Vol.1, No.3, 75-88 (2011)
opyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/OJAS/
Open Journal of Animal Sciences
Meat quality in “in door” and “out door” production
systems of poultry and swine
W agner A. G. Araújo1*, Luiz F. T. Albino1, Nilva K. Sakomura2, Pedro V. R. Paulino1,
Anastacia M. Campos1
1Animal Science Department/Departamento de Zootecnia, Federal University of Viçosa (UFV), Viçosa, MG., Brazil; *Corresponding
Author: azisoo@yahoo.com.br
2Animal Science Department/Departamento de Zootecnia, State University of São Paulo (UNESP), Jaboticabal, SP., Brazil.
Received 6 June 2011; revised 11 July 2011; accepted 2 August 2011.
The meat quality can be influenced by many
interacting factors before and af ter the slaughter.
Currently more sustainable production systems
are t argeted in general, whether or not they have
any effect on meat quality. The sustainability is
a condition of agroecology and necessarily im-
plies on the animal and plant association and
succession. A condition for sustainability is to
minimize or even eliminate the use of inputs
from processes of chemical synthesis. In the
case of pigs and poultry, this is feasible by
adopting production systems that allows nutria-
ents recycle directly on the soil at levels that do
not involve pollution. Although we have the
understanding that the general principles of
sustainability to be observed are universal, the
solution is not simple. For each situation a vi-
able alternative must be sought, depending on
the social, economic, ecological and cultural
realities. In tropical and subtropical climates the
production of pigs and poultry outdoors can be
an appropriate option. This also leads to nutria-
ents recycle and promotes a better energy bal-
ance of the system. Among the alternatives that
can be taken to introduce differentiating factors
in meat production as food is the type of pro-
duction system, due to its direct impact on the
meat quality. These systems have a direct in-
fluence through the consumed food, by the
conditions of animal wellbeing, physical activity
and the environment provided. The performance
and meat quality depend on the interaction of
genotypes, rearing conditions, pre-slaughter
handling and processing of the meat and the
carcass. The influence of the rearing system on
the animal performance, on the carcass and
finally on t he m eat is th e res ult of t he inter ac tive
effects among facilities, feeding level and
genotype used in the production systems. The
production of poultry and pigs more exten sively
tend to get a final product with its own or-
ganoleptic characteristics, changing the meat
default color and content, place of fat deposi-
tion and the fatty acid profile deposited on the
Keywords: Alternative Systems; Meat Quality;
Poultry; Swine
The technological, nutritional and sensorial meat
quality can be influenced by many interacting factors
before and after the slaughter. Currently more sustain-
able production systems are targeted in general, whether
or not they have any effect on meat quality.
Following the example of what happens in the world,
the alternative rearing of swine and poultry in Brazil has
found more supporters among the business makers,
which is also an alternative for small and medium pro-
ducers who aim at a more profitable market niche (De-
mattê Filho & Mendes, 2001).The main desired charac-
teristics in these farming systems are: health security, the
organoleptic quality of the product, the growing concern
over the environment, animal welfare and consumers’
health (Bastianelli, 2001).
The sustainability is a condition of agroecology and
necessarily implies on the animal and plant association
and succession. A condition for sustainability is to
minimize or even eliminate the use of inputs from proc-
esses of chemical synthesis. In the case of pigs and poul-
try, this is feasible by adopting production systems that
allows nutrients recycle directly on the soil at levels that
do not involve pollution.
W . A. G. Araújo et al. / Open Journal of Animal Scie nces 1 (2011) 75-88
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/OJAS/
Although we have the understanding that the general
principles of sustainability to be observed are universal,
the solution is not simple. For each situation a viable
alternative must be sought, depending on the social,
economic, ecological and cultural realities. In tropical
and subtropical climates, such as in Brazil, the produc-
tion of pigs and poultry outdoors can be an appropriate
option. This also leads to nutrients recycle and promotes
a better energy balance of the system.
In the past few years it has been consolidated, in many
countries, a consumer market willing to pay more for
products with “ethical quality” (Warriss, 2000). In Brit-
ain, for example, organic pork is twice the price of con-
ventional and the demand is greater than the supply
(Edwards, 1999). Also in Brazil there are indications that
at least a portion of the consuming public is willing to
pay more for organic beef and pork (Machado Filho,
Among the alternatives that can be taken to introduce
differentiating factors in meat production as food is the
type of production system, due to its direct impact on the
meat quality. These systems have a direct influence
through the consumed food, by the conditions of animal
wellbeing, physical activity and the environment pro-
vided (Dal Bosco et al., 2002).
The performance and meat quality depend on the in-
teraction of genotypes, rearing conditions, pre-slaughter
handling and processing of the meat and the carcass. The
influence of the rearing system on the animal perform-
ance, on the carcass and finally on the meat is the result
of the interactive effects among facilities (type of floor,
the space, environmental temperature, physical activity),
feeding level and genotype used in the production sys-
tems (Lebret, 2008).
Some studies indicate increased water retention ca-
pacity in meat produced outdoors. On the other hand, the
outdoor production may further increase the meat shear
force compared to conventional systems (Olsson &
Pickova, 2005). The color can be affected in different
ways, generating more pigmented or pale meat (depend-
ing on the system), structurally affecting the meat (Ols-
son & Pickova, 2005). The greater unsaturated lipid pro-
file of meat produced in a system that includes foods
containing polyunsaturated fatty acids (fodder) is favor-
able, in relation to the nutritional meat quality, when
compared to conventional total confinement (Olsson &
Pickova, 2005).
1.1. Implications
So the best knowledge of the organoleptic changes in
pork and chicken, through alternative systems of pro-
duction, could determine the encouragement of agricul-
tural activities that would ensure better welfare of ani-
mals through the rationale of improving the quality of
the final product. From another viewpoint, these systems
would fit better on little farms with family labor, making
them more competitive with differentiated products of
high added value.
1.2. Muscle Fiber Types and Meat Quality
Understanding the growth and muscle development is
one of the most important aspects in animal science,
since this is the end product of systems aimed to meat
production. There are two types of skeletal muscles, the
red and the white. The red is composed predominantly of
oxidative fibers and the white muscle is composed pre-
dominantly of glycolytic fibers (Lawrie, 2005).
