An alternative to drenching

If drenching fresh cows with propylene glycol to control ketosis isn't one of your favorite things to do, then a new study from PennStateUniversity may just make your day.

Researchers found that feeding 250 grams of dry propylene glycol per cow per day as a top-dress or mixed into a TMR for the first three weeks of lactation was as effective as an oral drench of the liquid form in the prevention of ketosis.

The strategy is ideal as a preventative solution for clinical or subclinical ketosis, says Gabriella Varga, PennStateUniversity animal science professor. That is, as long as you have a post-fresh pen or cows are housed in a tie-stall or stanchion barn.

Here's why you should consider feeding dry propylene glycol instead of drenching it to control ketosis.

Negative energy balance

After calving, cows often fall prey to a negative energy balance. This makes them more susceptible to a variety of metabolic diseases, including subclinical and clinical ketosis. In fact, research shows that ketosis is the most common metabolic disorder during the first 30 days of lactation.

Ketotic cows have an excessive amount of ketone bodies in their blood, urine and milk, as well as reduced blood-glucose levels. In clinical cases, you'll note rapid weight loss, appetite loss, rapid milk production decline, abnormal rumen contractions and nervous disturbances. Subclinical cows do not usually exhibit these physical signs, but they do have high levels of ketones in their body fluids.

Researchers peg the cost of subclinical ketosis at about $78 per cow per incidence. For clinical cases, the cost doubles due to body weight loss, lost production, treatment cost and premature culling cost.

To offset ketosis, you can drench prefresh cows with propylene glycol, which is an effective tool in controlling the disease. A study in the June 2003 Journal of Dairy Science indicates that a short-term drenching strategy using propylene glycol effectively decreased blood plasma nonesterified fatty acid (NEFA) concentrations during the first 21 days of lactation. And it tended to decrease plasma concentrations of beta-hydroxybutyrate (BHBA) during the first seven days of lactation. These changes led to improved cow health and productivity.

Stress reduction

However, drenching takes time. Someone skilled at the procedure can drench a cow in about 10 to 15 minutes. But the process is stressful for both people and cows. Feeding dry propylene glycol takes a mere fraction of that time, and eliminates the stress part of the equation.

In addition, research has found that one out of every 250 cows that undergoes the procedure dies from improper drenching, notes Varga. When drenched incorrectly, the liquid ends up in cows" lungs and not in the rumen. Plus, even when things go correctly, cows tend to cough up a portion of the drenching liquid, which means they don't always receive a full dose.

Comparable results

Just as previous studies discovered, the PennState researchers found that propylene glycol works. The only difference is that they used the product in dry form — at a rate of 250 grams per cow per day. The propylene glycol was fed either as a top-dress or mixed in a TMR for the first three weeks of lactation.

The findings indicate that BHBA levels were cut nearly in half, and subclinical ketosis rates dropped from 36 percent to 13 percent. Clinical ketosis cases were cut in half.

Overall mean milk production for treated cows was not different from cows in the control group. However, cows fed the dry propylene glycol, over time, did show improved performance versus control cows. Treated cows got off to a better start, which resulted in a more productive lactation and higher feed intakes, says Varga.

Dollars and cents

If dry feeding propylene glycol prevents just one case of subclinical ketosis, the program is cost-effective, says Varga. "If ketosis is reduced by at least 25 percent in the herd, the protocol more than pays for itself," she adds. (At least it was at the time of the study earlier this year. Rising propylene glycol cost, due to increased petroleum cost, may increase that goal level, so you'll need to pencil out the economics on your dairy.)

Penn State scientists are now looking to determine if dry pure glycerin, a byproduct of biofuel production, may provide a worthy and more cost-effective alternative.

One caveat: Producers with free-stall operations that do not have a separate post-fresh pen should not use the dry feeding practice, as it is not economically feasible.

However, for tie-stall barns or those of you with a separate post-fresh pen, the researchers do recommend feeding dry propylene glycol as an effective ketosis preventative measure. Just remember that it does not replace fresh-cow monitoring as part of a regular fresh-cow program. "Any fresh-cow program should still contain a follow-up protocol," Varga concludes.

The researchers are finishing up one last leg of this research before it is published in the Journal of Dairy Science. They are performing a direct comparison of the propylene glycol delivery methods — oral drench, as part of a TMR and pulse-dose which is directly infused into the rumen of cannulated cows — to determine the metabolic adaptation of cows to propylene glycol and how they respond to the different delivery methods.



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