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Livestock Production Science 89 (2004) 121–128

Genetic parameters for birth and weaning traits in French

specialized beef cattle breeds

F. Phocas, D. Laloe*

Institut National de la Recherche Agronomique, Station de Genetique Quantitative et Appliquee, 78352 Jouy-en-Josas Cedex, France

Received 22 April 2003; received in revised form 30 January 2004; accepted 27 February 2004

Abstract

Genetic parameters for birth and weaning traits of beef calves were estimated in Charolais, Limousin, Blonde d’Aquitaine

and Maine-Anjou breeds. These traits took into account the following calf and cow abilities: calving (calving difficulty score,

calf birth weight), calf growth and muscular development (direct effects on weaning weight and muscle score) and suckling

ability (maternal effects on calf weaning weight). Data sets consisted of the observations of the largest 236 Charolais and 120

Limousin herds recorded from 1985 to 1999 and the observations of the largest 147 Blonde d’Aquitaine and 116 Maine-Anjou

herds recorded from 1986 to 2002. In general, estimates of heritability were in the range of values given in the litterature and

were relatively similar across breeds. Concerning birth traits, estimates were around 0.10 for both direct and maternal effects on

calving difficulty score, around 0.30 (Charolais and Maine-Anjou breeds) or 0.40 (Limousin and Blonde d’Aquitaine breeds)

for direct effects on birth weight and 0.10 for the corresponding maternal effects. Concerning weaning traits, estimates for

heritability of direct effects on weaning weight were around 0.10 in the Charolais breed, 0.20 in the Maine-Anjou breed and

around 0.30 in the other breeds with corresponding estimates on maternal effects around 0.10. Maternal heritabilities on

muscular development score were small and corresponding direct heritabilities were estimated around 0.20 in the Charolais and

Maine-Anjou breeds and 0.30 in the other breeds. Most of the genetic correlation estimates between direct and maternal effects

were significantly negative. In general, correlation estimates between traits were low to moderate (below 0.50) and similar from

one breed to another. A higher association was only estimated between direct effects on birth weight and calving difficulty score

in three out of the four breeds. Direct and maternal genetic correlations between calving difficulty score and weaning traits were

slightly unfavourable in the four breeds.

D 2004 Elsevier B.V. All rights reserved.

Keywords: Dystocia; Conformation; Charolais; Limousin; Blonde d’Aquitaine; Maine-Anjou

1. Introduction

French beef cattle genetic evaluation program on

farm is based on birth conditions (birth weight and

0301-6226/$ - see front matter D 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.livprodsci.2004.02.007

* Corresponding author. Tel.: +33-1-34652200; fax: +33-1-

34652210.

E-mail address: phocas@dga.jouy.inra.fr (D. Laloe).

calving difficulty score) and on weaning traits

(weight at 210 days and conformation scores). These

traits are of primary economical importance in

French beef cattle production systems whose consist

mainly of suckler herds (Phocas et al., 1998). The-

oretically, the discrete nature of the calving difficulty

score should be taken into account for the genetic

evaluation by using a threshold model (Gianola and

Table 2

Summary of the Blonde d’Aquitaine and Maine-Anjou data sets

concerning sires with at least 15 calves recorded in herds with at

least 20 calves recorded per year

Item Blonde

d’Aquitaine

data set

Maine-Anjou

data set

Birth records from 1986 to 2002 82,417 37,956

Weaning records 54,402 27,052

Herds with at least 20 calves/year 147 116

Herd-year levels at birth 2482 1601

Herd-year-group levels at weaning 2258 1444

Dams 25,368 15,502

Dams with at least 2 calves 16,906 9221

Dams with their own birth records 15,367 8503

Sires 1151 669

Sires also used as MGS 988 553

Maternal grandsires (MGS) 2266 1217

Records in the pedigree file 3884 2145

F. Phocas, D. Laloe / Livestock Production Science 89 (2004) 121–128122

Foulley, 1983). When dealing with small herds or

with the absence of some scores within some herd-

years, the herd-year effects in the threshold models

cannot be estimated as fixed effects and they are

considered as random effects. Such a statistical

treatment of herd-year effects is incorrect from a

theoretical point of view and it creates errors in the

ranking of animals based on their estimated breeding

values (Phocas and Laloe, 2003). Consequently, the

French genetic evaluation under implementation is

based on a linear model for calving difficulty scores.

