bs_bs_banner
Animal Science Journal (2014) 85, 770–779
doi: 10.1111/asj.12207
ORIGINAL ARTICLE
The comparison of energy metabolism and meat quality
among three pig breeds
Linyuan SHEN,* Huaigang LEI,* Shunhua ZHANG, Xuewei LI, Mingzhou LI, Xiaobing JIANG, Kangping ZHU
and Li ZHU
College of Animal Science and Technology, Sichuan Agricultural University, Ya’an, Sichuan, China
ABSTRACT
The objective of this study was to evaluate the effects of muscle-fibre types and hormones on glycolytic potential and meat
quality traits and their association with glycolytic-related gene expression in three different altitude pig breeds. The pig
breeds studied were the Tibetan pig (TP, high altitude), the Liang-Shan pig (LSP, middle altitude) and the
Duroc × (Landrace × Yorkshire) cross (DLY, flatland). The results indicated that TP and LSP had better meat quality than DLY
(P < 0.01). The glycolytic potential (GP) increased in the order of TP < LSP < DLY and decreased with time post mortem. DLY
had higher glucagon and epinephrine contents than LSP and TP (P < 0.01). The proportions of myosin heavy chain muscle
fibers type I in the Longissimus dorsi increased in the order of DLY < TP < LSP, whereas the proportion of type IIb increased
in the order of TP < LSP < DLY. The expression of gene PKM2 played an important role in the glycolysis rate of the different
genotypes. Compared with the other two pig breeds, the high-altitude breeds had better meat quality attributes, which
may be due to the slow rate of glycolysis metabolism.
Key words: glycolytic potential, hormone, meat quality, muscle-fiber type, pig.
INTRODUCTION
In animals, the conversion of muscle to meat is a
process of energy metabolism with glycolysis after
slaughter (Binke 2004). However, the rate and extent
of glycolysis causing pH to decline during the conversion of muscle to meat are affected by many factors.
One of the main factors is the composition of the
muscle-fiber type, which affects final meat quality by
influencing muscle glycogen status and post mortem
energy metabolism, as well as the glycolytic potential
(GP), an indicator of energy metabolism (Channon
et al. 2000). Another important factor is hormone
content; epinephrine and glucagon induce an increase
in cyclic adenosine monophosphate (cAMP), which
leads to the phosphorylation of glycogen by phosphorylase kinase. This results in an increase in the rate
of glycogenolysis and glycolysis, whereas the function
of insulin is to achieve the opposite (Scheffler &
Gerrard 2007). Furthermore, the major genes controlling the rate-limiting enzymes for glycolysis reaction
and adenosine-5′-triphosphate (ATP) generation, can
also influence the rate and extent of pH decline. The
ATP synthase genes (ATP5a1 and ATP5b) play important roles in ATP synthase subunits alpha and beta; the
ATP-citrate lyase gene (ACL) also plays an important
© 2014 Japanese Society of Animal Science
role in the breakdown of cytosolic citric acid. These are
both essential steps in the pathway of ATP synthesis
and glycolysis reactions (Hatzivassiliou et al. 2005;
Højlund et al. 2010). Hexokinase plays an important
role as the first rate-limiting enzyme of glycolysis,
catalyzing glucose to glucose 6-phosphate, which is
coded by genes HK-1, HK-2 and HK-4. The PFKM gene
codes for phosphofructokinase, which catalyzes the
conversion of fructose 1-phosphate and ATP to fructose 1,6-bisphosphate and adenosine diphosphate
(ADP), which is an essential step in the glycolytic
pathway. The PFKM gene codes for pyruvate kinase,
which catalyzes the irreversible conversion of
phosphoenolpyruvate and ADP to pyruvate and ATP
(Fontanesi et al. 2003; Sieczkowska et al. 2010).
The Tibetan pig (TP) is a typical native pig breed that
lives in cold plateau areas at high altitude for its whole
Correspondence: Li Zhu, College of Animal Science and
Technology, Sichuan Agricultural University, 46# Xinkang
Road, Yucheng District, Ya’an 625014, China. (Email:
[email protected])
*These authors contributed equally to this work.
Received 30 August 2013; accepted for publication 7 January
2014.
ENERGY METABOLISM EFFECT ON MEAT QUALITY OF PIG
lifetime (about 3000 m altitude), which gives its meat
special characteristics, such as high pH value and a
tender texture (Zhu et al. 2009; Iournals 2011). The
Liang-Shan pig (LSP) is a Chinese native pig breed; it
lives in the middle mountainous areas (about 1500 m
altitude) and has a reputation for excellent meat
quality. The Duroc × (Landrace × Yorkshire) pig (DLY)
is a commercial crossbred pig and lives on the plains
(about 100 m altitude) and has inferior meat quality
attributes compared with Chinese native pig breeds
(Tang et al. 2008; Men et al. 2012). To some extent, the
environment at different altitudes may lead pig breeds
to have special energy metabolism mechanisms during
their adaptation and evolution. It is well known that
meat quality is determined by the rate of glycolysis
post mortem. Therefore, the three pig breeds, living in
Sichuan province at different altitudes simultaneously,
are the perfect experimental materials to study the
mechanism of energy metabolism rate and its effect on
meat quality. Meanwhile, we tracked the meat quality
change for a long time until 96 h post mortem, and
analyzed some new factors that had correlations with
meat quality, such as hormones and the expression of
ATP synthase-related genes. All the work was aimed to
evaluate the influence of different energy metabolism
rates on meat quality and to explore some new factors
that are associated with this mechanism.
MATERIALS AND METHODS
The experimental protocol was approved by the Animal Care
and Ethics Committee of Sichuan Agricultural University,
Sichuan, China, under permit No. DKY-S20093030.
