A field trial of production and financial consequences of helminthosis control in sheep production in Ethiopia.

We used a partial-budget analysis to evaluate profitability of different management strategies of three genotypes of sheep in a 2 x 2 x 3 factorial experiment conducted at Debre Berhan research station in the central highlands of Ethiopia. This involved two anthelmintic-treatment levels (treated vs. non-treated), two supplementary nutrition levels (protein-energy supplementation yes/no) and three genotypes: indigenous Menz (n=40), 50% Awassi x 50% Menz crosses (n=38) and 75% Awassi x 25% Menz crosses (n=31). All sheep were exposed to natural sub-clinical helminthosis challenge. Supplemented sheep were offered a concentrate mix daily on an individual basis. Anthelmintic-treated sheep were drenched with fenbendazole against nematodes and with triclabendazole against trematodes. Data were collected during the experimental period (for 10 months from approximately 1 year of age) on feed intake, live weight, eggs per gram (EPG) of faeces, packed-cell volume (PCV), wool weight, and adult-worm burden. Actual market input and output prices were recorded. Supplemented sheep had significantly higher marginal profit (MP) per sheep than non-supplemented sheep (ETB 33 vs. 4). Likewise, anthelmintic treated sheep performed significantly better than their non-treated contemporaries (MP=ETB 28 vs. 8). The 75% Awassi crosses were least profitable.

Genetic relationships of lamb weight, maternal ability, and mature ewe weight in Swedish finewool sheep.

Genetic parameters were estimated for weights of lambs from birth to 1 d before slaughter and mature ewe weight (EMW) using REML procedures and single- and two-trait animal models. The data consisted of weight registrations from 5,001 animals descended from 131 sires, 788 dams, 48 maternal grandsires, and 530 maternal granddams in an experimental flock with Swedish finewool sheep. Direct heritabilities increased with lamb age from .07 for birth weight to .21 for weight before slaughter. Maternal heritabilities declined with age from .30 to .07. Direct-maternal genetic correlations were positive and increased with age from .11 for birth weight to .73 for weight before slaughter. For daily gain during shorter periods, direct heritability increased from .07 for the period from birth until 3 wk of age to .14 for the period from weaning until 1 d before slaughter. The values for maternal heritabilities were .16 and .03, respectively. The direct-maternal genetic correlations ranged from -.11 to .59. The direct heritability for EMW varied between analyses from .29 to .63. A nonsignificant maternal heritability of .22 was noted for EMW. Direct genetic correlations between EMW and various lamb weights varied between .36 to .85. Genetic correlations between direct effects on EMW and maternal effects on lamb weights varied between .39 and .53. Direct and maternal genetic correlations between the lamb weights were positive. The results showed that the maternal influence on lamb weights decreased with age. It was indicated that positive genetic relationships exist between ewe weight and maternal effects on lamb weight. Therefore, selection for larger lamb weights alone will not only increase ewe weights but also improve the maternal ability to the ewe.

Genetic relationships between calving and carcass traits for Charolais and Hereford cattle in Sweden.

The objective of this study was to estimate genetic correlations between calving difficulty score and carcass traits in Charolais and Hereford cattle, treating first and later parity calvings as different traits. Genetic correlations between birth weight and carcass traits were also estimated. Field data on 59,182 Charolais and 27,051 Hereford calvings, and carcass traits of 5,260 Charolais and 1,232 Hereford bulls, were used in bivariate linear animal model analyses. Estimated heritabilities were moderate to high (0.22 to 0.50) for direct effects on birth weight, carcass weight, and (S)EUROP (European Community scale for carcass classification) grades for carcass fleshiness and fatness. Heritabilities of 0.07 to 0.18 were estimated for maternal effect on birth weight, and for direct and maternal effects on calving difficulty score at first parity. Lower heritabilities (0.01 to 0.05) were estimated for calving difficulty score at later parities. Carcass weight was positively genetically correlated (0.11 to 0.53) with both direct and maternal effects on birth weight and with direct effects on calving difficulty score. Carcass weight was, however, weakly or negatively (-0.70 to 0.07) correlated with maternal calving difficulty score. Higher carcass fatness grade was genetically associated with lower birth weight, and in most cases, also with less difficult calving. Genetic correlations with carcass fleshiness grade were highly variable. Moderately unfavorable correlations between carcass fleshiness grade and maternal calving difficulty score at first parity were estimated for both Charolais (0.42) and Hereford (0.54). This study found certain antagonistic genetic relationships between calving performance and carcass traits for both Charolais and Hereford cattle. Both direct and maternal calving performance, as well as carcass traits, should be included in the breeding goal and selected for in beef breeds.

