One of the most vulnerable times in a dairy cow’s lactation is also one of the most physically demanding.

Dairy cows deserve a lot of attention when transitioning, said Patrick Gorden, DVM, clinical professor at Iowa State University’s College of Veterinary Medicine, at the Midwest Dairy Day held Dec. 1 at the Iowa Dairy Center, Calmar, Iowa.

“We need to have an appreciation for this metabolic machine during the most difficult time of her life,” Gorden said.

There is so much more going on than just delivering a calf. According to Gorden, during the period of time just before and after giving birth, transition cows must:

• Acclimatize to a new ration and a new energy level
  
  
• Adjust to a new social order
  
  
• Reduce the size of the uterus within hours of calving
  
  
• Have adequate energy in the face of reduced dry matter intake, which usually requires metabolizing fat

The cow must also mobilize sufficient glucose and calcium not only for calving and body maintenance but also to start milk production, Gorden said.

“It’s very important to understand the impact of metabolic disorders,” he said. “Cows that lose too much body condition or undergo significant transition disease challenges are simply harder to breed back.”

A good transition program will improve both milk production and reproduction.

Focus on prevention

“Prevention of metabolic disorders is key,” Gorden said, emphasizing the importance of adequate space for eating and resting. Providing 30 to 36 inches of bunk space is a must for both prepartum and postpartum cows. Remember, large pregnant cows take up more space, and housing should only be filled to 80 percent capacity.

Also, keep the number of pen moves to a minimum for transition cows, and avoid putting first-lactation cows in pens with older cows immediately prepartum and postpartum.

Calving impacts immunity

Calving and starting lactation also affects the cow in several more ways, Gorden said. The high levels of cortisol released during the calving period have “a dramatic negative effect” on the cow’s immune system by reducing white blood cells, specifically neutrophils. The negative energy balance often experienced in postpartum also negatively influences the white blood cells which fight infections. Dutch studies have found ketosis further negatively impacts neutrophil function.

Gorden cited research stating the length of negative energy balance experienced correlates with the severity of immune system suppression. There is also a connection between the suppression of the immune system’s white blood cells to the severity of mastitis in non-ketotic cows.

Cows with uterine health issues initially have lower dry matter intake (9.7 pounds less) versus healthy cows at one week prepartum, and they continue to exhibit decreased feed intake of 5 to 8 pounds through five weeks after calving.

Gorden said in this particular study researchers associated time spent eating and dry matter intake on the impact of development of metritis (an inflammation of the uterus caused by bacterial infection). Cows with metritis spent 22 fewer minutes a day feeding. “For every 10-minute decrease in feeding time, cows were twice as likely to be diagnosed with metritis,” he said.

Fresh cow monitoring

Gorden said investing the time and effort into fresh cow monitoring will result in improved milk production, reproduction rates, cow health and profitability. Areas to focus include dry matter intake, milk deviations, fat-to-protein ratios and diagnostic testing such as blood beta-hydroxybutyrate acid (BHBA), non-esterified fatty acids (NEFA) and calcium levels.

Dry matter intake is very important when it comes to pre-fresh and fresh cows, and should be monitored closely. If dry matter intake decreases in the two weeks before calving, the risk of postpartum infection increases. “However,” Gorden said, “dry matter intake can be difficult to accurately monitor in pre- and post-fresh pens due to calving activity.”

Another useful tool for diagnosing metabolic problems is milk production deviations. Pay attention to what your activity and milk monitoring systems are telling you, he said.

All dairy producers on DHI testing programs could check milk fat-to-protein ratios on postpartum cows, which ideally should be 1.4 to 1 or less on an individual basis. Ketotic cows tend to have a higher fat test. Gorden said this metric is not an absolute but rather an indicator that further investigation is warranted.

Fresh cow monitoring could also include the detection of ketone bodies, primarily BHBA, due to available cowside tests. Ideally, the test should be done four to five hours after feeding on cows five or more days fresh. “Our current cut-point for treatment interventions are greater than 14.4 milligrams per deciliter. However, it is important one of the highest risk factors for the development of ketosis is high milk production,” he said. “Therefore, it is really important to evaluate the cow as a whole.”

Herds with BHBA problems in the post-fresh period should do further testing to determine the source of their problems. Pre-fresh cows can have a NEFA test done, looking for negative energy balance.

NEFA testing measures the fat in the blood that has been mobilized for energy usage. Gorden recommended testing two to 14 days before calving, ideally at feeding time for peak concentration. Prepartum NEFA levels should be less than 0.4 mEq per liter, and postpartum levels should be less than 0.6 mEq per liter. However, once the results are received on prepartum cows, look at calving dates to make sure none of the cows tested subsequently calved within two days of blood collection.

When herd monitoring, Gorden recommended testing at least 12 cows to have fairly high confidence in the test results. If more than 10 percent of cows have elevated BHBA or NEFA results, there is cause for alarm.

High NEFA levels are also associated with increased risk of displaced abomasum, retained placenta, metritis and subclinical ketosis – all of which lead to an increased risk of early culling from the herd and lower milk production. He noted in a problem situation, the extra work and costs of testing are definitely worth it. A case of milk fever costs at least $100 per cow, and ketosis is more in the range of at least $200 to $300, and all metabolic disorders can have an effect on your overall reproduction rates.  

PHOTO: Dr. Patrick Gorden says investing the time and effort into fresh cow monitoring will result in improved milk production, reproduction rates, cow health and profitability. Photo by Chris Gannon.

Kelli Boylen is a freelance writer based in Waterville, Iowa.