Animals and treatments
Three pig breed groups from different altitudes were used in
this study, and each group had 24 pigs. The first group was
Tibetan pig (TP), a high altitude (about 3000 m altitude)
native pig breed in China. The second group was Liang-Shan
pig (LSP), a middle altitude (about 1500 m altitude) native
pig breed. The third was flatland (about 100 m altitude)
Duroc×(Landrace × Yorkshire) cross (DLY). All pigs were
housed in individual pens (2 m2) located in MingXing Livestock Industry Co., Ltd, Sichuang Province, China (about
100 m altitude). All pigs were fed twice a day with the same
diet from weaning to slaughter. During the experimental
period, pigs had ad libitum access to diet and water (nipple
drinkers). The experimental diets were based on corn and
soybean meal, and were formulated with crude protein concentrations, trace minerals and vitamins to meet the National
Research Council (NRC 1998) recommendations for the different growth phases. During the experimental period, the
corn–soybean meal diet was offered to all pigs. All groups
were slaughtered at their suitable slaughter weight, including
24 TP (50 ± 2.0 kg, 180 days old), 24 LSP (60 ± 2.5 kg, 180
days old) and 24 DYL (100 ± 2.5 kg, 180 days old). When
being slaughtered, the pigs were kept off feed but given free
access to water for 24 h, and then electrically stunned,
exsanguinated, scalded and rinsed. Samples were obtained
from the core of the Longissimus dorsi adjacent to the last rib
immediately after exsanguination, and rapidly frozen in
Animal Science Journal (2014) 85, 770–779
771
liquid nitrogen for gene expression and biochemical analysis.
Samples were obtained from the Longissimus dorsi adjacent to
the third and tenth rib for meat quality traits measurement at
45 min post mortem, and then stored at 4°C for the remaining meat quality trait measurements.
Meat quality measurements
pH was measured using a pH meter (model 720A; Orion
Research Inc., Boston, MA, USA) at 45 min, 24 h, 48 h, 72 h
and 96 h post mortem on the third rib Longissimus dorsi, The
electrode was calibrated with pH 4.6 and 7.0 buffers equilibrated at 35°C for the measurements of the warm carcass
after 45 min and equilibrated at 4°C for the measurements at
24 h, 48 h, 72 h and 96 h post mortem. Color parameters
were determined using a Minolta CR-300 colorimeter
(Minolta Camera, Osaka, Japan) with an illuminant D65, a
10° standard observer, and a 2.5-cm port/viewing area.
Water-holding capacity was measured as drip loss from the
Longissimus dorsi (Honikel 1998). About 30–50 g meat sample
was trimmed and weighed. The sample was then placed in a
net surrounded by an inflated plastic bag and suspended for
48 h at 4°C. Then the sample was reweighed at 24 h and 48 h
post mortem, and drip loss was expressed as the weight
change percentage. Warner-Bratzler shear force (WBS) was
determined using a Texture Analyzer (TA.XT. Plus, Stable
Micro Systems, Godalming, UK) equipped with a WarnerBratzler shearing device. Six cores (1.27 cm diameter) were
removed from each steak parallel to the longitudinal orientation of muscle fibers. Samples were sheared perpendicular
to the long axis of the core at 72 h post mortem. Samples
were heated in 80°C water until their inner temperature
reached 70°C. Hot dog shearing procedure was used in the
test, with the parameters at pre-test speed as 2 mm/s, test
speed as 2 mm/s and post-test speed as 10 mm/s. The basic
chemical components (water and dry matter, total protein
and intramuscular fat) were measured according to the
methods of Horwutz (2000); samples were measured from
the Longissimus dorsi adjacent to the 10th rib.
ELISA biochemical indexes
and hormones
A 500 mg frozen muscle sample was weighed and homogenized in 500 mL of 0.9% saline and then centrifuged
at 4200 × g for 10 min at 4°C. The supernatant was diluted
50 times for measuring Gly (glycogen, E07G0023), Glu
(glucose,
E07G0030),
G-6-P
(glucose-6-phosphate,
E07G0036), LA (lactate, E07L0004), insulin (E07I0004),
glucagon (E07G0101) and epinephrine (E07A0007) content
by using standard commercial kits from BlueGene Biotech
Co., Ltd. (Shanghai, China); optical density (OD) at 450 nm
was immediately measured utilizing an ELISA microplate
reader. Consequently, a calibration curve was constructed
using OD values corresponding to each concentration of the
standard. Compound contents were expressed as mmol/g
wet weight and GP values were calculated by the formula:
GP = 2 × (Gly + Glu + G-6-P) + LA (Monin & Sellier 1985).
Real-time PCR analysis
The expression levels of selected genes were quantified
using real-time RT-PCR analysis. Briefly, total RNA was
extracted from the Longissimus dorsi using TRIZOL reagent
(Invitrogen Corp, Carlsbad, CA, USA) according to the
© 2014 Japanese Society of Animal Science
772 L. SHEN et al.
manufacturer’s instructions. Reverse transcription was performed using oligo (dT) random 6-mers primers provided in
the PrimeScript RT Master Mix kit (TaKaRa, Dalian, China),
following the manufacturer’s recommendations. Quantitative PCR was performed using the SYBR Premix Ex Taq kit
(TaKaRa, Dalian, China) on a CFX96 Real-Time PCR detection system (Bio-Rad, Richmond, CA, USA). All measurements contained a negative control (no cDNA template) and
each RNA sample was analyzed in triplicate. Relative expression levels of the target mRNAs were calculated using the
ΔΔ
Ct method (Livak & Schmittgen 2001).
Statistical analysis
Statistical analysis was performed using the analysis of
vaiance (ANOVA) procedure of the SAS System (SAS 9.2;
SAS Inst. Inc., Cary, NC, USA). Hormones content, muscle
fiber type composition and gene expression were compared
using a one-way ANOVA. The rest of the data was analyzed
using two-way ANOVA; factor 1 was post mortem storage
time and factor 2 was breeds. Tukey-Kramer test was applied
to post hoc test. Mean values and standard errors were
reported in the tables. Differences were considered significant if P ≤ 0.05. Correlation among the different indices was
evaluated with Pearson bivariate analysis and a two-tailed
test of significance.
RESULTS AND DISCUSSION
Meat quality attributes in different
altitude genotypes
Meat quality attributes of Longissimus dorsi in the three
altitude genotypes are shown in Table 1; there were
significant differences among the three genotypes.
