genetic analyses of calving traits in the swiss black and white, braunvieh and simmental breeds by...

Livestock Production Science, 24 (1990) 93-107 93 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Genetic Analyses of Calving Traits in the Swiss Black and White, Braunvieh and Simmental Breeds by REML and MAPP Procedures

C. HAGGER and A. HOFER

Institute of Animal Sciences, Swiss Federal Institute of Technology, CH-8092 Zurich (Switzerland)

(Accepted for publication 28 August 1989)

ABSTRACT

Hagger, C. and Hofer, A., 1990. Genetic analyses of calving traits in the Swiss Black and White, Braunvieh and Simmental breeds by REML and MAPP procedures. Livest. Prod. Sci., 24: 93- 107.

Fixed effects, genetic and phenotypic parameters were estimated for birth weight, gestation length, dystocia and stillbirth using a multitrait REML (Restricted Maximum Likelihood) procedure on a model that included effects of herd × year, season, sex of calf, parity of cow, genetic group of sire of calf and sire of calf. Observations on the calves of test sires from the three Swiss cattle breeds Black and White (BW), Braunvieh (BR) and Simmental (SI) were used. Sex of calf and parity of cow (first vs. later) had the largest influence on all traits analysed and in all breeds. Genetic groups of sires, according to percentage of U.S. Brown Swiss genes in BR and Red Holstein genes in SI had also a moderate to large effect on these traits. Considerably smaller heritabilities for dystocia and for stillbirth were found in BR than in the other two breeds. Some breed differences were observed in the genetic correlations. It was found that a model containing a random herd classification with a ratio of error to herd variance between 5 and 20 yielded useful heritability estimates for dystocia with a MAPP (Maximum A-Posteriori Prediction ) or a REML procedure. Correlations of 0.97 and 0.99 were observed between breeding values estimated by a linear or a nonlinear procedure for dystocia and for stillbirth. For both traits slightly higher correlations between the two breeding values of the same sire, after randomly splitting the daughters into two groups, were found within the linear than within the nonlinear procedure.

INTRODUCTION

Reducing the frequency of calving difficulties (dystocia) would primarily reduce the loss of calves (Martinez et al. (1983) among others), and thus im- prove the efficiency of production in any type of cattle. After a difficult birth, conception rate and lactation yield of the cow may be influenced negatively, as found by Bar-Anan (1973) for first parity cows. Calving difficulties are highly correlated with birth weight (Philipsson et al. (1979)). A reduction in rate of

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94 C. HAGGERANDA. HOFER

dystocia would reduce birth weight directly, and indirectly through a positive correlation with birth weight and daily gain (Burfening et al. (1978)). In dual purpose and beef breeds this has to be taken into account in the design of the breeding goal for calving traits.

Reliable population parameters and breeding values are prerequisites to im- plement a successful breeding scheme for calving traits. The well-known linear procedures for sire evaluation, Best Linear Unbiased Prediction (BLUP) (Henderson, 1973 ) and for the estimation of variance components, Restricted Maximum Likelihood (REML) (Patterson and Thompson, 1971) are theo- retically not suitable for categorical traits like dystocia and stillbirth, as pointed out by Gianola and Foulley (1983a) and others. But simulation studies by Meijering and Gianola (1985) and analyses of field data on dystocia and stillbirth by Meijering (1985) and by Weller et al. (1988) did not show relevant differences between sire rankings from a BLUP and from a nonlinear method in certain important cases. HSschele (1986) found in a simulation study that a nonlinear procedure was superior to a REML procedure to estimate the heritability of a binary trait. The superiority increased with an increasing true heritability and an incidence rate increasing from 0.96 to 0.99.

The main objective of this study was to estimate phenotypic and genetic parameters as well as fixed effects for birth weight, gestation length, dystocia and stillbirth with a multitrait REML procedure for the three main cattle breeds in Switzerland. On part of the data, comparisons between genetic parameters and between ranking of sires, evaluated with a linear and a nonlinear procedure, were made to investigate the suitability of the methods for large sets of field data in a small herd.

MATERIAL AND METHODS

Data

The Swiss AI organisation uses a questionnaire system to collect information on birth weight, gestation length, dystocia and stillbirth of calves from test sires. For each insemination with a test sire in a registered herd a questionnaire, containing the known information on sire and dam of the expected calf, is sent to the farmer. He is asked to complete the form with estimated or measured weight, sex, number of parity, status of birth (normal or difficult), calf alive or dead within 24 h and single or multiple birth. To indicate the reason for a difficult birth he is asked whether it was caused by the size of the calf, abnormal position, caesarean delivery or others. Gestation length is calculated from the dates of insemination and birth.