Up to 2003, only birth weight and weaning traits

were included in the on-farm evaluation. Genetic

parameters used for the genetic evaluation of French

specialized beef cattle breeds were estimated for the

Limousin breed by Shi et al. (1993). The aim of this

study is the estimation of genetic and phenotypic

parameters needed for the French genetic evaluation

program on farm in all the specialized beef cattle

breeds.

2. Materials and methods

2.1. Field data

Birth records were analysed from 237,147 Cha-

rolais and 116,177 Limousin calves born from 1985

to 1999, bred by 3078 Charolais sires and 1497

Limousin sires. The characteristics of the data sets

are given in Table 1. Records were selected from

Table 1

Summary of the Charolais and Limousin data sets concerning sires

with at least 30 calves recorded in herds with at least 40 calves

recorded each year from 1985 to 1999

Item Charolais

data set

Limousin

data set

Birth records from 1985 to 1999 237,147 116,177

Weaning records 191,463 101,775

Herds with at least 40 calves/year 236 120

Herd-year levels at birth 3536 2008

Herd-year-group levels at weaning 4218 2324

Dams 81,708 30,602

Dams with at least 2 calves 53,118 22,755

Dams with their own birth records 45,555 17,897

Sires 3078 1497

Sires also used as MGS 2740 1302

Maternal grandsires (MGS) 8467 3824

Records in the pedigree file 13,353 6067

the largest 236 Charolais herds and 120 Limousin

herds in order to ensure a minimum herd-year group

size of 40 calves during 15 years and were then

selected from sires with at least 30 calves. Records

were selected because estimation of variance com-

ponents using all records (about 3.7 million of

Charolais records and 1.8 million of Limousin

records) was unfeasible for available computing

resources.

Birth records were also analysed from 82,417

Blonde d’Aquitaine and 37,956 Maine-Anjou calves

born from 1986 to 2002, bred by 1151 Blond sires

and 658 Maine-Anjou sires. The characteristics of

the data sets are presented in Table 2. Records were

selected from the largest 147 Blonde d’Aquitaine

herds and 116 Maine-Anjou herds in order to ensure

a minimum herd-year group size of 20 calves during

15 years and were then selected from sires with at

least 15 calves. Selection was less severe for these

breeds than for the Charolais and Limousin breeds

because of their great difference in terms of popula-

tion size.

Under a given number of records in a half-sib

families structure, Robertson (1959) derived the op-

timal number of offspring per sire to minimize the

standard error of a genetic correlation estimate. He

showed that this optimal number is fourth or fifth

time the optimal number to minimize the standard

error of an heritability estimate (about 10–40 prog-

eny records when the heritability is in the decreasing

Table 3

Means and standard deviations for calving difficulty score (CS),

birth weight (BW), weaning weight (WW) and muscular develop-

ment score (MS)

Breed CS BW WW MS

Mean SD Mean SD Mean SD Mean SD

Charolais 1.52 0.72 47.1 5.5 279.8 51.3 65.8 10.8

Limousin 1.06 0.29 39.5 3.4 258.3 40.8 60.5 8.2

Blonde

d’Aquitaine

1.38 0.63 46.2 5.9 256.5 56.4 62.4 8.5

Maine-Anjou 1.52 0.72 49.4 4.6 274.9 44.3 62.7 10.0

F. Phocas, D. Laloe / Livestock Production Science 89 (2004) 121–128 123

range from 0.4 to 0.1). When requiring for at least 30

calves per sire in the Charolais or Limousin breeds

and at least 15 calves per Blonde d’Aquitaine or

Maine-Anjou sire, the average progeny number per

sire were about 50–80 in the sampled datasets, i.e.

probably not sufficient to minimize the standard error

of a genetic correlation between two traits of herit-

abilities above 0.2.

Considering the largest herds across 15 years

enabled to accurately estimate the herd-year fixed

effects and to ensure genetic links across herd-year

levels. These herds are the sustainable herds, i.e.

those that really composed the breed selection

nuclei. The minimum requirements about the data-

sets still left a large number of herds (over 100)

and a great number (over 1000) of sires and

maternal grandsires to be used for a reliable esti-

mation of variance components. It had been proved

by Monte-Carlo simulation that an accurate model-

ling of herd-year fixed effects and a good level of

connectedness across herd-year levels was necessary

to get unbiased estimates of direct-maternal corre-

lations (Robinson, 1996a).