Compared with the two Chinese native breeds (TP,
LSP), DLY had a lower dry matter content (P < 0.05),
lower intramuscular fat content (P < 0.01) and a
higher drip loss at 24 and 48 h post mortem
(P < 0.001). In addition, other meat quality traits such
as meat lightness and shear force increased in the
order of TP < LSP < DLY, whereas the order was
reversed for pH. However, no significant differences in
water content, dry matter content and protein content
were seen between the three breeds (Table 1). The
results agreed with Suzuki et al. (1991), who found
that two Chinese native pig breeds (Meishan and
Mingzhu) had a higher intramuscular fat (IMF)
content, water-holding capacity and sensory scores
than crossbreeds between Landrace and Duroc. Dai
et al. (2009) reported that the Chinese native Lantang
pig had a higher IMF content than the Landrace. Miao
et al. (2009) also found native Jinhua pigs had lower
color scores, higher IMF percentages, higher marbling
scores and lower drip losses than the Landrace. Low
drip loss means high meat water-holding capacity
(WHC), and high WHC values might bring advantages
in processed meats for the industry and in fresh meat
appearance for the consumer (Den Hertog-Meischke
et al. 1997). IMF depended on the genotype of pigs and
was an important holder of flavor (Affentranger et al.
1996). Generally, meat with low intramuscular fat
content tastes insipid, straw-like and dry. All results
suggested that the Chinese native breeds (TP and LSP)
Table 1 Effect of genotype on meat quality
Trait
Composition of lean†, %
Water
Dry matter
Protein
Intramuscular fat
Drip loss‡, %
24 h§
48 h§
pH values‡
45 min§
24 h§
48 h§
72 h§
96 h§
Meat lightness‡ (L*)
45 min§
24 h§
48 h§
72 h§
96 h§
Shear force‡, kg
Genotype
Level of significance
(genotype)
TP
LSP
DLY
S.E.
72.56
25.26A
21.64
3.15A
72.81
25.22A
21.85
3.43A
74.49
23.54B
21.38
1.90B
0.85
0.78
0.63
0.12
NS
*
NS
**
1.01C
3.51B
1.99B
3.66B
2.45A
5.35A
0.09
0.87
***
***
6.78A
5.87A
5.59A
5.61A
5.55
6.71A
5.77A
5.63A
5.64A
5.58
6.53B
5.69B
5.47B
5.48B
5.62
0.03
0.03
0.02
0.02
0.04
***
*
**
**
NS
37.55B
40.89B
45.70B
45.13B
47.96B
3.64C
36.59B
43.61A
48.57A
51.05A
48.32A
4.24B
39.68A
45.94A
49.37A
49.03B
51.44A
6.33A
0.73
0.83
0.78
1.15
8.52
0.13
*
*
*
*
*
***
DLY, Duroc × (Landrace × Yorkshire) cross; LSP, Liang-Shan pig; TP, Tibetan pig. L* = a measure of darkness to lightness (higher value
indicates a lighter color). †Longissimus dorsi at thith rib; ‡Longissimus dorsi at 10th rib; §time post mortem.
NS, no significant difference, P > 0.05; *significant at the 5% level; **significant at the 1% level; ***significant at the 0.1% level.
A,B,C
Means within the same row sharing the same superscript letter are not significantly different (P > 0.05).
© 2014 Japanese Society of Animal Science
Animal Science Journal (2014) 85, 770–779
ENERGY METABOLISM EFFECT ON MEAT QUALITY OF PIG
A
B
7.00
TP
Breed P < 0.001
Time P < 0.001
Interaction P = 0.008
6.80
180
DLY
Lactic acid ( µmol/g muslce )
The trend of pH
Breed P < 0.001
Time P < 0.001
Interaction P = 0.73
LSP
6.60
6.40
6.20
6.00
5.80
5.60
5.40
160
140
120
100
80
TP
60
LSP
DLY
40
20
5.20
45min
24h
48h
72h
96h
45min
24h
48h
72h
96h
Time (hours postmortem)
Time (hours postmortem)
D
C
60
50
40
30
Breed P < 0.001; Time P = 0.92; Interaction P = 0.99
120
Free glucose ( mg/dl )
70
130
DLY
LSP
TP
TP
LSP
DLY
Breed P < 0.001
Time P < 0.001
Interaction P = 0.13
80
Glycogen ( µ mol/g muslce)
773
110
100
b
90
80
c
b
b
c
c
c b
b
c
70
20
60
10
45min
24h
48h
72h
96h
Time (hours postmortem)
45min
24h
48h
72h
96h
Time (hours postmortem)
Figure 1 The change in trends of pH values and biochemical indices in Longissimus dorsi during the period from 45 min post
mortem to 96 h post mortem: The change in trends of Tibetan pig (TP), Liang-Shan pig (LSP) and
Duroc × Landrace × Yorkshire cross (DLY) pH values (A), lactic acid (B), glycogen (C) and free glucose (D) of Longissimus dorsi
from 45 min post mortem to 96 h post mortem. Values are presented as means + SE, using two-way analysis of variance.
had better sensory attributes of tenderness, juiciness
and taste than the DLY.
To further explore the factors that caused meat
quality difference among the three breeds, the relationship between energy metabolism and meat quality
was analyzed. First, we needed to understand the
change rule of the meat quality. However, there has
been some debate about whether the ultimate meat
quality should be measured at 24 or 48 h post mortem;
for example, it is measured at 48 h post mortem in
some European countries. To ensure the relevance of
this study, we tracked the meat quality traits until 96 h
post mortem. We found that all genotypes had a
similar change in pH values over time; within the first
24 h post mortem, pH decreased rapidly; for the
second 24 h post mortem it decreased slightly, and it
remained constant after 48 h post mortem (two-way
ANOVA: effect of breed, P < 0.001; effect of time,
P < 0.001; interaction, P < 0.01, Fig. 1A). This demonstrated that the ultimate meat quality determined at
48 h post mortem was more precise than that at 24 h
post mortem. The results agreed with a previous study
(Dransfield et al. 1985) which measured the ultimate
meat quality at 48 h post mortem. Meanwhile, we also
found meat lightness, shear force and drip loss were
significantly negatively correlated with pH values
(data not presented). This result also agreed with previous reports (Scheffler & Gerrard 2007; Sieczkowska
Animal Science Journal (2014) 85, 770–779
et al. 2010) which found that the higher pH values, the
higher the cooking loss and shear values, but the lower
the drip loss. After slaughter, with decreasing muscle
pH, denaturation of sarcoplasmic proteins occurred
and the degenerative myofibrillar proteins changed
the meat color from red to white (Huff-Lonergan et al.
