What if you could predict the potential a heifer may have for reduced milk production due to calf-hood respiratory challenges long before she ever freshened?
Dr. Elizabeth Adams, a consulting veterinarian in California, hopes her research will make it possible someday.
Adams, a recent graduate of the UC – Davis School of Veterinary Medicine, has been using ultrasound technology to assess the lung damage heifers may have experienced from early bouts of pneumonia on her clients’ dairies.
“With this research, I am trying to prove that calves who suffer pneumonia at a young age will produce less milk when they become cows,” Adams says.
For the past two years, Adams has been studying her theory on three California dairies, testing more than 300 calves, so far, at 3 months old.
Research at her alma mater and other veterinary institutions shows that calves who have had pneumonia produce less milk later in life compared to calves that have not had pneumonia. Adams wants to correlate the severity of damage from pneumonia with a quantifiable decrease in milk production.
To do this, she has developed her own system to score the health of calf lungs. She uses ultrasound to analyze the amount of scarring present in a calf’s lungs.
“In order to perform an ultrasound, the hair on each side of the chest of each calf must be clipped down to the skin,” Adams says. More specifically, she says, the clipping should be done from the third rib to the ninth rib, the area of the lung field.
She then applies alcohol on the skin and uses the same rectal probe she uses for pregnancy diagnosis to scan the lungs of the calf. She scans each lung looking for scar tissue, which appears as white streaks or shades of gray on an ultrasound.
“As the immune system is fighting an infection, it will lay down scar tissue within the lungs,” Adams says. This is especially true in calves under 3 months old.
Adams says the ultrasound enables her to confirm which calves have previously had pneumonia. But her work aims to go beyond just confirmation of a previous pneumonia case.
The industry does not currently have a published rating scale to rank the level of scarring or damage found in calf lungs. As part of Dr. Adams’ research, she proposes to create a four-level scale for lung scores.
A score of one would be a normal lung with no scarring present during an ultrasound; a score of four would show severe scarring on ultrasound.
“The majority of the lung scores are either a one or two,” Adams says. However, Adams is still researching whether there is a significant, measurable difference in future milk production between calves with either of the two scores.
“I would not recommend that a producer looks for the abnormal conditions through the ultrasound device on their own,” she says.
Adams learned what to look for during her first year of vet school and has had a lot of practice since then. However, she says, a dairy producer’s veterinarian, even one without formal ultrasound training, could do an ultrasound lung assessment.
Danny Avila, dairy manager on Clauss and Sunwest Dairies in Hilmar, California, says Adams’ research is a multi-year trial that is just getting going.
“I think we’re going to get a lot of great information in regards to health and possibly the future milk production of the calves we study. If we find that an animal has pneumonia and give it a vaccination, we can look to see how well the vaccination worked with the ultrasound,” Avila says.
One of the applications of Adams’ work could be to evaluate the quality of replacement heifer care. As many dairymen do not raise their own calves, they often wouldn’t know if a calf had pneumonia while raised off-site.
This could be a tool for producers to use when making decisions about where to send their heifers to be raised. The technique could also be used to cull heifers with lung scores of three or four that are not worth the continued investment to raise.
“We can make an educated decision on which animals we should sell or which animals we shouldn’t treat anymore,” Adams says.
Adams says it’s a fast, inexpensive way to get a lot of information which doesn’t cause any pain for the calf and is great for the producer. Her research will continue for two more years through the heifers’ first lactation before she will be able to report how lung scores correlate to potential milk production decreases. PD
Dr. Elizabeth Adams wants to correlate the severity of damage from calf-hood pneumonia with a quantifiable decrease in milk production.