Plenish^® High Oleic Soybeans for Dairy Diets

Milk fat is composed of about 40% pre‐formed long‐chained fatty acids (LCFA, >16 carbons in length) derived from the diet or mobilized body reserves, 35% mixed fatty acids (16 carbons in length) and 25% are short chained fatty acids synthesized in the udder (de novo) from rumen produced volatile fatty acids such as acetate and butyrate generated from fiber digestion. Cows cannot synthesize fatty acids longer than 16 carbons so about half of the mixed source come from the diet and half from de novo synthesis in the udder.

All rations fed to dairy cows contain fat, which come from a variety of sources including forages, grains, by‐products and fat supplements. The type of fat in the diet can be either saturated (no double bonds), such as 16 carbon palmitic acid (denoted as C16:0) or unsaturated (one or more double bonds), such as linoleic acid (denoted as C18:2 with 2 double bonds). Excessive dietary polyunsaturated fatty acids (PUFA), like linoleic acid can be toxic to fiber-digesting rumen microbes.

Rumen biohydrogenation is a process that converts unsaturated fatty acids (with double bonds) into saturated fatty acids (with no double bonds), thus detoxifying the PUFAs. Under normal rumen pH’s the biohydrogenation process converts linoleic acid to stearic acid (C8:0).

However, when ruminal fermentation is characterized by low rumen pH, or overwhelmed with excessive PUFA load (often occurring in cows being fed for high milk yield) the pathway is altered resulting in the production of trans‐10, cis‐12 CLA (right side of diagram). This intermediate is a potent, bioactive, and undesirable CLA linked to milk fat depression (MFD). Research shows that even small amounts, just 3‐4 grams reaching the intestines, can dramatically reduce milk fat synthesis¹, and lower transfer of LCFA into the mammary gland².

The germ of a corn kernel contains about 60% linoleic acid. Corn grain and corn silage are the foundation of most dairy diets. Even though corn silage is low in fat, it also contributes significant levels of linoleic acid. The combination of corn grain and corn silage can add to the ruminal linoleic (PUFA) load, which has been clearly linked to MFD³. Likewise, conventional soybeans fed at high levels, especially when the high linoleic oil contained is exposed through fine grinding, can lead to MFD. It's important to note that MFD can be caused by multiple factors, including PUFA intake, fermentable starch, slug‐feeding, and more. To successfully include high levels of corn silage in dairy rations, it’s essential to pay close attention to excessive ruminal starch digestion and lack of dietary effective fiber, to mitigate this MFD risk.

Soybeans are a valuable source of protein, that also contain about 20% fat. Conventional soybeans have about 22% oleic acid and 63% linoleic and linolenic acids (PUFAs). In contrast, Plenish soybeans contain 75% oleic acid and only 9.5% PUFAs. This change represents a groundbreaking innovation in dairy nutrition, allowing for a shift in the way nutritionists can utilize soybeans in formulating rations.

1. Penn State University⁴ compared Plenish vs. commodity extruded soybean meal at the same inclusion rate (17% of diet DM), and the same level of fat in the ration (4% of diet DM). Neither intakes (59 lb DM/d), nor milk yield (93 lb/d) were affected. However, milk fat increased 0.2% (from 3.5 to 3.7%). In addition, PUFA in milk decreased ~50% (from 4.93 to 2.49%). Researchers concluded that high oleic soybeans are likely to increase milk fat concentration and yield, with no negative effects on intake, or yields of milk or protein.
2. University of Wisconsin² researchers compared raw, full fat Plenish vs. commodity soybeans fed either whole or ground. Inclusion was ~17% of diet DM with fat at ~7% of diet DM. Intakes were not affected; however, milk fat increased when Plenish soybeans were fed ground (3.09 vs. 3.50%), but not when fed whole (3.40 vs. 3.53%). Similarly, milk fat yield increased significantly when Plenish soybeans were fed ground (3.28 vs. 3.62 lb/d), but not when fed whole.
3. Michigan State University⁵ investigated the feeding of roasted, ground Plenish soybeans at 0, 8, 16 and 24% of diet DM. Dietary starch and protein levels were kept constant but fat was increased from 3.25 to 7.1% of DM. Milk and milk fat yield increased by 9 lb/d and 0.35 lb/day respectively from 0 inclusion to the highest inclusion level (16 lb/c/d). Results also showed a decline of 1.6 lb/d in DMI from the 0 inclusion to the highest inclusion rate thus improving feed efficiency.

