Feed Efficiency (FE) is the primary driver of profitability for meat producing animals. The multiple requirements for nutrients involved in producing milk complicates the process, but does not reduce its usefulness. Within a herd, changes in FE can be used to help determine the economic impact of feeding and management changes.
Feed is the single largest expense in milk production. Many other livestock industries use feed efficiency as a benchmark for performance; however, dairy producers have only recently started to evaluate feed efficiency. Differences in production systems prevent a straightforward comparison of feed efficiencies.
Measuring Feed Efficiency:
Feed efficiency (FE) can be calculated most simply as pounds of milk produced per pound of dry matter consumed. The problem with this simple approach is that the fat content of the milk is not considered. Since fat contains more energy than other components of milk, ignoring milk fat can skew FE calculations.
The best way to account for fat content is to calculate FE as pounds of 3.5 percent fat corrected milk produced per pound of dry matter consumed.
Factors Affecting Feed Efficiency:
Feed efficiency can vary from 1.0 to nearly 2.0 across stages of lactation or farms. This means that a number of factors other than dry matter intake and fat corrected milk production must be considered when using FE as a benchmark.
Major Factors:
Milk production – Higher production nearly always means higher FE. This is because maintenance requirements are diluted more with the higher intake associated with higher milk production.
Body weight – Body weight affects maintenance requirements. At equal milk production, cows with lower body weights will have higher FEs.
Body weight/condition change – When nutrients are directed towards weight gain, rather than milk production, FE is reduced. This is often a desirable situation, for example in cows replenishing body stores lost during early lactation. Conversely, cows may have very high FEs when they are losing weight. In this situation, a high FE might be a cause for concern, not celebration. In general, differences in FE may occur due to the body weight/condition changes that occur over the course of lactation.
Minor Factors:
Genetics – Genetics ultimately determine how nutrients are allocated for maintenace, milk production and other body functions. Genetic lines that are highly productive will have higher FEs than less productive lines.
Changes in maintenance requirement – Any change in the maintenance requirement will affect feed efficiency. Three common factors are; cold or heat stress, walking or exercise and extended standing. Increases in walking distances or standing times will lower FE. Extremes of heat or cold will also decrease FE.
Feed digestibility – Higher feed digestibility usually increases milk production, thereby increasing FE. Common methods to increase feed digestibility include proper feed processing and improving forage quality and/or NDF digestibility.
Growth and/or reproduction – Young cows will generally have lower FE because substantial amounts of ingested nutrients will be used for growth. Pregnant cows will have reduced FEs in late gestation because of fetal growth; this would most likely be a factor in herds using shortened dry periods.
Nutrient imbalance – Overfeeding or underfeeding nutrients may adversely affect FE. Research has shown that overfeeding protein decreases both FE and efficiency of nitrogen use.
Feed Efficiency Guidelines:
1. Check intake and milk production numbers for accuracy before worrying about feed efficiency. Feed refusals must be accurately measured for meaningful calculations.
2. Target for an entire herd or mid-lactation cows (180-220 DIM, [days in milk] average for the herd or group) – 1.4 to 1.6 lbs FCM/lb DM intake is normal. (FCM is fat content, DM is dry matter.)
3. Early lactation (less than 30 DIM) a. 1.5-1.8 lbs FCM/lb DM intake is good.
b. FE greater than 1.8 may indicate excessive weight loss and ketosis problems.
c. FE below 1.4 indicates milk production problems or erroneous feed intakes.
4. Late lactation (greater than 300 DIM)
a. FE follows the lactation curve downwards after milk production peaks
b. 1.1-1.4 FE is normal. It may be difficult to achieve an FE of 1.0 if cows are gaining weight and are well beyond 300 DIM.
Take Home Messages
Feed Efficiency is the primary driver of profitability for MEAT producing animals. Using FE to evaluate dairy operations where there are multiple requirements for nutrients (milk production, body weight changes, reproduction and growth) complicates the process, but does not reduce its usefulness.
Because of the many factors affecting FE, no single FE value can be set as a standard or goal that would be appropriate for all cows, all stages of lactation or all herds.
Within a herd, changes in FE can be used to help determine the economic impact of feeding and management changes.
Improvements in FE can improve profit whether they result from increased milk production per pound of dry matter intake or getting the same milk from a lower intake.
Dr. James G. Linn is the Department Head of Animal Science at the University of Minnesota.
