The average dairy cow in the U.S. today produces about 2.8 lactations before she is removed from the herd and replaced with a younger counterpart. As a result, more than one third of the total U.S. lactating dairy population is made up of first-calf heifers.
That’s not a completely bad thing, according to Dr. Alvaro Garcia, feeds specialist, nutritionist and cattle management consultant for Dellait Animal Nutrition and Health.
“Younger cows are often more genetically advanced and economically efficient,” Garcia notes.
But those young lasses do lag behind their more seasoned herdmates in a number of other aspects that influence herd success, specifically:
(1) Colostrum volume and quality – Garcia said younger cows usually produce less at first milking, and research has shown their colostrum contains 30% to 50% less IgG than mature cows. Low-quality colostrum results in higher rates of failure of passive transfer (FPT) of immunity in calves. FPT is a handicap to calves in both the short and long term.
Affected animals may be weak, have poor suckle reflex, and have greater susceptibility to infections causing diarrhea, pneumonia, and septicemia. In the long game, these calves often have reduced average daily gain, poorer feed conversion, delayed puberty, lower first-lactation milk yields and are likely to be culled earlier.
(2) Calving challenges – First-calf heifers are more prone to dystocia due to their smaller pelvic size and inexperience. The result can be oxygen deprivation in calves and a greater likelihood they will become injured or die during birth.
(3) Mothering deficiencies – After their first delivery, young heifers often exhibit poorer maternal behavior like cleaning off their calf. Garcia says this can lead to delayed bonding and thermoregulation.
(4) Multiple nutrition demands – Because heifers are still growing at the time their first calf arrives, nutrient partitioning may favor their own development, impacting colostrum production and threatening calf vitality.
First-time bovine moms are asked to do a lot of novel things in a small amount of time. With these multiple new demands hitting them all at once, it’s no wonder they lag behind in the colostrum department.
“Colostrum from first-lactation cows should never be used without testing,” Garcia says. “If it falls short, it should be blended with higher-quality colostrum from older cows or supplemented with IgG replacers.”
Additionally, he advises dairies to maintain a reserve bank of high-quality, frozen colostrum, ideally sourced from older cows. He also emphasizes the importance of milking fresh cows within two hours of delivery, before colostrum becomes diluted with transition milk.
Finally, Garcia says ongoing herd surveillance for passive transfer of immunity is critical for all dairy herds, but especially young herds. When evaluated at 24 to 48 hours of life, he suggests calves show serum total protein of 6.2g/dL or Brix score of at least 8.4% for adequate transfer.
“If more than 10% of calves fall below this threshold, it is a sign that colostrum protocols need urgent revision,” he states.
Your Next Read:
California’s Dry Dilemma: No Clear Winners in the Battle for Water Conservation