Six years of data from three Swiss breeds, i.e. Black and White (BW), Braunvieh (BR) and Simmental (SI) were available. Each set contained the questionnaires for inseminations between November 1980 and October 1986.

GENETIC ANALYSES OF CALVING BY REML AND MAPP 95

TABLE 1

Number of calvings, sires, herds, herdXyears and population means of birth weight, gestation length, dystocia and stillbirth in the Black and White (BW), Braunvieh (BR) and Simmental (SI) breeds of Switzerland

Breed

BW BR SI

Calvings 55284 227686 236692 Sires i39 456 512 Herds 2587 14115 13749 Herd × years 11465 61594 63277 Birth weight (kg) 43.5 43.5 44.4 Gestation length {days) 281.9 288.5 286.6 Dystocia (%) 2.6 1.3 3.0 Stillbirth (%) 2.8 2.0 2.6 Heifer calvings (%) 35.4 35.7 27.7

The insemination periods of successive batches of test sires did not overlap. Only normal births and difficult births due to the size of the calf, with a gestation length between 260 days and 310 days were kept in the data. Status of birth (normal = 1, difficult = 2 ) and calf alive ( = 1 ) or dead ( = 2 ) were defined as all or none traits. These two traits are related to each other because a difficult birth sometimes also results in a dead calf. Table I contains the number of observations and number of sires, averages of birth weight, gestation length, percentage of dystocia and stillbirth, and percentage of heifer calvings for each breed. This table shows that the BR and SI populations are of similar size whereas the BW population is about a quarter of the size of a main breed. On average 398, 499 and 462 observations per sire could be analysed in BW, BR and SI, respectively.

Crossing with U.S. Brown Swiss in Braunvieh and with Red Holstein in Simmental had to be taken into account in the analyses. The Black and White breed resulted from a repeated back cross of a local black and white breed to Canadian and U.S. Holsteins. The sires of this breed included in the investigation were 75% or more Holstein.

METHODS

Fixed effects, sire effects and genetic parameters of the four traits, birth weight, gestation length, dystocia and stillbirth were estimated by a multitrait REML procedure. The following linear model was used:

Yijhl(m) no = H Y i + Seasonj + S e x k ..~ Pl + ( Gm ) .4- s (m) n "t- eijhl (m) no

where:

9 6 C. HAGGER AND A. HOFER

Yijkl{m)no ~ - o b s e r v a t i o n on a particular calf; HYi= fixed effect of herd × year; Seasonj = fixed effect of season; Sexk = fixed effect of sex of calf; Pl = fixed effect of parity of cow (first or later); (Gin) = fixed effect of genetic group of sire of calf (for BR and SI); 8(m)n = random effect of sire of calf (within group for BR and SI); e i j k l ( m ) n o ---- residual.

Months were grouped into four seasons as follows: November-January, Feb- mary-April , May-July and August-October. Five genetic groups of sire of calf were built according to the percentage of U.S. Brown Swiss genes in BR and percentage of Red Holstein genes in SI. Relationships between sires were ig- nored. Repeated observations on a given cow were assumed unrelated. Owing to lack of information, the genetic group of the calf could not be taken into account. Equal design matrices were assumed for the four traits analysed and so a transformation to canonical scale was feasible, as outlined by Meyer (1985). The transformed traits are uncorrelated and a series of univariate analyses can then be applied which reduces the computational requirements substantially. A more detailed description of the computing strategy is given by Meyer (1986).

Dystocia and stillbirth were defined as binary traits. The well-known statis- tical procedures in animal breeding like BLUP (Henderson, 1973 ) may not be adequate for this type of trait. Thus, in recent years, methods were developed by Gianola and Foulley (1983a,b), Gilmour (1983), Harville and Mee (1984) and HSschele (1986) which take the categorical nature of these traits into account.

Harville and Mee (1984) pointed out that, in these methods, subgroups with all observations in one extreme class will cause numerical difficulties and sug- gested that the herd × year classification is taken as random. It was assumed that in Switzerland with its small herd sizes this problem may be particularly relevant. To gain more information on this subject in practical situations, an extended investigation on the BW data was performed. Breeding values and heritabilities of dystocia and stillbirth were estimated with a univariate threshold model described by Gianola and Foulley (1983a,b). The method assumes an underlying normal scale with a fixed threshold and connects it with the observed categorical responses. Parameters, i.e. the effects in the model, loca- tion of the threshold and heritability, are estimated on the underlying scale. The prior distribution of the parameters and the likelihood function are com- bined to yield the posterior density function. The mode of the posterior distribution is taken as an estimate of the parameters. HSschele (1986) popularized the notation of MAPP (Maximum A-Posteriori Prediction) for this procedure.

