Estimation of genetic parameters and ( co ) variance components for weaning traits of Charolais population in Hungary *

Weaning performance of 10 808 purebred offsprings (4991 male and 5817 female) of 80 sires in 13 farms were analised using animal model. Heritability, breeding value, (co)variance components for weaning weight (WW), preweaning daily gain (PDG), 205-day weight (CWW) were calculated. Farm, parity, year of birth, season of birth, sex were treated as fixed, and the maternal permanent environment was treated as random effects. In case of WW and PDG, the age of the calves at weaning was fitted as a covariant. Data were analyzed with MTDFREML (Boldman et al. 1993) program. The overall mean value and standard deviation of WW, PDG and CWW were 221±47 kg, 1,111±0.21 kg/day and 226±42 kg, respectively. The age of the calves at weaning was 202 days. The direct heritability (hd) of WW and PDG were 0.57±0.08, 0.49±0.07 and CWW was 0.44±0.06, respectively. The maternal heritability (hm) of these traits were 0.32±0.09, 0.33±0.10 and 0.33±0.09, respectively. The direct-maternal correlations (rdm) were strong and negative. The medium heritability estimates for direct effects suggest that progeny tests should be used in this population to increase genetic improvement.


Introduction
Weaned beef calves are the products of beef cattle sector, therefore the results are influenced by weaning weight.On the other hand the weaning weight expresses the calf rearing ability of cows, so changes in weaning weight are important factors at selection.However there are results about variation and genetic parameters of the most important beef traits of dairy and dual purpose breeds (ATIL et al., 2005;JACUBEC et al., 2003;CANTET et al., 2003;GOYACHE et al., 2002;REINSCH and KALM, 1995) it is important requirement to estimate the breeding value based on weaning results very exactly.NELSEN and KRESS (1981) found that sex and the age of dam influenced the weaning weight of Aberdeen Angus and Hereford herds (P<0.01).JAKUBEC et al. (2000) showed that year, sex and the age of dam influenced the weaning weight and daily gain of Aberdeen Angus calves (P<0.01).GÁSPÁRDY et al. (1998) analysed the weaning weight of Charolais calves.They found that parity (number of calving) and year of birth had an effect on the adjusted 205-day weight.MASSEY and BENYHSEK (1981) in a crossbreed population showed the effect of dam's age on weaning performance.According to SZABÓ and GAJDI (1993) age of dam, sex, year and season had significant effect on 205-day weight of Hereford calves.SZABÓ (1993) summarized the results of 35 publications and reported that heritability of calf's daily gain before weaning was 0.27 on average.Heritability of weaning weight was 0.30 on average according to 61 publications.BOURDON and BRINKS (1982) found that heritability of the preweaning daily gain and weaning weight was 0.60 and 0.63, respectively.LEE et al. (1997a) examined the weaning weight of Simmental calves.They found that the direct heritability (h 2 d ) of weaning weight was 0.21, maternal heritability (h 2 m ) was 0.10.MASSEY and BENYHSEK (1981) found that heritability of the 205-day weight and preweaning daily gain was 0.11 and 0.08, respectively.SZABÓ et al. (2001) showed that heritability of weaning weight was 0.29.DUANGJINDA et al. (2001) examined the heritability value of weaning weight in Charolais herds.They found that direct heritability of weaning weight was 0.33, maternal heritability was 0.15.VAN VLECK at al. (1996) found that direct heritability of weaning weight was 0.16 and maternal heritability was 0.12, respectively.TŐZSÉR et al. (2002) showed that heritability of weaning weight of Limousin calves was 0.14 and CANTET et al. (2003) found h²=0.32 in Angus beef cattle.Correlation between direct genetic and maternal effects (r dm ) is different.DODENHOFF at al. (1999) examined the genetic parameters of weaning weight in five different breeds.They found that the direct-maternal correlation varied between -0.10 and -0.37.BASCHNAGEL et al. (1998) found that the direct-maternal correlation was -0.50 for Angus in Sweden.MEYER (1992) showed that the direct maternal correlation of weaning weight was -0.59.NUNEZ-DOMINGUEZ at al. (1993) found high positive direct-maternal correlation (r dm =+0.63) in the case of weaning weight.VAN VLECK et al. (1996) showed that the direct-maternal correlation of the weaning weight was 0.40.There have not been any investigations in connection with covariance and genetic parameter estimation in Hungarian beef population so far.That is the reason why analyes of genetic parameters and breeding value of the Hungarian Charolais population were carried out using animal model.

