How to offset spring slump in milk fat

Overcoming naturally occurring challenges in spring milk fat drop off.

Seasonal changes in milk components are inevitable. While environment and heat stress play a role, lower milk fat during the spring and summer months is part of the cow’s internal biological rhythm, meaning the cow is programmed to lower components during this time period.  This seasonal variation is driven by changes in de novo fatty acids, those made by the cow influenced by ruminal fermentation. Therefore, it is vital to improve de novo fatty acid synthesis in order to offset that spring slump in milk fat.

“Today we have a much deeper understanding of the cow’s biological systems, and how she makes milk components,” says Dr. Mac Campbell, Cargill Technical Dairy Specialist. “We can use this knowledge to help combat some of the naturally occurring challenges that each season brings, and provide the nutrients she needs to synthesize milk fat.”

In his role, Dr. Campbell works closely with dairy farmers and Cargill Dairy Focus™ Consultants to fine-tune diets and management practices to achieve high component efficiency. Dr. Campbell advises farms to assess the following four categories to boost de novo fatty acids in the spring:

  • Amount of unsaturated fat in the ration – Unsaturated fat is toxic to rumen microbes, therefore they try to de-toxify their environment by saturating the fatty acids. During this process of biohydrogenation, the microbes create a compound known as trans-10, cis-12 CLA which has a devasting impacts on fatty acid synthesis. This often reduces milk fat significantly, ranging from 0.4-1%. Once unsaturated fat is minimized in the diet, milk fat responds rapidly, though it can still take up to three weeks to fully return.
  • Balancing starch digestibility with other dietary energy sources and effective fiber – Starch digestibility in fermented feeds increases with time ensiled, and therefore forages need to be monitored closely heading into the spring. Excess starch digestibility can have a negative impact on rumen pH and milk fat. Focus on other sources of fermentable carbohydrates like digestible NDF or sugar to prevent sub-acute ruminal acidosis. Provide enough physically effective fiber to stimulate rumination and maintain rumen mat integrity, Also be sure to monitor forage particle length to prevent sorting.
  • Feed additives that boost de novo production – There is a range of products that can help stabilize rumen pH, minimize fermentation disruption and support milk fat synthesis such as yeast products, HMTBa sources, mycotoxin products, osmolytes and buffers. Each dairy should work with their nutritionist to determine what’s best for their herd.
  • Environmental stress and combinations of stressors that will lower de novo fatty acids – Inconsistent environment leads to inconsistency in the bulk tank. Heat stress, overcrowding and feed restriction are all known to depress milk fat independently. However, when these conditions are combined, the problem can be exacerbated. Work to minimize the number of stressors the cow experiences throughout the day by optimizing the feeding, resting, and ambient environments.

“While component loss in the spring is inevitable, we can take steps to minimize loss by influencing de novo fatty acid production. It’s the best way to minimize seasonal component loss,” reminds Dr. Campbell.

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