According to Rehfeldt et al. (2000), muscle mass is
mostly determined by the number of muscle fibers and
the size of these fibers. Animals with more moderately
sized muscle fibers produce better quality meat. During
myogenesis, the number of muscle fibers is determined
by genetic and environmental factors. The same authors
state that after birth the total number of fibers remains
constant in mammals and birds and that the increased
skeletal muscle mass is mainly due to hypertrophy of
fibers, together with the proliferative activity of satellite
cells, which are source of new cores that are going to be
embedded in the muscle fiber.
According Lefaucheur & Gerrard (2000), the muscle’s
weight is a function of the fiber type, relative size and
length of the fiber. The growth capacity is related to the
number of muscle fibers. The glycolytic fibers have
higher relative volume and the increase in the proportion
of these could lead to an increase in muscle weight.
To understand the muscle development is essential
studying the mechanisms that regulate the number, type
and size of muscle fibers. These variations of the muscle
fibers are related to several factors that interfere with
muscle development in the prenatal and postnatal de-
velopment periods (Dauncey & Gilmour, 1996). Among
these factors it can be cited those intrinsic to the animals
(genetic, growth regulators, transcription activators, en-
docrine status, muscle proteinases and innervation ),
environmental factors (diet and temperature), motor ac-
tivity, agents splitters of nutrients (ractopamine in pig
feed), age, sex, disease, type and location of muscle fi-
bers in the muscle (Gonzales & Sartori, 2002).
To understand the importance of the factors that affect
growth and protein deposition in muscle, one must con-
sider the impact of these factors on the quality of the
muscle that will be transformed into food for human. But
the meat quality is not only determined by the intrinsic
(physiological) and extrinsic (environment) influences
on the bird’s muscle in the period preceding his death.
Once the muscle tissue is dynamic, it also responds to
W . A. G. Araújo et al. / Open Journal of Animal Scie nces 1 (2011) 75-88
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environmental influences during and after the animal’s
death. The type of processing, considering the slaughter
and the carcass treatment, interacts with the muscle’s
characteristics and, together, will determine the meat
quality (Pearson & Young, 1989).
Both in birds and mammals, three types of muscle fi-
bers can be identified based on their metabolic and con-
tractile characteristics: Type I - slow twitch and oxida-
tive (SO), type IIA-fast twitch oxidative (FOG) and type
IIB / X- fast twitch glycolytic (FG) (Macari et al. 2002;
Lawrie, 2005).
The type I fibers are small, have many mitochondria,
myoglobin pigment in abundance and are well vascular-
ized, which gives them their red color. The mitochondria
are large and have numerous cristae. The storage of
oxygen by myoglobin prevents fatigue. The type IIA
fibers are medium sized with oxidative and glycolytic
energy metabolism, having numerous mitochondria and
myoglobin, high vascularization and are resistant to fa-
tigue, while the type IIB fibers are large, with few mito-
chondria and myoglobin, with glycolytic energy metabo-
lism and poor vascularization , besides being easily fati-
gable and easily accumulate lactic acid (Macari et al.
2002; Lawrie, 2005).
The predominant muscle fiber type is especially im-
portant for the carcass quality of pigs. Due to the gener-
ally higher content of glycogen in type II fibers com-
pared to type I, there would be a great anaerobic glycol-
lytic potential on those during the post mortem. This
results in sharp drop in pH, resulting in a meat called
PSE (pale, soft and exudative) (Lawrie, 2005).
Swines of the Piétrain breed have greater genetic ten-
dency to higher prevalence of such a failure, both due to
the presence of the halothane gene and the predominance
of type II fibers (Lawrie, 2005). However other factors
may influence the formation of the fibers, thereby
changing their characteristics, such as exercise and the
animal’s age (Lawrie, 2005). In general physical training
(long term) may increase the myoglobin content of mus-
cle fibers. In this way there is a change in their initial
physical characteristics, making the fibers more likely to
express aerobics features, since myoglobin becomes an
intracellular oxygen reserve (Lawrie, 2005).
Also Sosnicki et al. (1996) reported the importance of
the presence of white fibers, affecting the meat quality,
due to change in meat pH, making it acidic after slaugh-
ter, due to the glycogen content of the cells that form the
white muscle fibers. This implies on a loss in industrial
yield from certain carcass cuts of pork, especially ham,
when cooked without the addition of phosphate.
Another determining factor in swine carcass quality is
the content of intramuscle fat (marbling), affecting the
meat appearance and taste. This has been identified as an
important factor in determining the consumer preference
for the consumption of pork (Plastow, 2000).
In birds the chest muscle, white colored, has pre-
dominantly FG and FOG fibers and histologically pre-
sents low density of blood capillaries and contain few
mitochondria. The red muscles, from the thigh and
drumstick, on the other hand, are richly vascularized and
contain a large number of mitochondria in the fibers
which are mainly of the SO and FOG types (Macari et
al., 2002).
According to Gonzales & Sartori (2002), the distribu-
tion of muscle fibers in a certain type of muscle is a
functional adaptation from its various kinds of activities.
Thus, the rate of different muscle fibers types in a mus-
cle is directly correlated with its function in the bird’s
body. In agreement, Remignon et al. (1994) reported that
the frequency of different types of muscle fibers in
broilers is primarily related to the muscle function. The
breeding of broiler chickens for increasing muscle mass
and speeding growth reduced the muscle’s oxidative
capacity, resulting in a more anaerobic muscle (Soike &
Bergmann, 1997). Therefore, the meat of broiler chick-
ens has lighter color due to the muscles being more an-
According to Macari et al. (2002), after the bird’s
death, the tissues are deprived of oxygen, resulting in
anoxia. In this situation, with the continuity of their
metabolic activity, the muscle fibers rely solely on the
anaerobic mechanisms for the ATP production. Thus,
using the glycogen that is quickly consumed. Concomi-
tantly, occurs an accumulation of lactic acid, the end
product of anaerobic metabolism, due to its non-removal
via the bloodstream. The anaerobic metabolism reduces
sarcoplasmic pH level which inhibits glycolysis, ceasing
the ATP production. But the ATP consumption continues,
reaching critical mass, so that the dissociation of the
actin-myosin system is not performed. Due to the forma-
tion of the actin-miosin complex, the muscle loses its
plasticity and gets unable to relax; hence the rigor mortis
takes place (Gonzales & Sartori, 2002).
The time to develop the process of rigor mortis de-
pends on the muscle type, the frequency of fibers types
in the muscle, the speed of pH tissue fall and the envi-
ronmental factors before and after slaughter that the
animals were submitted (Gonzales & Sartori, 2002).
Changes in the establishment of the rigor mortis may
increase the meat pallor and its ability to reduce fluid
retention, worsening the quality of the processed prod-
ucts (Dransfield & Sosnicki, 1999).
