250 S
. Hermesch et al. Livestock Production Science 65 2000 249 –259
1. Introduction The housing system in the test station from 18 to 22
weeks consisted of single penning. Carcase traits The genetic evaluation of farm animals is based on
were recorded on the live animal as well as on the multitrait best linear unbiased prediction BLUP
carcase and included backfat at P2 site, and backfat procedures which require knowledge of genetic
and muscle depth between the third and fourth last correlations between all analysed traits. Estimates of
ribs LFDP2, LFD3 4, LMD3 4, FDP2, FD3 4. In genetic correlations might differ between populations
addition, weight of the whole back left leg and the due to genetic differences or differences in manage-
slash boned ham were recorded as further carcase ment practices. For example, lean meat percentage
traits BLW, LMW. Meat quality traits included pH and meat quality traits are unfavourably correlated in
recorded 45 min and 24 h after slaughter pH45, populations carrying the halothane gene Cole et al.,
pH24, colour of the m . longissimus dorsi and m.
1988. In contrast, de Vries et al. 1994 found no multifidus dorsi CLD, CMD, drip loss percentage
unfavourable relationship between lean meat per- DLP and intramuscular fat content IMF. The
centage and meat quality traits in a halothane free fixed effect models included date of recording all
population. In the past, the main emphasis of selec- traits, breed not significant for ADG2, FDINT,
tion decisions has been on growth rate, food conver- FCR, pH24 and CMD and parity ADG1, ADG2,
sion ratio and lean meat content Ollivier et al., BLW, LMW. Weight of the animal at test begin was
1990. Genetic parameters have been obtained fre- fitted for feed intake and feed conversion ratio.
quently for these traits as reviewed by Stewart and Backfat
measurements, muscle
depth and
in- Schinckel 1990. In addition to these traits, meat
tramuscular fat content were corrected for weight of quality traits have received greater attention in
the animal at slaughter. Litter was fitted for growth breeding programs with the main focus on reduction
rate and back leg weight traits as an additional of incidence of pale, soft and exudative PSE and
random effect. A further description of the data and dark, firm and dry DFD meat. In Australia, genetic
the analysed traits was given in Hermesch et al. parameters have been obtained for growth rate and
2000 along with derivation of the appropriate backfat for a number of herds Klassen, 1992.
model and heritability estimates for each trait. However, genetic parameters for further performance
Variance components together with standard errors and carcase traits as well as meat quality traits are
of genetic correlations were obtained applying an not available yet and selection for meat quality has
average information algorithm Johnson and Thomp- only
been achieved
by selecting
against the
son, 1995 implemented in DFREML Meyer, 1997. halothane gene. In order to include meat quality
Only genetic correlations obtained from the com- traits in breeding decisions knowledge of genetic
bined analysis of Large White and Landrace data set parameters is required. The objective of this study
are presented since standard errors for genetic corre- was to obtain genetic parameters for meat quality,
lations estimated for the individual breeds generally carcase and performance traits as well as reproduc-
exceeded differences in genetic correlations between tive traits of the sow. This paper presents genetic and
breeds Hermesch, 1996. Genetic correlations were environmental correlations between production, car-
obtained by bivariate analyses. The development of case and meat quality traits.
the average information algorithm makes multi- variate analyses of variance components feasible.
However, comparing bivariate estimates with multi-
2. Material and methods variate estimates of genetic correlations showed no
significant differences Hermesch, 1996. Data were recorded at Bunge Meat Industries
between July 1992 and June 1995 and include 1799 Large White and 1522 Landrace boars. Performance
3. Results and discussion
traits comprised of growth rate from 3 to 18 weeks and from 18 to 22 weeks ADG1, ADG2, feed
Estimates of genetic correlations were mostly of intake FDINT and feed conversion ratio FCR.
higher magnitude than environmental correlations. Animals were group penned until 18 weeks of age.
