UNIT 10 DRESSING TECHNIQUES
AND CARCASS YIELD
Structure
10.0 Objectives
10.1 Introduction
10.2 Line Dressing System
10.3 DressingofAnimals
103.1 Dressing of Cattle/ Buffalo
10.32 Dressing of Sheep1 Goat
10.3.3 Dressing of Pig
10.4 CarcassYield
10.5 LetUsSumUp
10.6 Key Words
10.7 Some Useful Books
10.8 Answers to Check Your Progress
10.0 OBJECTIVES
After reading this unit, you will be able to:
define line dressing system;
narrate different line dressing systemswith their advantagesand disadvantages;
describe the steps involved in dressing of different meat animals like cattle1
buffalo, sheeplgoat and pig;
explain carcass yield of different meat animals;and
evaluatedressing percentage of different meat animals.
10.1 INTRODUCTION
In unit-5 of this course you have already studied that the slaughter and dressing of
livestock may be carried out either on the rail or on the floor. Dressing of the
animals involves various steps like removal of skin, leg, head and visceral organs
(lungs, liver, heart, spleen etc.) and washing of the carcass etc. through which an
animal after stunning and bleeding becomes ready for marketing or fiuther
processing. The storage life of meat depends on conditions during slaughter and
dressing.A uniform appm_achto k i n g technique in all the countriesis not possible
due to climatic conditions, stage of development, social differences and religious
practices. In general, following are essential during slaughter and dressiig of animals:
Proper ante-mortem examinationto ensurethat the animals are healthy and fi.ee
fiom diseases.
Humane slaughter which refers to stunning of animal prior to bleeding.
Complete bleeding to prevent growth of microorganismsand to improve the Dressing Techniques
and Carcass Yield
appearance of carcass.
Hygienic dressing (i.e., dehiding, eviscerationetc.) to obtaingood quality meat.
Proper postmortem inspection to ensure the production of hygienic and
wholesome meat.
In this unit we will discuss line dressing system, dressing techniques for different
meat animals, carcass yield and dressing percentage of different meat animals in
&tail.
10.2 LINE DRESSING SYSTEM
After stunning of the animal, bleeding and complete b i n g is carried out speedrly
on overhead rail. This is called as line dressing or rail dressing systems. Line
method of dressing is essential for high rate of production. This is achieved by
combination of several machines,tools and equipmentsto reduce cost Line dressing
is usefid for buffido/cattle, sheep and goat, pig and poultry. Without the line method
of slaughter, it would not be possible to reach the production level achieved in a
modem meat plant which may be as high as 5000 cattle~buffidoor 10000 sheep/
goat every 10 hours.
Advantages of rail slaughter system
This system is safer to operators than conventional system
This is hygienic method as carcasses do not touch the floor
It is easy to handle mechanical heavy tools on conveyorslrail
It saves space and reduces unnecessary movement of the carcass movements
It enhancesthe value of hidelskin and organs as the overhead line removes the
hurdles of floor dressing
It systematically synchronizes inspection of carcasses and organs with their
identification
It increases the throughput i-e.,slaughter rate as there is no chance of idleness
for workers.
Disadvantages of rail slaughter system
The mil system requires high engineering skill and any dislocation on the line w
il
l
totally stop the production.Absence of particular skilled worker may adversely
affect the production.
The repetitive nature of work leads to loss ofjob interest.
Meat inspection is sometimessaid to be more difficult and possibly less efficient
as the carcasses and their respective viscera follow different ways and require
I
marking to match at the time of conclusion.
It requires a large capital investment.
Slaughter Technlquer The line dressing system has been classified into four categories on the
m o d Meat Inspection
basis of mode of operation.
(i) Gravity rail system: Here the movement of spreader and single wheel trolley
or runner is under the influenceof gravitational force. The carcass is gravitated
to each station and manually stopped at each station for operation.
Advantages
Simplest in design, so less chances of serious breakdown with consequent
loss of production.
Various items of equipment may be used with the gravity rail, e.g., a
moving top viscera inspection table or a paunch truck.
Disadvantanes
Low slaughter rate i.e., 10 to 40 beef 1 hour
Adequate ceiling height is necessary because of pitch of the rail to gravitate
carcass.