The replacement of part of the concentrate feed (diets
based on corn and soybean meal) for fodder (forages), is
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one of the causes of the production system influence on
pigs’ and poultry’s carcass. The animals when begin to
eat forage have a greater development of the gastrointes-
tinal tract as an adaptation to increased dietary fiber.
This is due mainly to the production of volatile fatty
acids by allozyme processes (bacterial activity), espe-
cially in the cecum of these animals. However only a
small portion of the energy required for both mainte-
nance and production is resulting from such sources,
being essential the concentrate feeding to not compro-
mise the production index. Also due to the low protein
content of these sources and low nutritional contribution
of bacterial protein in the nutrition of monogastric ani-
mals, it becomes necessary the protein nutrition almost
in its entirety coming from the concentrated feed.
One of the main influences is the lipid type contained
in these forages and how they are deposited on the car-
cass. The total lipids content in forages is variable (4% -
12% of the dry matter), being greater the younger they
are, with the highest proportion in the leaves, and from
these the majority are chloroplast lipids. The latter may
have an impact mainly on aspects related to the meat
The fatty acid composition of forages is characterized
by a high percentage of polyunsaturated acids, particu-
larly linolenic acid (C18: 3 -3), which represents over
50% of total fatty acids, followed by linoleic acid (C18:
2 -6, 10% - 20%).They present a relationship -6/-3
of 0.20, whereas the content of saturated fatty acids
(10% - 20%) and monounsaturated fatty acids (1% -
17%) is low.
The forages are rich in linoleic acid and low in satu-
rated lipids when young and rich in oleic acids in vege-
tative stages more advanced (Morand-Fehr & Tran,
2001). Moreover, the quality of the adipose tissue in
relation to its nutritional value, organoleptic characteris-
tics and conservation is related to its fatty acid composi-
tion (Lizardo et al., 2002).
The composition of lipids in the carcass of pigs and
poultry is influenced by several factors, such as geno-
type, sex, age, animal’s weight (Girard et al., 1988), the
location of fat deposition in the carcass (Miller et al.
1990), environmental temperature (Katsumata et al.
1995) and especially nutrition. The latter is mainly in-
fluenced by the energy and fat content in the diet, fatty
acid composition and daily fatty acids consumption
(Wiseman & Agunbiade, 1998).
In their study, Ponte et al. (2008), broilers of the Red-
Bro Cou Nu X RedBro M genotype were fed on a ce-
real-based diet in portable floorless pens located either
on subterranean clover (Trifolium subterraneum) pas-
tures and without access to pasture. Unlike the imagined,
the pasture intake had a low impact on the fatty acid and
vitamin E homologue profiles of meat from free-range
broilers. However, breast meat from birds with free ac-
cess to pasture presented lower levels of the n-6 and n-3
fatty acid precursors linoleic acid (18:2n-6) and α-lino-
lenic acid (18:3n-3), respectively. In the same work, con-
trary to other results, the levels of eicosapentaenoic acid
(20:5n-3) in breast meat were significantly greater in
birds consuming pastures, which suggests greater con-
version of α-linolenic acid into eicosapentaenoic acid in
these birds.
The production of pigs outdoors offers a greater vari-
ety of environments for animals and greater freedom of
behavior, but poses challenges for the breed adaptation,
management control, biosafety and ambience. Each of
these has potential implications for the real and per-
ceived quality of the product.
According to Edwards (2005) in most conventional
production systems of northern Europe only adult ani-
mals and infants remain in the pasture. However, in the
Mediterranean traditional systems and in organic pro-
duction systems, animals can be kept throughout his life
outdoors. Influences on the organoleptic quality of
products derive from the choice of breeds better suited to
outdoor systems, changes to the rate of growth and in-
creased proportion of roughage on the diet.
According to Honeyman (2005) recently in the United
States the production of pigs outdoors using tents has
been used for finishing pigs and gestating sows. The
seasonal outdoor lambing and indoor (winter/summer) in
some systems, along with lactation group has also been
used, as the example of the French system (plein air).
Most of the meat markets, mainly in Europe, has re-
quired adjustments in order to encourage the use of out-
door systems or straw, the withdrawal of subtherapeutic
doses of antibiotic growth promoters and there are still a
encourage to a family environment agricultural produc-
tion (Honeyman, 2005).
Indirect consequences would have positive and nega-
tive influences on the physiological responses to stress
during pre-slaughter (Edwards, 2005). Although some
aspects of animal health and hygiene can be improved,
in broader conditions, the exposure to parasites and con-
tact with wild animals may increase the risk of zoonotic
infection (Edwards, 2005). Product quality attributes can
be influenced positively or negatively, depending on the
consumers’ opinion, the quality of management and the
creation of units of pigs outdoors visible to the public as
marketing, reiterating the argument of the ethical quality
of the product.
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Currently, the goal to continue increasing the content
of meat in the carcass is becoming more complex, since
there is a trend of increase in slaughter weight of pigs
which decreases the rate of lean deposition at the ex-
pense of a higher rate of fat deposition (Moreira, 1998).
Also, the intense genetic selection for production of pig
carcass with less fat content has caused a negative effect
on meat quality (Terra & Fries, 2000; Rübensam, 2000),
besides contributing for the reduction of food intake,
thereby affecting the animals growth rate.
Especially, animals selected for muscle deposition
have low rate of feed intake and lower growth rate and
are associated with the presence of the halothane gene
whose effect is related to the metabolic changes that
leads to the intense and accelerated decrease of pH that,
in turn, affects the color and the ability to retain water,
besides affecting the organoleptic properties of meat
such as tenderness, juiciness and flavor.
The Table 1 shows the heritability values for color,
marbling, water holding capacity, tenderness, pHu (pH
after 24 hours of slaughter) and the genetic correlation
among these meat quality characteristics with the daily
weight gain, backfat thickness,% carcass meat and the
intramuscle fat content (Sosnicki et al. 1996).
Thus the improvement to the amount of carcass meat
results in an adverse effect on color, intramuscle fat con-
tent, water holding capacity, tenderness and meat’s pHu.
According to Lebret (2008), the environmental en-
richment (more space, straw bedding) generally in-
creases the rate of growth, carcass fat and can improve
the juiciness of the meat and taste due to the increased
intramuscular fat. The outdoor criation and organic pro-
duction systems have different effects on growth rate
and carcass fat, depending on the weather conditions and
the feed (Lebret, 2008).
