Dairy Nutritionist and producers have discussed the effect of season on milk composition for years. In the spring, the trend for both lower milk fat and protein begins reaching a low in mid to late summer (July and August). Milk fat declines linearly from spring to summer at a rate of 0.061% units per month.
For example, milk fat is 3.9% in May if it follows the general trend it will be 3.9 – (0.061 X 3) = 3.72% by the end of July. Milk protein also declines linearly at a rate of 0.03% units per month. If milk protein is 3.1% in March expected milk protein will be 3.10 – (0.03 X 5 months) = 2.95% in August.
Feed changes that take place in May or June can maintain or even raise the milk fat or protein levels, but it is not uncommon to have a herd's componets drop during the summer time. To offset the negative effects of the summer season feed a rumen healthy diet. Lower starch, higher fibre and frequent feedings (even with a TMR) will help.
Your Soyex is a great source of degradable protein and energy. It's great to increase the energy to cows or keep the energy the same and feed them more forages. Healthy rumen leads to healthy cows...and better components.
Component information provided from Akey Dairy Newsletter and New Brunswick Department of Agriculture and Aquaculture Article written by Independent Nutritionist: Louis Dedecker of Denovo cna