(ii) Intermittent powered system: Here the suspended carcasses on spreader
(gambrel) and trolley are moved along a level rail at interval by mechanical
means of variabletiming device which can be preset to suit the slaughter rate.
Advantages
Faster slaughter rate (10 to 75 beef/ hour) as compared toyavity rail
system*
Leveled rail and therefore height of ceiling is not a major problem.
The timing as per slaughter rate is to be fixed previously.
(iiii) Continuouspowered system: Here the movement of carcass is by mechanical
means but continuous.
Advanta~es
A much higher slaughter rate i.e., 40 to 120 beef7 hour.
The carcass can be revolved a 111 3600 as per convenience of the worker.
Efficiency of worker is increased.
Disadvantage
Same as those discussed for line dressing system.
(iv) Can pak System: This system is a continuousconveyorisedmethod in which
the carcasses are spread by trolley or runner from the overhead rail and
nospreader or gambrel is used. This system has been developed by Canada
Packers Limited, Toronto, Canada. Probably this is the most common system
used in large modem plant.
Advantage
Disadvantane Dressing Techniques
and Carcass Yield
Same as those discussed for live dressing system.
10.3 DRESSING OF ANIMALS
Generally sheep, goat, cattle, buffalo, pig and poultry are slaughtered in India. In
our country, slaughter of buffalo is much prevalent as compared to cattle. Sheep
and goats have no religious taboos compared to cattle and pigs. Poultry meat is
acceptable to many due to lower price compared to other meats and lesser chances
of adulteration with other meat. Beef, veal, pork, lamb, mutton, chevon art known
as red meat whereas chicken i.e., poultry meat is known as white meat. In India,
Halal method for Muslim and Jhatka method for Sikh are more prevalent than
other method of slaughter.
You have already studied about stunning and bleeding of different meat animals in
unit-9. So we will learn here the steps involved in dressing of these animals.
10.3.1 Dressing of Cattle/ Buffalo
I)ressing of cattle and buffalo after stunning and bleeding, involves following steps:
Dehiding: Dehiding is the removal of hide or skin. At first the head is flayed by
making an incision with knife from the poll to the muzzle. From the base of the
neck, another incision is made to the middle of lower jaw. After reflecting the hide
over head, atlanto-occipitaljoint is cut to separate the head. Then an incision is
made from the midventral line of the base of the neck to the brisket, belly and
base of the tail. The medial aspect of the fore limbs is incised from the knee joint
to the rnidventral incision. Similarly, medial aspect of hind limb is also incised. The
shanks are removed at flat joint. Then the hide/ skin over the fore limb and hind
limbs is removed and followed by the skidhide of belly, chest and neck. Practically,
flaying of back or butt region is difficult because the skin is highly adherent to
underlying tissues in this area. The tail is removed fiom the base of the tail.
Evisceration: Evisceration is process of removal of v i d organs. A circumcision
is made around the anus by a sharp knife and the attachments of large intestine
are removed. This helps in easy pulling of intestines from the ventral aspect. The
distal end of the anus is tied with a small rubber band to prevent the contamination
of the carcass by intestinal contents. A sharp knife is used to make midventral
incision from the mid point of pubic symphysis to the level of sternum.After exposing
the abdominal cavity, omental and mesenteric fats are removed and then abdominal
contents are removed. Care should be taken not to puncture the visceral organs
accidentally. The attachments of diaphragm to liver are cut to separate the liver
without puncturing the gall-bladder. Then thorasic cavity is opened by a rnidventral
incision from the sternum temidpoint of neck. Diaphragm and the thorasic o r g m
are removed. In case of cattle and buffalo carcass, laryhx, trachea, lungs, heart
and liver are collectively known as 'pluck'. All these are placed for post-mortem
examination along with the carcass. You will study the post-mortem examination
in detail in unit-12.
Splitting: The beef (cattle) and buffalo carcasses are split vertically &om the pelvis
upto the neck by sawing or cleaving. This splitting of carcass makes two halves
(right and left). The saw or cleavers should be sterilized properly before use.
Slaughter Techniques Carcass washing: Carcass is washed to remove soil, blood, stains etc. Only potable
and Meat Inspection water should be used for carcass washing. Carcass may be washed before or &er
splitting. Surface of the carcass and thorasic and abdominal cavity are washed by
spraying of potable water. Then the carcass should be dried as far as possible to
avoid the bacterial growth.