The analyses were done once with the model described above and once with


herd × years replaced by herds. These two effects were then taken as fixed or as random with ratios of error to herd variance 2 2 of 2=ae/ah =0.1, 1, 5, 10 and 20. When taking the herd × year or herd classification as random, two types of heritability estimates can be thought of. The within heritability would be h~=4a~/(a~+a~) whereas the overall heritability would be ho2=4as/2 ( a ~ + 2 2 ah + ae ) with ~ the sire variance. In addition, univariate REML estimations were done for both models. Finally heritabilities were estimated for both categorical traits in the BR and SI data using one variance ratio ~.

Ranking properties for estimated breeding values of the two methods were analysed for the BW data and both traits. The correlation between the breeding values estimated by the linear and the nonlinear method were taken as a direct measure of these properties. The repeatability of estimates from the same procedure was investigated by a method described by Dempfle and Hag- ger (1983). The daughters of each sire were split randomly into two groups of equal size. Breeding values were estimated from the whole data set again by each procedure and for both traits. The correlation between the two breeding values of a sire within procedure was then taken as a measure of repeatability of the two procedures.

RESULTS AND DISCUSSION

Fixed effects and population parameters from a multitrait REML analysis

Averages of the four traits, birth weight, gestation length, dystocia and stillbirth included in the REML analysis are given in Table 1. Simmental calves were about I kg heavier at birth than calves from either BW or BR. Gestation length in BR was I week longer than in BW. BR had less than half the dystocia frequency of the other two breeds and had the lowest stillbirth frequency. It should be noted that in SI a smaller percentage of heifers was bred to test sires than in BW and BR, 27.7% vs. 35.5%. This will lower the frequency of dystocia and stillbirth in SI. Meijering (1985) found a lower birth weight, a shorter gestation length and a higher dystocia frequency in Dutch Black and White cows and an equal rate of stillborn calves. Weller et al. (1988) reported considerably higher frequencies of dystocia and stillbirth in Israeli-Holsteins. Dif- ferences between countries may arise mostly through a combination of the definition of the ease of calving classes and the calving management practices of the farmers. Different ranges of traits included in data sets may also con- tribute to differences. Meijering (1985) excluded observations with a gestation length over 299 days whereas in the present data, records were excluded if gestation length was over 310 days. Therefore it is difficult to compare absolute values of dystocia percentages between countries.

Sex of calf and parity of cow in all breeds, and genetic group of sire of calf in BR and SI were by far the most important effects on all traits. Table 2 contains

98 c. HAGGER AND A. HOFER

TABLE 2

Estimated differences between effects of sex of calf and parity of cow for birth weight, gestation length, dystocia and stillbirth

Breed Birth Gestation Dystocia (%) Stillbirth (%) weight (kg) length (day)

Maleminus~malecalf BW 1.9 1.0 2.4 1.0 BR 2.2 1.4 1.7 0.7 SI 2.4 1.1 3.2 1.1

Laterminusfirstpari~ BW 2.7 1.3 -2.6 -2.8 BR 2.7 1.3 -1.4 -1.3 SI 3.1 1.3 -2.7 -2.6

the estimated differences between male and female calves and between first and later parity cows for all traits and breeds included in the investigation. Male calves were 1.9, 2.2 and 2.4 kg heavier than female calves in the BR, BW and SI breed, respectively. Gestation length of male calves was I day longer in all breeds. Male calves caused between 1.7% and 3.2% more dystocia and about 1% more stillbirth than female calves. Calves from later parity cows were nearly 3 kg heavier at birth than calves from first parity cows and had a longer gestation length of 1.3 days. Later parity BW and SI cows had 2.7% less dystocia and stillbirth than first parity cows. In BR this figure was 1.4%, only half that of the other two breeds.

Table 3 contains the classifications of sires into groups and the estimated differences between the sire groups within BR and SI breeds. Calves from sires with increasing percentages of foreign genes decreased in weight, had a de- creasing gestation length and caused considerably less dystocia. Calves from crossed BR sires also showed less stillbirth whereas in SI no differences between calves from pure and crossed sires could be observed. Farmers must be aware of the differences between sire groups in ease of calving. The increasing percentage of heifers, 22.7% to 40.9% in BR and 20.4% to 36.1% in SI (Table 3 ), bred to sires with an increasing percentage of foreign genes could at least partly be due to this fact.

