Colostrum Yields and Photoperiod
Nearly all dairies have frustrating times when their supply of good quality colostrum runs short. In an investigation involving one 2,500 cow Jersey dairy they observed a connection between photoperiod and volume of colostrum harvested.
The average colostrum yield was 14.5 pounds (6.6kg) in June and 5.5 pounds (2.5kg) in December. The subsequent May colostrum yield was back up to 10.6 pounds (4.8kg). Up and down and back up again pattern.
The seasonal (photoperiod variation) differences were greater for second and later lactation cows than first lactation cows (correlations ware respectively 0.84 and 0.53).
Genetics played a strong role in overall colostrum volume produced - but, aside from that there remained a strong seasonal effect.
Thus, the authors summarized, "These data indicate that photoperiod, in some cow families, may be involved with seasonal low colostrum production in Jersey cows." p 154
Reference: Gavin, K. and Others, " Factors associated with low colostrum yield in Jersey cows." JDS Vol 101, Suppl 2, ADSA 2018 abstracts # 99 p154.