Sometimes,by quartering, each side (left or right half) is divided into fore quarter and
hind quarter. After postmortem examination of the carcass and offals, the carcass is
placed in a chilling room for proper setting of the carcass and further storage. You
will learn about chilling and freezing storage in next course.
Fig. 10.1: Slaughter of Catlle
10.3.2 Dressing of SheepIGoat
You have studied the stunning and bleeding of sheep and goat in previous unit. After
bleeding, the carcass is dressed in the following way:
Decapitation: It is the removal of the head. Head is separated with skin at atlanto-
occipital joint.
Removal of legs: The fore legs are disjointed at the knee joint.
. .
f&mm@Fbying: Skinning or flaying is startedby making an elliptical incision around
the hock joint on either side of hind legs. Skin is reflected on both sides by twisting and
thumbing and this pmcess is called fisting. Flaying is continued in this manner upto the
level of sternumand finally the whole skin is removed by pulling out in a single flap. Skin
is also removed by putting air in between the skin and underlying tissue.
Evisceration: For removal of visceral organs, same process is followed as in case
of cattle but the composition of 'pluck' is slightly different in case of sheep/goat.
Here, the 'pluck' includes larynx, trachea, heart, liver, lungs and spleen. Paunch i.e.,
stomach is first removed, then 'pluck' is removed. In sheep and goat, the kidneys
remain attached to the carcass until the carcass is split down the back bone. Generally,
the sheep and goat carcasses are not split and sold entire. Dressed carcass and offals
are placed for postmortem inspection.
Dressing Techniques
Carcass washing: Sheep and goat carcasses should be washed by spraying and Carcass Yield
potable water on the surface of the carcass and on the thorasic and abdominal
cavity.
19) @! IGJ
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=c@w %W#ddW rapnmofaLep Farcrr ~ r P a P u &
Eh)
Fig.103: Slaughter of Goat
10.3.3 Dressing of Pig
Dressing of pig is slightly different fium cattle or sheep because the skin of the pig
is not removed during dressing. We have discussed the stunning and bleeding of
pig in the previous unit of this course.Steps involved in'the dressing, are discussed
below:
Scalding: As the skin of the pig is consumed with the meat, skinning or flaying is
not done. Instead of that the carcass is exposed to hot water treatment which is
known as scalding. Scalding is done to loosen the attachment of haul bristles by
partial cooking of hair follicles. Scalding temperature for pig is about 62-64O C.
Dehairing: Hairs or bristles of the pig can he removed either by dehairing machine
i.e., mechanical .scrapper or manually. Dehairing should be done in the direction of
the hair follicles. When it is done manually, a blunt knife is used for this purpose.
All the bristles and fine hairs may not be removed by scrapping. Then the skin
surface is exposed to blow lamp which chars the remaining bristles and hairs.
This process is called as singeing. Then the charred bristles and hairs are removed
by shaving with a fine knife.
Rinsing: The entire carcass is rinsed thoroughly with cold potable water to give
the carcass a clear appearance.
23
Slaughter Techniques Evisceration: The procedure is almost same as followed in case of cattle. A sharp
and Meat Inspection
end knife is used to make incision through subcutaneous fat from mid point of pubic
symphysis to midpoint of neck. A knife is introduced through the opening of the
pelvic cavity towards abdominal cavity and all the pelvic and abdominal organs are
pulled out except the kidneys. To open the thorasic cavity, sternal cartilage is cut by
a cutting knife. Then diaphragm along with other thorasic organs is removed. The
carcass and the organs are then placed for postmortem examination.
Final washing: Clean, cold and potable water is used to remove blood and dirt
adhering to the carcass.
The carcass is then kept in the chilling room for proper setting. Sometimes the carcass
is divided into two equal halves.
Fig.lO.3: Slaughter of Pig
10.4 CARCASS YIELD
Carcass yield is one of the criteria of the grading. Generally sheep, goat, cattle and
buffalo carcasses include the portions of body after removal of the blood, hidelskin,
head, feet, digestive tract, bladder, pluck and adhering tissues etc. In case of pig
carcass, skin and head are included in the carcass. Carcass mainly consists of muscular
tissues, fatty tissues, bones, tendons and other connective tissues, large blood vessels
etc. Approximately, 50,55 and 75 per cent of the live weight of sheep, cattle and
pigs respectively remains in the carcass.