The influence on meat quality is also controversial:
higher drip, smaller pHu and more tender meat systems
were reported in “indoor (confinement), while some
studies show better meat juiciness through outdoor crea-
tion (Lebret, 2008). The discrepancies could probably be
due to differences among studies in the creation of con-
ditions and the physiological responses of pigs to pre-
slaughter treatment.
Specific systems of production in the Mediterranean
area based on local breeds (low growth rate, high fat)
and finishing systems “Free Range” (pastures, forests),
which allow the animal to express its genetic potential
for intramuscle fat deposition, clearly demonstrate the
positive effects of the interaction “genetic VS production
system” in the quality of pork and its derivatives.
In Brazil, there are few studies reporting the differ-
ences of systems indoor and outdoor on pork quality.
Bridi et al. (2003a) verified that pigs housed in the out-
door system showed lower performance and carcass
characteristics (carcass weight, warm and cold) com-
pared to the conventional system and housed in bunk
beds (Tables 2 and 3). Similar results were observed by
Sather et al. (1997) in the Canadian summer conditions.
However, on the cold season, the pigs raised in confine-
ment on a bed of wood shavings had similar warm car-
cass weight to the outdoors. According to Heyer et al.
(2006) outdoor pigs also had lower dressing percentage
than the pigs indoor.
To Bridi et al. (2003b), the rearing system have not
affected the values of initial and final pH or water hold-
Table 1. Heritability and genetic correlations among meat quality traits, carcass traits, and growth rate.
Parameter Value Color Intramuscle Fat Water retention capacity Tenderness pHu
Average 0.3 0.50 0.20 0.30 0.20
H2 Amplitude 0.10/0.60 0.25/0.65 0.05/0.65 0.20/0.40 0.10/0.40
Average –0.15 (U) 0.40 0.00 –0.15 (U)
Rg Weight Daily Gain Amplitude –0.5/0.15 0.15/0.60 –0.80/0.50 –0.40/0.50
Average 0.20 (F) 0.20 0.20 (F) 0.20 (F) 0.15 (F)
Rg Backfat Thickness Amplitude –0.20/0.60 –0.20/0.60 –0.20/0.80 –0.20/0.40 0.40/0.50
Average –0.25 (U) –0.20 (U) –0.35 (U) –0.20 (U) –0.10 (U)
Rg % carcass meat Amplitude –0.60/0.20 –0.50/0.40 –0.80/0.25 –0.60/0.20 –0.70/0.35
Average –0.20 (U) –0.05 (U) 0.25 (F) 0.00
Rg Intramuscle Fat Amplitude –0.10/0.35 0.20/0.30 –0.20/0.40
H2 - Herdability Values; Rg - Genetic Correlation; pHu - Meat’s pH 24 hours after slaughter; F - Value of Favorable Correlation; U - Value of Unfavorable Cor-
relation; Source: Sosnicki et al. 1996.
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Table 2. Effect of the production system type on the carcass
parameters of pigs.
Warm carcass
weight (kg)
Cold carcass
weight (kg)
yield (%)
loss (%)
“Indoor” no
bed 74.5 ab 72.6
ab 75.5 2.62
with bed 75.0 a 73.3
a 75.0 2.26
“Outdoor” 71.1
b 69.4
b 74.9 2.48
abMeans followed by different letters in the same column show significant
difference (P < 0.05), Source: Bridi et al. (2003a).
Table 3. Effect of the production system type on the quantita-
tive carcasses characteristics of pig obtained by the Hennessey
Grading Probe.
of lean meat
Amount of
carcass meat
“Indoor” with
bed 17.2 a 56.6 53.8
b 40.1
“Outdoor” 13.3
b 56.6 56.2
a 40.0
abMeans followed by different letters in the same column show significant
difference (p < 0.05); Source: Bridi et al. (2003a).
ing capacity of pork. The higher incidence of PSE meat
(pale, soft and exudative) was observed in the carcasses
of pigs reared under confined systems compared to out-
door animals.
However, in a previous study comparing the carcasses
of pigs reared outdoors with the confined, Bridi et al.
(1998) verified no significant difference for the variable
warm carcass weight. Whereas, Hoffman et al. (2003),
working with crossbred (Landrace X Large White) ob-
served lower carcass fat deposition and greater percent-
age of lean meat in animals raised in outdoors rearing
systems when compared to the conventional system.
However, the creation type did not affect the distribution
of commercial cuts, expressed in percentage of cold
Comparing carcasses with the same weight, Van der
Wal et al. (1993) verified that pigs raised outdoors
tended to have more subcutaneous fat and lower amount
of lean meat. However, Jones et al. (1993), Enfält et al.
(1997) and Sather et al. (1997) found that pigs reared
outdoors had a higher amount of lean meat and lower fat
ratio than pigs finished in confinement. In the work de-
veloped by Jones et al. (1993) and Bridi et al. (1998),
there were no significant differences among the means
of fat thickness and depth of back muscles from pigs
reared outdoors and in confinement. However on the
study conducted by Bridi et al. (2003a) have been de-
tected differences.
Butko et al. (2007), working with Black Slavonian pig
breed, reared outdoors and fed with natural pastures and
crop residues, compared to conventional (ending with
the 137 kg BW), verified higher proportion of leg and
lower proportion of ribs when the weight of these were
compared with the total weight of the carcass. Further-
more, it was verified a bigger amount of meat on the
carcass of pigs reared outdoors compared to the system
indoor, concluding that there would be a greater value in
the carcass of pigs reared outdoors.
Large White pigs reared outdoors also had a higher
content of lean meat and lower content of intramuscle fat
on the carcass. However, the intramuscle fat in Longis-
simus and Rectus femoris muscles was greater in these
than in pigs raised in the conventional system (Bee et al.,
Strudsholm & Hermansen (2005), working with ani-
mals originated from the crossing type tricross (matrices
“Large White X Landrace”, mated by Duroc boars), re-
ported that the animals kept in confined system had a
lower content of lean meat (2.3%) and higher fat thick-
ness (1.1 mm), however there were those who consumed
less feed (5 MJ ME/ kg gain) compared to the farming
system outdoors.
Another issue to be related to carcass quality of pigs
in the near future is not only the content but also the
profile of fatty acids present on it. According to Basso et
al. (2007) the growing and finishing pigs in outdoor sys-
tems with pasture, presented better meat quality than the
confined system, introducing more favorable character-
istics to human health (less teratogenic). In the fatty acid
composition of intramuscle fat there were more C18: 1,
C18: 2 and C18: 3 in animals reared outdoors (Table 4).