   

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4. Perdue University⁶ researchers fed supplemental high oleic soybean oil to mid‐lactation cows (87 ± 26 DIM) at 1.5% of diet DM, resulting in 5.5 vs 6.8% fat diets. No effects on intake, or milk yield; but milk fat (0.16%) and protein (0.07%) were increased. Positive effects of high oleic oil on the apparent increase in total‐tract fat digestibility were attributed to being fed as oil which might have a faster rate of passage from the rumen to intestines. Multiparous cows gained weight and body condition score, but not primiparous cows reflecting differences in energy partitioning among immature cows. Back fat depth in all cows was increased, suggesting high oleic soybean oil may have reduced lipolysis and increased insulin sensitivity.

All Plenish soybeans must be fed on‐farm or delivered to an approved processor for oil extraction. There are several ways to access Plenish soybeans or high oleic oil for use in dairy cow diets. Producers (or their contract grower) can sign on‐farm feeding agreements to grow Plenish soybeans on their farm. Alternatively, producers can access Plenish soybeans from approved grower/processors. Finally, certain approved crush plants are marketing Plenish soybean meal containing 7‐9% high oleic oil versus only 1‐2% oil in commodity soybean meals.

Soybean protein is highly soluble. Feeding raw soybeans lowers their nitrogen use efficiency and leads to higher ruminal ammonia, lower rumen undegraded protein (RUP, bypass protein) and increased milk urea nitrogen (MUN). It may also result in lower yields of milk and milk protein⁷. Roasting soybeans can double the protein escape from the rumen⁸ thus increasing RUP. Heating soybeans to effective levels will denature urease (thus allowing for urea use in diets) and denature trypsin inhibitor (not a concern in mature ruminants). It is also a common practice to prevent rancidity and enhance soybean palatability. Feeding quartered soybeans is preferred to whole. Research has shown that fine grinding may not to be justified⁹ and due to increased surface area, may reduce the RUP of the soybeans.

Roasting typically costs $25‐$35 per ton. Losses by open flame roasting are near 12% as water and pods/hulls. Losses when using electric or hot air are mostly water. Roasting too hot or too long can decrease protein value by binding them with sugars (Maillard reaction). Low roasting temperatures will reduce RUP and may fail to denature urease. Steeping the roasted soybeans (~30 minutes) to allow time for heat to penetrate is also required. The protein dispersibility index (PDI) laboratory method can be used to evaluate roasting effectiveness. A PDI value of between 9‐11 indicates optimal roasting and steeping.

• ¹ Overton, T.R. Feeding for high components in Herd Health and Nutrition Conference. 2017. Liverpool, NY: PRO‐DAIRY, Cornell University.
• ² Weld, K.A. and L.E. Armentano. 2018. Feeding high oleic acid soybeans in place of conventional soybeans increases milk fat concentration. JDS. 101(11):9768‐9776.
• ³ Diaz, F. Effects of linoleic fatty acid intake on milk fat production. Dellait, 2020.
• ⁴ Lopes, J.C., et al. 2017. Effect of high‐oleic‐acid soybeans on production performance, milk fatty acid composition, and enteric methane emission in dairy cows. JDS. 100(2):1122‐1135.
• ⁵ Bales, A.M. and A.L. Lock. Harnessing the potential of a high oleic acid soybean to improve milk production responses of high producing dairy cows in Great Lakes Regional Dairy Conference. 2023. Mt. Pleasant, MI: Michigan State University.
• ⁶ Hanno, S.L., et al. 2024. High oleic soybean oil maintains milk fat and increases apparent total tract fat digestibility and fat deposition in lactating dairy cows. JDS Communications.
• ⁷ Faldet, M.A. and L.D. Satter. 1991. Feeding heat‐treated full fat soybeans to cows in early lactation. JDS. 74(9):3047‐3054.
• ⁸ Faldet, M.A., et al. 1992. Determining optimal heat treatment of soybeans by measuring available lysine chemically and biologically with rats to maximize protein utilization by ruminants. J Nutr. 122(1):151‐60.
• ⁹ Dhiman, T., et al. 1997. Particle size of roasted soybeans and the effect on milk production of dairy cows. JDS. 80(8):1722‐1727.