By Dr. Dave Jones, Ph.D., P.A.S.
Fatty acids are components of lipid molecules most commonly stored in the form of a triglyceride (1 glycerol, 3 fatty acids). The nutritionally important component of fats are the fatty acids and they serve many different functions:
Saturated fats are given this name because they are saturated with hydrogen ions and contain no double bonds. The lack of double bonds gives a saturated fat a higher melting point and, therefore, likely to be solid at room temperature.
Unsaturated fats have 1 or more double bonds (not saturated with hydrogen ions) giving them a lower melting point creating a liquid (oil) at room temperature.
Fatty acids are typically represented in numerical form which is relatively easy to follow. For example, 18:2 n-6 represents a fatty acid with 18 carbons, 2 double bonds (unsaturated), and the first double bond starts 6 carbons from the methyl end of the fatty acid.
Biohydrogenation of unsaturated fatty acids to saturated fatty acids in the rumen is an important process. It will not, however, be discussed in this article. The effect of oils on the rumen has been discussed in other Agri-King Advantage and Viewpoint articles (see references).
Recent work from Michigan State University has explored combinations of three fatty acids with some interesting results. These fatty acids include:
This work has created a ‘buzz’ in the industry with nutritionists trying to feed fat supplements to generate some specific fatty acid ratios. It is important to note, everything we will discuss moving forward pertains to rumen inert fat sources (rumen bypass fat).
Studies have recognized that feeding palmitic acid (PA) to dairy cows can help increase milk fat (Figure 1. de Souza and Lock, 2018). This occurs because palmitic acid, when fed in the diet, can go directly to the mammary gland as a source of milk fatty acids. Remember, palmitic acid is a saturated fat that escapes the rumen untouched and is available to the cow in its original dietary form.
The milk fatty acid effect of palmitic acid lead to the question “is there an ideal ratio of dietary fatty acids for the dairy cow.”
Work out of Michigan State University demonstrated the following (against a no fat control) when various percentages of palmitic acid, stearic acid, and oleic acid (80% palmitic; 40% palmitic:40% stearic; 45% palmitic:35% oleic) were fed (de Souza et al., 2018.):
The responses seen with palmitic acid and oleic acid lead researchers to further investigate if there is an ideal ratio between these two fatty acids. Four different ratios of palmitic acid to oleic acid (80:10, 77:13, 66:24 and 60:30) were studied across high and low producing cows. They observed the following results:
The results demonstrate, although preliminary, that the ratio of palmitic acid and oleic acid in the diet can have differing results on low and high producing cows. If fresh cows are fed a diet to support more energy corrected milk (at a time of negative energy balance) the cows can then lose more body weight to support the production. This tells us that we should not overlook total energy of the diet when considering fatty acid ratios.
Further research from Michigan State demonstrates abomasal infusion of emulsifiers helps the absorption of fatty acids in the GI tract. (Figure 3. Lock, 2019). This is quite important because animals cannot utilize fatty acids for energy, or any other function, if they do not absorb the fatty acides across the epithelial layer of the intestines.
Recently, Agri-King updated Ru-Mend and Zy-Mend with technology that provides emulsifiers to the intestine of the dairy cow to assist with fatty acid absorption. This works alongside previous technology in these two products that assists with non-fatty acid nutrient absorption.
Therefore, it is recommended that Ru-Mend or Zy-Mend (follow Agri-King feeding guidelines) be fed in diets attempting to supplement fatty acids with rumen inert fat/fatty acid products to assist with fatty acid absorption.
Contact your Agri-King representative to investigate how you can use supplemental fat/fatty acids and Ru-Mend/Zy-Mend technologies on your operation. AK
Koch, L. Milk fat metrics – more than meets the eye. Agri-King Advantage. November, 2018. Volume 9, Issue 6.
Schauff, D. Why did milk fat drop?….It’s complicated. Agri-King Advantage. November, 2016. Volume 7, Issue 6.
Jones, D. Feeding fat to dairy cows. Agri-King Viewpoint. June, 2006. Volume 31, Issue 2.
de Souza, J. and A. L. Lock. Long-term palmitic acid supplementation interacts with parity in lactating dairy cows: Production responses, nutrient digestibility, and energy partitioning. 2018. J. Dairy Sci. 101:3044-3056.
de Souza, J., C. L. Preseault, and A. L. Lock. Altering the ratio of dietary palmitic, stearic, and oleic acids in diets with or without whole cottonseed affects nutrient digestibility, energy partitioning, and production responses of dairy cows. 2018. J. Dairy Sci. 101:172-185.
de Souza, J., N. R. St-Pierre, and A. L. Lock. Altering the ratio of dietary C16:0 and cis-9 C18:1 interacts with production level in dairy cows: Effects on production responses and energy partitioning. 2019. J. Dairy Sci. 102:9842-9856.
de Souza and A. L. Lock. Effects of timing of palmitic acid supplementation on production responses of early-lactation dairy cows. 2019. J. Dairy Sci. 102:260-273.
Lock., A. L. Opportunities to improve fatty acid digestibility. 2019. Discover Conference.