Research Note

Transition Hypocalcemia:
Rumination Time for Very Early ID of Cows at Risk

Data generated from ear or neck loggers used for cow feeding and management also shows rumination time (RT). A closer look at RT — especially during the first four days-in-milk (DIM) — can help identify dyscalcemic cows.

If cows experience subclinical hypocalcemia at DIM 4, then it’s putting them at risk for reduced milk production and feed intake. It’s also negatively impacting reproductive outcomes and increasing their risk for other health disorders.

Rumination time correlates with good cow health and performance, notes the University of New Hampshire’s Dr. Claira Seely. Today, she says, precision technologies “cow-side” generate huge amounts of data that can help predict health and performance at the individual, group, and herd level.

For example, automatic measurement of RT by means of ear tag or collar radio frequency transponder systems such as SCR Dairy and others, have the potential to help differentiate cows with dyscalcemia from normocalcemic cows.

“RT data is especially valuable during transition,” Seely says. “Given an individual farm’s baseline for RT immediately after calving — say 400 minutes per day at DIM 1 — you can watch for RT to increase through DIM 4. At that point, if RT is not increasing beyond the normal baseline, there may be a problem with transition, and the cow may be dyscalcemic.”

Previous research indicates negative production and health outcomes associated with reduced blood calcium at DIM 4, when the cow’s biology fails to meet the increased demands for calcium required of early lactation. Ultimately, the healthy, lactating cow ought to budget RT around 460-540 min/day, earlier research suggests.

Other researchers have used reduced RT to diagnose metritis, ketosis, and displaced abomasum in early lactation cows and noted how a dip in RT over as little as two days could presage disease.

Rumination time (A) and activity time (B, including lying, feeding, standing) in multiparous cows with and without dyscalcemia in early lactation (n = 182; asterisks show P ≤ 0.05; error bars represent 95% CI).

However, no one had yet looked closely at early transition RTs for signs of incipient subclinical hypocalcemia.

Seely’s recent research found differences in postpartum RT and AT between dyscalcemic cows and those that remain eucalcemic.

“On the farm, using activity and rumination time data in the immediate postpartum period can help identify cows with dyscalcemia very early in transition.

“First, know the farm’s baseline RT for optimal transition and lactation, then look at individual cows and groups for RT up through DIM 4. Pay attention to the outliers.”

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