficiency doesn’t account for feed intake or growth during the dry period or heifer-rearing stages since it focuses only on lactating cows.  Therefore, ECM/DMI alone cannot tell the whole story. 

Feed efficiency does not directly reflect economic efficiency (4).  A higher ECM/DMI ratio doesn’t always mean better profit, especially if increased feed costs or shifts in component production offset gains.  Similarly, cows, groups, or herds with the same feed efficiency may still differ in economic return.  For example, in Table 1, both cows have identical feed efficiency, but Cow B generates more milk and more income over feed cost (IOFC) than Cow A. This is because, in this case, each additional pound of milk adds more revenue than the cost of the extra dry matter, assuming feed costs per pound of DM remain constant. 

Table 1

Feed Efficiency: Neat to Know or Need to Know?

Feed efficiency can be an interesting (“neat to know”) number on your farm, but its value expands when it becomes part of your decision-making (“need to know”). 

In the “neat to know” stage, you might collect and review the data out of curiosity.  When feed efficiency becomes “need to know”, it’s because you’re actively using it to guide management decisions such as adjusting rations, targeting forage use, or tweaking cow management strategies.  When paired with other farm metrics, feed efficiency can be a valuable, although imperfect, tool for tracking progress towards goals.  Accurate feed efficiency data depends on reliable measures of DMI, milk yield, and milk components.  Errors in estimating intakes or milk production can distort this calculation.

Building from the Basics

Feed efficiency is a basic metric that provides a basic overview of how well your cows convert feed into milk.  While it’s not a perfect measure of efficiency and doesn’t capture the full complexity of dairy farm efficiency, it offers a starting point for evaluation.   

Author

 

Katelyn Goldsmith

Dairy Outreach Specialist– In her role as a statewide Dairy Outreach Specialist, Katelyn connects research with practical farm management practices to create educational programming addressing the needs of Wisconsin dairy producers.

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