Page 64 - The Welfare of Cattle

CattLe eCtoParasItes 41

table 6.2 Production System Characteristics affecting ectoparasite Impacts
System Characteristics extensive Intensive
Presence of pasture habitat Yes no
habitat shared with wildlife Yes no
density of cattle Low high
Cattle feed stored on site no Yes
Cattle manure collected and stored on site no Yes
herd manager interaction with cattle Low high
easy application of insecticides to cattle no Yes

(b) sharing of habitat with wildlife, (c) density of cattle in a pasture or pen, (d) storage of cattle feed
and supplemental rations on site, (e) collection and storage of cattle manure on site, (f) frequency
of interaction between herd managers and cattle, and (g) ease of implementing ectoparasite control
including the application of insecticides to animals (Table 6.2).
While the decision to design and operate a cattle facility as an extensive or intensive production
system is not likely to be driven solely by concern over ectoparasite effects on cattle, it is nevertheless
important to consider ectoparasite impacts and management when considering design and opera-
tional parameters. Neither production system is the “best” one for management of all ectoparasites.
Each production system provides advantages to some ectoparasite species while disadvantaging
other species. Absent any pest control measures applied by herd managers, the presence and
abundance of ectoparasites on a cattle facility will be related to the availability of immature devel-
opment habitat, survival of ectoparasites when off the host, and the opportunity for ectoparasites
to acquire a new host whenever needed for feeding. In addition, a herd manager trained to rec-
ognize ectoparasites and effectively apply control measures can reduce or even eliminate some
ectoparasites even when production system characteristics might seem ideal for the ectoparasite.
The presence of suitable immature development habitat is perhaps the most important cattle
system characteristic to determine both presence and abundance of cattle ectoparasites (Table 6.3).
It should be no surprise that a pasture-based cattle system provides suitable immature habitat for
most cattle ectoparasites, as cattle and their ectoparasites co-evolved in similar natural habitats.
As cattle move across a pasture, they leave behind fresh, intact fecal pats that serve as the required
development site for horn flies and face flies. These flies are rarely abundant in intensive cattle
systems, because cattle move back and forth across their pens disturbing and breaking apart the
fecal pats. In contrast, stable flies and house flies can be far more numerous in intensive produc-
tion systems where cattle feces is often collected and stored on site providing a substantial amount
of the moist and fermenting feces that these two species prefer. Intensive systems also must keep
quantities of animal feed on site, much of which is fermented either deliberately or as a result of
piling or stacking moist feed; or due to placement of dry feed in a location where it is wetted by
rainfall, sprinklers, or runoff from pens. Stored feed may include hay, silage, grains, and fruit or nut
waste among many other possible plant materials. Stable flies can be particularly numerous where
intensively managed cattle are provided plant-based bedding (typically hay or straw) resulting in a
fermenting mixture of plant material, feces, and urine. On pastures, stable flies can be numerous
when cattle are provided supplemental hay placed at fixed locations for days or weeks allowing for
the mixture of hay, feces, and urine at these locations.
Many biting flies develop in aquatic or semiaquatic habitats that are probably not an intentional
design component of a cattle operation, but are instead simply natural features of the surrounding
habitat. Aquatic habitats are not unusual in or near pasture-based systems. However, even intensive
systems may be constructed near wetlands, rivers, streams, or other aquatic features that might
result in large numbers of biting flies. It is really distance between animals and aquatic habitat,
rather than the design of the facility or the choice of an extensive or intensive production system that