Cutting Edge

FDA Approves Dectomax-CA1 for Prevention and Treatment of New World Screwworm

In late September, the US Food and Drug Administration conditionally approved Dectomax-CA1 (doramectin injection) injectable solution for the prevention and treatment of New World Screwworm larval infestations, and prevention of NWS reinfestation for 21 days.

According to Zoetis, this conditional approval applies to beef cattle, female dairy cattle less than 20 months of age, pregnant beef cows, newborn calves, and bulls. “We understand the urgency with which America’s farmers and ranchers are asking for tools to fight New World Screwworm,” says FDA Commissioner Marty Makary, MD, MPH in a press release. “Today’s conditional approval — the first in the US for NWS — shows our dedication to rapidly advancing important animal medicines when they are needed most. We continue to work tirelessly to complete review of other NWS products to protect multiple animal species in the US.”

Dectomax-CA1 is eligible for conditional approval because it is intended to prevent and treat a serious or life-threatening disease in cattle, it addresses an unmet animal health need, and demonstrating effectiveness of the drug would require complex or particularly difficult studies.

“Under this conditional approval, the FDA has determined the drug is safe and has a reasonable expectation of effectiveness. We are making this treatment available to cattle producers immediately while the sponsor collects the data needed for a full approval,” says Timothy Schell, PhD, acting director of the FDA’s Center for Veterinary Medicine. “The FDA will continue to expedite review of animal drugs to help the US fight this devastating threat to our nation’s livestock and the livelihoods of the farmers and ranchers who care for them.”

Dectomax is already fully approved under a New Animal Drug Application for treatment and control of certain nematode and arthropod parasites in cattle and swine. Dectomax and Dectomax-CA1 contain the same active ingredient (doramectin injection) at the same dose. Because the original approval of Dectomax included adequate target animal safety studies, manufacturing information, and human food safety information, the FDA did not require new information to support those aspects for the conditional approval of Dectomax-CA1.

“New World Screwworm has the potential to bring unprecedented economic and animal health harm to livestock producers,” says Mike Lormore, DVM, MS, MBA, director of cattle and pork technical services at Zoetis. “Our top priority is to support keeping animals healthy and provide timely, efficacious solutions to our customers and partners. With this conditional approval, Dectomax-CA1 Injectable can now be used as part of safe, effective control measures against New World Screwworm.”

The withdrawal period for cattle is 35 days for Dectomax-CA1, as it is for Dectomax. Warnings to prevent drug residues in meat from treated cattle are the same for Dectomax-CA1 as for Dectomax: Not for use in female dairy cattle 20 months of age or older. A withdrawal period has not been established for this product in pre-ruminating calves. Do not use in calves to be processed for veal.

In the first half of 2026, producers and veterinarians will begin to see the 250-milliliter and 500-milliliter bottles of Dectomax Injectable with a new label for Dectomax-CA1 (doramectin injection). Dectomax-CA1 is the same effective doramectin formulation as Dectomax Injectable. Dectomax-CA1 label will contain both Dectomax and Dectomax-CA1 indications while each drug has a unique application number.

To reduce the risk of antiparasitic resistance and preserve drug effectiveness against other parasites, producers and veterinarians are encouraged to use antiparasitic drugs like Dectomax-CA1 only when medically necessary, in accordance with the product labeling, and as part of a comprehensive parasite management strategy.

Livestock producers are encouraged to work closely with their herd veterinarian to implement strategic prevention and control measures. Visit Zoetis’ website for more information about Dectomax-CA1.

The Effects of Aging Period and Freezing Sequence on Consumer Palatability Ratings, Tenderness, and Color Stability of Longissimus Dorsi, Semitendinosus, and Biceps Femoris Steaks

Kansas State University

The objective of this recent Kansas State University study was to examine the effect of freezing and aging sequence on palatability, overall tenderness, and objective color readings of three different beef muscles and two aging periods.

The longissimus dorsi (LD; ribeye), semitendinosus (ST; eye of round), and biceps femoris (BF; bottom round) were fabricated into one-inch steaks, and assigned to one of the following treatment combinations: age (21 days) then freeze, freeze then age (21 days), age (28 days) then freeze, or freeze then age (28 days). Consumers evaluated samples for flavor, juiciness, tenderness, overall liking, and acceptability for each sensory trait. Samples designated for Warner-Bratzler shear force (WBSF) were allowed 20 minutes to bloom for raw color evaluation and then cooked for analysis.