Bayesian analysis of birth weight and litter size in Baluchi sheep using Gibbs sampling.

Variance and covariance components for birth weight (BWT), as a lamb trait, and litter size measured on ewes in the first, second, and third parities (LS1 through LS3) were estimated using a Bayesian application of the Gibbs sampler. Data came from Baluchi sheep born between 1966 and 1989 at the Abbasabad sheep breeding station, located northeast of Mashhad, Iran. There were 10,406 records of BWT recorded for all ewe lambs and for ram lambs that later became sires or maternal grandsires. All lambs that later became dams had records of LS1 through LS3. Separate bivariate analyses were done for each combination of BWT and one of the three variables LS1 through LS3. The Gibbs sampler with data augmentation was used to draw samples from the marginal posterior distribution for sire, maternal grandsire, and residual variances and the covariance between the sire and maternal grandsire for BWT, variances for the sire and residual variances for the litter size traits, and the covariances between sire effects for different trait combinations, sire and maternal grandsire effects for different combinations of BWT and LS1 through LS3, and the residual covariations between traits. Although most of the densities of estimates were slightly skewed, they seemed to fit the normal distribution well, because the mean, mode, and median were similar. Direct and maternal heritabilities for BWT were relatively high with marginal posterior modes of .14 and .13, respectively. The average of the three direct-maternal genetic correlation estimates for BWT was low, .10, but had a high standard deviation. Heritability increased from LS1 to LS3 and was relatively high, .29 to .37. Direct genetic correlations between BWT and LS1 and between BWT and LS3 were negative, -.32 and -.43, respectively. Otherwise, the same correlation between BWT and LS2 was positive and low, .06. Genetic correlations between maternal effects for BWT and direct effects for LS1 through LS3 were all highly negative and consistent for all parities, circa -.75. Environmental correlations between BWT and LS1 through LS3 were relatively low and ranged from .18 to .29 and had high standard errors.

Long-term study of Toxoplasma gondii infection in a Swedish sheep flock.

The infection rate of Toxoplasma gondii was studied during 6 years in a sheep flock in central Sweden. The flock consisted of 165-249 breeding ewes of which 20-35% were lambs less than 1 year old. Most ewes were slaughtered when 5 years old. The sheep were kept indoors from end of September to early May. Lambing took place in March and April. Individual serum samples were collected twice a year, once just before turning the sheep out to pasture in the spring and again after housing in the autumn. Sera were analysed by ELISA for antibodies to T. gondii. The seroprevalence varied between 10% and 45% during the 6 years of observation. Seroconversion was detected predominantly at the autumn sampling, indicating that in most cases infection was acquired at pasture. Subclinical effects of T. gondii infection on lamb weight, litter size, total litter weight and ewe weight were also studied. Lambs born to chronically infected ewes were lighter at birth than those of uninfected ewes, but this disparity was no longer evident at weaning.

Genetic relationships between carcass cut weights predicted from video image analysis and other performance traits in cattle.