Therefore environmental correlations are not dis-
S . Hermesch et al. Livestock Production Science 65 2000 249 –259
251
cussed explicitly. Lower environmental correlations this low genetic correlation in this study these effects
in comparison to genetic correlations were also were confounded and cannot be distinguished.
found by Cameron 1990, Hovenier et al. 1992 Growth rate during station testing and feed intake
and de Vries et al. 1994. De Vries et al. 1994 were highly correlated rg: 0.82 while feed conver-
explained these higher genetic correlations in com- sion ratio was moderately correlated with these two
parison to environmental correlations with uncorre- traits rg: 2 0.48 with ADG2, rg: 0.19 with FDINT.
lated random measurement errors. These estimates correspond to genetic correlations
presented by van Steenbergen et al. 1990, Mrode 3.1. Production traits
and Kennedy 1993, Cameron and Curran 1994, ¨
Hofer and Schworer 1995 and Labroue et al. Both growth rate traits ADG1, ADG2 were only
1997. In contrast, feed intake and feed conversion lowly correlated rg: 0.32; Table 1. Two factors
ratio were both positively correlated with growth rate might have caused this low genetic correlation.
prior to station testing rg: 0.23 with FDINT, rg: 0.27 Firstly, animals were at a different stage of growth
with FCR. In growing pigs feed intake is higher for when these two traits were recorded. In the studies of
heavier animals Memmert, 1991; Smith et al., 1991; Siebrits et al. 1986, Memmert 1991 and Kemm et
Thompson et al., 1996. Consequently, feed conver- al. 1995 boars reached a plateau in growth rate
sion ratio increases since growth rate remains at a between 60 and 80 kg liveweight after which growth
constant level or even decreases at the later stage of rate declined. In this study, animals entered the test
the growth curve Siebrits et al., 1986; Memmert, station at a fixed age rather than a fixed weight. High
1991; Kemm et al., 1995. Due to the testing growth animals might have reached the growth
procedure pigs with high growth rate entered the test plateau when they entered the test station. As a
station with a higher live weight. As a consequence consequence their growth rate is reduced. In contrast,
feed intake is increased while growth rate is near its animals with a lower growth rate until 18 weeks
plateau leading to an inferior feed conversion ratio. might not have reached their growth plateau and
By incorporating the animal’s weight at test start in were therefore more likely to have a higher growth
the model for feed intake and feed conversion ratio it rate between 18 and 22 weeks. Secondly, animals
was attempted to take these relationships into ac- were kept in two different housing systems. The
count. Apparently this could not be achieved com- genetic relationship between animals kept in these
pletely although genetic correlations were reduced in two different housing systems, single penned and
comparison to the model when these two traits were group penned, was studied by von Felde et al.
not corrected for the animal’s weight at test begin. 1995. Genetic correlations between growth rate
recorded in these two housing systems were 0.55 for 3.2. Carcase traits
average daily gain recorded over the testing period and 0.10 for lifetime average daily gain. However,
Genetic correlations between backfat measure- although both differences in growth stage and differ-
ments were not significantly different from one ences in housing systems, may have contributed to
Table 2. Although two muscle depth measurements
Table 1 Genetic correlations above diagonal with standard errors in brackets and environmental correlations below diagonal for production
a
traits ADG1
ADG2 FDINT
FCR ADG1
0.320.23 0.230.19
0.270.24 ADG2
0.05 0.820.11
2 0.480.21 FDINT
0.11 0.61
0.190.27 FCR
0.24 2 0.70
0.02
a
Abbreviations: ADG1, average daily gain from 3 to 18 weeks; ADG2, average daily gain during station testing from 18 to 22 weeks; FDINT, feed intake recorded during station testing from 18 to 22 weeks; FCR, feed conversion ratio defined as feed intake over growth rate
18–22 weeks.