2.2. Definition of traits

Birth traits analysed were the birth weight (BW)

and the calving difficulty score (CS). CS can take

values from 1 (calving without assistance), 2 (calv-

ing with easy pull), 3 (calving with mechanical

assistance) to 4 (caesarian section or embriotomy).

Calving difficulty scores are attributed by the farm-

ers. Unobserved calvings are scored like calvings

without assistance by the farmers. Some farmers

truly measured all birth weights, but most of them

only measured a few calves and estimated the other

birth weights. Weaning traits were the weight at 210

days (WW) and the muscular development score

(MS). MS is scored over 100 points (average values

around 60 points) from the visual notation of five

different items in order to assess the calf muscular

frame (thickness and width) of its shoulders, back

and rump. Technicians belonging to agricultural

institutes, which are independent of the breed soci-

eties, measured the weaning weights and performed

the scoring for muscular development. Table 3 gives

means and phenotypic standard deviations for these

four traits.

2.3. Analysis models

The observation vector yi on trait i was described

by the following sire-dam within maternal grandsire

model:

yi ¼ Xibbbbbbbbbbbiiii þ Zisi þ Witi þ Cidi þ eeeeeiiii

bi is the vector of fixed effects, si is the vector of

random sire effects, ti is the vector of random maternal

grandsire (mgs) effects, di is the vector of random dam

effects within mgs effects and ei is the residual vector.Xi, Zi, Wi and Ci are the corresponding incidence

matrices. All random effects were assumed to be

normally distributed. A relationship matrix between

sires and mgs was accounted for.

The fixed effects were the birth season, the calf sex

and the class of dam age for all traits, and the herd-

year effect for birth traits, or the contemporary group

(management group-herd-year) effect for the weaning

traits. The management group related to calf–dam

couples which all managed in an homogeneous way

and in the same paddock. Classes of dam age were

made up as follows: class 1 for first parity dam and

age at calving lower than 30 months; class 2 for first

parity dam or class 3 for second parity, and age at

calving between 30 and 45 months; class 4 and class 5

for first and second parity dams, and age at calving

between 46 and 59 months; class 6 for mature cows

with age at calving between 60 and 179 months, and

lastly class 7 for calvings over 15 years old.

The season effect depended on the breed. The

number of season levels were defined after running

analyses of variance for the birth and weaning traits

with a month effect; consecutive months were

grouped together when they had no significantly

F. Phocas, D. Laloe / Livestock Production Science 89 (2004) 121–128124

different estimates of least square means. It had 10

levels in the Maine-Anjou corresponding to each

month, except that May and June, and also July and

August, were gathered, six in the Charolais and

Limousin breeds (1 = January, 2 = February,

3 =March, 4 =April, 5 = from May to August, 6 from

September to December) and also six levels in the

Blonde d’Aquitaine breed (1 = January and February;

2 =March and April; 3 =May and June; 4 = July and

August; 5 = September and October; 6 =November

and December).

The software ASREML developed by Gilmour et

al. (2000) was used for the estimation of variance

components in bivariate analyses. Estimates of param-

eters within trait were averaged over 3 very close

estimates under different bivariate analyses.

2.4. Estimation of genetic parameters

The relationships between the (co)variances esti-

mated under a sire-dam within maternal grandsire

model and the (co)variances of direct and maternal

effects were as follows: the direct genetic variance

was 4rs2, the maternal genetic variance was rs

2 + 4rt2�

4rst, the direct-maternal covariance was � 2rs2 + 4rst,

the permanent environmental variance was rd2� 3rt

2,

the environmental variance was rr2� 2rs

2 and the

phenotypic variance was rs2 + rt

2 + rd2 + rr

2, where rs2,

rt2, rst and rd

2 denote the sire variance, the mgs

variance, the sire-mgs covariance and the dam within

mgs variance, respectively, and ra2, rm

2, ram, rc2, re

2,

rp2 are the derived estimates. The same formulae held

for covariances between two traits numbered 1 and 2,

replacing the terms rv2 by rv1v2 where the subscript v

denotes s, t, d or r.