The objective of this study was to quantify the genetic associations between a range of carcass-related traits including wholesale cut weights predicted from video image analysis (VIA) technology, and a range of pre-slaughter performance traits in commercial Irish cattle. Predicted carcass cut weights comprised of cut weights based on retail value: lower value cuts (LVC), medium value cuts (MVC), high value cuts (HVC) and very high value cuts (VHVC), as well as total meat, fat and bone weights. Four main sources of data were used in the genetic analyses: price data of live animals collected from livestock auctions, live-weight data and linear type collected from both commercial and pedigree farms as well as from livestock auctions and weanling quality recorded on-farm. Heritability of carcass cut weights ranged from 0.21 to 0.39. Genetic correlations between the cut traits and the other performance traits were estimated using a series of bivariate sire linear mixed models where carcass cut weights were phenotypically adjusted to a constant carcass weight. Strongest positive genetic correlations were obtained between predicted carcass cut weights and carcass value (min r g(MVC) = 0.35; max r(g(VHVC)) = 0.69), and animal price at both weaning (min r(g(MVC)) = 0.37; max r(g(VHVC)) = 0.66) and post weaning (min r(g(MVC)) = 0.50; max r(g(VHVC)) = 0.67). Moderate genetic correlations were obtained between carcass cut weights and calf price (min r g(HVC) = 0.34; max r g(LVC) = 0.45), weanling quality (min r(g(MVC)) = 0.12; max r (g(VHVC)) = 0.49), linear scores for muscularity at both weaning (hindquarter development: min r(g(MVC)) = -0.06; max r(g(VHVC)) = 0.46), post weaning (hindquarter development: min r(g(MVC)) = 0.23; max r(g(VHVC)) = 0.44). The genetic correlations between total meat weight were consistent with those observed with the predicted wholesale cut weights. Total fat and total bone weights were generally negatively correlated with carcass value, auction prices and weanling quality. Total bone weight was, however, positively correlated with skeletal scores at weaning and post weaning. These results indicate that some traits collected early in life are moderate-to-strongly correlated with carcass cut weights predicted from VIA technology. This information can be used to improve the accuracy of selection for carcass cut weights in national genetic evaluations.

Equine hospital data as a source for study of prevalence and heritability of osteochondrosis and palmar/plantar osseous fragments of Swedish Warmblood horses.

REASONS FOR PERFORMING STUDY: Disturbances in skeletal development, primarily osteochondrosis (OC) and palmar/plantar osseous fragments (POF), have been commonly reported as problems in young horses. However, there are few reports of such findings for epidemiological analyses or breeding purposes. OBJECTIVES: To evaluate equine hospital data as a possible source of information for genetic evaluations by estimating prevalence and heritability of OC in the stifle, hock and fetlock joints and of POF in the fetlock. METHODS: Data on Swedish Warmblood (SWB) horses were obtained from a large equine hospital in south Sweden. Prevalences were based on radiographic examinations of 879 screened horses, mainly evaluated as part of a prepurchase examination and 3639 horses with a reported history of orthopaedic problems. For the heritability study the 2 data sources were pooled and 3199 examined horses with pedigree information were considered for the linear animal model analyses. RESULTS: The overall prevalence of OC was 13% (stifle 9%, hock 6% and dorsal osseous fragments in fetlock [DOF] 10%) and POF 10%. The overall heritability of OC was 0.05 on the visible binomial scale. The corresponding heritabilities for OC in the stifle were 0.03, hock 0.08, DOF 0.10 and POF 0.13. These values correspond to heritabilities of 0.09-0.38 on the underlying quantitative scale. CONCLUSIONS AND POTENTIAL RELEVANCE: Obtained prevalences and heritabilities were in accordance with other studies, supporting the hypothesis that data regularly obtained from equine hospitals may be a valuable source in studies of inherited disorders such as OC and POF. There is a need for more standardised documentation of diagnoses and consistent recording of identity of examined horses using passports or breed databases. Compilation of results from major clinics is desired in order to cover most progenies of stallions used in a region or nation.

Genetic variation in wholesale carcass cuts predicted from digital images in cattle.