252 S
. Hermesch et al. Livestock Production Science 65 2000 249 –259 Table 2
a
Genetic correlations above diagonal with standard errors in brackets and environmental correlations below diagonal for carcase traits LFDP2
LFD3 4 LMD3 4
FDP2 FD3 4
BLW LMW
LFDP2 0.99 0.01
2 0.16 0.15 0.93 0.04
1.00 0.03 2 0.25 0.15
2 0.63 0.13 LFD3 4
0.73 2 0.14 0.16
0.94 0.03 1.0 0.03
2 0.21 0.16 2 0.62 0.13
LMD3 4 2 0.01
2 0.07 2 0.10 0.18
0.01 0.21 0.54 0.21
0.54 0.21 FDP2
0.36 0.34
2 0.02 0.96 0.04
2 0.23 0.18 2 0.70 0.09
FD3 4 0.00
0.00 2 0.04
0.48 2 0.25 0.20
2 0.70 0.11 BLW
0.06 0.01
0.18 2 0.02
2 0.04 0.86 0.06
LMW 2 0.33
2 0.35 0.24
2 0.34 2 0.38
0.88
a
Abbreviations: LFDP2, backfat depth at P2 measured with real time ultrasound; LFD3 4, backfat depth between the third and fourth last ribs measured with real time ultrasound; LMD3 4, muscle depth of m
. longissimus dorsi between the third and fourth last ribs on the live animal; FDP2, backfat depth at P2 measured with Hennesy Chong grading machine; FD3 4, backfat depth between third and fourth last ribs
measured with Hennesy Chong grading machine; BLW, weight of whole left back leg; LMW, weight of slash boned left back leg.
were taken Hermesch et al., 2000, only relation- This corresponds to the high genetic correlation of
ships between muscle depth recorded on the live 0.65 between loin eye area and lean meat percentage
animal LMD3 4 and other carcase traits are pre- presented by Stewart and Schinckel 1990 in their
sented. Standard errors were greater than one for review. Given that muscle depth is measured on the
genetic correlations between the second muscle live animal this measurement together with backfat
depth measurement recorded on the carcase with measurements opens the possibility of selecting
Hennesy Chong equipment and other carcase charac- indirectly for the two weight measurements.
teristics. Muscle depth recorded with real time ultrasound and backfat measurements were only
3.3. Production and carcase traits lowly genetically related rg range: 2 0.16 to 0.01.
In contrast, Lo et al. 1992 analysed eye muscle 3.3.1. Growth rate traits and carcase traits
area and backfat measurements finding high genetic Estimates of genetic correlations between average
correlations from 2 0.81 to 2 0.56. Backfat mea- daily gain recorded prior to station testing and
surements and muscle depth were highly correlated backfat measurements were negative ranging from
with ham weight absolute rg range 5 0.54–0.70. 2 0.35 to 2 0.26 Table 3. In contrast, genetic
Table 3 Genetic correlations first row with standard errors in brackets and environmental correlations second row between production and
a
carcase traits ADG1
ADG2 FDINT
FCR LFDP2
2 0.35 0.13 0.31 0.18
0.56 0.11 0.19 0.19
0.06 0.00
0.21 0.17
LFD3 4 2 0.29 0.14
0.29 0.18 0.54 0.11
0.23 0.19 0.03
0.02 0.23
0.15 LMD3 4
0.18 0.20 2 0.13 0.25
2 0.13 0.20 0.07 0.27
0.05 2 0.03
2 0.06 2 0.02
FDP2 2 0.26 0.16
0.33 0.17 0.62 0.12
0.34 0.20 0.05
0.03 0.12
0.06 FD3 4
2 0.21 0.19 0.48 0.22
0.63 0.14 0.20 0.25
0.13 0.07
0.18 0.11
BLW 0.83 0.07
0.48 0.14 0.45 0.24
2 0.83 0.33 0.74
0.43 0.46
2 0.48 LMW
0.61 0.12 0.23 0.16
2 0.11 0.18 2 0.71 0.29
0.66 0.37
0.20 2 0.44
a
For abbreviations see Tables 1 and 2.
S . Hermesch et al. Livestock Production Science 65 2000 249 –259
253
correlations between growth rate recorded during between growth rate during station testing at the later
station testing and backfat measurements were un- stage of the growing period and backfat measure-
favourable rg range: 0.29–0.48. ments is an indication that pigs at that age have a
In this study feed intake was not restricted by the high feed intake which exceeds their maximum
feeding regime before or during station testing. protein deposition and extra energy is deposited as
Genetic correlations between average daily gain fat tissue. This hypothesis is supported by von Felde
during station testing and backfat and muscle depth et al. 1996 who found that feed intake at the
measurements are in good agreement with literature beginning of the growing period has more favourable
values which are based on ad libitum feeding genetic correlations with leanness than feed intake
systems van Steenbergen et al., 1990; Kaplon et al., over the entire growing period. The level of in-
1991; Cardellino and Siewerdt, 1992; Lo et al., 1992; sufficient feed intake of young pigs in relation to
Ducos et al., 1993; Mrode and Kennedy, 1993; their protein deposition is further enhanced with the
Cameron and Curran, 1994. In contrast, estimates of use of entire boars in this study which have a higher
genetic correlations between average daily gain protein deposition potential than castrates Campbell
measured before the test period and these described and Taverner, 1988.