2002; Smith et al. 2011). The formation of the meat
protein lattice would have been influenced, leading to
soft textured meat (Huff-Lonergan et al. 2002). Furthermore, denatured actin and myosin would reduce
the water-holding capacity (Westphalen et al. 2005).
Therefore, we could conclude that pH was the most
important factor of all the meat quality traits. Generally, the pH values declining during the conversion of
muscle to meat was caused by the extent of glycolysis.
It was reasonable to research the formation mechanism of meat quality through research on energy
metabolism. These results also suggested that ultimate
meat quality determined at 48 h post mortem was
more precise than that at 24 h post mortem.
The effect of GP on meat quality
The glycogen and lactate content of Longissimus dorsi in
the three altitude genotypes are shown in Figure 1B
and C. Compared with the two Chinese native breeds
(TP, LSP), DLY had a lower glycogen (P < 0.001) and
higher lactate (P < 0.001) content. Glycogen quickly
decreased and lactate rapidly increased before 48 h
© 2014 Japanese Society of Animal Science
774 L. SHEN et al.
Table 2 Correlation coefficients about Tibetan pig between GP, lactate and meat quality attributes
Trait
GP
45 min
pH values†
45 min§
−0.47**
24 h§
−0.39**
48 h§
−0.41**
72 h§
−0.43**
96 h§
−0.29**
Meat lightness† (L*)
45 min§
0.38**
24 h§
0.25*
48 h§
0.24*
72 h§
0.21*
96 h§
0.22
Drip loss†, %
24 h§
0.24
48 h§
0.21*
Shaer force†, kg
0.14
Chemical composition‡, %
Water
0.29**
Dry matter
−0.53*
Protein
−0.31*
Intramuscular fat
−0.17
Lactate
24 h
48 h
72 h
96 h
45 min
24 h
48 h
72 h
96 h
−0.38*
−0.57**
−0.32*
−0.26*
−0.26*
−0.25*
−0.39*
−0.21*
−0.14
−0.18
−0.18
−0.24
−0.16
−0.12
−0.13
−0.15
−0.22
−0.05
−0.09
−0.06
−0.62***
−0.56**
−0.45**
−0.31*
−0.23*
0.45**
−0.72***
−0.52***
−0.38*
−0.22*
−0.49**
−0.49**
0.64***
−0.40**
−0.31*
−0.36**
−0.38*
−0.45**
−0.58***
−0.36**
−0.47*
−0.25*
−0.41*
−0.45**
−0.45**
0.25*
0.37**
0.16*
0.17
0.17
0.21
0.23*
0.15
0.14
0.07
0.15
0.19
0.17
0.08
0.13
0.17
0.14
0.13
0.11
0.12
0.47***
0.58*
0.33*
0.14
0.15
0.32**
0.67**
0.24*
0.27*
0.23*
0.29**
0.38*
0.28**
0.23*
0.21
0.36*
0.27*
0.19*
0.34**
0.24*
0.28*
0.18
0.24*
0.08
0.38*
0.17
0.16
0.18
0.14
0.08
0.13
0.22*
0.13
0.06
0.13
0.07
0.08
0.26*
0.22*
0.17*
0.19**
0.13
0.23*
0.13
0.22**
0.32**
0.12
0.15
0.22*
0.09
0.21
0.28*
0.25
−0.17
−0.18
−0.08
0.23
−0.16
−0.26
−0.07
0.13
−0.15
−0.09
−0.06
0.16
0.32**
−0.07 −0.42*
−0.14 −0.23*
−0.17 −0.19
0.18
−0.14
−0.19
−0.16
0.14
−0.23
0.17
−0.14
0.19
−0.18
−0.06
−0.09
0.07
−0.13
−0.15
−0.13
GP, glycolytic potential; L* = a measure of darkness to lightness (higher value indicates a lighter color). †Longissimus dorsi at 10th rib;
‡Longissimus dorsi at thith rib; §time post mortem. *significant at the 5% level; **significant at the 1% level; ***significant at the 0.1%
level.
post mortem (P < 0.001), but the rate of change
slowed down at 72 h post mortem and stayed constant
after then. The content and change in G-6-P in the
three altitude genotypes were similar to those in
lactate (data not presented). With lactate increasing
and glycogen decreasing post mortem, the GP significantly decreased following the process of glycolysis,
and the GP of DLY was significantly higher than the
two Chinese native breeds (P < 0.001). The GP of LSP
was also higher than that of TP (P < 0.05, data not
presented). This result also agreed with previous
reports; Shen et al. (2006) found that the lactate
content in pigs at slaughter was 4 mg/g and increased
to 12 mg/g at 24 h post mortem, but the content of
glycogen decreased from 13 to 5 mg/g. Some results
agreed with previous findings (Hamilton et al. 2003),
which also showed that for live pigs, GP was
201 μmol/g and decreased to 149 μmol/g at 24 h post
mortem. TP and LSP are high-altitude breeds adapted
to low oxygen levels and a cold environment over
thousands of years, leading to special glycolysis characteristics. To adapt to a cold, high altitude environment, TP and LSP must have enough energy supply to
maintain body temperature. The anaerobic metabolism (glycolysis) is inefficient and produces only two
ATP molecules for each glucose molecule, whereas
complete oxidative metabolism produces 38 ATP molecules (Gatenby & Gillies 2004). Thus, TP and LSP
must improve the efficiency of energy production,
which could induce high altitude breeds to increase
© 2014 Japanese Society of Animal Science
oxidative metabolism and decrease anaerobic metabolism. The results also agreed with Li et al. (2013), who
found that TP had a striking expansion of 27 ferritin
family genes while there were only 12 ferritin genes in
the Duroc pig (Li et al. 2013). According to these
results, we can deduce that TP and LSP have a lower
GP than DLY, which may lead to their superior meat
quality characteristics compared with DLY.