Heritabilities, genotypic and phenotypic correlations are given in Table 4. Most of the heritabilities found were in the range of values given by Philipsson et al. (1979). The BR breed had the lowest genetic determination for dystocia and stillbirth among the breeds analysed, i.e. the smallest heritabilities for these two traits. For Dutch black and white cows Meijering (1985) reported a heritability of 0.09 for dystocia which was twice the estimate for BW in Table 4, but a much smaller value of 0.003 for stillbirth. Martinez et al. (1983) found

GENETIC ANALYSES OF CALVING BY REML AND MAPP

TABLE 3

Estimated effects of sire groups on calving traits in the BR and SI breeds

99

Sire group

0-12 .5% -37 .5% -50% -75% > 75%

B R 1

Birth weight (kg) 0 - 0 . 4 - 0 . 7 - 0 . 9 - 0 . 9

Gestation length (day) 0 - 0 . 6 - 1.0 - 1.5 - 1.5 Dystocia (%) 0 0.0 - 0.4 - 0.6 - 0.6

Stillbirth (%) 0 - 0 . 2 - 0 . 4 - 0 . 4 - 0 . 3 Number of sires 40 49 169 166 32

Heifer calvings (%) 22.7 31.1 36.8 39.9 40.9

SI 2

Birth weight (kg) 0 - 0 . 5 - 1 . 0 - 1 . 4 - 2 . 1

Gestation length (day) 0 - 1.7 - 2 . 9 - 3 . 7 - 4 . 5 Dystocia (%) 0 0.1 - 0 . 7 - 1.1 - 1.7 Stillbirth (%) 0 0.1 0.1 0.1 0.1

Number of sires 183 71 133 103 12 Heifer calvings (%) 20.4 27.3 31.4 36.6 46.1

1Percentage of U.S. Brown Swiss genes. 2percentage of Red Holstein genes.

heritabilities of 0.041 for dystocia and of 0.009 for stillbirth in U.S. Holstein cattle. Their estimates are close to the values of the BW breed in Table 4. Most recent estimates from Israeli-Holstein data were lower for dystocia, 0.023, and higher for stillbirth, 0.031, with higher incidence rates for both traits than given in Table 1 (Weller et al., 1988).

High genetic correlations were found between birth weight and the other traits. For birth weight and gestation length a higher correlation was observed in BR than in SI, 0.59 vs. 0.49, whereas between birth weight and stillbirth a higher value was found in SI than in BR, 0.72 vs. 0.55. All estimates of the genetic correlations between gestation length, and dystocia and stillbirth were slightly higher than the values given by Philipsson et al. (1979). In the BW breed the genetic correlation between gestation length and stillbirth seems to be above the other two breeds, 0.47 vs. 0.38 and 0.35. High genetic correlations between dystocia and stillbirth were found in all breeds and confirm the average values given by Philipsson et al. (1979) and Martinez et al. (1983). It can partially be explained by the well-known fact that quite often a difficult calving results in a dead calf. The percentages of dead calves after a difficult calving were 28.0%, 22.6% and 26.0% in the BW, BR and SI breed, respectively. Martinez et al. (1983) observed a higher value of 37.4% in U.S. Holstein data.

I00 C. HAGGERANDA. HOFER

TABLE 4

Heritabilities (diagonal), genetic (above diagonal) and phenotypic (below diagonal) correlations of birth weight, gestation length, dystocia and stillbirth in the BW, BR and SI breeds of Switz- erland, from multitrait REML estimates of variance (covariance) components

Trait

(1) (2) (3) (4)

Birth weight ( 1 ) BW 0.146 0.574 0.927 0.681 BR 0.124 0.589 0.917 0.553 SI 0.167 0.487 0.926 0.724

Gestation length (2) BW 0.266 0.407 0.517 0.469 BR 0.301 0.456 0.455 0.376 SI 0.302 0.500 0.461 0.354

Dystocia (3) BW 0.303 0.085 0.046 0.730 BR 0.210 0.081 0.018 0.690 SI 0.338 0.114 0.047 0.830

Stillbirth (4) BW 0.060 0.008 0.242 0.016 BR - 0.014 - 0.018 0.170 0.006 SI 0.093 0.015 0.260 0.010

F r o m the genet ic cor re la t ions found it seems obvious t h a t select ion for lower b i r th weight would reduce calving diff icult ies to some extent . Bu t in dual-purpose breeds the re la t ionship be tween b i r th weight , and growth ra te and growth capaci ty would have to be t aken into account . Bur f en ing et al. (1978) r epor t ed posi t ive genet ic cor re la t ions of 0.33 and 0.17 be tween b i r th weight, and 205- day weight and average daily gain in S immenta l - s i r ed calves. Selec t ion for a reduced ra te of diff icult calvings would reduce the ra te of dead calves and also birth weight and thus, could also reduce average daily gain.

Moderate phenotypic correlations could be observed between birth weight, and gestation length and dystocia as well as between dystocia and stillbirth. Other phenotypic relationships were small (Table 4).