carcase characteristics correspond to genetic correla- Another difference between the two growth rate
tions between growth rate and backfat obtained traits is manifested in different housing systems. Pigs
under restricted feeding Lundeheim et al., 1980; were group penned prior to station testing and single
Johansson, 1987; McPhee et al., 1988. penned during station testing. Therefore, a higher
Pigs of superior genotype have higher require- percentage of energy might be required for mainte-
ments of dietary protein and amino acids to support nance in the group penning as a result of competition
their higher potential of protein deposition in com- among animals and more movement of pigs. This
parison to pigs with a reduced capacity of lean meat might specially be the case with boars. However,
growth Campbell and Taverner, 1988. The effect these two explanations were confounded and can not
of protein content in the diet on selection was studied be distinguished in this project.
by Stern 1994 who showed that the genetic po- Estimates of genetic correlations between growth
tential for lean meat growth was expressed more rate and ham weight were positive in the study of
strongly on the high protein diet than on the low Johansson 1987 which was based on a restricted
protein diet. In this project, pigs were performance feeding regime with values of 0.16 for Landrace and
tested on a high protein diet with 1.15 lysine 0.25 for Yorkshire. Based on ad libitum feeding
content which exceeds the lysine content of 0.96 in regimes, estimates of genetic correlations were nega-
¨ the high protein diet in the study by Stern 1994.
tive Hofer et al., 1992; Hofer and Schworer, 1995. Therefore, no limitations on lean meat growth were
In this study all genetic correlations between growth imposed through the protein content of the diet used
rate characteristics and weight measurements of the in this study. The favourable and unfavourable
back leg and lean meat weight of the back leg were relationship between growth rate and lean meat
positive. However, further analyses showed that percentage is therefore dependent on energy intake.
these positive genetic correlations were largely due Studies including restricted and ad libitum feeding
to not adjusting both back leg weight measurements have shown that the genetic correlation between
for hot carcase weight. When both weight measure- growth rate and leanness is more favourable when
ments were adjusted for hot carcase weight genetic feed intake is restricted McPhee et al., 1988. Since
correlations were reduced. Estimates of genetic younger pigs are limited in feed intake capacity
correlations were favourable between back leg Campbell et al., 1986 their lean meat growth
weight measurements and growth rate prior to station potential exceeds their appetite which might lead to a
testing rg: 0.46 for BLW; rg: 0.26 for LMW but favourable relationship between average daily gain in
unfavourable for growth rate during station testing the period between 3 and 18 weeks and leanness,
rg: 2 0.09 for BLW; 2 0.13 for LMW. These traits closely related to backfat and muscle depth
estimates might support the hypothesis that these measurements. The unfavourable genetic correlation
pigs are restricted in their feed intake capacity prior
254 S
. Hermesch et al. Livestock Production Science 65 2000 249 –259
¨ to station testing which leads to this stronger favour-
Curran, 1994. Only Hofer and Schworer 1995 able relationship.
analysed feed intake and ham weight and found a stronger relationship between these two traits rg:
3.3.2. Feed intake and feed conversion ratio with 2 0.72. In contrast, genetic correlations between
carcase traits feed conversion ratio and ham weight as presented
¨ Genetic correlations between feed intake and
by Sonnichsen and Kalm 1984 and Hofer and ¨
carcase traits were consistent and show that a higher Schworer 1995 were of lower magnitude with a
feed intake during the growth period between 18 and mean of 2 0.52. However, given the high standard
22 weeks is associated with a decrease in lean meat errors of 0.33 and 0.29 for correlations in this study
content of the carcase. Genetic correlations between these differences are not significant.
feed intake and backfat measurements ranged from 0.54 to 0.63 and were 2 0.13 for muscle depth and
3.3.3. Meat quality traits 2 0.11 for ham weight.
A paler colour of the m . longissimus dorsi muscle
Webster 1977 compared the energy required for was associated with a reduced pH rg with pH45:
protein deposition and fat deposition and concluded 2 0.23; rg with pH24: 2 0.83. Colour of the m.
