Researchers wanted to know if what dairy farmers feed their cows affects how hard or soft butter becomes at room temperature. They tested whether adding palmitic acid (a type of fat) to cow feed would make butter harder, and whether stearic acid (another type of fat) would have a different effect. Using 12 dairy cows, they found that palmitic acid did make milk fat harder at room temperature, while stearic acid actually made it slightly softer. This research helps explain why some people noticed changes in their butter’s texture and shows that what cows eat really does affect the milk they produce.

The Quick Take

  • What they studied: Whether adding different types of fatty acids to cow feed changes how hard or soft milk fat becomes at room temperature
  • Who participated: 12 Holstein dairy cows that were in their second year of milk production, each cow tested multiple times over several weeks
  • Key finding: When farmers added palmitic acid to cow feed, the milk fat became noticeably harder at room temperature (about 5% more solid). When they added stearic acid instead, the milk fat became slightly softer (about 3% less solid).
  • What it means for you: If you’ve noticed butter being harder or softer lately, it may be related to what farmers are feeding their cows. This research suggests that dairy farmers can influence butter texture by choosing different supplements, though this is just one factor among many that affect butter quality.

The Research Details

Scientists conducted a carefully controlled experiment with 12 dairy cows using what’s called a Latin square design, which is a special way to test multiple treatments fairly. Each cow received three different treatments: regular feed with no added fat, feed with extra palmitic acid (a hard fat), and feed with extra stearic acid (a softer fat). The researchers gradually increased the amount of each supplement over time, starting at small amounts and going up to larger amounts. They collected milk samples and measured exactly what types of fats were in the milk, then tested how those fats behaved at room temperature using a special machine that measures melting properties.

The study was designed like a puzzle where each cow got each treatment in a different order, and there were at least 10 days between treatments to let the cow’s system return to normal. This design helps scientists make sure any changes they see are really caused by the feed supplement and not by other factors. Milk samples were collected on specific days and analyzed using two main techniques: one to identify the exact types of fats present, and another to measure how solid the fat was at different temperatures.

This research approach is important because it controls for individual differences between cows. By having each cow try each treatment, scientists can see the real effect of the supplements without other factors getting in the way. The gradual increase in supplement amounts also helps show whether more supplement causes more change, which is important for understanding how the effect works.

This study was published in the Journal of Dairy Science, a respected scientific journal. The researchers used precise scientific equipment to measure results rather than just observing changes. However, the study used only 12 cows, which is a relatively small number, so results might vary if tested with more cows. The study was well-designed with proper controls and washout periods between treatments, which strengthens the reliability of the findings.

What the Results Show

When farmers added palmitic acid to cow feed, the amount of palmitic acid in the milk increased in a predictable way—the more palmitic acid they fed, the more ended up in the milk. At the highest dose tested (750 grams per day), palmitic acid in the milk increased by 5.7 percentage points compared to cows eating regular feed. Most importantly, this extra palmitic acid made the milk fat noticeably harder at room temperature (20°C), increasing the solid fat content by 5.3 percentage points.

When stearic acid was added to the feed instead, something different happened. The stearic acid in the milk did increase, but the body also converted some of it into oleic acid (a softer fat). At the highest dose, stearic acid increased by 2.4 percentage points and oleic acid increased by 3.0 percentage points. Interestingly, this combination actually made the milk fat slightly softer at room temperature, decreasing the solid fat content by 3.2 percentage points.

The researchers explained this difference by pointing to an enzyme in the cow’s body called stearoyl-CoA desaturase. This enzyme converts stearic acid into oleic acid at different rates, which is why stearic acid had a different effect than palmitic acid. The palmitic acid stayed mostly as palmitic acid in the milk, making it harder, while the stearic acid got partially converted to a softer fat.

The study also found that palmitoleic acid (a related fat) increased slightly when palmitic acid was added to the feed. The dose-response relationship was linear and predictable for palmitic acid, meaning that doubling the supplement roughly doubled the effect. The changes in milk fat composition happened relatively quickly, appearing within 3-4 days of starting the new feed.

This research directly addresses a consumer concern that had not been thoroughly studied before. While scientists knew that different fatty acids had different properties, there was limited data on how feeding these specific supplements at various doses would affect the actual melting properties of milk fat from dairy cows. This study fills that gap and provides concrete evidence supporting the hypothesis that palmitic acid supplementation does make milk fat harder.

The study used only 12 cows, which is a small number, so results might be different if tested with more cows or different breeds. The cows were all Holstein breed in their second lactation, so results might not apply to other breeds or older cows. The study only tested up to 750 grams per day of supplements, so we don’t know what would happen at even higher doses. Additionally, this study only measured the effect on milk fat properties in the laboratory—it didn’t test whether consumers could actually taste or notice a difference in real butter made from this milk.

The Bottom Line

Based on this research, dairy farmers who want to make milk fat softer at room temperature might consider using stearic acid supplements instead of palmitic acid supplements. Conversely, if harder milk fat is desired, palmitic acid supplements would be more effective. However, farmers should also consider other factors like cost, cow health, and milk production when making feeding decisions. This is one piece of information among many that affects butter quality.

Dairy farmers and milk processors should care about this research because it gives them a tool to influence butter texture. Consumers who have noticed changes in butter texture might find this research interesting as an explanation. People interested in food science and how farming practices affect food quality would also find this relevant. However, this research doesn’t suggest that either type of butter is healthier or unhealthier—it only addresses texture.

Changes in milk fat composition appeared within 3-4 days of changing the cow’s feed. If a dairy farmer switched supplements, consumers might notice a difference in butter texture within about a week, as milk would be processed and butter made relatively quickly.

Want to Apply This Research?

  • Track the firmness of butter at room temperature using a simple scale (very soft, soft, medium, firm, very firm) when you purchase butter from different sources or at different times of year. Note the brand and purchase date to see if patterns emerge.
  • If you’re interested in butter texture, you could experiment by purchasing butter from different dairy brands or at different seasons and comparing how firm they are at room temperature. Keep notes on which products you prefer and see if you can identify patterns related to when or where they were produced.
  • Over several months, track your preferred butter texture and note any changes. This personal tracking won’t be scientifically rigorous, but it can help you understand your own preferences and potentially identify seasonal or brand-related patterns in the butter you buy.

This research describes how cow feed affects milk fat properties in laboratory conditions. It does not make health claims about whether any type of butter is better or worse for your health. The study was conducted on a small number of cows and may not apply to all dairy operations or milk products. If you have specific health concerns about dairy consumption, please consult with a healthcare provider or registered dietitian. This information is for educational purposes and should not replace professional nutritional or medical advice.