Comparison of results from single trait MAPP and REML procedures

The BW data were used to compare the heritabilities calculated from MAPP and from REML variance components. Heritabilities of dystocia were estimated with two models, one containing herd X year effects, the other only herd


effects. These effects were taken as fixed or as random. In the random case, different ratios of error to herd × year (herd) variances, ,~ = a ~ / a ~ , were used. Results are given in Table 5. The MAPP procedure was very sensitive to the definition of herd × year and herd as fixed or as random. It yielded very large heritabilities in the fixed cases. With the herd × year classification, the influence of the model (fixed or random) was much stronger than with the herd classification. With the variance ratio, 2, increasing from 0 (fixed) over 0.1 to 1, the within heritability, h2w, dropped in the herd× year model considerably from 0.701 to 0.493 and 0.281. In the herd model the decrease was less pro- nounced, the estimate dropped from 0.426 over 0.398 to 0.328. According to Harville and Mee (1984), this seems to be a consequence of the small group sizes which will often result in groups with only one dystocia class. It was found that only 10.3% and 35.1% of the herd X year and herd subclasses, respectively, contained observations on both dystocia scores. Increasing the variance ratio,

T A B L E 5

Sire components (a~) and heritabilities 2 2 (hw, ho ) of dystocia in the BW breed, estimated from single trait MAPP and REML analyses using herd×years and herds fixed or random (a~ = 1 )

2 2

0 0.1 1 5 10 20

Herd × year M A P P

a~ 0.21246 0.14064 0.07565 0.06879 0.06946 0.07026 0.07157 h~ 0.701 0.493 0.281 0.257 0.260 0.263 0.267 ho 2 (0) 0.051 0.146 0.217 0.238 0.251 0.267

R E M L a~ 0.01097 0.01464 0.01325 0.01203 0.01166 0.01140 0.01136 h~ 0.043 0.058 0.052 0.048 0.046 0.045 0.044 ho 2 (0) 0.005 0.026 0.040 0.042 0.043 0.044

Herd MAPP

a~ 0.11926 0.11062 0.08926 0.07591 0.07326 0.07203 0.07157 h~ 0.426 0.398 0.328 0.282 0.273 0.269 0.267 ho 2 (0) 0.040 0.171 0.238 0.250 0.257 0.267

R E M L a~ 0.01136 0.01206 0.01199 0.01181 0.01168 0.01154 0.01136 h2w 0.045 0.048 0.047 0.047 0.046 0.046 0.044 ho 2 (0) 0.004 0.024 0.039 0.042 0.044 0.044

= 0 herd fixed, ~l = oo without herd effect. h~ = within heritability, h~ = 4a~ / (a~ + a~ ). ho 2 =overal l heritability, 2 2 2 2 2 ho --4a8 / (a~ +ah +ae ).

102 C. HAGGER AND A. HOFER

7t, further changed the heritability towards the limit attained with 2-- oo. This pattern can be seen for both estimation procedures and both models (Table 5 ). The MAPP estimates with 2 = 10 are less than twice the estimate of Djemali et al. (1987) of 0.148 with 2 = 10.4 for U.S. Holsteins. The within heritabilities from the REML estimates were all very similar. Djemali et al. (1987) observed the same pattern in REML estimates of heritability for dystocia for the herd X year × season fixed or random (2 = 8.2) cases. Their within heritabilities of 0.055 and 0.061 are slightly higher than the corresponding values in Table 5.

The definition of the heritability according to the model used is very important, as the comparison between the within and overall estimates in Table 5 shows. The overall heritability is influenced much more through a bad estimate of 2 with both estimation procedures, especially with small values of 2.

With the MAPP procedure the standardized (a~ = 1 ) sire components (a~) also dropped when the herd classification was changed from fixed to random. Increasing 2 from 0.1 to 20 in the herd model decreased the sire component continuously towards the limit with 2 = oo. In the herd × year model this change was curvilinear. After a decrease from changing/1 from 0.1 to 5, the sire component increased slightly towards the limit. With the REML procedure, changing the herd classification from fixed to random increased the sire component. The change was considerable in the herd × year model but only slight in the herd model. Increasing 2 from 0.1 to 20 decreased the sire component towards the limit with 2 = oo with both models. From the results in Table 5 it can be seen that for the small herd situation analysed, a random herd classification with a ratio of error to herd variance/l of 5-20, the most likely range of this parameter, yields similar heritabilities for dystocia, which therefore are regarded as useful estimates. If computing costs are of importance, even models without a herd classification could be used to estimate variance components with both estimation procedures. In the BW breed the univariate REML estimate of heritability from the fixed herd × year model (Table 5 ) was slightly smaller than the multivariate REML estimate from the same model (Table 4), 0.043 vs. 0.046.

