Milk fat above 4% is the new normal (to access original article, click here)

by Isaac J. Salfer, assistant professor of dairy nutrition, University of Minnesota

I can remember sitting in my Dairy Management class at the University of Minnesota in 2012 and learning that a good milk fat benchmark for a Holstein herd was 3.75%. This was backed up by historical milk market data, which saw average butterfat tests in the Upper Midwest hovering between 3.7% and 3.8% from 2000 to 2012.

Fast-forward 10 years and we have seen this number rapidly increase, with 2021 seeing an average milk fat of over 4.0% for the first time. The trend is continuing into 2022 with an average bulk tank fat test of 4.25 in January, up 0.13% from last year's January average. I fully expect that in a few years, I will be teaching my class that a 4.0% milk fat test is on the low end of what a herd should expect.

The incredible strides in milk fat are related to four main factors:

1. Improved ration formulation with an emphasis on feeding rumen-protected fatty acid products and focusing on fatty acid digestibility.
2. Improved forage quality and fiber digestibility, which allows you to feed higher fiber diets without sacrificing available energy for milk production
3. Improved feed and bunk management to maximize cows' time at the feed bunk.
4. Improved genetic selection for milk fat percentage, mainly due to the use of the Net Merit $ selection index, which puts heavy emphasis on milk fat and protein yield

Increased demand for high-fat dairy

The improvement in the average butterfat test coincided with increased consumer demand for high-fat dairy products, particularly butter, in recent years. One contributor to this is the changing public perception of saturated fat, particularly after the now-famous book "The Big Fat Surprise" by Nina Teicholz was published in 2014. This book critiqued the long-held belief that saturated fats were the primary dietary risk factor for heart disease and showed that the science suggested that sugar intake was a much larger contributor.

The increased demand for butter has been reflected in increasing Class III milk prices over the past decade. I foresee this demand for butter continuing to rise as consumers better understand the health benefits of butter compared to vegetable-based alternatives.

While the market improvements over the past decade have been amazing, it puts even more pressure on farmers to keep pace and capitalize on high premiums. To do this, we must understand the factors that influence milk fat production.

Adding fat to your nutrition program
Milk fat comes from two sources: either directly from the fat present in the diet and body reserves (we call this 'preformed' fat) or from synthesis in the udder (we call this "de novo" - meaning "new" - fat). There are milk testing and academic labs that can test the composition of fat in milk to determine the percentage of milk fat from each source. This information can be valuable to farmers and nutritionists when it comes to managing their nutrition programs.

Low concentrations of preformed fat (>30% of total fatty acids) indicate that the dairy could benefit from feeding supplemental fat, particularly saturated fat sources like palm oil, rumen-protected fat supplements or tallow. Right now, these sources are very expensive, with tallow prices being at an all-time high, so any supplemental fat feeding should be done in the context of income over feed costs. Several commercial products exist that can provide excellent courses of rumen-protected fat. Fatty acid products made of a blend of palmitic and stearic acid tend to be more digestible than products made up of a single fatty acid.

De novo fatty acids should make up at least 23% of total fatty acids. Increasing the amount of de novo fatty acids is a cheaper approach to modifying milk fat because modification of de novo fat is heavily influenced by rumen fermentation.

The production of a specific fatty acid (trans-10, cis-12 C18:2) by rumen microbes leads to direct inhibition of milk fat synthesis in the udder. This fatty acid is increased in the rumen during times of low rumen pH and high rumen unsaturated fatty acid concentration. Factors such as high diet fermentability (through feeding highly digestible feeds), high unsaturated fatty acids, poor bunk management, and poor feed consistency are all risk factors for the production of this fatty acid, and therefore risk factors for decreases in milk fat.

Strategies for managing feeding
Feeding management strategies that increase the number of visits a cow makes to the feed bunk can have major benefits on de novo fat synthesis. Research has shown that to improve milk fat production substantially:

• Increase feeding frequency from 1 to 2 or more times per day.
• Push up feed 7 to 12 times a day
• Reduce stocking density below 110%.
• Increase bunk space to at least 24 inches per cow.
• Feed at a consistent time each day.

Increasing the physically effective fiber in a diet also increases milk fat if feed intake isn't reduced.

In this current butter-loving market, it is important to focus on these strategies to continue to improve your herd's butterfat test.