The freezing treatment or aging period did not impact (P > 0.05) consumer sensory rating of tenderness, flavor, or overall liking. The consumers rated the ribeye as the juiciest (P < 0.05) compared to the eye of round and bottom round. As expected, the ribeye resulted in the highest (P < 0.05) tenderness rating for the consumer. The ribeye had the lowest (P < 0.05) WBSF values, indicating it was the most tender. Within flavor, the consumers rated the ribeye as the most flavorful (P < 0.05) followed by the eye of round, and then the bottom round. For raw and cooked color, the L* (lightness) values differed (P < 0.05) between all main effects, including freezing treatments (Age Freeze > Freeze Age), aging periods (21 days > 28 days), and muscle (ST > LD > BF). These results showed freezing and then aging or aging and then freezing does not affect palatability or shear force values. This indicates that reversing the freezing order is not an effective way to improve the tenderness of historically tough muscles.

The bottom line: The results indicate reversing the typical age and freezing order does not improve tenderness and therefore is not a valid way to improve palatability of historically tough muscles.

The full report is available at newprairiepress.org.

Feedlot Production Continues to Decline

by Derrell S. Peel, Oklahoma State University Extension

The September 1 feedlot total was 11.08 million head, down 1.1% year-over-year and the tenth consecutive monthly decrease compared to one year earlier. Feedlot inventories continue to decline slowly. Average inventories the past year are down just 3.1% from the peak in 2022, but the September 12-month moving average is at the lowest level since January 2019. With the September on-feed total up slightly from the previous month, the August total was likely the seasonal low for the year. The feedlot inventory on August 1 this year was the lowest monthly inventory since October 2017.

Total feedlot production is declining more rapidly than the slowly declining feedlot inventories would indicate. Feedlot placements in August were 90.1% of last year and the smallest August placement total since 2015. Figure 1 shows the relative comparison between 12-month moving averages of cattle on-feed and feedlot placements. Placements have declined more than the on-feed inventory up to this point, aided by a slower turnover rate in feedlots.

 

August marketings were down 13.6% compared to last year. Feedlot marketings for the first eight months of 2025 are down 5.4% year-over-year. Average feedlot marketings the past year are down 8.2% from peak average marketings in 2022. Smaller calf crops and limited feeder cattle supplies mean there are fewer cattle available for feedlot production. Feedlot production and beef production are expected to continue to decline into 2027.

The Impact of Degree of Doneness, Muscle Source, and Bloom Time on Cooked Color and Cooked Color Stability

Kansas State University

This recent Kansas State University study examined the differences in color stability among three different muscles cooked to varying degrees of doneness by taking color readings at four different time points. Steaks from longissimus lumborum (LL), psoas major (PM), and semitendinosus (ST) were cooked to medium rare (MR), medium (MED), or well done (WD) degree of doneness (DOD). Color was measured at zero, three, six, and nine minutes to observe color stability changes.

There was an interaction (P < 0.05) between DOD and muscle for L* (lightness) readings. The ST had the highest L* reading within the MR and MED DOD followed by the LL; however, there were no differences between muscles (P > 0.05) within the WD DOD. The zero-minute readings had a lower (P < 0.05) L* reading in comparison to nine minutes, while not being different (P > 0.05) from three or six minutes. Similar to the L* readings, there was an interaction (P < 0.05) between DOD and muscle for a* (redness) readings. Within the MED DOD, the ST had the highest (P < 0.05) a* reading, followed by the LL, while the LL had the highest (P < 0.05) a* reading within the MR and WD DOD. There was an interaction (P < 0.05) between DOD and muscle and DOD and time for the oxymyoglobin (OMb, indicates color stability) percentage. Within the MR samples, the LL and ST muscles resulted in similar (P > 0.05) OMb percentage. The MR DOD had the highest (P < 0.05) OMb percentage for three, six, and nine minutes, while the zero-minute readings for MR and MED were similar (P > 0.05) and higher (P < 0.05) than alltime points for the WD DOD.