that the same amount of metabolic energy is de- multifidus dorsi was genetically positively correlated
posited in 1 kg of fat as in about 8 kg of fat-free with pH measurements rg with pH45 5 0.20; rg with
muscle which supports favourable genetic correla- pH24 5 0.03; Table 4. This is an indication that
tions between feed efficiency and backfat measure- these colour measurements of m
. longissimus dorsi ments rg range: 0.19–0.34. Feed conversion ratio
and of m . multifidus dorsi are different traits which is
has a strong genetic relationship with weight of the supported by only a moderate genetic correlation of
whole back leg rg with BLW: 2 0.83 and lean 0.47 between these two traits. In addition, Warner et
meat weight of the back leg rg with LMW: 2 0.71. al. 1993 showed that meat quality measurements
All three traits, feed conversion ratio and both taken on the m
. longissimus dorsi were only reliable weight measurements are larger in heavier animals
indicators of colour and exudate for other muscles in and were increased by only adjusting feed conver-
DFD carcases. In PSE meat quality measurements sion ratio for weight of the animal. For example,
taken on the m . longissimus dorsi were only reliable
genetic correlations were reduced to 2 0.25 for both indicators of colour and exudate for the four major
traits by also adjusting back leg weight measure- ham muscles which are also white muscles in
ments for hot carcase weight. contrast to the m
. multifidus dorsi analysed in this A number of studies found similar genetic correla-
study. tions between feed intake or feed conversion ratio
Drip loss percentage had moderate to strong and backfat measurements van Steenbergen et al.,
genetic correlations with colour and pH measure- 1990; Mrode and Kennedy, 1993; Cameron and
ments taken on the m . longissimusdorsi while no
Table 4 Genetic correlations above diagonal with standard errors in brackets and environmental correlations below diagonal between meat
a
quality traits pH45
pH24 CLD
CMD DLP
IMF
b
pH45 2 0.12
2 0.23 0.24 0.20 0.25
2 0.44 0.23 0.48 0.23
b
pH24 0.12
2 0.83 0.11 0.03 0.24
2 0.71 2 0.20 0.24
CLD 2 0.17
2 0.47 0.47 0.16
0.80 0.14 0.26 0.19
b
CMD 2 0.10
2 0.25 0.33
2 0.01 0.20 0.19
DLP 2 0.17
2 0.30 0.47
0.12 2 0.06 0.21
IMF 2 0.01
2 0.09 0.11
0.08 0.04
a
Abbreviations: pH45, pH measured 45 min after slaughter; pH24, pH measured 24 h after slaughter; CLD,
L
-value of Minolta chromameter of m
. longissimus dorsi; CMD,
L
-value of Minolta chromameter of m . multifidus dorsi; DLP, drip loss percentage; IMF,
intramuscular fat content.
b
Approximation of standard error failed to converge.
S . Hermesch et al. Livestock Production Science 65 2000 249 –259
255
genetic relationship existed with colour of the m .
relationship indicates a potential problem of using multifidus dorsi. The estimated genetic correlations
colour as an indicator of PSE meat. were 2 0.44 for pH45, 2 0.71 for pH24 and 0.80
Favourable genetic
correlations between
in- for colour of the m
. longissimus dorsi. These correla- tramuscular fat content, pH45 and drip loss per-
tions reflect characteristics of PSE and DFD meat. centage are confirmed by Hovenier et al. 1992, de
¨ Meat with a high drip loss percentage has a low pH
Vries et al. 1994 and Hofer and Schworer 1995. and a pale colour PSE meat and in DFD meat, a
In regard to genetic associations between in- low drip loss percentage is associated with a high
tramuscular fat content and pH24 and colour mea- ultimate pH and a dark colour. These relationships
surements literature values have a wide range with were stronger between traits measured on the same
estimates of genetic correlations ranging from day 24 h after slaughter. Generally, these genetic
2 0.18 to 0.39 for pH24 and from 2 0.33 to 0.07 for correlations between meat quality traits recorded on
colour Hovenier et al., 1992; Bidanel et al., 1994; the m
. longissimus dorsi agree with estimates pre- de Vries et al., 1994; Goodwin, 1995; Hofer and
¨ sented by Cole et al. 1988, Hovenier et al. 1992,
Schworer, 1995. ¨
de Vries et al. 1994 and Hofer and Schworer 1995.
