To get their best start, calves should consume high-quality colostrum as soon as possible after birth. High-quality colostrum isn't always an automatic from all dams though. Photoperiod during the dry period and how it relates to high-quality colostrum was the focus of a University of Illinois study. Results were published in the August 2010 issue of the Journal of the American Veterinary Medical Association.

Eighty-one Holstein cows were assigned to multiple photoperiod lengths: natural day length, long days (16 hours), or short days (8 hours) for the entire dry period. At calving, colostrum samples were taken hourly following birth. Results found that colostrum immunoglobulin concentration decreased by 3.7 percent during each subsequent hour after calving. They also found that the amount of time between calving and first milking as it relates to volume of colostrum produced was significantly and negatively related to colostrum immunoglobulin concentration. Finally, photoperiod showed no affect on either volume of colostrum produced or immunoglobulin concentration.

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