Moreover, the level of C18:3 in intramuscle fat was
higher in animals fed forage, than in animals reared
outdoors and confined without food bulky.
Studies of Lebret & Mourot (1998), regarding the
rearing conditions of pigs, showed higher levels of
omega-3 fatty acid and vitamin E in backfat and intra-
muscle fat of animals raised in extensive systems. On
pigs’ lard from Cinta Senese breed reared outdoors, Pug-
liese et al. (2005), reported a higher percentage of
monounsaturated fatty acids (MUFA) (55.1% vs. 53.3%)
and polyunsaturated (PUFA) (13.2% vs.10.4%). The
pigs raised in outdoors systems also showed higher rela-
tion polyunsaturated fatty acid (PUFA)/stearic fatty acid
(SFA) (0.43 vs.0.29).
The Subcutaneous fat from pigs of Nero Siciliano
breed reared outdoors showed a higher percentage of
monounsaturated fatty acids (MUFA) (53.3% vs. 47.2%),
but lower percentage of polyunsaturated fatty acids
(PUFA) (10.85 % vs.14.45%) (Pugliese et al. 2004). No
differences were found in omega-3 content between the
two groups, though the meat of animals reared outdoors
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Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/OJAS/
Table 4. Fatty acids profile of intramuscle fat of pigs under dif-
ferent production systems.
Fatty acids Indoor system Outdoor systemRSD
Palmitic C16:0 24.84 24.67 24.560.145
Palmitoleic C16:1 3.19 3.33 3.16 0.058
Estearic C18:0 12.65 12.17 16.660.142
Oleic C18:1 39.88 b 42.62 a 41.28 ab0.293
Linoleic C18:2 10.93 a 8.81 b 10.32 ab0.281
Linolenic C18:3 0.41 b 0.57 a 0.44 b0.017
CFA+21:0 0.11 b 0.28 a 0.13 b0.014
Arachidonic C20:4 2.00 1.81 1.89 0.107
Eicosapentaenoic C20:5 0.09 b 0.13 a 0.08 b0.008
Docosahexaenoic C22:6 0.03 0.05 0.04 0.002
SFA 40.12 39.36 39.520.244
UFAM 45.23 b 48.03 a 46.52 ab0.328
UFAS 14.62 12.58 13.980.39
n6/n3 23.67 a 14.26 b 21.03 a1.751
Different letters in the same row indicate significant differences (p < 0.05).
Source: Basso et al. (2007).
showed lower rates of teratogenicity (0.48 vs. 0.53) and
thrombogenicity (1.03 vs. 1, 21), related to the develop-
ment of cardiovascular diseases.
The content of fatty acid stearic (C18: 0) was lower,
while the content of linoleic acid (C18: 2-6) and poly-
unsaturated fatty acids (PUFA) was higher in meat from
pigs (Landrace X Large White) from outdoor systems
when compared to the pigs from the indoor system
(Hoffman et al. 2003). Enfält et al. (1997) and Bridi et
al. (1998), found no difference in loin eye area of pigs
raised confined and outdoors. Sather et al. (1997) veri-
fied that pigs reared outdoors produced loin and ham
heavier than those raised in confinement on wood shav-
ings, being these differences more pronounced in sum-
mer than in winter. To Bridi et al. (2003a) the rearing
systems induced differences in loin eye area (Ta ble 5).
Pigs raised in confinement on a concrete ground pro-
duced loin with larger area than those kept outdoors. On
the other hand, Gentry et al. (2004) commented that
there are no differences between the parameters of car-
cass of animals raised in and outdoor”. The animals
produced in “outdoor” systems had more fibers to the
darker gray type (IIB) that the animals reared in conven-
tional, in yours Semimembranosus muscles, but the cross
section of these fibers no differ significantly (Figures 1
and 2).
Table 5. Effect of the production system type on the loin eye
area and weight of ham and carrè.
Production systemLoin eye
area (cm2)
Ham weight
(kg) Carrè
weight (kg)
Indoor no bed 53.8a 10.4 4.2
Indoor with bed 51.2ab 10.3 4.2
Outdoor 50.1
b 9.9 4.1
abMeans followed by different letters in the same column show significant
difference (p < 0.05). Source: Bridi et al. (2003a).
(a) (b)
Figure 1. Photomicrograph of muscle Semimembranosus of: (a)
pigs reared in conventional system and (b) pigs reared outdoors.
The darker fibers are of the type I (SO), the lighter gray center
of the type IIA (FOG), around the type I, and the darker gray
are of the type IIB (FG) (Gentry et al. 2004).
Figure 2. Cross section of muscle fibers in Longissimus and
Semimembranosus of pigs reared outdoor and indoor: Type I -
slow twitch and oxidative (SO), type IIA - fast twitch and oxi-
dative (FOG) and type IIB / X - fast twitch and glycolytic (FG).
Charts of paired columns, having different letters differ sig-
nificantly (P < 0.05) (Gentry et al. 2004).
In Cinta Senese pig breed, Pugliese et al. (2005) re-
ported that pigs raised in outdoor systems, when com-
pared to indoor systems, demonstrated a lower percent-
age of the Longissimus lumborum muscle (46% vs. 48%)
and higher percentage of intermuscle fat (7.2% vs.4.7%)
and bones (20.9% vs. 19.2%). Also on this muscle from
pigs raised billboard was verified a higher percentage of
intramuscle fat (4.04% vs. 3.29%) and crude protein
(23.5% vs. 22.8%) and lower drip loss and when sub-
jected to baking in an oven (0.66% vs. 2.14% and 28.6%
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Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/OJAS/
vs. 32.3% respectively) and under a high pressure in
autoclave (30.3% vs. 26.6%).
One of the arguments for such differences in the car-
cass of these animals are the types of muscle fibers de-
veloped during their lifetime. Pigs are born with a pre-
dominance of type I fibers (red-SO), due to their devel-
opment, these fibers change to the type IIA (FOG) and
IIB / X (FOG), usually of lighter pigmentation. In gen-
eral, physical activity leads to a shift of muscle fibers
from the IIA, to IIB / X and from these to the type I;
reduced levels of activity lead to a reversal of this path
(Lefaucheur and Gerrard, 2000). According to Petersen
et al. (1998) the spontaneous physical activity signify-
cantly increases the proportion of fiber type IIA to IIB/X
in the Longissimus muscle.
