Agriculture Reference
In-Depth Information
lairage. The positioning of a drainage gully in the middle
of a walkway frequently causes animals to baulk, as do
harsh shadows, puddles of water or shafts of light. It is
well established that, owing to their natural curiosity,
animals move more readily along curved rather than
straight passageways and that sharp corners slow move-
ment considerably. A bend in a raceway of 45° slowed
the progress of pigs by about 10%; a bend of 90° or 120°
slowed progress by 19%; and a 180° bend slowed their
progress by 44% (Warriss
et al.
, 1992a).
Pigs rest more contentedly if they can lie against a
solid wall rather than rails, and there is less fighting if
they are confined to long narrow pens rather than square
ones. Either rails or walls are satisfactory for cattle and
sheep. With walls, it is possible to wash out a pen without
causing stress, by splash and noise, to animals in neigh-
bouring pens. However, animals are much easier to
inspect in railed pens, unless an overhead catwalk is pro-
vided. Vertical supports should be cylindrical and tubu-
lar to reduce the possibility of injury, and the tops capped
to allow effective cleansing and disinfection to be carried
out. Horizontal rails should also be cylindrical and tubu-
lar, as they are easier to clean effectively with a pressure
washer than rails of tubular box cross section.
The introduction of
automatic systems
to move pigs
through the lairage in groups in larger slaughter estab-
lishments has improved both the welfare of the animals
and the efficiency with which the facility operates. The
push gates move the pigs in groups of 15 along the pas-
sageways at a steady pace from the loading to a holding
position. Pigs rest within 20 minutes, contrasted with an
hour under normal lairage conditions; and aggression is
much reduced.
Facilities should be checked to ensure there are no
defects which could cause bruising or even death.
Projections and sharp corners are taboo, and if rails are
being used for pen partitions, it is essential that there is no
possibility of animals getting their heads between rails and
being strangled; rail gaps must be of the proper width.
In some countries, cattle are sprayed with jets of water
and walked through footbaths before entering the
slaughterhouse area. This practice is of benefit in warmer
climates where the hair is short and the skin of cattle is
fine, but where hair is long in housed stock and there is a
build-up of manure and dirt on the hair, spraying would
only serve to make matters worse. A light spraying of
pigs is widely considered of value in preventing pigs
fighting and also reduces the build-up of contamination
in the scald tank. However, research work has failed to
demonstrate that sprays actually reduce fighting, and it
has been suggested the improvement in meat quality in
sprayed pigs is due to a cooling effect, rather than a
reduction in stress.
pigs transported in the early morning fare better than
those transported in the afternoon.
The National Livestock Safety Committee of the US
Livestock Conservation Inc. has developed a
livestock
weather safety index chart
which, in relation to current
temperature and
relative humidity
, indicates in hot
weather how safe stock in transit may be. They have also
devised for low-temperature conditions a
wind chill
chart
giving the relationship between actual tempera-
tures and the wind speed, which is particularly impor-
tant if animals are not sufficiently protected in moving
vehicles.
The
post-mortem findings
in
pigs which have died in
transit
are usually those of acute cardiac dilation and
acute pulmonary hyperaemia. The left ventricle of the
heart is no longer conical but more oval, while the papil-
lary muscles and muscular ridges, normally apparent on
the endocardium as prominent projections, are much
flattened. Pericardial fluid is increased and there is, in
severe cases, a diffuse skeletal muscle degeneration. The
lungs are heavy and firmer than normal, finger impres-
sions remain on palpation, and a frothy fluid oozes from
the cut surface. Acute passive hyperaemia of the liver
and spleen may be observed.
Lairage construction (see also Chapter 3)
During the rest period in lairages, animals must be kept
under conditions which prevent any further contamina-
tion of feet, hides, fleeces or skins. Most lairages have solid
non-slip floors, suitably sloped to adequate drains. Slatted
floors have also been considered for cattle, but while con-
tamination is reduced in most cases, there are problems in
manure removal and disinfection, for example, after out-
breaks of anthrax and salmonellosis, or where tuberculo-
sis or brucellosis reactors are routinely slaughtered.
Movable slats, and especially expanded-metal floors,
are particularly useful for sheep, where circulation of air
below the floor can be useful for drying wet fleeces. Straw-
bedded pens also provide a satisfactory environment for
sheep, as long as there is good ventilation and drainage,
while solid floors with no bedding, combined with regular
hosing and good drainage, provide satisfactory conditions
for cattle and pigs. Adequate hose points conveniently
placed and providing sufficient volume and pressure of
water are absolutely essential. So also are hoses with noz-
zles giving a fishtail spray which can quickly remove soil.
The provision of pens with gates which can be used for
closing pens and passageways assists the handling of stock
and their transfer from one pen to another, thereby facili-
tating the cleansing operation.
The detail of design of animal walkways and races is
important if animals are to move easily through the