3.4. Production and meat quality traits Meat quality is currently not paid for in Australia
but a high drip loss is of direct economical impor- A high growth rate between 3 and 18 weeks was
tance to the processing industry due to the weight related to a darker colour rg 5 2 0.21 for CLD and
loss during processing. Recording of drip loss per- 2 0.31 for CMD; Table 5. In contrast, genetic
centage in this project was labour intensive and correlations between average daily gain during sta-
therefore costly. However, drip loss percentage is tion testing and colour measurements were positive.
highly correlated with colour of the m . longissimus
Estimates in other studies Cole et al., 1988; de Vries ¨
dorsi CLD which is less costly to measure and et al., 1994; Hofer and Schworer, 1995 showed a
could be used in breeding programs instead. similar range indicating no clear genetic relationship
The merit of a high intramuscular fat content lies between growth rate and meat quality traits.
in its favourable relationship with eating quality Growth rate prior to station testing was genetically
Cameron, 1990; Lo et al., 1992. The minimum not correlated with intramuscular fat content while
level of intramuscular fat content to improve eating average daily gain during station testing was nega-
quality is somewhat debated. Among studies and tively correlated rg 5 2 0.21 with intramuscular fat
countries, minimum level of intramuscular fat con- content. These estimates are within the range of
tent ranges from 2.0 to 3.0 de Vol et al., 1988; genetic correlations 20.16 to 0.27 presented by
Hovenier et al., 1993; Glodek, 1997. However, all Lo et al., 1992; Knapp et al., 1995.
of these levels of intramuscular fat content are above Feed intake was strongly correlated with pH45
the mean of Large White and Landrace pigs in this rg 5 0.66 but had no significant genetic relation-
study of 1.69 Hermesch et al., 2000. Both ships with further meat quality traits. Only two
genetic relationships between intramuscular fat con- studies included these trait combinations de Vries et
¨ tent and pH measurements were favourable with an
al., 1994; Hofer and Schworer, 1995 finding low to increase in intramuscular fat content leading to a
moderate genetic correlations. In the study by de lower incidence of PSE rg with pH45 5 0.48 and
Vries et al. 1994 a lower feed intake and residual DFD meat rg with pH24 5 2 0.20. The positive
feed intake was associated with a darker colour and a genetic correlations of 0.26 and 0.20 between in-
lower waterholding capacity. De Vries et al. 1994 tramuscular fat content and colour measurements
suggested that it might result from higher mainte- indicate that a higher intramuscular fat is associated
nance requirements. Animals with higher mainte- with a paler colour. This paler colour should not be
nance requirements could have faster glycogen de- regarded as an indicator of a higher incidence of
pletion before slaughter, and therefore a higher risk PSE. In contrast, the paler colour could be caused by
of DFD meat. a higher intramuscular fat content in the meat. This
Genetic correlations between feed conversion ratio
256 S
. Hermesch et al. Livestock Production Science 65 2000 249 –259 Table 5
Genetic correlations first row with standard errors in brackets and environmental correlations second row between production and meat
a
quality traits ADG1
ADG2 FDINT
FCR pH45
0.00 0.25 0.35 0.31
0.66 0.19 0.40 0.30
0.22 0.06
0.02 2 0.04
pH24 0.05 0.24
0.07 0.30 2 0.04 0.24
2 0.16 0.31 0.06
2 0.08 2 0.02
0.07 CLD
2 0.21 0.20 0.23 0.24
2 0.10 0.20 2 0.59 0.23
2 0.09 0.02
0.02 0.00
CMD 2 0.31 0.20
0.07 0.23 2 0.03 0.19
2 0.19 0.25 2 0.20
2 0.09 2 0.04
0.09 DLP
0.02 0.21 0.10 0.25
2 0.15 0.21 2 0.58 0.23
0.06 0.03
0.01 0.02
IMF 0.01 0.18
2 0.21 0.18 0.03 0.20
0.21 0.27 2 0.02
0.10 0.17
0.03
a
For abbreviations see Tables 1 and 4.
