For dairy farms of all sizes – and all animal agriculture for that matter – the cost of feeding your animals is the single largest operating expense of the business. Even if dairy farms graze their herd part of the year, there’s still a financial cost associated with owning or renting the land and with upkeep of the pastures. For the average dairy farmer, getting the maximum nutritional value out of the purchased feedstuffs or the crops grown on the farm is a never-ending challenge. A top management priority on dairy farms should be to get the most milk out of any given pound of feed – whether grains or commodity byproducts or forages, both home-grown or purchased.

Complicating the matter is the fact that feed availability and the cost of feed is constantly changing, making the proper balancing of diets an even bigger challenge. Adding to that challenge is the never-ending volatility of the milk price. With narrowing profit margins, feed intakes of milk cows should be optimized for efficiency as well as maximized for production. One of the most important analytical tools available to dairy farmers is the measurement of feed efficiency (FE) – a calculated ratio that helps determine how much milk is being produced by every pound of feed consumed.

Determining feed efficiency

Feed efficiency is calculated by simply dividing the amount of feed dry matter consumed by a cow by the amount of milk produced on a fat-corrected basis. The FE, which is a ratio, is a benchmark that allows us to track how efficiently cows convert feed to milk. Well-managed dairy herds should average a FE of 1.4 to 1.6. This means that for every 1 pound of feed dry matter consumed, 1.4-1.6 pounds of fat-corrected milk is being produced.

If a dairy producer has set a FE goal of 1.5, for instance, this means if the cows are consuming an average of 40 pounds of feed dry matter per day, the herd’s milk average should be 60 pounds per cow per day. If a cow is consuming 50 pounds of feed dry matter per day, her milk production should be 75 pounds. The higher the FE is on a dairy at any given time, the more efficiently feed is being converted to milk. If a cow is eating 60 pounds of feed dry matter and she’s producing 110 pounds of milk, her FE is 1.8 – which is very good.

Comparison of FEs by breed

To compare FE across different breeds, we must standardize the milk production to 3.5 percent fat-corrected milk. A Jersey cow that consumes 35 pounds of dry matter and is only producing 45 pounds of milk has a FE of only 1.28. However, her high milk fat level of 5 percent will convert the milk production to over 60 pounds of 3.5 percent fat corrected milk. Now her FE calculates to 1.7, which is very desirable and indicates a high value of feed conversion to milk revenue.

Certain aspects of herd health can be managed very effectively by monitoring the FE in the herd. A high FE in early lactation could mean too much bodyweight is being put into milk production. Ketosis may be around the corner if the dietary energy level is not increased. Watch the body condition of fresh cows that have a very high FE. Days-in-milk will have an influence on FE. Cows in late lactation tend to have lower feed efficiency as they gain body condition in preparation for the next lactation. Cows in late lactation are generally less profitable as they do a poorer job of converting feed to milk (see chart below).

Source: University of Illinois

Cows in first lactation also tend to have lower FE since they are still in the process of growing. Once cows reach maturity in later lactations, they no longer have an energy requirement for growth and that energy can be used for milk production.

Milk production is dependent upon feed dry matter intakes and how well the feed is fermented in the rumen. The efficiency of the feed conversion is determined by the digestibility of the fiber and cellulose components of the feed and how quickly the rumen microbes can ferment feedstuffs into the volatile fatty acids (VFA) needed for energy metabolism. A second component of high FE is how much metabolizable protein gets absorbed in the small intestine.

How to attain high FE ratio

Balancing feed diets for both optimal and maximal rumen fermentation is the key to attaining a high FE ratio. Milk cow rations must be properly balanced for carbohydrates and protein so that rumen fermentation will be maximized. Forages tend to be the most variable feedstuff in dairy cow diets. Since forages are critical for proper rumen function, they are often the single largest component of a diet. Feed efficiency is directly related to forage digestibility and any changes in forage quality and digestibility can have profound influence on a cow’s feed efficiency.

Low FE in a herd can often be traced back to poor forages – in fiber digestibility, protein content and silage fermentation profiles. Poorly fermented silages can quickly upset the microbial population and activity in the rumen. Feed efficiencies of less than 1.3 are an indication that there is room for improvement in the feeding program. Herds with FE at 1.0 have major herd management and nutritional issues. Rebalancing of diets for proper levels of rumen degradable protein and adequate starch in grain mixes and feeding forages with higher fiber digestibility will improve the rumen environment. Herds with long days-in-milk consistently over 200 will have chronically low FE.

Evaluating FE in a herd should be done in conjunction with the monitoring of income-over-feed-cost (IOFC) for the feeding program. Evaluating both IOFC and FE together will enable dairy farmers to optimize the feeding program while, at the same time, maximizing milk revenue. Getting the most milk out of a pound of feed will almost always ensure higher levels of profitability for the dairy.

Cover photo: ewastudio/istock