3. Results and discussion

3.1. Estimation of phenotypic means and standard

deviations

The Charolais and Maine-Anjou breeds had the

highest incidence of calving difficulties, with over 3%

of caesarian sections and only 57% of unassisted

calvings, while the figures drop to 1.6% and 0.2%

of caesarian sections, respectively, for the Blonde

d’Aquitaine and Limousin breeds, with 69% and

95% of unassisted calvings. These figures follow the

ranking observed on average birth weights. The

Maine-Anjou calves were the heaviest at birth, then

followed the Charolais calves and the Blonde d’Aqui-

taine and, lastly, the Limousin calves were the lightest

(Table 3). At weaning, the ranking of the heaviest

calves was different: first, the Charolais calves, next

the Maine-Anjou calves, then the Limousin calves,

and, finally, the Blonde d’Aquitaine. Concerning

muscular development score at weaning, the highest

score was also obtained by the Charolais calves,

followed by the Maine-Anjou calves and the Blonde

d’Aquitaine calves.

3.2. Estimation of genetic parameters within trait

3.2.1. Birth traits

Table 4 presents the estimates of genetic parame-

ters for birth weaning traits in the four breeds.

Estimates of direct and maternal heritabilities of birth

traits (CS and BW) were very similar from one breed

to another.

Values were around 0.10 for direct or maternal

effects on CS. These results were in the range of most

values seen in the literature (Koots et al., 1994a;

Gregory et al., 1995; Carnier et al., 2000). However,

Bennett and Gregory (2001) found quite higher her-

itabilities for CS in beef heifers. In the Charolais

breed, we verified that CS could be considered as

the same trait for heifers than for multiparous cows,

i.e. it had similar heritability and the genetic correla-

tion between heifer CS and cow CS was estimated

close to 1 (Phocas and Laloe, 2003).

Direct heritability of BW ranged from 0.28 for the

Maine-Anjou breed to 0.38 for the Limousin breed,

while maternal heritability varied from 0.08 to 0.11 in

these breeds. These results confirmed previous results

derived in the Limousin breed (Shi et al., 1993).

Negative genetic correlations between direct and

maternal effects of birth traits were estimated around

� 0.40 in general, except for the Limousin breed. This

average is very close to the average estimate (� 0.35)

proposed by Koots et al. (1994b) for the direct-

maternal correlation for BW. In the peculiar case of

the Limousin breed, the correlations between direct

and maternal effects on CS and BW were estimated at

� 0.69 and � 0.59, respectively. The fact that genetic

variances of CS and BW were far less much in this

Table 4

Parameter estimates within birth traits in the Charolais (Ch), Limousin (Li), Blonde d’Aquitaine (Bl) and Maine-Anjou (Ma) breeds

Parametera Calving difficulty scoreb Birth weight c

Ch Li Bl Ma Ch Li Bl Ma

H2d 0.13 0.10 0.09 0.09 0.33 0.38 0.37 0.28

H2m 0.12 0.08 0.08 0.09 0.11 0.11 0.10 0.08

Rdm � 0.35 � 0.69 � 0.45 � 0.41 � 0.41 � 0.59 � 0.49 � 0.39

H2c 0.08 0.02 0.07 0.17 0.03 0.02 0.04 0.02

Ve 0.277 0.065 0.251 0.295 12.0 4.5 13.03 10.42

Vp 0.390 0.076 0.314 0.432 20.0 7.5 22.49 15.41

a H2d, H2m, Rdm, H2c, Ve and Vp denote the direct heritability, the maternal heritability, the genetic corrrelation between direct and

maternal effects, the ratio of the permanent environmental variance over the phenotypic variance, the environmental variance and the phenotypic

variance, respectively.b Standard errors for either direct or maternal h2 estimates of calving difficulty score were about 0.006 for the Ch breed, 0.008 for the Li

breed, 0.010 for the Bl breed and 0.016 for the MA breed. Corresponding standard errors for Rdm were 0.035, 0.040, 0.079 and 0.111 for the

respective breeds.c Standard errors for direct (maternal) h2 estimates of birth weight were about 0.011 (0.007) for the Ch breed, 0.018 (0.011) for the Li breed,

0.023 (0.013) for the Bl breed and 0.029 (0.016) for the MA breed. Corresponding standard errors for Rdm were 0.028, 0.035, 0.053 and 0.096

for the respective breeds.

