Why do you feed supplemental fat to your herd? Perhaps you’re aiming to propel your milkfat higher to capture more revenue in your milk check, or you recognize the impact bypass fat can have on feed efficiency. And let’s not forget about reproduction and how challenging it can be to get enough energy to early lactation cows to support their strong drive to milk and your need for her to get pregnant on time. All these reasons have one goal in common: providing more energy to cows to help them do what they were made to do.
The reality is that feeding bypass fat is a “yes, and…” proposition. Yes, you’re adding more energy by increasing energy density and greater delivery to the small intestine. Additionally, fatty acids are signaling molecules that directly impact other key functions, including embryo development, immune function, and metabolism. Let’s look under the hood at three examples of fatty acid signaling beyond energy and what impact this may have on your fat supplementing strategy.
1) Body condition loss post-calving.
While the common assumption for decades was that all cows lose weight after calving, that is simply not true (Carvalho 2014). There are many factors that can impact how much body weight cows lose after calving, and the quantity and type of fatty acids fed is high on the list. Two fatty acids are key to this regulation: oleic and palmitic. Oleic (35% in traditional calcium salts) activates genes that promotes the formation of new lipids, reducing negative energy balance and leading toward lower nonesterified fatty acids (NEFAs). Meanwhile, too much palmitic in the fresh period can have the opposite effect, as palmitic is preferentially utilized by the mammary gland to make milkfat and can lead to greater bodyweight loss post-calving (deSouza 2018) (Figure 1).
2) Embryo development and retention.
EPA/DHA omega-3s are essential fatty acids that are directly involved in early embryo development and pregnancy retention. Recent research has shown that less than a gram of DHA in-vitro resulted in a doubling of the day-7 blastocyst growth rate (Oseikria 2016) and similar increases in the percent good quality embryos when EPA/DHA was fed (Freret 2019). These findings underscore the essential role EPA/DHA plays in not only pregnancy retention (Santos 2005, Silvestre 2008), but also in very early stages of embryo development.
3) Reduce leaky gut, especially in heat stress.
Cows experience immune challenges throughout their lactation, especially during heat stress, at calving, and after dry-off. EPA/DHA omega-3 is essential to enabling cows to quickly resolve inflammation and has been shown to reduce intestinal permeability (less leaky gut). In a 2022 study by Rico and Ruiz-Gonzalez, greater levels of EPA/DHA resulted in lower levels of LPS-binding protein, a key marker for leaky gut. This reduction in inflammation led to reduced body temperature and respiration rates, greater milk production, and in a subsequent study, greater lying time (Boucher 2023) (Figure 2).
Take home points
While fat feeding will always be first and foremost about meeting the energy needs of high-performing cows, that is just scratching the surface of what fatty acids are doing in your cows. Take this “quick peek under the hood” as a reminder that fat is not just fat…these individual fatty acids have different roles.
- Look closely at the balance in your fresh pen to make sure you’re signaling for less fat loss and not more by feeding palmitic and oleic in an appropriate balance.
- Review your reproductive and health goals to determine if an 8- to 12-cent investment in EPA/DHA supplementation can be that next step toward helping your high-producing herd achieve that same level of success from a reproductive standpoint.
- Lastly, look at the complexity of fatty acid feeding as an opportunity. We’ve known for decades that we can rely on fat supplementation to deliver more energy. And today, because of the great leaps in understanding the science of fatty acids, we can add fatty acids to our toolbox for reducing pregnancy losses, improving gut health, and having healthier cows through their transition.