It is well known that pH value is a crucial factor
influencing ultimate meat quality. Generally, the
decline in pH values is mainly caused by increasing
lactic acid after slaughter (Monin & Sellier 1985). GP is
a measure of all compounds present in the muscle that
can be converted into lactic acid. Therefore, GP had a
significant correlation with meat quality. For example,
the correlation coefficients for TP between GP and
meat quality traits are shown in Table 2. Dry matter
content and protein content had a negative correlation
with GP (r = −0.53, P < 0.05; r = −0.31, P < 0.05;
respectively) and with lactate (r = −0.42, P < 0.05;
r = −0.23, P < 0.05; respectively) only at 45 min post
mortem. Shear force had a significant positive correlation with lactate (P < 0.05) but not with GP
(P > 0.05). pH values and meat lightness had significant correlations with GP at 45 min and 24 h post
mortem. However, lactate always had a high correlation with pH values and meat lightness. These results
suggested that for TP, the correlation coefficients
between GP and meat quality decreased with time post
mortem, but lactate maintained a strong correlation
Animal Science Journal (2014) 85, 770–779
B
6
3
2.5
2
1.5
1
0.5
0
TP
LSZ
DLY
775
C
Epinephrine in muscle (mg/dl)
A
3.5
Glucagon in muscle (mg/dl)
Insulin in muscle (mg/dl)
ENERGY METABOLISM EFFECT ON MEAT QUALITY OF PIG
5
4
3
2
1
0
TP
LSZ
DLY
16
14
12
10
8
6
4
2
0
TP
LSZ
DLY
Figure 2 Comparison of the content of hormones in the Longissimus muscle among the following three genotypes: Tibetan
pig (TP), Liang-Shan pig (LSP) and Duroc × Landrace × Yorkshire cross (DLY). (A) Insulin content in TP, LSP and DLY Longissimus
muscle measured at 0 min post mortem. (B) Glucagon content in TP, LSP and DLY Longissimus muscle measured at 0 min post
mortem. (C) Epinephrine content in TP, LSP and DLY Longissimus muscle measured at 0 min post mortem. Samples were
obtained from the core of Longissimus dorsi adjacent to the last rib immediately after exsanguination, and rapidly frozen in
liquid nitrogen.
with meat quality. The same results were also found
with LSP and DLY (data not presented). These results
agreed with a previous report (Hamilton et al. 2003)
that showed that, for live pigs, GP had a negative
correlation with the ultimate pH, that the degree of
correlation was lower than for GP at 24 h post
mortem, and that free glucose had a higher correlation
with meat quality than GP. Scheffler et al. (2013)
found that a high GP did not affect the decline in pH
post mortem in pork. Therefore, we could make a
conclusion that lactate was a more accurate predictor
of meat quality attributes than GP.
The change in free glucose in the process
of post mortem energy metabolism
There are two main factors influencing GP post
mortem: glycogen influencing free glucose content,
and free glucose breakdown to lactate through
glycolysis. To better understand which procedure contributes to the difference in meat quality, we tracked
the free glucose content post mortem (Fig. 1D).
According to the results, DLY always had a higher free
glucose content than LSP and TP post mortem and TP
had a lower free glucose content than LSP (P < 0.001).
More interestingly, the level of free glucose always
remained constant post mortem (two-way ANOVA:
effect of breed, P < 0.001; effect of time, P > 0.05; interaction, P > 0.05; Fig. 1D). The free glucose content of
the Longissimus dorsi muscle agreed with a previous
report (Hamilton et al. 2003), which showed that
Hampshire sires had 110.11 mg/dL free glucose in the
same muscle. According to our results, we could conclude that when the substrate for glycolysis was in
sufficient quantity, glycogen synthesis and disassembly
were not the crucial factors influencing the lactate
content to change meat quality attributes. Therefore
the mechanism, explaining the differences in meat
quality attributes for the different breeds, only related
to the process of glucose breaking down to lactate
through glycolysis.
Animal Science Journal (2014) 85, 770–779
Hormone content in the three different
altitude breeds
Free glucose content did not change post mortem, but
did show differences for the different altitude types of
pig breeds. Insulin, glucagon and epinephrine were
the important hormones that could control glycogen
synthesis and disassembly to keep glucose levels constant. Insulin (Fig. 2A), glucagon (Fig. 2B) and epinephrine (Fig. 2C) hormone levels of the three breeds
were measured and increased in the order of
insulin < glucagon < epinephrine. However, there was
no significant difference (P > 0.05) in insulin content
between the three breeds, although DLY had a higher
glucagon and epinephrine content than LSP and TP. In
general, the rate of post mortem glycolysis could be
accelerated by high levels of G-6-P. Therefore,
increased phosphorylase activity could increase the
level of free glucose through glycogenolysis (Briskey
et al. 1966). The hormones, epinephrine and glucagon,
induced an increase in cAMP that led to an increase in
phosphorylase kinase a (PKa), which is allosteric and
activates glycogen phosphorylase, resulting in increasing glycogenolysis (Scheffler & Gerrard 2007).
However, insulin is a unique hormone able to synthesize glycogen and decrease glucose content. It is generally accepted that insulin, glucagon and epinephrine
keep the free glucose level in balance through synthesizing and disassembling glycogen. DLY had a higher
glucagon and epinephrine content than LSP and TP,
which may have been caused by the breed’s special
characteristics. The results also demonstrated that DLY
had a higher free glucose level than LSP and TP.