F. Phocas, D. Laloe / Livestock Production Science 89 (2004) 121–128 125

breed than in the others may automatically result in

higher estimates without any real biological difference

across breeds. Estimates of any direct-maternal corre-

lation (within or across traits) are always highly

sensitive to any difference in data structure designs

and it is really difficult to distinguish a biased estimate

from a true negative correlation between direct and

maternal effects (Robinson, 1996a,b). When looking

at direct genetic correlations between heifer CS, its

calf BW and the heifer pelvic opening (PO) adjusted

for its weight at calving, Phocas and Sapa (2003) had

already found quite different estimates for these three

indicators of heifer calving ability across Blonde

d’Aquitaine, Charolais and Limousin breeds. Direct

effects on CS are related to calf BW and maternal

effects on CS can be related to the dam PO. Correla-

tion between BW and PO was estimated to be mod-

erately positive in Limousin and Blonde d’Aquitaine

breeds, while it was moderately negative (� 0.2) in

Charolais breed. Because the adjustment of PO for

weight at calving (WC) was only reliable in the

Charolais breed (resulting in a zero genetic correlation

between WC and the adjusted PO), it suggests that the

antagonism observed between direct and maternal

effects on CS may be due to a genetic antagonism

between BW and PO. Other studies (Burfening et al.,

1981; Mc Neil, 1988) have shown that the genetic

relationships both between and within breeds indicate

that an increase in cow size or muscularity is associ-

ated within increased dystocia, particularly owing to a

larger increase in calf BW than in PO.

3.2.2. Weaning traits

Table 5 presents the estimates of genetic parame-

ters for weaning traits in the four breeds. Estimates of

genetic parameters were more variable across breeds

for weaning traits than for birth traits. Estimates of

direct heritabilities were the lowest in the Charolais

breed, with values for WW and MS equal to 0.13 and

0.16, respectively. Corresponding estimates were the

highest in the Limousin and Blonde d’Aquitaine

breeds with values around 0.30, and they were inter-

mediate (around 0.20) in the Maine-Anjou breed.

These estimates were not very far from the average

mean (0.24) derived for WW by Koots et al. (1994a).

These authors also found that breed effects were

significant for BW and WW over the studies they

had pooled.

Heritabilities of maternal effects on WW were

around 0.10, ranging from 0.07 in the Maine-Anjou

breed to 0.12 in the Limousin breed. Heritabilities of

maternal effects on MS were very low, ranging from

0.02 in the Maine-Anjou breed to 0.06 in the Blonde

d’Aquitaine and Charolais breeds. The negative ge-

netic correlations between direct and maternal effects

on weaning traits were stronger in the Charolais

(� 0.41 and � 0.48) than in the Blonde d’Aquitaine

and Limousine breeds (� 0.22 and around � 0.35 for

Table 5

Parameter estimates within weaning traits in Charolais (Ch), Limousin (Li), Blonde d’Aquitaine (Bl) and Maine-Anjou (Ma) breeds

Parametera Weaning weightb Muscular development scorec

Ch Li Bl Ma Ch Li Bl Ma

H2d 0.13 0.29 0.32 0.20 0.16 0.26 0.28 0.22

H2m 0.09 0.12 0.13 0.07 0.06 0.04 0.06 0.02

Rdm � 0.41 � 0.22 � 0.22 � 0.09 � 0.48 � 0.37 � 0.33 � 0.34

H2c 0.08 0.05 0.02 0.09 0.05 0.05 0.01 0.04

Ve 851 382 576.9 780.6 35.4 37.1 40.73 63.64

Vp 1141 662 1006 1188 45.7 54.0 58.94 85.57

a H2d, H2m, Rdm, H2c, Ve and Vp denote the direct heritability, the maternal heritability, the genetic corrrelation between direct and

maternal effects, the ratio of the permanent environmental variance over the phenotypic variance, the environmental variance and the phenotypic

variance, respectively. phenotypic variance, respectively.b Standard errors for direct (maternal) h2 estimates of weaning weight were about 0.006 (0.006) for the Ch breed, 0.015 (0.012) for the Li

breed, 0.024 (0.018) for the Bl breed and 0.027 (0.018) for the MA breed. Corresponding standard errors for Rdm were 0.034, 0.054, 0.075 and

0.145 for the respective breeds.c Standard errors for direct (maternal) h2 estimates of muscular score were about 0.006 (0.004) for the Ch breed, 0.014 (0.010) for the Li

breed, 0.024 (0.013) for the Bl breed and 0.028 (0.012) for the MA breed. Corresponding standard errors for Rdm were 0.035, 0.066, 0.094 and

0.156 for the respective breeds.

