Profits Are Long Lost By the Time Parasite Symptoms Appear

Published on: 11:07AM Dec 20, 2010

Taking a proactive approach by treating for internal and external parasite control can preserve cow comfort and production.

Merial   Frank Hurtig5   sm
Merial's Frank Hurtig
Dairy cattle preoccupied with scratching and itching mange or lice won’t be counted among top producers this winter, even if a rescue attempt is made. Mange and lice prosper in fall and winter, taking advantage of cool, dark weather and bunched cattle to reproduce and spread. While producers may not initially notice an infestation, the parasites are likely already doing damage.
“By the time cattle show hair loss, excessive scratching and other telltale signs of external parasites, the economic damage has been done and the large parasite populations can make treatment challenging along with the need for healing of damaged skin,”1 says Dr. Frank Hurtig, director, Merial Veterinary Services.
Taking a proactive approach by treating for internal and external parasite control can preserve cow comfort and production.
“Feed consumption — and, therefore, milk production — suffer when dairy cattle are dealing with external parasites,” Hurtig says. “Cattle are more concerned with rubbing and itching than eating.”
Cattle treated for Chorioptic mange have shown a 3.3 lb./day increase in milk production while those treated for Sarcoptic mange saw daily milk production increased by 4.4 lb./cow/day.2,3
“Close proximity in barns and dry lots make transmission between animals highly probable, putting the entire herd at risk,”1 Hurtig says.
Symptoms of internal parasites are possibly even less visible to producers. But, Hurtig says, addressing internal parasites in the fall is just as important.
“Dairy cattle are most vulnerable to parasite infections during early lactation when stress leads to a negative energy balance,”4 says Hurtig. “Subclinical infections can cause decreased milk production, reduction in weight gain and lowered conception rates.4
He adds that in young replacement cattle, parasites can even delay entry into the herd and impact lifelong production.1 And that means it takes more time to recoup the estimated $1,200 to $1,500 spent developing a heifer.5
Studies have shown marked increases in milk production in treated cattle. One study showed a 4.8% increase in milk production following treatment for internal parasites.6
Another study showed dairy cattle with subclinical parasite burdens that were treated with eprinomectin at calving produced 2.07 lb. more milk per day the first six months of lactation than a placebo group.3 That’s more than 370 additional pounds of milk production.
Dr. Hurtig recommends treating the entire herd in late fall with an endectocide that controls Chorioptic and Sarcoptic mange, biting and sucking lice, and internal parasites.
“Producers should make sure they’re using a product that effectively controls internal and external parasites and that is approved for lactating cows to avoid milk withholding,” Hurtig says.
He warns producers also should take precautionary steps when introducing new cows to their herd. Isolating all incoming cattle and treating them for internal and external parasites before introducing them to the main herd can help prevent reinfestation of a treated herd.
“Never assume your herd is parasite-free just because you can’t see outward signs of parasitism,” advises Hurtig. “Taking a proactive approach to parasite control helps ensure cattle will be comfortable, be efficient and produce to their full potential.”
Contact Dr. Hurtig at [email protected].
®EPRINEX and IVOMEC are registered trademarks of Merial Limited. ©2010 Merial Limited. Duluth, GA. All rights reserved.
1Rutz DA, Geden CJ. Pest Management Recommendations for Dairy Cattle. Cornell and Penn State Cooperative Extension.
2Schonberg J, Ilchmann G, Schein E. Eradication of Chorioptic mange in a grazing dairy herd with Eprinex Pour-On.  Berl Munch Tierarzt Wsch 2000;112:144-148.
3Nodtvedt A, Conboy G, Dohoo I, Sanchez J, Keefe G, Descoteaux L, Leslie K, Campbell J. (2001) The Effect of IVOMEC® EPRINEX® On Milk Production in Pastured Dairy Cattle. 46th annual meeting of the American Association of Veterinary Parasitologists. Boston, MA.
4Gadberry S, Pennington J, Powell J. Internal Parasites in Beef and Dairy Cattle. University of Arkansas Cooperative Extension Service. FSA3045.
5Gooding RC, Dechow C. When Dairy Cows Leave Too Soon. The Dairy Focus. 2007; 8(1):7.
6Spence SA, Fraser GC, Dettmann EB, Battese DF. Production responses to internal parasite control in dairy cattle. Aust Vet J 1992;69(9):217-220.