Optimize milk fat: an ongoing challenge

Dairy farmers generally experience a seasonal decline in milk fat concentration that accompanies prolonged warm weather. Reduced milk fat is a disadvantage in the developed dairy markets, where the "butter market" has been relatively strong, even though the markets as a whole have remained weak.

In the United States, for example, dairy fat receipts accounted for more than 50% of total dairy product receipts for many operations last year. Thus, maintaining a high concentration of fat in milk throughout the year has become a major factor in the overall success of dairy farming. Producers have found that reducing or preventing the usual decrease in fat concentration in milk, in the summer or hot season, can significantly improve profitability.

Cows rich in milk. Photo: Diamond V

"Most dairy farmers and nutritionists recognize a seasonal shift in milk fat that is sometimes attributed to changes in forage sources, weather, or herd days," notes Dr. Kevin Harvatine, Associate Professor of Nutrition. Nutrition physiology at Pennsylvania State University, his report "Managing Depression of Milk". "A highly reproducible seasonal trend is observed in the concentration of milk fat and protein in all milk markets …"

Strong demand for milk fat

In the United States, says Dr. Bill Sanchez, a specialist in ruminant technical services at Diamond V, where milk fat can account for more than half of milk revenue for most producers, milk fat production is strongly encouraged. As a result, says Dr. Sanchez, "the main producers are very competent at minimizing the low levels of milk fat in summer".

Still, Dr. Adam Lock, a dairy researcher at Michigan State University, said, "Resolving milk fat problems on dairy farms remains one of the most difficult tasks of management. overall nutritional value of dairy cows. "

Dr. Lock previously wrote a report from the University of Vermont titled "Understanding the Causes of Milky Depression: From Basic Concepts to Practical Application", which reads, "Although the fatty depression of milk has been observed in a wide range of feeding situations, occurs as a result of several concomitant factors of diet or management rather than just one factor. "

Minimize PUFA

Two things are needed for a milk lipid depression to occur:

1. the presence of polyunsaturated fatty acids (PUFAs) and
2. altered ruminal fermentation.

However, the degree of MFD can vary from one situation to another.

PUFA comes mainly from vegetable oils found in almost all diets. In the United States, the main source is corn oil (corn) derived from corn or silage. Higher amounts of PUFA come from feeds such as DDGS, some bakery co-products, soybean oils (with higher PUFAs in some sources of soy protein) and some animal fats. The amount of PUFA that each cow can tolerate depends on the stability of its environment in the rumen. As a result, saving money on feed in the short term can result in a reduction in milk fat content and increased financial loss.

All PUFAs are toxic to rumen bacteria, which attempt to saturate the double bonds of these by adding hydrogen atoms so that fatty acids (FAs) do not harm the bacteria. This saturation process forms different types of FA. If these FAs leave the rumen before being completely saturated, they may be in a form that can lead to severe MFD. Some unsaturated fatty acids of a length of 18 carbon atoms (C18) are a major cause of MFD.

The safest approach is to minimize as much as possible the amount of PUFA in the diet. Nevertheless, PUFAs are a normal component of dairy foods and cows and their rumen can certainly absorb a certain amount.

Avoid alterations of fermentation in the rumen

The amount of PUFA needed to start causing MFD is strongly influenced by rumen stability. The more stable the rumen, the lower the rumen outflow of depressing milk fatty acids.

Dairy farmers can think about how food is managed in their operations and how it might affect rumen stability. For example, the following factors may affect the rumen microbiome and the resulting fermentation:

• Sorting food
• Food is not available on the entire berth
• More hearty and less frequent meals
• Subacute ruminal acidosis
• Thermal stress

In addition, Dr. Lock conducted research on the significant reduction in the amount of depressant fatty acid (trans-10, cis-12 CLA) produced in bad milk when cows were fed with a food available in the trade. Saccharomyces cerevisiae fermentation product.

Saturated fatty acid diet

To cope with the seasonal decline in the concentration of fat in milk, experts recommend consuming saturated fatty acids, especially palmitic acid. In his guidebook "Nutritional Management of Milk Fat," Dr. Lock notes that palmitic (C16) and stearic (C18) fatty acids appear to be inert in the rumen and not involved in MFD. In reviewing the research, he notes that researchers have discovered that supplementation with palmitic acid induces a higher response of milk fat, both in concentration and in yield. In addition, it seems that the efficiency of absorption of the mammary gland is higher for palmitic acid than for other fatty acids.

A study conducted by Dr. Lock and his colleagues found that the use of a fat supplement with 85% palmitic acid (2% dry matter in the diet) improved the fat concentration in milk and milk. yield of 8%, as well as the efficiency of the conversion of food to milk compared to a diet without supplement of fat. .

Taking steps to promote rumen health and a beneficial microbial balance will help improve the efficiency of dairy products and optimize the performance of dairy cattle, including the concentration of fat in milk during the hot months of the year. 39; summer. Diamond V is actively exploring this area. For any questions about milk fat optimization, contact your Diamond V representative.

Summary of suggestions

• Diet: Minimize polyunsaturated fatty acids (PUFAs), including DDGS, some bakery co-products, soybean oils, some animal fats
• Management: Avoid altering the fermentation in the rumen, which can result from poor management of compartments, food sorting, heat stress and so on.
• Management: Feeding between milking (rather than milking), increasing the number of meals while decreasing the size of each meal
• Diet: Consider consuming saturated fatty acids, including palmitic fatty acid (C16)
• Diet: Food to support rumen health, including a balanced rumen microbiome.

References available upon request

Author: Bill Stone, Director of Technical Services for Ruminants, Diamond V