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Summary Biology of Domestic Animals - Case 2b Meat
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Summary of case 2b (meat) of course Biology of Domestic Animals
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Biology of domestic animalsCase 2b:
1.0 Meat
1.1 Introduction
o Animals used for food by ancestors of humans. Mainly cattle. Easiest meat to get a
hold of.
o Some humans eat primarily meat, as there are no edible plants where they live. So
they eat animal in order to convert inedible vegetable products into food suitable for
humans
1.2 Consumption and production of meat
o Meat provides large number of important nutrients.
o Cooked meat is easily digestible and ingredients are easily absorbed by the body.
Besides that, meat is also very tasty for a lot of humans. Therefore, meat is often
centre of the meal. Certainly during festive meals and cultural ceremonies.
o Meat consumption per person per year ±80 kg. Most to least: pork, chicken, cattle,
goat and sheep. Slightly under 50% is actually eaten. Rest of meat consists of bone,
hide, tendon, fat etc. that is mostly used in part as pet food
o A not inconsiderable part of the meat that is produced in NL is for export, mainly to
EU member states. Not all animals slaughtered in NL are raised in NL. Large number
of calves are imported for rearing and slaughtering here. Conversely, piglets born
here are exported to be fattened and slaughtered there.
o Different categories of animals for slaughter can be distinguished within some animal
species. Slaughtered pigs are mostly fattening pigs and poultry meat is mostly from
meat chickens
1.3 The slaughtering process
1. Arrival, lairage, health inspection of live animals.
2. Stunning: using a bolt (cattle), CO2 (pigs) or electric shock (pigs, poultry). Animal is
killed by cutting the arteries in the neck or (rarely) with a cut to the heart.
3. Bleeding. As rapidly and completely as possible, because blood is an outstanding
medium for bacterial growth (rapid spoiling) Muscles go from aerobic to anaerobic
metabolism. Progression of pH decline are essential processes for meat quality. If pH
drops too rapidly, protein denaturation can occur leading to a drop in meat quality.
(PSE: Pale Soft Exudative). When pH barely declines, the meat becomes tough, dark
and dry (DFD: Dry Firm Dark)
4. Treating + cleaning: Eyes, hooves, feathers etc. are removed.
5. Washing the body
6. Opening the body + evisceration. The organs are removed
7. Washing + cleaning carcass on inside
8. Splitting the carcass in halves
, 9. Inspection of carcass + organs for parasites, diseases etc.
10. Weighing of carcass
11. Carcass grading + classification
12. Sometimes electrical stimulation of cattle carcasses to improve meat tenderness
13. Carcass chilling for at least 24 hours.
o ‘dirty area’ = 1 -5
o ‘clean area’ = 6-13
o Next day/days the carcass is divided into cuts, deboned, processed etc.
1.4 Slaughtering cattle, pigs and poultry
o Forbidden to slaughter without prior notice to the competent authorities. Before
slaughtered, must be inspected first while alive by vet. Animals must be stunned
before slaughtered, except for Jewish or Islamic rites.
o Cattle: Most frequented method is the so-called bolt. A metal pin is driven through
the top of the skull, into the brain cavity causing instant loss of consciousness.
o Ritual slaughter: Animals are not stunned. Throat must be cut immediately after the
animal is laid down and/or restrained. Blood pressure falls sharply and
unconsciousness occurs within seconds. Thereafter the slaughtering process
proceeds as is usual in NL.
o Pigs: Varies from 200 up to 900 pigs an hour being slaughtered. Stunned by electric
current or CO2. With CO2, 8-12 pigs in room with 80-90% with CO2. Animals are
unconscious on average after 20 sec but they stay in there for 40 sec to ensure all of
them are anaesthetised. Advantage of CO2 by contrast with using electricity, suffer
from less stress. With electrical stunning, muscle contractions occur that can cause
cones to break or blood vessels to burst. Disadvantage is that CO2 takes longer and
that pigs show strong resistance in stunning chamber. Animals suffer from
asphyxiation and pain. Stunning with electricity, they inducing an epileptic fit within
one sec resulting in immediate loss of consciousness. Electrical stunning does lead to
PSE meat more often than CO2 stunning.
o Animals should be killed after being stunned first withing 1 minute. With electrical
stunning of pigs, this must be done within 30 sec. Proceeding with slaughtering
during or after exsanguination (bleeding) before animal is permanently motionless is
forbidden.
o Poultry: 60-110 chickens per minute. Stunning in an automatic water basin with
electricity. The hooks from which they are hung is earthed, so that an electric current
runs through the bird’s entire body. At least 150 Volts. Sections are partitioned by a
wall, so that the path from incoming material right up to the end product does not
cross over itself and runs directly from unclean (supply) to clean side (dispatch room).
1.5 Systematic butchering of pork and beef carcasses
o A body can be split up in carious ways. A carcass is often cut up into so-called trade
pieces (with the pig for example hams, cutlets, shoulders and bellies.
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