As a result of the preceding analyses a variance ratio of/l--10 and the herd classification were used to estimate MAPP heritabilities for dystocia and stillbirth from the BR and SI data. For the comparison of MAPP and REML estimates, the latter (Table 5) were transformed to the supposed underlying normal scale (REMLT) by the formula of Robertson (1950) using the population means from Table 1.

h2n = h~, , p , ( 1 - p ) / z 2

where: h l = heritability on the normal scale; hE = heritability on the binomial scale;


z = height of the normal curve at the threshold point corresponding to the population frequency p.

Results are given in Table 6. The smallest values for both traits and with all procedures (MAPP, REML and REMLT) were found in the BR breed. For both traits and in all breeds, estimates from REMLT were somewhat larger than from MAPP. MAPP estimates were always substantially larger than REML estimates. The same ranking of MAPP and REMLT according to size of estimates was found by HSschele { 1986) in a simulation study.

The MAPP heritabilities for dystocia given in Table 6 are considerably larger than values from the same procedure reported by Karb and Karras (1988). They found heritabilities of 0.134, 0.098 and 0.090 for German Black and White, Braunvieh and Fleckvieh, respectively. In their investigation dystocia was defined in a different way as it contained three classes. Much smaller progeny groups, 114-141, and observations on heifers only were further differences from the present investigation. Gaillard { 1979) and Philipsson et al. (1979) reported larger {Henderson III) heritabilities on the discontinuous scale for dystocia when estimated from heifers compared with later parity cows. If the heritabilities found by Gaillard (1979) were transformed to the underlying normal scale the estimate from heifers was smaller than from later parity cows, 0.267 vs. 0.296. For stillbirth his transformed values were 0.142 and 0.114, respectively. The heritability for dystocia was close to the REMLT estimate for SI in Table 6. The transformed heritability for stillbirth was nearly twice the value found here.

For the ranking properties of the linear and the nonlinear method for esti- mating breeding values of categorical traits, only very small differences were found. The correlations between linear and nonlinear breeding values from the whole BW data set were 0.971 for dystocia and 0.990 for stillbirth. Meijering (1985), Djemali et al. {1987) and Weller et al. {1988) also found very high correlations between these types of breeding values for the two traits. Meijer-

TABLE 6

MAPP and transformed REML (REMLT) heritabilities for dystocia and stillbirth in the BW, BR and SI breeds 1

Breed Dystocia Stillbirth

MAPP REMLT MAPP REMLT

BW 0.273 0.317 0.080 0.105 BR 0.172 0.210 0.045 0.049 SI 0.268 0.295 0.057 0.069

1Untransformed REML estimates from Table 4. Population means used in transformation from Table 1. MAPP estimates (h~) from model with herds random and ~t= 10.


TABLE 7

Correlation between breeding values for dystocia and stillbirth in the BW breed, estimated from split daughter groups within the nonlinear and the linear procedure, herds random with )l = 10

Dystocia Stillbirth

MAPP 0.630 0.398 REML 0.649 0.409

ing ( 1985 ) and Djemali et al. (1987) observed that ranking differences in stillbirth occurred mostly around the mean and thus would not have influenced selection decisions. Djemali et al. (1987) observed further that the correlation between these two types of breeding values was slightly higher if herd X year × seasons were taken as random.

It was found by Dempfle and Hagger (1983) that the correlation between two breeding values of the same sire estimated by the same procedure from split daughter groups is a good criterion to rank procedures in view of the genetic gain achievable. This method was used to look at the repeatability of linear and nonlinear breeding values under the condition of the available BW data. The daughters of all BW sires were thus randomly split into two groups. With both procedures two breeding values for dystocia and stillbirth, two at a time, were estimated for all sires. The model described earlier, including a random herd effect and a variance ratio of ~-- 10 was used. The correlations between breeding values within procedures are summarized in Table 7. The correlation within the linear procedure (single trait) was slightly higher than within the nonlinear procedure. The correlations between breeding values for dystocia were substantially higher than for stillbirth. This is a consequence of the higher heritability found for this trait.

No clear preference for one of the two estimation procedures can be deduced from our results. The large offspring groups with an average of 398 daughters may partly be responsible for our findings. If computing costs are still the limiting factor, a linear procedure (REML, BLUP) might be preferable. HSschele (1986) pointed out that the superiority of the MAPP procedure increases with increasing heritability and a very high incidence (99%). She also discussed the higher computing costs of the nonlinear method. Meijering and Gianola (1985) in a simulation study, Meijering (1985) and Weller et al. (1988) in analyses of field data did not find the nonlinear evaluation procedure to be superior. Meijering and Gianola (1985) noted that in cases with smaller and more vari- able group sizes and particularly for binary traits the nonlinear procedure might be an advantage for sire evaluation.