Muscle fiber-type composition in
different altitude pig genotypes
The differences in muscle fiber-type composition
between the breeds are presented in Figure 3. The
amount of myosin heavy chain (MyHC) I muscle fiber
increased in the order of DLY < TP < LSP; the amount
of MyHC IIa and MyHC IIx muscle fiber increased in
© 2014 Japanese Society of Animal Science
776 L. SHEN et al.
MyHC ΙΙ a
MyHC Ι
MyHC ΙΙ b
MyHC ΙΙ x
100
90
MyHC mRNA proportions (%)
80
70
60
50
40
30
20
10
0
TP
LSP
DLY
Figure 3 Myosin heavy chain (MyHC) muscle fiber
proportions (%) composition among the three breeds:
Tibetan pig (TP), Liang-Shan pig (LSP) and
Duroc × Landrace × Yorkshire cross (DLY). From bottom to
top, the composition of fiber types are MyHC II x, MyHC II
b, MyHC I and MyHC II a, separately.
the order of DLY < LSP < TP; and the amount of MyHC
IIb muscle fiber increased in the order of TP < LSP <
DLY. The proportions of MyHC I, IIa and IIx muscle
fibers were all below 20% with the proportion of
MyHC IIb muscle fiber above 50%. Interestingly,
several studies supported our results. It has been
reported that Laiwu pigs have higher levels of MyHC I
and IIa mRNA in Longissimus dorsi than Duroc pigs (Hu
et al. 2008), and Meishan (Tanabe et al. 2001),
Zhongbai (Men et al. 2012) and Jinhua pigs (Guo et al.
2011) all had higher levels of MyHC I, IIa and IIx
mRNA in Longissimus dorsi than Landrace pigs. In our
study, the relative proportions of MyHC I, IIa and IIx
mRNA were higher in TP and LSP than in DLY. This
supported the hypothesis that native pig breeds have
more type I, IIa and IIx fibers and a lower number of
type IIb fibers than Western breeds, and that muscle
fiber types were significantly influenced by genetic
background.
In general, type I fibers were rich in mitochondria
and had a high oxidative capacity (Zierath & Hawley
2004). However, these fibers were also poor in glycogen and had a lower glycolytic enzyme activity, compared with type IIb fibers. Therefore, type I fibers were
mainly used for oxidative metabolism, while type IIa
and IIb fibers were mainly responsible for the
glycolytic pathway, their metabolism contributing to a
rapid pH decline. These results suggest that increasing
the percentage of type I fibers and decreasing the per© 2014 Japanese Society of Animal Science
centage of type IIb fibers were related to meat quality
improvement. In this study, TP (15.54 ± 0.24%) and
LSP (19.84 ± 0.51) had a higher proportion of MyHC I
muscle fibers than DLY (2.23 ± 0.45) and a lower proportion of MyHC IIb muscle fibers (Fig. 3). This result
demonstrated that TP and LSP had a lower rate of
glycolysis than DLY, which led to TP and LSP having
better meat quality. A connection between fiber-type
composition and GP was reported by Ryu and Kim
(2005), who found that pigs with higher numbers of
type I and IIa fibers had lower drip loss, lower meat
lightness and higher muscle pH at 45 min post
mortem. Drip loss was inversely related to the percentage composition of type I and IIa fibers (r = −0.25 and
−0.26, respectively) and positively related to the percentage area of type IIb fibers (r = 0.39). Similar trends
were found between drip loss and percentage of fiber
numbers. Therefore, meat quality would be influenced
by muscle fiber characteristics, especially by type I and
IIb fibers. TP and LSP had high numbers of type I and
low numbers of type IIb muscle fibers, which may be
related to the fact that these breeds range freely in the
high-altitude mountain areas. Some studies have
reported that physical movement can cause the transformation of MyHC IIb muscle fibers to MyHC I
(Simoneau et al. 1985; Röckl et al. 2007).
Expression of energy metabolism-related
genes
The rate of glycolysis was the crucial factor determining meat quality. The genes for the expression of ratelimiting enzymes controlling glycolysis and ATP
generation are shown in Figure 4. There were no significant differences in the mRNA level of the ACL,
ATP5a1, ATP5b, HK-1 and HK-4 genes between the
three different altitude breed types. The mRNA expression of PFKM in TP was higher than in LSP and DLY
(P < 0.05). The mRNA levels of HK-2 in the TP breed
(∼1.32-fold, P < 0.05) and the LSP breed (∼1.17-fold,
P < 0.05) were both higher than that in the DLY breed.
However, the mRNA expression of PKM2 in the TP
breed (∼0.73-fold, P < 0.05) and the LSP breed (∼0.82fold, P < 0.05) were lower than in the DLY breed
(Fig. 4). The GP of the three altitude breed types
increased in the order of TP < LSP < DLY, but not all
the related gene expressions are regulated. The ACL,
ATP5a1 and ATP5b genes played important roles in
coding ATP synthase and ATP-citrate lyase, further
influencing ATP content, the energy source for
glycolysis. The results suggested that the ATP synthesis
rate was faster than the ATP disintegration rate, the
gene related to ATP generation being unable to restrict
the rate of glycolysis. HK-2 played an important role in
coding the first rate-limiting enzyme of glycolysis,
which could lead to a high rate of glycolysis in cancer
cells through the influence of MicroRNA-143 (Fang
et al. 2012). However, the expression of HK-2 had a
Animal Science Journal (2014) 85, 770–779
ENERGY METABOLISM EFFECT ON MEAT QUALITY OF PIG
777
1
a
LSP
mRNA expression levels
0.
0.
0.
0.
0.
05
07
8
4
6
TP
c
a
a
a
a a
a
a
a
a
a
0.
00
5
ACL
a
b
a a
a
a
0
b
DLY
ATP5A1
ATP5B
a
c
a
a
a
HK-1
HK-2
HK-4
PFKM
PKM2
Figure 4 The messenger RNA (mRNA) expression of gene-related glycolysis. ACL = ATP citrate lyase; ATP5A1&ATP5B = ATP
synthase; HK-1 = Hexokinase-1; HK-2 = Hexokinase-2; HK-4 = Hexokinase-4; PFKM = Phosphofructokinase; PKM2 = Pyruvate
kinase. Gene expression levels represent the relative mRNA expression compared to the controls. Values represent the
mean ± SE, all are normalized by the maximum value. Means with the same superscript letters in each post mortem time are
not significantly different from each other (P > 0.05).
quality determined at 48 h post mortem was more
precise than that at 24 h post mortem. Glycogen store
content did not influence the rate of glucolysis, and
lactate was a more accurate predictor of meat quality
attributes than GP. Not all rate-limiting enzymes of
glycolysis had an effect on glycolysis in different genotypes. Overall, higher altitude breeds had lower
glycolysis metabolism than flatland, which promoted
better meat quality.
negative correlation with GP, which may be due to the
high levels of hypoxia-inducible factor-1 (HIF-1) in TP
and LSP that live at high altitudes in a hypoxic environment. HIF-1 was a central regulator of these
hypoxic responses, which when activated, stimulates
the transcription of a series of genes for adaptation to
hypoxia, including HK-2 (Natsuizaka et al. 2007).
