In June of 2014 Time magazine’s cover was, “Eat Butter.” (June 23, 2014). The article was subtitled, “Scientists labeled fat the enemy: why they were wrong”. Since then, McDonald’s has eliminated margarine and American consumers have drastically increased the consumption of higher fat dairy products. This trend is expected to continue and is having an effect on mailbox milk prices. A milk plant field representative recently mentioned that there was nearly a $3.00 difference in pay price between his patrons farms (all Holsteins). This difference was primarily due to butterfat, protein tests and also somatic cell count. For a herd averaging 80 lbs of milk per day this a $2.00 difference in pay price and is a $1.60 difference in daily income per cow. This is over $58,000 income per 100 cows annually. Many farms are able to achieve high components and high milk production. There are farms that are achieving over 90 lbs of milk daily with over 3.9% butterfat and 3.1% protein.
Research from Cornell University and Miner Institute provides insight into this wide variation in component tests. Some milk butterfat is made in the udder tissue. These are called De novo fatty acids and are less than 16 carbons long. The mammary tissue uses volatile fatty acids produced in the rumen to synthesize these. The fatty acids longer than 16 carbons are absorbed whole from the blood and are called preformed fatty acids. Fatty acids that are 16 carbons long can come from either source and are called mixed fatty acids.
Dr. Barbano from Cornell analyzed bulk tank fat and protein tests on 40 dairy farms in Vermont and New York. They discovered that as the De novo and mixed fatty acid levels increased, so did the herds butterfat and protein tests (Figure 1 & 2). The preformed fatty acids were not nearly as well correlated to butterfat and protein test (Figure 3). This shows the importance of a well-functioning rumen to achieve high fat and protein milk. The ration and feeding management strategies both affect rumen health.
- Feed a well-balanced diet focusing on highly digestible fiber. Of particular importance is physically effective fiber
that promotes cud chewing.
- Diets higher in fat had lower De novo fat content.
- Herds with high levels of anti-nutritional factors such as mycotoxins or wild yeast may have low De novo fat content.
- Herds that have empty bunks for extended periods of time had lower De Novo fat content.
- Feed bunk space less than 18 inches was associated with lower De novo fat synthesis and lower fat and protein test.
- Stocking density of greater than 110% was associated with lower De novo fat and lower fat and protein test. Research shows that cows without adequate bunk and lying space eat faster and consume fewer meals. This may negatively affect rumen fermentation. Cows without adequate lying time may also have decreased rumination.
Both Minnesota DHI labs are able to analyze milk samples and will provide an interpretation of the results. Contact them for proper sampling procedures. It is also important to note that samples come from the herd or larger groups, not individual cows. These relationships can only be applicable for groups from 150 to 220 days in milk. Early lactation groups will be different because of cows in negative energy balance. If your herd’s components are low, this tool might provide some insight to you and your nutritionist as to the cause of the problem.
Figure 1. Relationship between De novo fat synthesis and bulk tank fat test.1
Figure 2. Relationship between De novo fat synthesis and bulk tank protein test.1
Figure 3. Relationship between preformed fat synthesis and bulk tank fat test.1
For more Dairy information visit: extension.umn.edu/agriculture/dairy
This article is reproduced with permission from the I-29 Moo University February e-newsletter
The I-29 Moo University is represented by dairy extension educators and allied partners from Iowa, Minnesota, Nebraska, North Dakota and South Dakota.