In relation to muscle fiber types found in the carcass,
Gentry et al. (2004) verified a higher percentage of type
I fibers (SO) and lower of type IIA (FOG) in the Longis-
simus muscle of pigs reared outdoors. In the same study
were found lower percentage of fibers type IIB/X (FG)
in Longissimus and semimembranosus of pigs reared
outdoors compared to pigs raised in confinement system
(indoor). However, there were negative correlations be-
tween the number of fibers and the size their cross-sec-
tion, being their number of greater significance for the
evaluation as a whole.
According Bee et al. (2004) in the Rectus femoris and
Longissimus muscles of Large White pigs reared out-
doors were found greater quantity of the type IIA (FOG)
fibers and lower fiber content of type IIB/X (FG), when
compared to traditional system confined.
Moreover, other features related to consumer accep-
tance are attributed to meat in general. Among these the
meat color, brightness and luminosity must be cited once
it may stimulate the purchase by the consumer.
According to Heyer et al. (2006), pigs reared outdoors
had the glycogen content and the values of L * (lightness)
in Longissimus dorsi higher, while values of b * (yel-
low pigmentation) were lower in the meat of pigs reared
in the indoor system. In Cinta Senese pig breed, Pugliese
et al. (2005), reported that in Longissimus lumborum
muscle of pigs raised in outdoor systems had lower L *
values (brightness) (45.8 vs. 50.1) and higher values of a
* (red pigmentation) (14.9 vs. 11.8) and Chroma (15.9
vs.12.8). In Addition, according to Pugliese et al. (2004),
pigs reared outdoors (Nero Siciliano breed) showed sig-
nificantly higher lightness (L * = 50 vs.46.7) and yellow
pigmentation (b * = 5.84 vs.4.88) in the meat. Gentry et
al. (2004) commented that there were higher values of L
* (lightness) and b * (yellow pigmentation) in chops
from pigs born and reared outdoors.
Meat from pigs crossbred (Landrace X Large White)
reared outdoors showed higher a * (red pigmentation)
than those raised in confinement system (Hoffman et al.
A very important factor and often overlooked in re-
search on meat quality is the acceptance of the final
consumer. Aparicio et al. (2007) investigated these fac-
tors in meat from Iberian pig breed Valdesequera raised
in confined systems, semi-confined (5 m2/animal) and
extensive (16,800 m2/20 animals) (Table 6). These re-
searchers concluded that there was more texture and
firmness in the meat of animals raised in extensive sys-
tems when compared to other systems. These character-
istics influenced the public’s assessment, having greater
acceptance ofof meat originated from more extensive
Broiler Production
The conventional chicken is generally known for its
lack of taste and the soft and white aspect of its meat.
Some consumers prefer firmer meat and with more pro-
nounced flavor, features that correspond to older animals,
near to the sexual maturity (Bastianelli, 2001), birds that
have not suffered intense breeding (redneck strains) or the
birds subjected to physical exercise (free range or semi-
According to Castellini et al. (2008), in Europe, alter-
native systems can be a viable production method, espe-
cially if suitable changes in EU Regulation. 1804/99 are
made. The market opportunity for both organic and free
range poultry products does not yet seem to be fully de-
Age at slaughtering, genetic strains (fast- and slow-
growing), physical activity, and pasture intake are key
factors in determining meat quality. In conventional farm-
ing, fast-growing chicks are generally used, but these are
not suitable for alternative systems, since they may de-
velop health and welfare problems, the most recurrent of
which are leg disorders and lameness (Castellini et al.
2008). Conversely, use of slow-growing strains in alter-
native systems has positive repercussions on both animal
welfare and product qualitative characteristics (eating
quality and appearance) perceived by consumers (Cas-
tellini et al. 2008).
Table 6. Indexes of consumer’s taste and preference of pork
originated from different production systems.
Production systemAverageStandard deviation Preference
Confined 2.82 b ±0.90 9.1%
Semi-confined 3.53 a ±0.96 36.4%
Extensive 3.68 a ±0.94 54.5%
Different letters in the same column indicate significant differences (p
<0.05). Source: Aparicio et al. (2007).
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Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/OJAS/
In Brazil, the creation of alternative chickens then
emerges as an option to consumers, in which the term
alternative certificated chic ken is to designate the chicken
of intensive farming raised without antibiotics, anticoc-
cidial, growth promoters, chemotherapeutic agents and
animal ingredients in the diet, besides a lower stocking
density (birds / m²) and other requirements and standards
adopted and made official in the Alternative Poultry In-
dustry Association AVAL (Demattê Filho & Mendes,
The redneck chicken or “brazilian colonial” is the
chicken in which its feed is exclusively composed of
ingredients of plant origin, being forbidden the use of
growth promoters of any kind or nature. The creation is
made in sheds until the 25 days old. After this age, the
birds are released into the field, being now their rearing
extensive, recommending 3 m 2 of pasture per bird. The
slaughter is performed with a minimum age of 85 days.
The strains used must be suitable for this purpose, being
forbidden strains specific for commercial broiler (Circu-
lar of the Ministry of Agriculture and Supply MAPA,
DOI / DIPOA No 007/99 of 19.5.1999, supplemented by
the Circular DOI / No 014/2000 of 11.5.2000 DIPOA).
To serve this market, several colonial strains are cre-
ated in Brazil, highlighting the Naked Neck Label Rouge
of French origin; Embrapa 041, produced by the Na-
tional Research Center of Embrapa Swine and Poultry in
Concordia, SC; Paradise Pedrês, produced by the Birds
Grange of Paradise in Itatiba, SP and Caipirinha, pro-
duced by ESALQ / USP in Piracicaba, SP (Takahashi,
According to Gessulli (1999), it should be noted that
the redneck chicken does not compete in scale of pro-
duction and the cost with the poultry industry, but does
in the meat quality, serving a market niche that can pay
more for these characteristics.
The strains of chicken produced commercially, al-
though belonging to a single specie (Gallus gallus) show
marked differences in conformation, size and color as its
output destination. Greater peculiarities can still be de-
tected by comparing these strains with their breeds of
origin, once these differences are reflected in the skeletal
The skeletal muscles of broiler chickens reared in in-
tensive system in comparison to those created in
semi-intensive (redneck chicken) presents greater mus-
cle mass, composed by muscle fibers of size and length
superior and with more DNA (Souza, 2005). The faster
growing and the larger size of muscles of industrial
chickens in relation to the rednecks are occasioned by
the greater number of myofibers and their rapid hyper-
trophy. But there could be influence of the production
system in these results.