It provides information about the amount of meat and different by products obtained
24 from alive animal after slaughter and dressing.
Table 10.1: Percentage 01 meat ana alnerent by-p~wauctsavailable messing lecnniques
frnm c s s t t l m nia and c h m m n carcaca and Carcass Yield
Slaughter Techniques Dressing percentage is a comparison of the carcass weight in relation to the live
and Meat Inspection
weight of the animal and it is calculated as follows:
Dressed weight (carcass weight)
Dressing percentage = x 100
Live weight of the animal
Sometimes edible offals like heart, liver, kidney, spleen etc. are also included in
the dressing percentage because these are sold with the meat at same price.
Dressing percentage of meat animals ranges ftom 45 to 70 per cent. The animals
with heavy fat and the carcass with skin usually provide k i n g percentage above
60 per cent. Generally pig carcass with skin and heavy subcutaneous fat provides
dressing percentage more than 60 per cent. In some animals, muscles exist in
double i.e., dopplender condition and these animals produce higher dressing
percentage. This condition is more common in cattle.
Dressing percentage of meat animals depends on the following factors:
(i)Species: Dressing percentage varies fiom species to species. For example,
dressing percentage ofpig is generally higher than that of cattle.
Table 10.3: Dressing percentage of different meat animals and poultry
Species Dressing %
BuEdo/cattle 43-54
Sheep 40-50
Goat 43-52
-
Pig 70-75
Poultry Broiler '7u
Hen 65
Duck 65
(in) Breed: The animalsfiom same speciesbut h m differentlmedpmduce d u o e t
dressing percentage. For example, large white Yorkshire pig yields more meat
than indigenous pig breed.
( i i Stage of maturity: Matured i.e., adult animal produces higher dressing
percentage than young (i.e.,immature) animal.
(iv) Degree of finish: Finish representsexternal, internal and intramuscular fht of a
carcass. Higher finish gives higher dressing percentage.
(v) Intestinal content: As dressed carcassis fke h m inteshal content, the animal
with more intestinal content produces the carcass of less dressing percentage.
For example, intestinal content of calf is relatively more (percentage wise) than
that of adult cow and calf produces less dressing percentage than adult cow.
Check Your Progress
1) What are the advantages of line dressing system?
2) What do you mean by evisceration? Dressing Techniques
and Carcass Yield
3) What is scalding?
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I 4)' Why singeing is done in case of pig dressing?
I 5) Define dressing percentage and write the factors affkdng dressing percentage
of meat animal.
6) What is the difference between pluck of cattle and pluck of sheep?
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7) How does intennittent powered system differ h m continuous pow& system
of dressing?
8) Why dressing percentage of pig is higher than any other meat animal?
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I ...................................................................................................................
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9) Write short note on Can pak system.
I Slaughter Techniques
and Meat Ins~ection 10.5 LET US SUM UP
After stunning and bleeding, carcasses are dressed. Dressing techniques depends
on the species of the animal. Generally skin,head, liver, heart, lungs, larynx, trachea,
diaphragm, intestinal content, stomach etc. are removed during dressing of cattle,
buffalo, sheep and goat. In case of pig, all the aforesaid body parts are removed
except skin and head. That's why skhmg or flaying is not done, only hairs/ bristles
are removed in case of pig dressing.Removal of visceral organ is known as
eviscemtion. After evisceration, carcasses are washed properly with potable water
and the carcasses along with visceral organs and head are placed for postmortem
-examination. After the postmortem examination, approved carcasses and organs
are either sold as hot or chilled for further storage. Generally, sheep and goat
carcasses are sold as unsplitted carcass. Cattle (beef carcass), buffalo and pig
carcasses are splitted into halves or quarters and then marketed. All the above
operation may be done either on slaughter floor or on overhead mil i.e., rail or line
dressing system. In modem abattoir, line dressing system is followed because it is
advantageousfinm the point of hygiene, slaughter rate, time and labour u ~ o n
Dressed carcass weight in relation to live weight of the animal is expressed as
dressing percentage. Dressing percentage of meat animal depends on species,
breed, stage of maturity, degree of finish and intestinal content of the animal.