Material and Methods
Field records were provided by the Association of Hungarian Charolais Breeders.The weaning results of 10808 pure bred calves (4991 male and 5817 female) born from 5388 cows mated with 80 sires were analyzed.36 of the sires with more than 100 offsprings were presented.There were Hungarian and French origin sires used in this population.Description of the samples is shown in Table 1.Estimated traits were the weaning weight (WW), preweaning daily gain (PDG) and 205-day weight (CWW).where, y is a N X 1 vector of observation, b denotes the vector of fixed effects (herd, parity, year, season and sex), X is the matrix that associates b with y; u is the vector of breeding values for direct genetic effects, Z is the matrix that associates u with y; m is the vector of breeding values for maternal genetic effects, W is the matrix that associates m with y; pe is the vector of permanent environmental effects contributed by dams to records of their progeny, S is the matrix that associates pe with y; and e is the vector of random residual effects.

Genetic parameters and (co)variances
The estimated genetic parameters and (co)variance components of the investigated traits are shown in Table 2. m , maternal heritability; r dm , direct-maternal genetic correlations; c 2 , the ratio of the permanent environmental variance to the phenotypic variance; e 2 , the ratio of the residual variance to the phenotypic variance; h 2 T , total heritability * estimated in kg/day Direct heritability (h 2 d ) of weaning weight, preweaning daily gain and 205-day weight were 0.57±0.081,0.49±0.076and 0.44±0.066,respectively.High estimates of direct heritability for the investigated traits may be due to the used foreign sires, which are increasing the direct additive genetic variance.Maternal heritability (h 2 m ) in the case of these traits were 0.32±0.094,0.33±0.10 and 0.33±0.098.Direct-maternal genetic correlations were high and negative (r dm =-0.95±0.07,-0.94±0.083,-0.97±0.080).These data in results were higher than the estimates of DODENHOFF (1999) -0.12, PHOCAS and LALOЁ (2003) -0.19, and DUANGJINDA et al. (2001) -0.46, but MEYER (1992) in the case of Zebu Cross found that the direct-maternal genetic correlation of weaning weight -0.78.Total heritability (h 2 T = 0.047, 0.092, 0.050) was low due to the high negative directmaternal genetic correlation.The ratio of the permanent environmental variance (c 2 ) was low (4-6%).Similar results were found by BASCHNAGEL et al. (1998) for Angus in Sweden, CARNIER et al. (2000) for Piedmontese in Italy, DUANGJINDA et al. (2001) for Gelbvieh, LEE et al. (1997b) for Simmental and VAN VLECK et al. (1996) for Simmental in USA.The residual variance were similar for the three traits.The ratio to the phenotypic variance (e 2 ) ranged from 46 to 55 %.

Breeding values
Table 3 shows the breeding values of the 36 examined sires, with more than 100 offsprings.The best sire was the registered by number 32500 (+66.51 kg in weaning weight, +0.304 kg/day in preweaning daily gain and +76.89 kg in 205-day weight).The worst sire was of the number 9823 (-46.1kg,-0.179 kg/day and -42.35 kg in the case of WW, PDG and CWW). Figure 1 and 2 show the overall breeding values of the Hungarian and French Charolais sires.Direct effect of French sires was higher than that of the Hungarian Charolais sires that explains the relatively high direct additive genetic variance.That means that French Charolais sires are genetically better as for the growing capacity than Hungarian ones.As both French and Hungarian Charolais sires had negative maternal EBV values, maternal genetic effect could be increased in order to make further improvement on the genetic merit of the population values.The medium heritability estimates for direct effects suggest that progeny tests should be used to increase genetic improvement.Based on the results obtained it can be suggested that both the direct and maternal effect, because of the high negative direct and maternal genetic correlation, should be takeen into account during selection.It is assumed that the high genetic variance could contribute to a more succesful selection in the future.

Table 1
Characteristic of the samples for univariate analyses (Charakteristik der einbezogenen Daten)