ACKNOWLEDGEMENTS

We thank J. Chavaz from the Swiss AI organization for preparing the large data set and for helpful discussions, K. Meyer and I. Misztal for kindly provid-


ing c o m p u t e r p r o g r a m s , P ro f s . N . K i inz i a n d G. S t r a n z i n g e r for c o n t i n u o u s s u p p o r t a n d t h e a n o n y m o u s re fe rees for v e r y use fu l c o m m e n t s .

REFERENCES

Bar-Anan, R., 1973. Breeding aspects of difficult calving and calf progeny characters. Ph.D. The- sis, University of Reading.

Burfening, P.J., Kress, D.D., Friedrich, R.L. and Vaniman, D., 1978. Calving ease and growth rate of Simmental-sired calves. II. Genetic parameter estimates. J. Anim. Sci., 46: 930-936.

Dempfle, L. and Hagger, Ch., 1983. Comparison of the efficiency of BLUP with other estimation procedures in dairy sire evaluation. I. Theoretical investigations. Z. Tierz. Zuechtgsbiol., 100: 196-208.

Djemali, M., Berger, P.J. and Freeman, A.E., 1987. Ordered categorical sire evaluation for dystocia in Holsteins. J. Dairy Sci., 70: 2374-2384.

Gaillard, C., 1979. Populationsanalyse verschiedener Merkmale des Geburtsablaufes beim Sim- mentaler Fleckvieh. Diss. ETH, Nr. 6624, 112 pp.

Gianola, D. and Foulley, J.L., 1983a. New techniques of prediction of breeding values for discontinuous traits. 32nd Annual National Breeders Roundtable, 6 May, Saint-Louis, MO.

Gianola, D. and Foulley, J.L., 1983b. Sire evaluation for ordered categorical data with a threshold model. G~n~t. Sel. Evol., 15: 201-223.

Gilmour, A.R., 1983. The estimation of genetic parameters for categorical traits. Ph.D. Thesis, Massey University, New Zealand, 195 pp.

Harville, D.A. and Mee, R.W., 1984. A mixed-model procedure for analyzing ordered categorical data. Biometrics, 40: 393-408.

Henderson, C.R., 1973. Sire evaluation and genetic trends. In: Proceedings of the Animal Breeding and Genetics Symposium in Honor of J.L. Lush. ASAS and ADSA, Champaign, IL, 10-41.

HSschele, I., 1986. Estimation of breeding values and variance components with quasi-continuous data. Doctoral thesis, University of Hohenheim, 214 pp.

Karb, H. and Karras, K., 1988. Zuchtwertschiitzung auf Leichtkalbigkeit. Der Tierzuechter, 40: 102-103.

Martinez, M.L., Freeman, A.E. and Berger, P.J., 1983. Genetic relationship between calf livability and calving difficulty of Holsteins. J. Dairy Sci., 66: 1494-1502.

Meijering, A., 1985. Sire evaluation for calving traits by best linear unbiased prediction and nonlinear methodology. Z. Tierz. Zuechtgsbiol., 102: 95-105.

Meijering, A. and Gianola, D., 1985. Linear versus non-linear methods of sire evaluation for categorical traits: a simulation study. G~n~t. Sel. Evol., 17: 115-132.

Meyer, K., 1985. Maximum likelihood estimation of variance components for a multivariate mixed model with equal design matrices. Biometrics, 41: 153-165.

Meyer, K., 1986. Restricted maximum likelihood to estimate genetic parameters - - in practice. In: Proceedings of the Third World Congress on Genetics Applied to Livestock Production, University of Nebraska Lincoln, NB XII: 454-459.

Patterson, H.D. and Thompson, R., 1971. Recovery of inter-block information when block sizes are unequal. Biometrika, 58: 545-554.

Philipsson, J., Foulley, J.L., Lederer, J., Liboriussen, T. and Osinga, A., 1979. Sire evaluation standards and breeding strategies for limiting dystocia and stillbirth. Livest. Prod. Sci., 6: 11- 127.

Robertson, A., 1950. In: E.R. Dempster and I.M. Lerner (Editors), Heritability of Threshold Characters. Genetics, 35: 212-236.


Weller, J.I., Misztal, I. and Gianola, D., 1988. Genetic analysis of dystocia and calf mortality in Israeli-Holsteins by threshold and linear models. J. Dairy Sci., 71: 2491-2501.

RESUME

Hagger, C. et Hofer, A., 1990. Analyses g~n~tiques des caract~res de v~lage dans les races bovines suisses, Pie noire, Brune et Simmental, h l'aide des proc~d~s REML et MAPP. Livest. Prod. Sci., 24:93-107 (en anglais).

