Page 69 - The Welfare of Cattle

46 the WeLfare of CattLe

known to feed on cattle include Dermacentor and Amblyomma ticks that primarily feed on cattle
during their adult stage. Heavy infestations of these ticks can reduce cattle grazing, resulting in
reduced weight gains. Cattle infested with adult Dermacentor ticks can also suffer paralysis due to
the introduction of toxins during tick feeding.
Due to their prolonged association with host animals while feeding, most ticks are primarily
controlled by application of topical acaricides to cattle and other hosts during seasons when adult
ticks are common. Leaving pastures or pens vacant of cattle and other suitable hosts has been sug-
gested for control of ticks, but this is challenging as most ticks can survive for months to years off
the host.

temporary ectoparasites

Most of the temporary ectoparasites of cattle are blood-feeding or “biting” flies. These flies
include the horn fly (Haematobia irritans), stable fly (Stomoxys calcitrans), horse and deer flies,
biting midges (Culicoides spp.), black flies, and mosquitoes. Biting flies complete their immature
development off cattle, seeking cattle as hosts only as adults to acquire protein from animal blood
during short feeding periods typically lasting just a few minutes. Biting flies often take several
bloodmeals from hosts during their adult life, with each bloodmeal usually acquired from a dif-
ferent individual animal. After acquiring a bloodmeal, most biting flies leave the host to rest
and digest the bloodmeal in the surrounding habitat. The horn fly is a notable exception to this
general life history, as these flies take many small bloodmeals from cattle each day, and rest on
their cattle hosts even when not feeding. However, horn flies disturbed by host movement and
defensive behaviors will readily fly to a nearby animal, so that bloodmeals are often taken from
different animals.
Biting flies often give sharply painful bites, using blade-like mouthparts to cut and tear through
host skin to pool blood at the wound site. This is particularly true for horn flies, stable flies, and
horse/deer flies. These painful bites often result in considerable cattle disturbance, with cattle exhib-
iting distinct bite avoidance behaviors including tail flicks, leg stamps, kicks, head throws, and
bunching. The type and frequency of bite avoidance behavior is related to the biting fly species and
the number of bites that an animal is receiving (biting rate). These avoidance behaviors increase
metabolic activity of cattle and reduce feed/water consumption, negatively impacting cattle pro-
ductivity. Some biting flies can also transmit blood-borne pathogens among cattle as they feed on
multiple animals.
The immature development site for biting flies varies by species. Of the species that develop
in cattle feces, horn flies develop only in undisturbed fecal pats, while stable flies develop in aged
cattle feces and fermenting animal feeds, particularly when animal manure is mixed with feed or
plant waste. The remaining biting flies develop in aquatic or semiaquatic habitats. A few species of
biting midges and mosquitoes can be quite numerous on cattle facilities that have wastewater ponds
or other aquatic habitats polluted with cattle feces.
Two non-biting fly species of importance to cattle production are the face fly (Musca autumnalis)
and the house fly (Musca domestica). These fly species affect cattle production by transmitting
pathogens or parasites among cattle, or by the nuisance they cause to humans who work on or live
near cattle facilities. While not a blood-feeding fly, the face fly does feed on cattle; feeding on mucus
and eye exudates. With this feeding behavior, the face fly is of particular concern as the vector of a
bacterium (Moraxella bovis) causing bovine pinkeye. The face fly, like the horn fly, develops only in
fresh cattle feces, while the house fly commonly develops in many fermenting materials including
animal feces, animal feed, and even household kitchen waste. House flies are particularly numer-
ous where cattle feces are collected and stored wet for more than a few days on an animal facility,
or where animal feces is allowed to accumulate within pens or barns, especially where manure is
wetted by animal urine, sprinkler systems, or spill from water troughs.