F. Phocas, D. Laloe / Livestock Production Science 89 (2004) 121–128126

WW and MS, respectively) and weaker in the Maine-

Anjou breed (� 0.09 and � 0.34 for WW and MS,

respectively). Koots et al. (1994b) derived a similar

mean (� 0.30) of the direct-maternal correlation for

WW across 23 studies. Results derived by Shi et al.

(1993) were confirmed for the Limousin breed. How-

ever, when running a univariate WW analysis of the

Limousin dataset, the estimate of the genetic correla-

tion between direct and maternal effects on WW was

only � 0.08 (unpublished result), instead of the very

constant value of � 0.22 estimated in three bivariate

analyses. This trend is in contradiction with previous

comparisons of univariate–bivariate estimates for

simmental cattle (Swalve, 1993) or Angus cattle

(Robinson, 1996b) in Australia. This point enlights

the difficulty of a reliable estimation of such correla-

tions. Indeed difficulties in estimation arise because

direct and maternal effects are partially confounded in

an animal’s performance. In some breeds, the fatty

udder syndrome (Mangus and Brinks, 1971) may

influence the estimate by a negative dam–offspring

environmental correlation. Many other environmental

factors can interfere with a correct estimation of

direct-maternal correlations (Robinson, 1996a,b).

Moreover, estimates of direct genetic correlation be-

tween milk yield and growth traits were found nil

(Blonde d’Aquitaine breed) to favorable (Charolais

and Limousin breeds) for beef heifers (Phocas and

Sapa, 2004). All these points can argue in favour of

considering zero correlation across direct and mater-

nal effects, at least for weaning weight.

3.3. Estimation of genetic parameters across traits

Table 6 presents the correlations estimated between

CS and the other traits for the different breeds. In

general, estimates are relatively similar from one

breed to another. The more variable estimates

concerned the correlations between direct effects on

CS and direct or maternal effects on the other traits.

Correlations between CS and WW or MS were very

moderate, with positive values below 0.30 for direct

effects. Genetic correlations between directs effects on

CS and BW ranged from 0.40 in the Limousin breed

to 0.78 in the Maine-Anjou breed. Direct effects on

calving difficulty has been shown to be highly corre-

lated (over 0.80) to birth weight in the litterature

(Koots et al., 1994b; Bennett and Gregory, 2001).

However, the moderate estimates of our study were

confirmed by previous results derived from calving

difficulty of beef heifers measured in progeny test

stations of French beef AI bulls (Phocas and Sapa,

2004).

Table 7 presents the correlations estimated between

birth or weaning weights and MS for the four breeds.

Genetic correlations between BW and WW were very

similar across breeds, with estimates of the direct

correlation around 0.3–0.4 and estimates of the ma-

Table 6

Correlationsa between calving difficulty score (trait 1) and other traits (trait 2)

Parameter Birth weight Weaning weight Muscle score

Ch Li Bl Ma Ch Li Bl Ma Ch Li Bl Ma

Rd1d2b 0.66 0.40 0.72 0.78 0.28 0.12 0.15 0.12 0.23 0.05 0.15 0.31

Rm1m2c 0.44 0.35 0.58 0.52 0.10 0.05 � 0.06 � 0.10 � 0.04 0.12 � 0.05 0.23

Rd1m2 � 0.50 � 0.34 � 0.61 � 0.60 � 0.20 � 0.09 � 0.13 � 0.14 � 0.19 � 0.09 � 0.13 � 0.60

Rm1d2 � 0.29 � 0.22 � 0.33 � 0.36 � 0.14 � 0.06 � 0.07 � 0.00 � 0.08 � 0.01 � 0.05 � 0.13

Rc1c2 1. 0.97 0.70 0.85 0.06 � 0.02 0.31 � 0.20 0.34 � 0.03 0.42 0.28

Re1e2 � 0.05 � 0.01 � 0.02 � 0.01 � 0.07 � 0.06 � 0.05 � 0.02 � 0.03 � 0.02 � 0.05 0.01

a Rd1d2, Rm1m2, Rd1m2, Rm1d2, Rc1c2, Re1e2 denote the genetic correlation between direct effects on both traits, the genetic correlation

between maternal effects on both traits, the genetic correlation between direct effects on trait 1 and maternal effects on trait 2, the genetic

correlation between maternal effects on trait 1 and direct effects on trait 2, the correlation between the two permanent environments and the

correlation between the two residual environments, respectively.b Average standard errors for the correlations between direct effects were about 0.03 for the Ch breed, 0.05 for the Li breed, 0.08 for the Bl

breed and 0.10 for the Ma breed.c Average standard errors for the correlations between maternal effects were about 0.05 for the Ch breed, 0.07 for the Li breed, 0.10 for the

Bl breed and 0.16 for the Ma breed.

