Feed prices for the last five years have been at historic highs. Coupled with periods of low milk prices, this has resulted in extremely tight (sometimes negative) margins for dairy producers. The ability of ruminants to convert lower-digestibility feedstuffs (forages and other high-fiber feeds) into edible products has always been a positive attribute and one that has historically allowed the use of lower-cost feedstuffs, often byproducts which would be wasted otherwise.
However, higher feed prices have affected even these lower-cost feeds. Thus, the need to evaluate and try to manipulate the conversion of feed to milk has been a focus, even in the dairy industry, where it has not been a traditional area of concentration.
Other production livestock species (poultry, swine, beef) have focused heavily on feed efficiency (FE) or feed conversion ratio (FC), the efficiency at which feed is converted to edible products (i.e. eggs, chicken, pork, beef), as it is one of the main factors affecting profitability.
The dairy industry has been slower to focus on feed efficiency and has primarily been driven to do so with higher feed prices. But now feed efficiency – or maybe a better term, feed conversion (feed converted to milk components) – has become a focus in the dairy industry.
Feed efficiency in the dairy industry has traditionally been measured as some measure of milk production (actual milk, fat-corrected milk (FCM) or energy-corrected milk (ECM) as a ratio to dry matter intake. FE is represented by:
Milk or FCM or ECM / dry matter intake
A new measure some people are evaluating is a feed conversion ratio (FCR), which is a measure of the pounds of feed (DM) that it takes to produce 1 pound of milk components. FCR is represented by:
dry matter intake / lbs. of milk fat + lbs. of milk protein
Although dry matter intake is a factor in both of these measures, increases in milk and/or components, almost always increases FE or FCR.
Traditionally, feed-related factors have been the focus when evaluating feed efficiency. Forage digestibility, feed particle size, protein levels, fat levels, starch levels and certain feed additives can affect feed efficiency.
Feed-related factors have been the focus because that’s what nutritionists know best and feel they can control the most. Certain cow and environmental factors (i.e., days in milk, lactation number, heat stress, exercise and acidosis) can affect feed efficiency. However, these can be more difficult to control and manage.
Variability in management practices can greatly affect production, components and dry matter intake and, thus, feed efficiency. A survey conducted in Spain on 47 herds (more than 3,000 cows) fed the same ration, from a central feed processing center, illustrates this.
Across these herds, production ranged from 47 to 74 lbs of milk, even though they were fed the same diet. Management factors such as stall design, stalls per cow, feeding for refusals, feed pushups and age at first calving had some of the biggest effects on production level.
An area that has gained attention but has not been a focus when it comes to feed efficiency is cow comfort. Cow comfort issues can affect milk production and components, reproduction and general health, but these effects in relation to feed efficiency have not traditionally been an area of focus. Many times, these factors can have greater impact on feed efficiency than feed-related factors. Some of these different areas include:
Stocking density or the number of cows per pen or stall, explained 32 percent of the production variability in the Spanish study. In that study, each 10 percent reduction in stocking density (cows per stall) equaled 1.7 lbs more milk per cow.
Stocking density can also have an effect on milk components and SCC. Overstocked cows tend to eat faster and ruminate less. Overstocked cows may also experience a greater pathogen load in the environment, have greater teat end exposu-re to pathogens and may experience immune suppression.
Overstocking can reduce milk, components, feed efficiency and affect immunity.
Lying time is a high priority for cows. Studies have shown that cows have a strong motivation to lie down for around 12 hours per day. There is a strong correlation between lying time and lameness, and cows will sacrifice eating time for lying time.
In a series of studies conducted at the Miner Institute in New York, they showed an increase of 2 to 3.5 lbs of additional milk for each additional hour of lying time. This increase in production can have a large effect on feed efficiency and feed conversion. Rest (lying time) is truly Vitamin R. Allowing cows adequate time to rest can have a large economic impact.
Time and distance away for milking
Cows have important time budgets. They must have enough time for adequate rest, eating time, drinking time and milking. Time away from the pen for milking can have an effect on production and health and is associated with lameness.
In an extreme example of this, a study from the University of Nebraska compared the effect of three versus six hours per day away from the pen for milking. Second-plus lactation cows gained two additional hours of resting time and 5 lbs of milk and first-lactation heifers gained an additional four hours of rest and 8 lbs of milk when time from the pen away was reduced.
Minimizing time outside the pen is important to optimal time budgeting. Meeting time budget requirements for resting may result in greater milk yield and improved FE or FCR.
Lameness can dramatically affect production, health and reproduction. However, even cows that are mildly lame (cows that walk with shortened strides, an arched back and a slight limp) can have reduced production and feed efficiency.
Researchers have shown even cows with a lameness score of 3 (mildly lame, 1 to 5 scale with 5 being severely lame), can have 3 to 5 lbs less production (greater than 900 lbs per lactation) vs. sound cows (score 1). Key point – Even mild lameness can negatively impact production and feed efficiency.
Cow comfort issues can affect milk production and components, reproduction and general health. While most of the research has shown increases in production with improved cow comfort, generally production or component increases translate into improvements in feed efficiency. Many times, these factors can have greater impact on feed efficiency than feed-related factors. PD
—From oral presentation at the 4-State Dairy Nutrition Conference in Dubuque, Iowa, June 13, 2012
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- Technical Manager for Dairy Business Unit
- Novus International
- Email Jim Sullivan