Nearly every dairy farmer will tell you that one of the most critical times of a cow’s life is around calving. The weeks preceding and following calving have been well-detailed in research. That time, dubbed the transition period, affects both the cow and newborn calf’s life.

Recent research from Cornell University analyzed the link between a cow’s pre-calving diet and the colostrum it produces. Four nutritional decisions were linked to colostrum quantity and quality: crude protein, starch levels, dietary cation-anion-difference (DCAD), and particle size.

In the cows on 19 New York dairies that were included in this research, first-calf heifers fed prepartum diets containing less than 13.5% crude protein (on a dry matter basis) had the highest colostrum yield. Contrarily, cows on their second calving or greater produced more colostrum when the protein level was between 13.6% and 15.5%. Quality was not impacted by crude protein level.

According to an article written by Rick Grant in the Miner Institute Farm Report, dietary starch content between 18.6% and 22.5% of ration dry matter correlated with the greatest colostrum production.

“Colostrum Brix percentage was higher for primiparous cows fed lower dietary starch, although the quality of colostrum for older cows wasn’t affected much by dietary starch,” he explained.

DCAD diets have become quite common on dairies. Lower DCAD diets were related to lower-quality colostrum. These diets also reduced colostrum production. That being said, Grant warned that other factors such as lower dry matter intake in DCAD diets could impact colostrum levels and quality.

Finally, they looked at particle size. “In higher straw diets, particle size is a key factor to monitor since too many long forage particles retained on the top screen of the Penn State Particle Separator (PSPS) leads to sorting and may affect intake,” he explained. “Diets containing 15.3% to 19.1% of ration particles on the top screen of the PSPS had the lowest colostrum yield.”

Grant warned that more research is needed to pinpoint the best particle length to balance cow health and colostrum yield. He also encouraged readers to consider that this work was done on farms with 620 to 4,600 cows and may not directly apply to all types and sizes of farms.

“Nonetheless, this study helps prioritize key nutritional factors that appear to affect colostrum quality and yield,” Grant concluded.