Glycolytic pyruvate kinase isoenzyme M2 (coded by
gene PKM2) determined whether glucose was converted to lactate for regeneration of energy or used for
the synthesis of cell building blocks; the expression
had a positive correlation with GP in all three breeds.
This result agreed with a previous report (Sieczkowska
et al. 2010), which found PKM2 expression in
D × (L × Y) crossbreeds was higher than in L × Y crossbreeds, which may closely relate to the high glycolytic
and energy metabolism of DLY during the early post
mortem period. Therefore, not all rate-limiting
enzymes of glycolysis had an effect on the different
breeds’ glycolysis; only the last rate-limiting enzyme,
glycolytic pyruvate kinase isoenzyme M2, played an
important role in glycolysis in the different genotypes.
ACKNOWLEDGMENTS
Conclusions
REFERENCES
In conclusion, the results of this study indicate that
high altitude breeds TP and LSP had better meat
quality than flatland breeds (DLY), which related with
higher type I muscle fibers composition and insulin
concentration caused lower glucose content in TP and
LSP. Moreover, TP and LSP had lower expressions of
gene PKM2 regarding the rate-limiting enzyme of the
glucolysis procedure and leading to lower glycometabolism post mortem. We also found ultimate meat
Affentranger P, Gerwig C, Seewer G, Schwörer D, Künzi N.
1996. Growth and carcass characteristics as well as meat
and fat quality of three types of pigs under different
feeding regimens. Livestock Production Science 45, 187–196.
Binke R. 2004. From muscle to meat. Fleischwirtschaft 5, 224–
227.
Briskey E, Kastenchmidt L, Forrest J, Beecher G, Judge M,
Cassens R, Hoekstra W. 1966. Biochemical aspects of
post-mortem changes in porcine muscle. Journal of Agricultural and Food Chemistry 14, 201–207.
Animal Science Journal (2014) 85, 770–779
The study was supported by the Initiation Foundation
Project of Chinese Education Ministry, the earmarked
fund for China Agriculture Research System (No.
CARS-36-05B), and the Sichuan Sci & Tech Support
Program (No. 2012NZ001 and 2013NZ0041). The
authors acknowledge the grant from Animal Husbandry Institute of Ganzi Tibetan Autonomous Prefecture, Sichuan, China, and technical support of the
Meat Science Lab, Department of Animal Science,
University of Illinois at Urbana-Champaign, USA.
© 2014 Japanese Society of Animal Science
778 L. SHEN et al.
Channon H, Payne A, Warner R. 2000. Halothane genotype,
pre-slaughter handling and stunning method all influence pork quality. Meat Science 56, 291–299.
Dai F, Feng D, Cao Q, Ye H, Zhang C, Xia W, Zuo J. 2009.
Developmental differences in carcass, meat quality and
muscle fibre characteristics between the Landrace and a
Chinese native pig. South African Journal of Animal Science
39, 267–273.
Den Hertog-Meischke M, Van Laack R, Smulders F. 1997.
The water-holding capacity of fresh meat. Veterinary Quarterly 19, 175–181.
Dransfield E, Nute GR, Mottram DS, Rowan TG, Lawrence
TL. 1985. Pork quality from pigs fed on low glucosinate
rapeseed meal: influence of level in the diet, sex and
ultimate pH. Journal of the Science of Food and Agriculture 36,
546–556.
Fang R, Xiao T, Fang Z, Sun Y, Li F, Gao Y, et al. 2012.
MicroRNA-143 (miR-143) regulates cancer glycolysis via
targeting hexokinase 2 gene. Journal of Biological Chemistry
287, 23227–23235.
Fontanesi L, Davoli R, Nanni Costa L, Scotti E, Russo V. 2003.
Study of candidate genes for glycolytic potential of
porcine skeletal muscle: identification and analysis of
mutations, linkage and physical mapping and association
with meat quality traits in pigs. Cytogenetic and Genome
Research 102, 145–151.
Gatenby RA, Gillies RJ. 2004. Why do cancers have high
aerobic glycolysis? Nature Reviews Cancer 4, 891–899.
Guo J, Shan T, Wu T, Zhu L, Ren Y, An S, Wang Y. 2011.
Comparisons of different muscle metabolic enzymes and
muscle fiber types in Jinhua and Landrace pigs. Journal of
Animal Science 89, 185–191.
Hamilton D, Miller K, Ellis M, McKeith F, Wilson E.
2003. Relationships between longissimus glycolytic
potential and swine growth performance, carcass traits,
and pork quality. Journal of Animal Science 81, 2206–
2212.
Hatzivassiliou G, Zhao F, Bauer DE, Andreadis C, Shaw AN,
Dhanak D, et al. 2005. ATP citrate lyase inhibition can
suppress tumor cell growth. Cancer Cell 8, 311–321.
Højlund K, Yi Z, Lefort N, Langlais P, Bowen B, Levin K, et al.
2010. Human ATP synthase beta is phosphorylated at
multiple sites and shows abnormal phosphorylation at
specific sites in insulin-resistant muscle. Diabetologia 53,
541–551.
Honikel KO. 1998. Reference methods for the assessment
of physical characteristics of meat. Meat Science 49, 447–
457.
Horwutz W. 2000. Official Methods of Analysis of AOAC International, 17th edn. 1. AOAC Int, Gaithersburg, MD.