According Fanatico et al. (2005b), fast growth geno-
type birds has greatest breast yield (%) and the lowest
wing yield (%), while slow growth genotype birds ex-
hibit lowest breast yield (%) and the greatest leg quarter
yield (%) in the same production systems. These results
suggests that the genetic strain is more significant that
system of rearing. Drip loss and cook loss (%) were af-
fected by genotype, with the highest losses occurring
with the slow growth genotype and the lowest losses
occurring with the fast growth genotypes (Fanatico et al.
Selection for high growth rate led to a relative in-
crease on the number and total cross-sectional area of
myofibers. This may explain the greater weight of the
muscles of animals of high growth rate. Madeira et al,
(2006) evaluating the morphological aspects of skeletal
muscle fibers types of the flexor Hallucis lon gus of four
strains of broiler chickens raised in confined systems
(Ross) and semi-confined (Naked Neck Label Rouge,
Caipirinha and Paradise Pedrês) observed that Ross
presented greater muscle mass (Ta ble 7). These results
indicate that the growth rate is related to the increase in
the area of the three muscle fiber types (SO, FOG and
FG) in birds selected for increased body growth. In rela-
tion to the rearing system no significant difference was
observed between the two genetic groups.
Similarly, Sartori et al. (1999) also observed a greater
area of FG and SO fibers in the flexor Hallucis longus
muscle of broilers when comparing strains of high
growth (Hubbard and Ross) to another of slow growth
(Naked Neck). According to these authors, the greater
muscle mass of broilers selected can be characterized by
Table 7. Mean values of area (mm²) of the glycolytic fibers
type (FG), intermediate (FOG) and oxidative (SO) from the
flexor hallucis longus muscle of broilers at 56 days old, ac-
cording to the strain and rearing system.
Ross 7104.51 a 4915.77 a 4860.84 a
Paradise Pedrês 4442.22 b 4270.18 a 2735.20 b
Caipirinha 3067.20 c 3308.73 b 2677.56 b
Naked Neck 3062.76 c 3148.09 b 2199.20 b
Production systemFG FOG SO
Confined 4466,29 4014,99 3087,65
Semi-confined 4597,96 3778,25 3093,33
a,bMeans in column followed by different letters differ (P < 0.05) by Tukey
test. Source: Madeira et al, (2006).
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Copyright © 2011 SciRes. http://www.scirp.org/journal/OJAS/Openly accessible at
the increase of the muscle fibers area, principally glycol-
lytic, indicating that the major selection pressure for
weight gain is manifested in the hypertrophy of the mus-
cle fibers.
The selection for high growth rate in broilers has
promoted structural and metabolic changes in muscles
and changed the meat quality. High growth rates leads to
injuries, larger diameter of muscle fibers, greater propor-
tion of glycolytic fibers and reduced muscle proteolysis.
These changes results in faster rigor mortis, which in-
creases the meat pallor and diminish their capacity to
fluid retention, worsening the quality of the processed
products. The decrease in muscle proteolysis increases
the hardness of the poultry meat (Dransfield & Sosnicki,
To evaluate the smoothness can be used subjective
methods like tasters in a taste test and equipment that
measure the force required to shear the samples, such as
methods of Allo-Kramer and Warner-Bratzler. Another
indirect measure of this characteristic is the pH, which is
related to the rigor mortis. To determine the rigor mortis
is also made the evaluation of the glycogen level (Smith
et al., 1992).
Fanatico et al. (2006) working with fast, medium and
slow growing strains of broilers, found that the breasts of
the medium growing birds were more tender than other
genotypes, however, all treatments scored “slightly to
moderately tender”. The thigh meat of the medium de-
velopment birds was more flavorful than that of slow
growing birds, and the flavor of the slow growing broil-
ers thigh meat was less liked than other genotypes.
Analyzing the characteristics of meat quality in four
strains of broiler chickens, being one of them commer-
cial (Ross) and the other specific to the colonial produc-
tion (Caipirinha, Naked Neck and Paradise Pedrês),
Takahashi (2003) verified that Ross showed less weight
loss due to cooking and greater shear force of breast
muscle fibers compared to colonial birds (Table 8).
Coelho, et al. (2007) verified that only two of eight
genetic groups of broilers reared under semi-intensive
system (Caipirão and Embrapa 041) presented a shear
force of the Pectoralis major muscle fibers lower than
the control group (Ross) reared under intensive system
(Table 8).
However, Rajar et al. (1999) and Lima (2005) ob-
tained lower values of shear force to the fibers of the
flexor Hallucis longus muscle of conventional broiler
breeds (1.97 and 2.94 kgf.cm–2, respectively) in relation
to redneck broiler breed (2.46 and 3.39 kgf.cm–2, re-
According to Souza (2005), these different results may
be related to muscle physiology, since the breast muscle
glycolytic metabolism decreases the effects of the dif-
ference between conventional rearing systems and semi-
confined (redneck), in addition of this muscle do not be
required to the birds’ movement, unlike what happens to
the Flexor hallucis. Additionally, Magalhães (2004) stated
that the location and function of the muscle are impor-
tant factors that influence the shear force of the muscle
fibers (Table 9).
According to Cothenet (1998), the meat of redneck
broilers Label Rouge reared under the semi-confined
system when compared to commercial broilers of inten-
sive farming, obtained in the taste test lower tenderness
and juiciness. However, the Label Rouge broiler had
higher scores for flavor and preference. Other important
features related to the meat quality are determining the
chemical composition, fatty acid profile, the color and
the sensory analysis.
According to Scheuermann (2004), with the selection
pressure for high growth in broiler chickens, have been
observed greater susceptibility to PSE meat (pale, soft
and exudative), due to the high glycolytic potential and
especially to the size of muscle fibers. These fibers de-
rive energy for contraction through the glycolytic path-
way and, under stress conditions with high energy de-
mand (such as stirring pre-slaughter), the metabolism
contributes to the rapid drop in the pH consequently
raising the lactic acid production, which cannot be re-
moved at post mortem. Concerning the increase in the
fiber size, this may negatively affect the meat quality,
leading to a greater tendency to PSE.
Table 8. Effect of the broiler strain on the meat quality pa- rameters (pectoralis major muscle) at 56 days old.
