What Milk Fat Depression Is Costing Dairy Farms

Milk fat represents a significant economic and nutritional component of dairy products. When fat production is reduced due to milk fat depression in cows, the hit to a farm’s profit quickly adds up. It’s essential to understand the impact milk fat depression can have and develop a strategy to retain fat – and income.
Realizing the True Cost of Milk Fat Depression
Milk fat depression can cause up to a 50% decrease in fat yield. The amount of fat lost varies by farm, and within herds, due to many factors – yet income left on the table remains consistent for farms without a management strategy.
Worse yet, milk fat depression tends to go unnoticed because milk production and other components remain unaffected. To quantify the potential economic impact, here’s a summary of field observations performed in dairy farms in Europe that used a control group and an experimental group (where milk fat depression risk was minimized via a feeding strategy utilizing MHA® Feed Supplement). In the chart below, the experimental group represents the realized increase in milk fat content with a feeding strategy (keep reading to learn more about the feed strategy and trial results).
Under milk fat depression conditions and by implementing the right feeding strategy, the milk fat content could be increased between 0.14 and 0.40 percentage points, resulting in between 0.28 to 1.07 € additional income per cow per day. Considering this additional income in a 100-cow herd over two months the additional profit would be between 1664 € to over 6000 €. The economic impact is clear. So, how can farmers capture those extra fat percentage points? Look to nutrition.
Nutritional Strategies to Reduce Milk Fat Depression Risk
Milk fat depression isn’t caused by a single factor. Aside from environmental challenges, several factors interact to disrupt the biohydrogenation** pathway, which ultimately inhibits fat synthesis in the mammary gland.
**The process in the rumen wherein unsaturated fatty acids are converted to saturated fatty acids, ultimately resulting in milk fat.
Managing the following dietary factors can reduce milk fat depression risk:
- Starch content and fermentability: Maximizing fermentability is important, but also comes with a risk for sub-acute ruminal acidosis and milk fat depression. High starch content or high fermentation rate of starch changes the ruminal pH, disrupting normal biohydrogenation pathways and leading to increased trans fatty acid production, which in turn, reduces milk fat content. To lower this risk, provide multiple starch sources or sources with slow fermentation rates and increase fiber sources with overlapping digestion rates. Reducing the starch content or substituting sugar for dietary starch can also reduce risk.
- Polyunsaturated fatty acids: Fresh grass, and oilseeds and their byproducts are shown to increase polyunsaturated fatty acid intake, impacting biohydrogenation and increasing the trans fatty acids that inhibit milk fat synthesis. Use the Rumen Unsaturated Fatty Acid Load (RUFAL) threshold reflecting the total daily unsaturated fatty acid supply from all feed consumed (not only from fat supplements) to monitor and adjust intake.
- Feeding strategies: Slug feeding grain is associated with sub-clinical rumen acidosis and milk fat depression. Total mixed ration feeding also comes with risk due to sorting and varying rates of feed intake. Feeding cows four equal meals every six hours, as compared to twice a day, has been shown to increase milk fat. Delivery of fresh feed stimulates intake – and delivery timing can be adjusted to drive higher intake during typically slow feeding times.
- Rumen modifiers: Feed additives and ingredients can have a big impact – negative or positive – on rumen microbial populations and biohydrogenation. Intelligent nutrition solution, MHA® Feed Additive, is shown to positively impact milk fat. MHA® Feed Additive is made with 2-hydroxy-4-(methylthio)butanoic acid, also known as HMTBa, which has been shown to decrease the risk of diet-induced milk fat depression by improving microbial protein synthesis and preventing shifts to altered biohydrogenation pathway of fatty acids that results in inhibited milk fat synthesis.
Using MHA® Feed Additive can be an effective, economical strategy to capture unrealized milk fat content.
Using MHA® Feed Additive to Increase Milk Fat Content
The case study table included at the start of this article is based on a feeding strategy utilizing MHA® Feed Additive under European feeding conditions. In a commercial dairy study done in Brazil, cows fed HMTBa as MHA® saw milk fat content increase by 0.2 percentage points (3.94% vs. 3.75% control) and energy-corrected milk yield improve by 1.8 kilograms per day (49.4 kg vs. 46.8 kg control). Higher milk yield did not dilute milk fat, showcasing the effectiveness of HMTBa in increasing milk fat production. The cows also showed signs of better rumen function, and optimized nitrogen utilization.
Using the HMTBa responses generated in this study, economic impact was calculated for two scenarios using German milk price conditions*** over one year:
- Scenario 1 used production levels observed in the study (49.4 kg per cow per day), with a simultaneous increase of 1.5 kg milk yield and 0.2% milk fat.
- Scenario 2 assumed a typical cow produces 35 kg of milk per day with HMTBa supplementation leading to a 0.2% increase in milk fat (no milk yield increase).
***Milk price set at 0.475€ per liter, with an additional 0.07€ per 1% milk fat content.
For a 100-cow farm, scenario 1 would generate an additional annual income of 46779€ with a return on investment of 10:1. Scenario 2 would result in +49 Ct € per cow per day for an additional annual income of 13414€ and an ROI of 3:1.
Capture a herd’s full milk fat and profit potential. To learn more, register for the milk fat depression webinars on European dairy farms.
1 Harvatine, K.J. “Managing Milk Fat Depression.” 2016.
2 Lourenço, J. C. S., Carrari, I. F., Aguiar, G. C. d., Janssen, H. P., Lanna, D. P. D., Teixeira, I. A. M. A., & Almeida, R. d. (2024). 2-Hydroxy-4-(Methylthio)-Butanoate Supplementation Affects Production, Milk Fatty Acid Profile, and Blood Metabolites of High-Producing Holstein Cows. Dairy, 5(1), 66-77. https://doi.org/10.3390/dairy5010006
3 Westreicher, E. “Field Research & Effect of MHA in Dairy Cows” presentation. 2024.

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