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FT. ATKINSON - Cows in transition are dealing with a catabolic Armageddon.

That makes understanding the impact, monitoring and management of the transition period of vital importance, Dr. Daryl Nydam, Cornell University, said during the June Hoard's Dairyman webinar.

The presentation, co-hosted by Corey Geiger, Hoard's Dairyman, and Dr. Mike Hutjens, University of Illinois, was sponsored by Cargill.

Calving brings on a host of challenges a dairy cow must deal with, Nydam said, including negative energy and protein balances, mineral imbalances and social pressures.

In particular, transition sparks a rapid change in her metabolic demands, causing energy requirements to double in very short order. Two days before calving, a cow's energy requirements are about 14 Mcals, compared to over 28 Mcals two days after calving.

"That's like you or I sitting on a couch and jumping up to run a marathon, without training," Nydam observed. "These modern dairy cows are indeed metabolic athletes."

However, that spike in energy demands, which cannot be met by intake alone, can set the stage for hyperketonemia or subclinical ketosis (SCK), which has impacts on milk production, treatment costs and culling rates.

In one study of 1,700 cows in New York and Wisconsin, 741 animals had at least one bout of ketosis, with herd levels ranging from 26 percent to as high as 56 percent. Most of the cases occurred at three to five days in milk (DIM), with few cases occurring after a week in milk.

"This was pretty interesting to me. It was not what I expected," Nydam said.

The study concluded that SCK happens in early lactation, and cows that get it then are at much higher risk for adverse events than those that get it later on.

"We now know that this affects lots of cows and the outcomes are pretty bad when it happens," Nydam said.

The average case takes about five days to resolve. Research puts the total average cost per case of hyperketonemia  (BHBA above 1.2 mm/L) at nearly $300. Of that, 34 percent is for reproductive losses, 26 percent for death losses, and 26 percent for future milk production losses.

Nearly 90 percent of displaced abomasum cases are attributable to hyperketonemia, as are 70 percent of metritis cases.

"And if this is something that's happening, on average, to 40 percent of cows, it turns out to be a pretty big deal, something we can turn our attention to and allocate resources to, to either prevent or treat," Nydam pointed out.

Treating ketotic cows

When using 50 percent dextrose to treat clinically ketotic cows, Nydam advised 125 g (1/2 bottle) by IV when the BHBA is at or above 3.0 mmol/L.

Propylene glycol  (PG) is a "pretty good" approach, Nydam said, advising 300 mL given orally once a day for five days when the BHBA is at or above 1.2 mmol/L.  PG offers two modes of action: an increased supply of propionate (glucogenic) and an insulin surge.

A randomized trial to determine the effect of oral PG administration in cows diagnosed with SCK in early lactation found cows treated with PG were 1.5 times more likely to resolve their SCK than the control cows and they produced, overall, about a pound of milk/cow/day more than the control cows.

Cows that did not get the oral PG when they needed it (control cows) were 60 percent more likely to develop a DA, and 2.1 times more likely to be removed from the herd by 30 DIM.

"Pretty profound effect there, as well," Nydam said.

The study concluded administering oral PG speeds resolution of ketosis, prevents progression to severe ketosis, and increases early lactation milk yield in some herds. It remarkably reduces the risk of DA and of premature culling.

"We found out oral PG really does help," Nydam said. 

Herd approach

Bear in mind that the incidence of subclinical ketosis is about two times the prevalence, Nydam said, noting positive cows have a BHBA at or above 1.2mmol/L.

Based on an economical analysis, Nydam advises monthly monitoring if the herd level prevalence is less than 15 percent (3 or less cows/ 20 cows). Sample about 20 cows each month and more frequently when there are changes, such as diet formulation.

If the herd prevalence is between 15 - 40 percent (4 - 8/20 cows), the approach switches to test and treat. Monitor the incidence of SCK, Nydam advised, by sampling cows 3-9 DIM twice a week, such as on Tuesdays and Fridays. Treat the positive cows and work on preventative measures.

If 40 percent or more (9+/20 cows ), the cost-effective approach for the short term is probably to treat all cows. Give 300 mL of propylene glycol once daily for five days starting at 3 DIM to all cows. Recheck the prevalence in one month.

Preventing ketosis

To stifle the incidence of ketosis, Nydam advised focusing on access to feed, crowding and social dynamics. Make sure there are 30 inches of linear feed space or 80 percent of headlocks or stalls. Keep group and pen changes to as few as possible, and separate first parity cows from older cows.

The energy density of dry cow rations, especially far off, are also critical. The guidelines are 0.6-0.63 Mcal/lb NEL, 12 - 16 percent starch, 40 - 50 percent forage NDF, and 15 - 18 Mcal/d for far-off and close-up cows.

Other important considerations are feeding rumensin, perhaps feeding rumen protected choline, and focusing on heat abatement, Nydam said. Other products that affect NEFA metabolism and/or liver physiology and support immune function, such as yeast products, might also be fed.

Dairy cows face big challenges in transition, but being mammals, it is normal and natural for them to visit a state of negative energy balance in early lactation. "We just want to keep that visit short and the depth of it pretty small," Nydam said.

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