Hu H, Wang J, Zhu R, Guo J, Wu Y. 2008. Effect of myosin
heavy chain composition of muscles on meat quality in
Laiwu pigs and Duroc. Science in China Series C: Life Sciences
51, 127–132.
Huff-Lonergan E, Baas T, Malek M, Dekkers J, Prusa K,
Rothschild M. 2002. Correlations among selected pork
quality traits. Journal of Animal Science 80, 617–627.
Iournals M. 2011. Association of PGC-1α Gene with intramuscular fat content and muscle fiber traits and gene
expression in Tibetan pigs. Journal of Animal and Veterinary
Advances 10, 2301–2304.
Li M, Tian S, Jin L, Zhou G, Li Y, Zhang Y, et al. 2013.
Genomic analyses identify distinct patterns of selection in
domesticated pigs and Tibetan wild boars. Nature Genetics
45, 1431–1438.
© 2014 Japanese Society of Animal Science
Livak KJ, Schmittgen TD. 2001. Analysis of relative gene
expression data using real-time quantitative PCR and the
2 – ΔΔCT method. Methods 25, 402–408.
Men XM, Deng B, Xu ZW, Tao X. 2012. Muscle-fibre types in
porcine longissimus muscle of different genotypes and
their association withthe status of energy metabolism.
Animal Production Science 52, 305–312.
Miao Z, Wang L, Xu Z, Huang J, Wang Y. 2009. Developmental changes of carcass composition, meat quality and
organs in the Jinhua pig and Landrace. Animal 3, 468–
473.
Monin G, Sellier P. 1985. Pork of low technological quality
with a normal rate of muscle pH fall in the immediate
post-mortem period: the case of the Hampshire breed.
Meat Science 13, 49–63.
Natsuizaka M, Ozasa M, Darmanin S, Miyamoto M, Kondo S,
Kamada S, et al. 2007. Synergistic up-regulation of
Hexokinase-2, glucose transporters and angiogenic factors
in pancreatic cancer cells by glucose deprivation and
hypoxia. Experimental Cell Research 313, 3337–3348.
NRC. 1998. Nutrient Requirements of Swine, 10th edn. National
Academies Press, Washington, DC.
Tanabe R-i, Muranami T, Kawahara T, Yamashiro R,
Mitsumoto M, Murya S, et al. 2001. Composition of
myosin heavy chain isoforms in relation to meat texture
in Duroc, Landrace and Meishan pigs. The Japanese Journal
of Zootechnical Science 72, 230–237.
Röckl KSC, Hirshman MF, Brandauer J, Fujii N, Witters LA,
Goodyear LJ. 2007. Skeletal muscle adaptation to exercise
training AMP-activated protein kinase mediates muscle
fiber type shift. Diabetes 56, 2062–2069.
Ryu Y, Kim B. 2005. The relationship between muscle fiber
characteristics, postmortem metabolic rate, and meat
quality of pig longissimus dorsi muscle. Meat Science 71,
351–357.
Scheffler T, Gerrard D. 2007. Mechanisms controlling pork
quality development: the biochemistry controlling postmortem energy metabolism. Meat Science 77, 7–16.
Scheffler T, Scheffler J, Kasten S, Sosnicki A, Gerrard D.
2013. High glycolytic potential does not predict low ultimate pH in pork. Meat Science 95, 85–91.
Shen Q, Means W, Thompson S, Underwood K, Zhu M,
McCormick R, et al. 2006. Pre-slaughter transport, AMPactivated protein kinase, glycolysis, and quality of pork
loin. Meat Science 74, 388–395.
Sieczkowska H, Koćwin-Podsiadła M, Zybert A, Krze˛cio E,
Antosik K, Kamiński S, Wójcik E. 2010. The association
between polymorphism of PKM2 gene and glycolytic
potential and pork meat quality. Meat Science 84, 180–
185.
Simoneau JA, Lortie G, Boulay M, Marcotte M, Thibault MC,
Bouchard C. 1985. Human skeletal muscle fiber type
alteration with high-intensity intermittent training. European Journal of Applied Physiology and Occupational Physiology 54, 250–253.
Smith R, Gabler N, Young J, Cai W, Boddicker N, Anderson
M, et al. 2011. Effects of selection for decreased residual
feed intake on composition and quality of fresh pork.
Journal of Animal Science 89, 192–200.
Suzuki A, Kojima N, Ikeuchi Y, Ikarashi S, Moriyama N,
Ishizuka T, Tokushige H. 1991. Carcass composition and
meat quality of Chinese purebred and European× Chinese
crossbred pigs. Meat Science 29, 31–41.
Tang Z, Peng Z, Liu B, Fan B, Zhao S, Li X, et al. 2008. Effect
of breed, sex and birth parity on growth, carcass and
Animal Science Journal (2014) 85, 770–779
ENERGY METABOLISM EFFECT ON MEAT QUALITY OF PIG 779
meat quality in pigs. Frontiers of Agriculture in China 2,
331–337.
Westphalen A, Briggs J, Lonergan S. 2005. Influence of pH
on rheological properties of porcine myofibrillar protein
during heat induced gelation. Meat Science 70, 293–299.
Zhu L, Li M, Li X, Shuai S, Liu H, Wang J, et al. 2009. Distinct
expression patterns of genes associated with muscle
Animal Science Journal (2014) 85, 770–779
growth and adipose deposition in Tibetan pigs: a possible
adaptive mechanism for high altitude conditions. High
Altitude Medicine & Biology 10, 45–55.
Zierath JR, Hawley JA. 2004. Skeletal muscle fiber type:
influence on contractile and metabolic properties. PLoS
Biology 2, e348.
© 2014 Japanese Society of Animal Science
本文献由“学霸图书馆-文献云下载”收集自网络，仅供学习交流使用。
学霸图书馆（www.xuebalib.com）是一个“整合众多图书馆数据库资源，
提供一站式文献检索和下载服务”的24 小时在线不限IP 图书馆。
图书馆致力于便利、促进学习与科研，提供最强文献下载服务。
图书馆导航：
图书馆首页
文献云下载
图书馆入口
外文数据库大全
疑难文献辅助工具