Shear force
Strain Weight loss due to cooking (%) Thickness (cm) Width (cm) Lenght (cm) pH
Ross 14.93 b 2.57 a 8.57 a 18.76 a 5.92 a 3.44 a
P. Pedrês 18.22 a 1.42 b 7.12 b 16.10 b 5.85 ab 2.46 b
Caipirinha 19.03 a 1.29 bc 6.34 c 14.85 c 5.80 b 2.79 b
N. Neck 18.75 a 1.25 c 6.45 c 14.99 c 5.84 ab 2.64 b
Means followed by different letters in columns differ by Tukey test (P < 0.05). Source: Takahashi (2003).
W . A. G. Araújo et al. / Open Journal of Animal Scie nces 1 (2011) 75-88
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/OJAS/
Table 9. Comparison of means to shear force, tenderness and flavor of the meat among strains of broilers reared under intensive and
semi-confined systems.
Strains Shear force (kgf.cm–2)1 Softness2 Flavor2
Ross (control) 4.02 a 4.75 a 4.32 a
Redneck 3.07 b 3.82 b 3.68 a
7P 3.30 a 4.56 a 4.00 a
Paradise Pedrês 3.16 a 3.97 b 3.55 b
Embrapa 041 2.67 b 4.26 a 3.37 b
Label Rouge 3.19 a 3.66 b 3.81 a
Naked Paradise 3.37 a 3.33 b 3.31 b
Caipirinha 3.58 a 4.33 a 3.97 a
Carijó Barbado 3.45 a 4.51 a 3.91 a
Overall Mean 3.31 a 4.13 3.77
1Means followed by different letters differ from control by Dunnett test (P < 0.05). 2Means followed by different letters differ from control by X 2 test (P < 0.05).
Source: Magalhães (2004).
According to Olivo (2004), fillets of PSE broilers are
also characterized by high levels of exudate, due to its
low water retention capacity, compromising its nutria-
tional properties. This occurs primarily in products in-
jected with brine and cooked in the cook-in system-bags,
due to release of moisture during the slicing and, also,
the pre-cooked steaks tend to be dry, fibrous and rancid,
when reheated, compromising their sensorial and nutria-
tional qualities.
In the other hand, the appearance of the meat and
carcass seems affected by the interaction between geno-
type and production systems of the birds. The meat and
skin of the slow growth birds become more yellow when
the birds had outdoor access; however, this did not occur
when the fast birds has outdoor access (Fanatico et al.
2007). In addition, the breast meat of the slow birds has
more protein and α-tocopherol than the fast growth
broilers and half the amount of fat (Fanatico et al.,
r and size of mito-
uscle fibers in sev-
The extensive production system differs from the tra-
ditional system relying primarily on two characteristics,
diet and the animals’ physical activity. Although there is
the inclusion of roughage in the most extensive systems
of broilers production, the vast majority of nutrients are
provided by the concentrated feed. In addition, the in-
crease in physical activity is crucial for the am
the meat color and texture aspects.
The effects of the exercise on the histochemical pat-
tern of skeletal muscle and, therefore in its fiber compo-
sition, are complex and variable and depend of several
factors including the exercise type (strength or resis-
tance), the intensity and duration, the status of individual
training, the muscle studied and possibly, the genetic
makeup. Associated to these changes, we observe the
weight increase, measure and conformation of the mus-
cle subjected to exercise (Gonzales & Sartori, 2002).
The physical exercise can promote biochemical changes
in the skeletal muscle, like increased capacity for oxida-
tion of pyruvate and long-chain fatty acids; increased
respiratory capacity, which varies with the intensity and
duration of the exercise; increased activity of a large
number of mitochondrial enzymes, which seems to be
the result of raising the concentration of enzyme proteins;
the concentrations of cytochromes and myoglobin in the
muscle and the increase of the numbe
ondria (Gonzales & Sartori, 2002).
According to Gonzales & Sartori (2002), the duration
of exercise can cause some modulation of white fibers
into red, since, in histochemical studies, it was observed
a decrease in the percentage of muscle fibers with white
character and an increase in the fibers with red character.
The changing pattern of fibers is accompanied by an
increased muscle vascularization, with a higher capillary
density and rate of capillaries per fiber. There are also
indications that certain forms of mechanical overload
(stress, exercise, compensatory hypertrophy) may pro-
mote an increase in the number of m
al animal species (Kelley, 1996).
In broiler chickens, Khaskiye et al. (1987) observed
an increase in the physical muscle characteristics (such
as weight and diameter) and modulation of its fibers due
to the exercise. The authors also verified that the pattern
of physical activity influences the intensity of muscle
W . A. G. Araújo et al. / Open Journal of Animal Scie nces 1 (2011) 75-88
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/OJAS/
, s
rowth rates and reared with
or without outdoor access.
ion and the fatty acid profile
deposited on the carcass.
n introductory text,
CAL e II simpósio sobre SISCAL, Concórdia,
da carne suína,
ve traits. Livestock Produc-
differentiation, and that both the placement of barriers
and ramps in conventional boxes are crucial for obtain-
ing heavier muscles, after three or four weeks of expo-
sure to the new situation. The production system also in-
terferes with bone formation in birds. Birds given out-
door access has greater bone strength in the tibia that ani- CNP
als reared in intensive system (Fanatico et al., 2005b).
Rearing broilers in sheds with ramps Sandusky &
Heath (1988), verified an increase in chest growth rate
and greater size of the Pectoralis major, Supracora-
coideo, Gastrocnemius (inside) and Femoro tibial mus-
cles in birds reared in boxes with simple ramps, however
in boxes with dual ramps it was found an increase in the
growth of fibula long and Femorotibial muscles of
broilers. Based on these considerations, it is verified that
the birds’ physical activity leads to adaptive changes that
elevate the oxidative capacity of skeletal musclesimi-
r to those that have been observed in mammals.
Studding broilers from fast and slow growing strains,
reared in outdoor and indoor systems, Fanatico et al.
(2005a), found that the principal effect of outdoor access
was to make the meat more yellow in the case of the
slow growing strain genotype, although not the fast grow-
ing birds. In the same work was observed that the ten-
derness was affected by production system, but only in
the fast growing strain birds. The pectoralis dry matter
(%), fat (%), and ash (%) were largely unaffected, both
the production system and genotype (Fanatico et al.,
2005a). However, the outdoor access did not impact fla-
vor of the thigh and breast meat of the birds in the sen-
sorial test (Fanatico et al., 2006). These data indicate
that differences in sensory attributes may exist among
geno- types with different g
The production of poultry and pigs more extensively
tend to get a final product with its own organoleptic
characteristics, changing the meat default color and con-
tent, place of fat deposit
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