F. Phocas, D. Laloe / Livestock Production Science 89 (2004) 121–128 127

ternal correlation around 0.3. For the Limousin and

Blonde d’Aquitaine breeds, estimates of the correla-

tion between permanent environments for BW and

WW were fixed at the boundary value 1. The same

phenomenon occured for the correlation between

permanent environments for WW and MS. Estimates

of the direct genetic correlation betwen WS and MS

varied from 0.22 for the Limousin breed to 0.41 for

the Charolais breed, while estimates of the maternal

correlation varied from 0.45 in the Limousin breed to

the boundary value 1 in the Maine-Anjou where the

estimate of maternal heritability of MS was the lowest

(0.02). Estimates of the direct genetic correlation

Table 7

Correlation estimates between birth (BW) or weaning (WW) weights and

Parametera 1 =BW, 2 =WW 1=BW, 2 =MS

Ch Li Bl Ma Ch Li

Rd1d2b 0.39 0.44 0.31 0.26 0.28 0.1

Rm1m2c 0.28 0.23 0.35 0.28 0.16 0.2

Rd1m2 � 0.27 � 0.29 � 0.22 � 0.25 � 0.24 � 0.1

Rm1d2 � 0.26 � 0.34 � 0.22 � 0.09 � 0.22 � 0.1

Rc1c2 0.70 1 1 0.37 0.39 0.0

Re1e2 � 0.08 � 0.29 � 0.15 � 0.01 � 0.09 � 0.0

a Rd1d2, Rm1m2, Rd1m2, Rm1d2, Rc1c2, Re1e2 denote the genetic co

between maternal effects on both traits, the genetic correlation between

correlation between maternal effects on trait 1 and direct effects on trait 2

correlation between the two residual environments, respectively.b Average standard errors for the correlations between direct effects we

breed and 0.09 for the Ma breed.c Average standard errors for the correlations between maternal effects

Bl breed and 0.16 for the Ma breed.

between BW and MS varied from � 0.02 (not signif-

icantly different from 0) in the Blonde d’Aquitaine

breed to 0.28 in the Charolais breed. In fact, BW and

MS seemed to be genetically and environmentally

uncorrelated in the Blonde d’Aquitaine breed.

4. Implications

The review of the estimates of heritabilities for

birth weight and weaning traits is likely to modify

significantly the genetic evaluations of weaning traits

in the Charolais and Maine-Anjou breeds because the

muscle score (MS)

1 =WW, 2 =MS

Bl Ma Ch Li Bl Ma

3 � 0.02 0.20 0.41 0.30 0.22 0.33

1 0.09 0.69 0.85 0.72 0.45 1

6 0.01 � 0.41 � 0.34 � 0.32 � 0.18 � 0.34

4 � 0.02 � 0.21 � 0.28 � 0.20 � 0.13 � 0.32

5 0.13 � 0.11 0.59 1 1 0.60

9 0.08 0.01 0.28 0.15 0.18 0.10

rrelation between direct effects on both traits, the genetic correlation

direct effects on trait 1 and maternal effects on trait 2, the genetic

, the correlation between the two permanent environments and the

re about 0.03 for the Ch breed, 0.04 for the Li breed, 0.06 for the Bl

were about 0.04 for the Ch breed, 0.07 for the Li breed, 0.10 for the

F. Phocas, D. Laloe / Livestock Production Science 89 (2004) 121–128128

new estimates are really different from the estimates

used at the moment in the evaluation and derived from

the Limousin breed. Due to the antagonism observed

between direct and maternal effects on birth and

weaning traits, it is necessary to combine in a selec-

tion index both direct and maternal estimated breeding

values of these traits in order to increase the econom-

ical efficiency of beef cattle herds (Phocas et al.,

1998). In the next future, selection for reduced calving

difficulty will not reduce strongly the genetic progress

on weaning weight and muscular development, be-

cause there are little unfavourable associations of both

direct and maternal effects between calving difficulty

score and weaning traits.

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