Generally, dressing percentage ranges fiom 45 to 70 per cent in different meat
animal.
10.6 KEY WORDS
Bristles : Short stiff hairs spread all over the external body
surface of the pig.
Beef : Meat of adult cattle.
Chevon
Dehiding : Removal of hide.
Dressing percentage : It is the carcass weight expressed as percentage
of live weight.
Evisceration : Removal of visceral organs.
Haying : Removal of skin.
Hide : The skin of a fdly grown large animal (for example,
I
cattle).
Live weight : Weight of the animal before slaughter and dressing.
Lamb : Meat of young sheep.
Mutton : Meat of adult sheep.
Scalding : To dip or spray hot water to facilitate defeathering
in poultry and dehairing in pigs.
: Burning of small hairs on body surface of poultry
and pig left after defeatheringldehauing respectively.
: Removal of skin.
Pluck : Pluck includes trachea,laryrur, heart, liver and lungs Dmsing Techniques
rod Carcau Yield
in case of cattle/ buffalo carcass. In case of sheep/
goat carcass spleen is also included. In case of
pig, esophagus is also included.
Pork : Meat of pig
I Veal
10.7 SOME USEFUL BOOKS
: Meat of calf.
Gracey, J.F, Collin, D.S. and Huey, R.J.(2000). Meat Hygiene, 1Om edn, W.B.
Saunders Company Ltd., London.
Biswas, S. (2001). Monograph on the elements of hygienic meat production.
University Publication. WBUAFS, Kolkata.
10.8 ANSWERS TO CHECKYOUR PROGRESS
1) Advantages of line dressing system are as follows:
Safer than conventional system
Hygienic as carcasses do not touch the floor
Easy to handle mechanical heavy tools on conveyodrail
Save space and reduce carcass movements
Enhance the value of hide/skin and organs as the overhead line removes
the hurdles of floor dressing.
Systematically synchronize inspection of carcasses and organ with their
identification
The throughput increases as there is no chance of idleness for workers.
2) Eviscerationis the process of removal of visceral organs during dressingof the
carcass. Different organslike heart, liver, lungs, spleen, kidney etc. are removed
during evisceration.
3) Scalding is the hot water treatment of a carcass to remove hairs/ bristles or
feathers. Hot water is used to loosen the hair or feather follicles. In caseof pig,
hot water at 62-64%C is used to remove the hairs/ bristles. In case of poultry
hot water of different temperatures is used to remove feathers.
4) In case of pig dressing, singeing is done to burn the bristles and fine hairs of the
carcasswhich remain after scalding and scrapping.
5) Dressing percentage is the expression of carcassweight as a percentage of live
weight ofthe animal.
The factors affectingthe dressing percentage ofthe animal are as follows:
Species
Slaughter Techniques Stage of maturity
and Meat Inspection
Degree of finish
Intestinal content.
6) Pluck of cattle differs from pluck of sheep because cattle pluck comprises of
larynx, trachea, heart, liver and lungs whereas sheep pluck consistsall these
along with spleen.
7) Intermittent powered system of line dressing differs from continuouspowered
system in the followingway: 1
Carcasses are moved along a railat interval in intermittentpowered system
and these are moved continuously in continuous powered system.
Slaughter rate is higher in continuous powered system (i.e., 40-120 beef/
hour) than that in intermittent powered system (i.e., 10-75 beenour). Ii
Efficiency of worker is more in continuous powered system.
I
8) Dressing percentage of pig is higher thanany other animal because- /
Pig carcass contains heavy subcutaneous fat which is not pronounced in
other animal,
Pig carcass includes skin which is removed in other carcasses.
II
Head of pig is included in the carcass whereas it is separated in case of
other animals.
9) Can pak system is a continuousconveyorised method of line dressing where
the carcasses are spread by runner or trolley fiom overhead rail. This system -
was developed by Canada Packers Limited, Toronto, Canada. This is most
commonlyused method in large modern abattoir because of its higher slaughter
rate (i.e. 50-150 beeflhour).