A l'aide du proc~i~ REML (maximum de vraisemblance restreinte) on a estim~ les effets et les param~tres g~nStiques et ph~notypiques, pour le poids ~ la naissance, la dur~e de gestation et les pourcentages de v~lages difficiles et de veaux mort-nSs. Le module utilis~ tient compte des effets suivants: troupeau X annie, saison de v~lage, sexe du veau, numSro de raise bas, groupe g~n~tique du p~re du veau et p~re du veau. Les observations ont ~t~ effectu~es sur les veaux de taureaux de testage des trois races bovines suisses, la Pie noire, la Brune et la Simmental, Le sexe du veau et le numSro de la mise bas de la m~re (premiere ou suivantes) ont exerc~ l'influence la plus impor- tante sur tous les caract~res analys~s, et cela dans toutes les races. Le groupe du p~re, ~tabli selon la proportion des g~nes Brown Swiss U.S. pour la Brune et Red Holstein pour la Simmental, a eu une influence de modSr~e ~ forte. L'h~ritabilit~ des pourcentages de v~lages difficiles et de veaux mort-n~s a ~t~ nettement plus faible chez la Brune que dans ies deux autres races. On a pu observer quelques differences entre races dans les corr$1ations g~n~tiques. Un module contenant un effet troupeau al~atoire avec un rapport de 5 ~ 20 entre l'erreur et la variance du troupeau, a permis d'obtenir des estimations utilisables de l'h~ritabilit~ pour le pourceut de v~lages difficiles, et cela aussi bien ~ l'aide des proc~<l~s MAPP (maximum de prgdiction a posteriori) que REML. Des correlations tr~s dlev~es (0.97-0.99) ont ~t~ trouv~es entre les valeurs gSn~tiques estimSes par les procSd~s lin~aires et non lin~aires pour les pourcentages de v~lages difficiles et de veaux mort-nSs. Pour ces deux caract~res, les corr$1ations entre les deux valeurs g~n~tiques d'un m~me taureau, estim~es sur la base des donnSes des filles r~parties alSatoirement en deux groupes, se sont av~r~es plus ~lev~es avec le procSd~ lin~aire qu'avec le proc~d$ non lin~aire.

KURZFASSING

Hagger, C. und Hofer, A., 1990. Genetische Untersuchung yon Abkalbemerkmalen beim schweizerischen Schwarzfleck-, Braun- und Simmentaler Fleckvieh mit REML und MAPP Yerfahren. Livest. Prod. Sci., 24:93-107 (auf englisch).

Mit einem REML Verfahren wurden fixe Einflilsse, genetische und phiinotypische Parameter fiir Geburtsgewicht, Triichtigkeitsdauer, den Anteil an Schwer- und an Totgeburten gesch~itzt. Im Modell wurden Herde X Jahr, Kalbesaison, Geschlecht des Kalbes, Nummer der Abkalbung der Kuh, genetische Gruppe des Vaters des Kalbes sowie der Vater des Kalbes beriicksichtigt. Die Beobachtungen stammten von K~lbern von Teststieren der drei schweizerischen Rinderrassen Schwarzfleckvieh, Braunvieh und Simmentaler Fleckvieh. Das Geschlecht des Kalbes und die Nummer der Abkalbung der Kuh (erste oder folgende ) hatten in allen Rassen den grSssten Ein- fiuss auf die untersuchten Merkmale. Auch die genetische Gruppe des Vaters, gebildet nach dem Anteil an US Brown Swiss Genen beim Braunvieh und nach dem Anteil an Red Holstein Genen bei den Simmentalern, beeinflussten die untersuchten Merkmale recht stark. Ffir den Anteil an Schwer- und an Totgeburten wurden beim Braunvieh wesentlich tiefere Heritabilitiiten als bei den andern beiden Rassen gefunden. Bei den genetischen Korrelationen konnten einige Rassen- unterschiede beobachtet werden. Die Verwendung eines zui'~lligen Herdeneffektes mit einem Ver- h~iltnis yon Fehler- zu Herdenvarianz zwischen 5 und 20 ergab sowohl mit dem MAPP- wie auch


mit dem REML-Verfahren brauchbare Sch~itzwerte ftir die Heritabili~t des Anteils an Schwer- geburten. Zwischen den mit der linearen und den mit der nichtlinearen Methode gesch~itzten Zuchtwerten fur den Anteil an Schwer- und an Totgeburten wurden sehr hohe Korrelationen von 0.97 und 0.99 gefunden. Die Korrelation zwischen den zwei Zuchtwerten eines Stieres, die nach einer zuf~lligen Aufteilung der T6chter in zwei Gruppen geschiitzt wurden, waren fiir den Anteil an Schwer- und an Totgeburten innerhalb des linearen Verfahrens leicht hSher als innerhalb des nichtlinearen Verfahrens.

genetic analyses of calving traits in the swiss black and white, braunvieh and simmental breeds by...

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