Individual Fatty Acids Will Lead to More Precision Feeding
When it comes to fat supplementation, new research has created a whole new ballgame. All fats supply energy to the diet. But individual fatty acids also affect digestibility, metabolism, energy partitioning and production responses in dairy cows. Timing of supplementation, stage of lactation and even the amount of forage in the diet all affect how cows respond.
This is an exciting time in dairy nutrition, says Adam Lock, associate professor of dairy cattle nutrition at Michigan State University. Research shows that not all fats are the same. Just as amino acids have replaced crude protein in diet formulation, individual fatty acids will replace dietary fat and supplemental fat in diet formulation.
About 10 years ago palmitic supplements became widely available in the United States. Nutritionists were asking if it was the same as other fats they were feeding. At the time, prevailing thought was that one saturated fatty acid would be similar to another saturated fatty acid. That they all behaved the same.
“Then we started looking into the research and found that might not be the case. We also looked at research with omega-3 and omega-6 in humans and soon realized that not all fatty acids were the same,” explains Lock. “That led us down a new path of scientific discovery.” Today, research clearly shows that not all fats are the same. Each fatty acid is unique and plays a specific role.
Understanding fatty acids
All of the fats traditionally fed are byproducts of other industries. None were developed with the specific needs of the dairy cow in mind. But because fats have a higher energy density than carbohydrates and proteins, it makes sense to feed them to provide extra energy.
Fresh cows in a negative energy balance and high-producing cows need a lot of energy. Adding energy-dense fats to the diet boosts the overall energy in the diet without requiring the cow to eat more. But too much fat in the diet can have negative consequences, too.
That’s where the new research comes in to play. “We are trying to utilize existing products in different ways. We are not just looking at fat as an energy source, but as part of precision feeding to meet cows’ needs,” says Lock. In their research his team blends three or four commercial fats to create specific fatty acid profiles to best match the cows’ needs. Palmitic acid (C16:0) and oleic acid (cis-9 C18:1) show the most promise so far. They have also studied stearic acid (C18:0) and plan to examine omega-3 and omega-6 fatty acids in the future.
Scientific discovery is generally a series of small, incremental steps. Researchers have examined the effects of fatty acids individually, and in different combinations and ratios on digestibility, energy partitioning, milk yield, component yield and changes in body condition. What they have discovered is that stage of lactation, amount of forage in the diet and even different fatty acid profiles all lead to unique responses in the cow.
In de Souza et al., 2016, individual cow data from 10 studies that fed palmitic acid supplements to post-peak dairy cows was analyzed. Milk fat yield and energy corrected milk (ECM) increased linearly with increasing palmitic supplementation. NDF digestibility also improved with supplementation but dry matter intake (DMI) did not change. Another study by Piantoni et al., 2015b, found that a combination of palmitic and stearic acids increased NDF digestibility in low forage diets but not in high forage diets.
In de Souza et al., 2018, when palmitic acid was fed in combination with oleic acid, it increased the energy allocated to body reserves. And when fed in combination with stearic acid (C18:0), it decreased nutrient digestibility.
Research with post-peak cows producing <95 lbs/day of milk supplemented with palmitic acid partitioned more energy toward milk production. But higher producing cows did not. Instead, cows producing 120 lbs/day or more of milk partitioned more energy toward milk production when supplemented with palmitic and oleic acids (de Souza and Lock, 2017a). This may suggest that palmitic and oleic acids are able to alter energy partitioning between the mammary gland and adipose tissue.
In a follow up study the timing of palmitic acid supplementation on performance of early lactation cows (1 to 24 days in milk) was examined. Compared to non-supplemented cows there was no difference in DMI or milk yield. However, cows supplemented with palmitic acid produced more ECM, about 10 lbs/day consistently over time. Supplemented cows also lost more body weight, ~50 lbs. In comparison, cows fed palmitic acid from 25 to 67 days in milk had increased milk yield, 7 lbs/day; increased ECM, 10.1 lbs/day; and lost about 22 lbs more body weight than non-supplemented cows (de Souza and Lock, 2017b).
And at this summer’s American Dairy Science Association meeting, several abstracts by Michigan State researchers demonstrated that altering the dietary ratio of palmitic to oleic acids; and stearic acid to oleic acid changes how cows respond. Production responses, DMI, milk yield and ECM of high-producing cows improved with more oleic acid in the diet while lower-producing cows responded better to more palmitic acid in the diet. In the second study with differing ratios of stearic to oleic acids, compared to non-supplemented cows, all cows that received the fatty acid supplements had increased milk yield, ECM, fat yield and preformed fatty acids in the milk, but nutrient digestion was improved with the higher level of oleic acid supplements.
Fatty acids affect reproduction, too. Research at the University of Florida with omega-3 fatty acids showed that feeding very long-chain fatty acids improved first-service or overall pregnancy rates in six studies.
The data speaks for itself, says Lock. Research has demonstrated that individual fatty acids have a direct effect on several metabolic processes. Feedback from dairy nutritionists and producers that have started focusing on fatty acid profiles in their nutrition programs is positive. But there is still more to learn.
Fatty acids are present in all feeds. Forages contain about 2 to 3% fatty acids, and diets are often 50% forage. That means to feed a precise fatty acid profile, you must pay attention to all sources of fatty acids in the diet.
New research will continue to delineate fatty acids’ effects on lactating dairy cows so that the ideal combinations of fatty acids to feed cows under specific physiological conditions and for specific purposes can be identified.
Not all fats are the same. And if someone wants to sell you a fat supplement, your first question should be, “What is the product’s fatty acid profile?”