and meat quality traits indicated that the more feed backfat measurements and pH45 rg range: 0.49–
efficient pigs have inferior meat quality. Estimates 0.64; Table 6. Selection for reduced backfat will
were moderate to high for traits indicating PSE in the therefore reduce pH45 and thus increase the inci-
m . longissimus dorsi rg with pH45 5 0.40; rg with
dence of PSE meat confirming results from Bidanel CLD 5 2 0.59; rg with DLP 5 2 0.58. Unfavour-
et al. 1994 who found a genetic correlation of 0.26 able genetic correlations between feed conversion
between these two traits. ratio and meat quality traits were also found by de
In general, no significant relationship existed ¨
Vries et al. 1994, Hofer and Schworer 1995 and between the meat quality traits pH24 and colour
Knapp et al. 1995. measurements and backfat and muscle depths mea-
surements. In contrast, genetic correlations between 3.4.1. Carcase and meat quality traits
drip loss percentage and backfat measurements were The strongest unfavourable relationships between
lowly negative rg: 2 0.20 to 2 0.14. Two publi- carcase and meat quality traits existed between
cations Hovenier et al., 1992; de Vries et al., 1994
Table 6 Genetic correlations first row with standard errors in brackets and environmental correlations second row between meat quality and
a
carcase traits pH45
pH24 CLD
CMD DLP
IMF LFDP2
0.62 0.16 2 0.04 0.19
2 0.08 0.15 2 0.03 0.15
2 0.16 0.16 0.26 0.15
0.10 0.05
2 0.07 2 0.04
2 0.01 0.09
LFD3 4 0.64 0.16
0.00 0.19 2 0.08 0.15
0.00 0.14 2 0.19 0.16
0.27 0.16 0.11
0.05 2 0.08
2 0.06 0.00
0.10 LMD3 4
0.00 0.26 0.13 0.26
0.04 0.21 2 0.17 0.20
0.04 0.22 0.16 0.21
2 0.06 2 0.09
0.08 0.06
0.10 2 0.13
FDP2 0.49 0.20
0.09 0.21 2 0.13 0.17
2 0.20 0.16 2 0.20 0.18
0.19 0.17 0.05
0.08 2 0.07
0.00 2 0.02
0.14 FD3 4
0.59 0.20 0.00 0.24
2 0.05 0.20 2 0.06 0.20
2 0.14 0.22 0.34 0.21
0.17 0.02
2 0.08 0.05
0.00 0.12
BLW 0.12 0.27
2 0.10 0.27 0.09 0.22
0.01 0.21 0.17 0.23
0.08 0.23 0.17
0.00 2 0.07
2 0.23 0.08
0.00 LMW
2 0.17 0.25 2 0.28 0.23
0.22 0.19 0.08 0.18
0.36 0.21 2 0.15 0.18
0.09 0.02
2 0.04 2 0.02
0.06 2 0.20
a
For abbreviations see Tables 2 and 4.
S . Hermesch et al. Livestock Production Science 65 2000 249 –259
257
also obtained low genetic correlations between these was analysed by Wilson et al. 1998 concluding that
traits and de Vries et al. 1994 suggested that the reasonable genetic progress should be possible in
unfavourable relationship between leanness and meat intramuscular fat content using ultrasonic scan mea-
quality might not exist in halothane free populations. surements. Different groups Ragland et al., 1997;
In contrast, Ducos et al. 1993 found a strong Eggert and Schinckel, 1998 are working on such a
unfavourable genetic correlation between leanness measurement technique in pigs. In addition, selection
and a meat quality index in a halothane free French for intramuscular fat content might be supported by a
Large White population but found no genetic rela- single gene affecting this trait which was indicated in
tionship between leanness and meat quality in French Meishan crossbreeds by Janss et al. 1994 using
Landrace. segregation analyses. Subsequently, the heart fatty
Both weight measurements were negatively corre- acid binding protein H-FABP gene, a candidate
lated with pH24 rg 5 2 0.10 for BLW, rg 5 2 0.28 gene for meat quality traits, has been localised on
for LMW thus reducing the incidence of DFD with chromosome six by Gerbens et al. 1997.
increasing weight of the whole back leg and higher ham weight. No relationship existed between pH24
and backfat measurements. Drip loss percentage was
4. Conclusions
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