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Seasonal Swings in Component Levels and SCC

May 3, 2020


The prior post reviewed the component levels and Somatic Cell Count (SCC) for the last five years.  The post received numerous reads.  This post will review the 2019 seasonal variations in component levels and SCC.  The seasonal variations are consistent with prior years.  The range between highs and lows are also similar to prior years.


The data for the charts below is based on the data from the Federal Orders.  As reviewed in a prior post, a lot of the Federal Order milk is being de-pooled for financial reasons and is not included in the pool.  However, because the charts below express percentage and SCC variations, de-pooling should not affect these analytics.  Because in all cases these measurements are the basis for producer milk payment, they are carefully measured and audited for accuracy.


  • Butterfat and milk protein follow very similar patterns as shown in Charts I and II, with lows in July and highs in November.  

  • Butterfat levels are higher (3.9 percent in 2019) than milk protein levels (3.16 percent in 2019. The spread between high and low was also numerically greater for butterfat than for milk protein, but in both cases the November high point was 8 percent above the low July point.  The spread between low and high for butterfat was .3 percent, while the spread for milk protein was .24 percent.  

  • "Other Solids" did not vary nearly as much.  While "Other Solids" averaged 5.76 percent in 2019 they varied monthly between the highest and lowest points by only .04 percent.

  • SCC varied from a low of 178 million cells per milliliter in April to a high of 233 in August and September, a spread of 33 million cells per milliliter.


Chart I below shows the monthly variation in butterfat.  Because butterfat averaged $2.51/lb. in 2019, the loss of up to 0.3 percent in the Summer months is significant.  All Federal Orders are paid for butterfat content, so the butterfat chart is based on a very high volume of milk.


The variations were similar for most all Federal Orders with just a few "outliers."  The outliers with the smallest spread between low and high were Florida and Arizona, both Federal Orders paid on the Advanced system.  They varied by only .19 percent. The Southwest varied the most with a spread between low and high of .44 percent. 

Chart I - 2019 Butterfat Levels by Month Chart II shows the monthly variation in milk protein.  The milk protein price averaged $2.38/lb. in 2019, which also makes the milk protein variation a significant financial variable. The outliers for milk protein were California where the variance was only .17 percent and on the other extreme the Pacific Northwest which varied by .32 percent.  This defies logic as both Orders are contiguous and on the Pacific Coast where temperatures are tempered by the Pacific Ocean.

Chart II - 2019 Milk Protein Levels by Month


Chart III shows the variation for "Other Solids."  The chart is the inverse of the the butterfat and milk protein charts with the high percentage level in June.  The variation is consistent for all seven Orders paid on the component system.


Payment for "Other Solids" averaged only $19/lb. in 2019, making the small variation and low value a non-financial issue.

Chart III - 2019 Other Solids Levels by Month

There are only four Federal Orders that have an incentive in the component payment system.  Above 350 million cells per milliliter, there is a penalty and below 350 million cells per milliliter there is a bonus.  As reviewed in the prior post to this blog, SCCs have decreased significantly over time. Many producers receive a bonus for lower SCCs outside the Federal Order payment system. so there is a strong incentive for many producers to achieve a lower SCC.

Chart IV 0 2019 SCC by Month


There are many reasons for the cyclical variations.  Summer heat, the calving seasonality, the new vs. old crop feed cycles, and other parameters are often sited.  There is a significant financial incentive to minimizing these variations.  However, very little research has been devoted to these seasonal variations.


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