Dairy producers have been feeding supplemental fat for years. So why get excited about new research with individual fatty acids? Because this new research has repeatedly demonstrated the ability of individual fatty acids to affect digestibility, metabolism, energy partitioning and milk production. In addition, the research shows that cow response varies by stage of lactation, the amount of milk produced and the amount of forage in the diet.
Individual fatty acids are a new tool that can be used to tailor dairy cows’ diets to improve health and productivity. During the past decade researchers have been feeding different blends of individual fatty acids in order to identify the right mix of fatty acids needed to optimize cow health and productivity during different stages of lactation.
Early Lactation Benefits
Two new studies in the March Journal of Dairy Science tracked fresh cows’ response to 3 different ratios of palmitic and oleic fatty acids. Researchers at Michigan State University (MSU) used 2 commercially available products to create 3 specific fatty acid blends: 80% palmitic with 10% oleic, 70% palmitic with 20% oleic and 60% palmitic with 30% oleic, which were fed at 1.5% of diet dry matter. A control diet without supplemental fatty acids was fed also. As cows freshened, they were randomly assigned to 1 of 4 diet treatments for the first 24 days in milk.
During the treatment period (1-24 DIM), all 3 fatty acid blends increased milk yield, 3.5% fat corrected milk, energy corrected milk, milk fat content and milk fat yield compared to non-supplemented control cows (de Souza et al., 2021a). Milk yield per day was 102.7 lbs, 107.1 lbs, 107.6 lbs and 109.6 lbs for control cows, 80:10 cows, 70:20 cows and 60:30 cows, respectively. That’s an increase of 4.4 to 6.9 lbs of milk per day from feeding fatty acids in early lactation.
The experiment also demonstrated that as the amount of oleic acid fed increased, so did cows’ dry matter intake; 44.7 lbs, 45.6 lbs, 46 lbs and 48 lbs per day control cows, 80:10 cows, 70:20 cows and 60:30 cows, respectively. Increasing levels of oleic acid in the diet also decreased losses in body weight and in body condition score.
Next researchers looked at the carryover period. From 25 to 63 days in milk all cows were fed the same lactation diet. All cows supplemented with fatty acids during the first 24 DIM had greater component yields and produced more 3.5% fat corrected milk and more energy corrected milk in the carryover period than non-supplemented cows. The change in these production variables was statistically significant and consistent throughout the first 9 weeks of lactation and was directly related to the fatty acid blends fed, explains Adam Lock, professor of dairy cattle nutrition at Michigan State University. Milk yield during the carryover period also increased by 3.7 to 6.8 lbs/day.
In a companion paper (de Souza et al., 2021b), MSU researchers examined the impact of the same fatty acid blends on nutrient digestibility, metabolism and energy balance in early lactation. All of the fatty acid blends fed increased digestibility of dry matter, neutral detergent fiber (NDF), 18-carbon fatty acid and total fatty acid compared to the control diet. The fatty acid blends also increased intake of digestible energy, metabolizable energy and net energy of lactation compared to control cows.
However, two important differences were noted. As the amount of oleic acid in the diet increased intake of digestible energy, metabolizable energy and net energy of lactation also increased; but both plasma NEFA and BHB levels decreased. In contrast, as the amount of palmitic acid in the diet increased, energy intake and milk energy output of supplemented cows increased, but so did NEFA and BHB levels. Further research is needed to understand the mechanism by which palmitic acid increases milk energy output at the expense of body reserves in the immediate postpartum period, explains Lock. And to determine if greater body weight and body condition score losses that accompanied the increase in palmitic acid in the diet impact health and reproduction of dairy cows.
While these studies improve our understanding, several questions remain. At this point, it appears that oleic acid could be a dietary strategy to improve energy status and health without sacrificing production in early lactation. However, the goal remains to find the right balance of palmitic and oleic acids to maximize production and minimize body condition losses in early lactation.
Mid-Lactation Cows
Another study using mid-lactation cows, appeared in the December Journal of Dairy Science (Western et al., 2020). This study was designed to further investigate the difference in cow response to fatty acid blends in order to determine the optimal fatty acid blends that will best benefit high and low producing cows in mid-lactation.
Two fatty acid blends were fed: 80% palmitic with 10% oleic and 60% palmitic with 30% oleic, to 32 mid-lactation cows (144 days in milk). Daily milk production ranged from 70.5 lbs to 143.3 lbs. Results include:
- High producing cows had greater DMI and energy corrected milk when fed more oleic acid (60:30 blend).
- Low producing cows had greater DMI and energy corrected milk when fed more palmitic acid (80:10 blend).
- The 80:10 blend increased milk fat content, fat yield and protein yield in all cows.
- In low-producing cows the 60:30 blend decreased yields of de novo and mixed fatty acids in milk.
- In high-producing cows the 60:30 blend increased milk fat yield due to an increase in preformed fatty acid without affecting the yield of de novo and mixed fatty acids in milk.
Results indicate that cow response to fatty acid supplementation varies based on milk production. Lock and his research team recommend producers consider milk production of mid-lactation cows when evaluating different fatty acid supplements and nutritional management strategies to maximize cow health and production.
References
de Souza et al., 2021a J. Dairy Sci. 104:2896-2909
