Potential complications must be considered when planning fat supplementation for early-lactation dairy cows.
December 9, 2024
Nutritionists have many factors to weigh when they are creating an optimal diet for dairy cows. This is especially true when cows are in early lactation and have a negative energy balance, according to a press release from the American Registry of Professional Animal Scientists (ARPAS).
One way to increase the energy density in a diet is to supplement with dietary fat, but many potential complications must be considered. A new perspectives and commentary article by Dr. Al Kertz in Applied Animal Science outlines these considerations and provides expert recommendations for field nutritionists.
The article first provides helpful definitions of the terms used in the discussion and then dives into the details of dietary fat nutrition and metabolism.
"Effects on feed intake, milkfat depression and body condition are discussed. Potential interactions with other factors such as dietary forage sources and their concentrations and length of chop are addressed, as they may affect responses to fat feeding," according to Dr. David K. Beede, editor in chief of Applied Animal Science.
In the article, Kertz, founder of ANDHIL LLC, an international dairy cattle consulting service based in St. Louis, Mo., reviews key factors involved in identifying and characterizing how dairy cows metabolize fat sources and the resultant effects on dry matter intake (DMI), milkfat depression and body condition, with an emphasis on early lactation. He then elaborates on these various considerations when planning a fat supplementation for early-lactation dairy cows.
Kertz points out that milkfat depression can be exacerbated by several factors, many of which are related to dietary fat. Some sources of fat, such as calcium salts of fatty acids, and how and when they are supplemented, are associated with decreased DMI, and Kertz notes that "maintaining DMI is the key factor in fat supplementation when fat is added to increase dietary energy density and, thereby, total energy intake. If DMI is decreased, however, that can reduce or eliminate that benefit.”
Kertz added, "Forms of fat, such as triglycerides or free fatty acids, whether unsaturated or saturated, affect DMI, milkfat depression and body condition."
Other considerations when choosing a fat supplement include the digestibility of the specific fatty acids in the supplement and the average degree of ruminal biohydrogenation for each fat source in the supplement.
Kertz also discusses how forage level and chop length can interact with other factors to affect body condition and milk production. The article includes results and discusses previous research about the primary fatty acids in dairy cow diets and supplements: palmitic, stearic, oleic and linoleic fatty acids.
The article provides a wealth of helpful information, according to ARPAS.
Kertz concludes the article by offering some recommendations for nutritionists who are formulating fat supplements for early-lactation dairy cows, emphasizing that nutritionists know what kinds of fat sources are being fed, including the fatty acid composition of feedstuffs fed and fat sources.
"The greater the unsaturated fatty acid sources are, especially the amount of linoleic acid, the more DMI and milk fat percentage may be negatively affected," he explained. "Whenever either palmitic or stearic acid is more than 80%, but especially more than 90%, of the fat supplement, it can be of concern because the fatty acids may be less digestible because they are more crystalline. However, if these two fatty acids are melted and then prilled, the crystalline formation is not likely to occur, and these fatty acids appear to incorporate the complementary benefits of both, in a recommended ratio of 1:1 to 2:1."
The article, "Perspectives & Commentary: Fat Nutrition & Metabolism of Early-lactation Dairy Cows,” appears in the December issue of Applied Animal Science, an open-access, peer-reviewed scientific journal that serves as a leading outlet for animal science research.
ARPAS provides certification of animal scientists through examination, continuing education and commitment to a code of ethics. Continual improvement of its individual members is catalyzed through publications – including the Applied Animal Science journal – and by providing information on educational opportunities. ARPAS is affiliated with five professional societies: American Dairy Science Association, American Meat Science Association, American Society of Animal Science, Equine Science Society and Poultry Science Association.
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