Ectoparasite Control in Cattle.

 By Nick Wagner, DVM. Article courtesy of Neogen.

 Ectoparasite control in cattle production requires the implementation of management practices to maintain animal health, to optimize performance, and to provide a comfortable environment to achieve success.  Ectoparasites are pests such as insects that are external to the host species and predominantly affect the skin and hair of the animal.  Ectoparasites in cattle can include flies, lice, mosquitoes, mites, and ticks.  Despite the life cycles of these pests occurring external to the animal, their overall impact results in diminished productivity that costs the cattle industry millions of dollars annually.  Each cattle operation will encounter unique challenges with variation resulting from geographic location, seasonal occurrences, and differences within the implemented production system.  Identifying the ectoparasites that may challenge your herd and understanding their life cycles are the key to implementing an effective control program and protecting profits.

Common ectoparasites that impact the cattle industry are horn flies, face flies, stable flies, house flies, horse flies, heel flies or cattle grubs, mosquitoes, lice, mites, and ticks.  These pests are responsible for transmitting disease, reducing production parameters such as weight gain and milk yield, disrupting animal comfort and behavior, serving as a challenge to on-farm food safety with dairies, and acting as a nuisance to personnel living and working in rural communities.  For example, a decrease in milk production for beef cows nursing calves could significantly impact weaning weights. Further, if the disruptive nature of these pests results in variations in the nutritional intake patterns of growing cattle this could significantly impact daily gains and increase their susceptibility to disease.  Therefore, it is quite evident the significant impact that this can have on the profitability of your herd.  As colder weather approaches, here is a closer look at the anatomical predilection sites, life cycles, production system pressures, and seasonal occurrences of the common ectoparasites that may target your herd.

Lice and mites are top of mind as temperatures start to drop in most areas. Lice and mites complete their life cycle, including the developmental stages, entirely on the host animal.  Both tend to be more prevalent during the cooler months of the year although their presence can occur throughout as well.  The life cycle of lice and mites can be completed in days to weeks.  Cattle are affected by both chewing lice and sucking lice.  The chewing lice consume hair and scaling skin whereas the sucking lice consume blood.  Mites are also present on the skin surface at the base of the hair however some species prefer to burrow into the skin of the host animal.  Lice have a predilection for the face, neck, shoulders, back, and tailhead of the animal.  Lice and mites cause irritation, itching, and crusting of the skin in addition to hair loss ultimately resulting in detrimental impacts on performance.  With a better understanding of the common ectoparasites that target cattle, producers can develop and implement effective integrated pest management control programs specific to their operations to protect those hard-earned assets.

An effective integrated pest management control program for ectoparasites in cattle should consider cultural, biological, and chemical measures.  Cultural control involves managing the environment on your operation in an effort to reduce or eliminate propagation areas for these pests.  For example, the removal of manure, stagnant water sources, or other decomposing organic material will assist in preventing an environment that is conducive to the development of flies and mosquitoes.  Biological control involves the utilization of other organisms through the principle of competitive exclusion or predatory action to interfere with pest development.  For example, the presence of an adequate population of dung beetles will assist in manure management which diminishes the available media present for flies to complete their development.  Chemical control involves the utilization of pesticides either on animal or in the environment to destroy these pests.  For example, this involves the use of topical sprays, pour-ons, back rubs, dusts, chemical formulated ear tags, feed additives, and injectables to directly treat cattle or chemicals to treat the premise for the purpose of destroying these pests.  When selecting chemical control, consideration should be given to the active ingredients and their mode of action.  Options might include active ingredients such as pyrethroids or organophosphates that destroy adults, insect growth regulators such as diflubenzuron or methoprene that inhibit developmental stages, or synergists such as piperonyl butoxide that enhance the potency of an active ingredient by diminishing the natural defense mechanisms of the pests.  Further, it is important to also consider that pesticide resistance may be present in ectoparasite populations in various geographic locations.  Therefore, a chemical control strategy that rotates between classes of pesticides is recommended.  In evaluating the status of your herd, the utilization of established economic thresholds for specific pests is a valuable tool.  An economic threshold is the level at which an infestation is impacting animal health and welfare resulting in financial loss realizing that specific pests may have a lower threshold population than others.  When a decision is made to proceed with chemical control, labor considerations will be a factor in selecting the appropriate pesticide product to provide proper coverage given the prolific and repetitive nature of the life cycles involved.  For example, the ease of cattle handling is different between many beef operations and dairy farms based on the production systems in place therefore this impacts the evaluation of topically applied pour-ons and sprays versus self-application products in finalizing a selection.  In addition, always read and follow label directions for EPA registered pesticide products approved for the specific use that meets your needs.  This is especially true to ensure the safety of both animals and personnel and to avoid any meat or milk residues.  A perfect solution does not exist however with the proper identification of the pest or pests impacting your herd, you will be able to implement the appropriate control measures targeting both adults and developmental stages with the proper timing and duration to achieve optimal results.  Dedicating the necessary attention to ectoparasite control will pay dividends.