The objective of this study was to quantify the genetic variation in carcass cuts predicted using digital image analysis in commercial cross-bred cattle. The data set comprised 38,404 steers and 14,318 heifers from commercial Irish herds. The traits investigated included the weights of lower value cuts (LVC), medium value cuts (MVC), high value cuts (HVC), very high value cuts (VHVC) and total meat weight. In addition, the weights of total fat and total bones were available on the steers. Heritability of carcass cut weights, within gender, was estimated using an animal linear model, whereas genetic and phenotypic correlations among cuts were estimated using a sire linear model. Carcass weight was included as a covariate in all models. In the steers, heritability ranged from 0.13 (s.e. = 0.02) for VHVC to 0.49 (s.e. = 0.03) for total bone weight, and in the heifers heritability ranged from 0.15 (s.e. = 0.04) for MVC to 0.72 (s.e. = 0.06) for total meat weight. The coefficient of genetic variation for the different cuts varied from 1.4% to 3.6%. Genetic correlations between the different cut weights were all positive and ranged from 0.45 (s.e. = 0.08) to 0.89 (s.e. = 0.03) in the steers, and from 0.47 (s.e. = 0.14) to 0.82 (s.e. = 0.06) in the heifers. Genetic correlations between the wholesale cut weights and carcass conformation ranged from 0.32 (s.e. = 0.06) to 0.45 (s.e. = 0.07) in the steers, and from 0.10 (s.e. = 0.12) to 0.38 (s.e. = 0.09) in the heifers. Genetic correlations between the same wholesale cut traits in steers and heifers ranged from 0.54 (s.e. = 0.14) for MVC to 0.79 (s.e. = 0.06) for total meat weight; genetic correlations between carcass weight and carcass classification for conformation and fat score in both genders varied from 0.80 to 0.87. The existence of genetic variation in carcass cut traits, coupled with the routine availability of predicted cut weights from digital image analysis, clearly shows the potential to genetically improve carcass value.

Effects of long-time series of data on genetic evaluations for performance of Swedish Warmblood riding horses.

For Swedish Warmblood sport horses, breeding values (BVs) are predicted using a multiple-trait animal model with results from competitions and young horse performance tests. Data go back to the beginning of the 1970s, and earlier studies have indicated that some of the recorded traits have changed through the years. The objective of this study was to investigate the effects of including all performance data or excluding the older ones compared to a bivariate model (BM) considering performance traits in early and late periods as separate traits. The bivariate approach was assumed to give the most correct BVs for the actual breeding population. Competition results in dressage and show jumping for almost 40 000 horses until 2006 were available. For riding horse quality test (RHQT), data of 14 000 horses judged between 1973 and 2007 were used. Genetic correlations of 0.69 to 1.00 were estimated between traits recorded at different time periods (RHQT data) or different birth year groups (competition data). A cross-validation study and comparison of BVs using different sets of data showed that most accurate and similar results were obtained when BVs were predicted from either the BM or the univariate model including all data from the beginning of the recording. We recommend using all data and applying the univariate model to minimise the computational efforts for genetic evaluations and for provision of reliable BVs for as many horses as possible.

Genetic variation in competition traits at different ages and time periods and correlations with traits at field tests of 4-year-old Swedish Warmblood horses.

For many years, the breeding value estimation for Swedish riding horses has been based on results from Riding Horse Quality Tests (RHQTs) of 4-year-olds only. Traits tested are conformation, gaits and jumping ability. An integrated index including competition results is under development to both get as reliable proofs as possible and increases the credibility of the indexes among breeders, trainers and riders. The objectives of this study were to investigate the suitability of competition data for use in genetic evaluations of horses and to examine how well young horse performance agrees with performance later in life. Competition results in dressage and show jumping for almost 40 000 horses from the beginning of the 1960s until 2006 were available. For RHQT data of 14 000 horses judged between 1988 and 2007 were used. Genetic parameters were estimated for accumulated competition results defined for different age groups (4 to 6 years of age, 4 to 9 years of age and lifetime), and for different birth year groups. Genetic correlations were estimated between results at RHQT and competitions with a multi-trait animal model. Heritabilities were higher for show jumping than dressage and increased with increasing age of the horse and amount of information. For dressage, heritabilities increased from 0.11 for the youngest group to 0.16 for lifetime results. For show jumping corresponding values increased from 0.24 to 0.28. Genetic correlations between competition results for the different age groups were highly positive (0.84 to 1.00), as were those between jumping traits at RHQT and competition results in show jumping (0.87 to 0.89). For dressage-related traits as 4-year-old and dressage competition results the estimated genetic correlations were between 0.47 and 0.77. We suggest that lifetime results from competitions should be integrated into the genetic evaluation system. However, genetic parameters showed that traits had changed during the over 35-year period covered due to the development of the sport, which needs to be considered in future genetic evaluations.

Genetic parameters for carcass cut weight in Irish beef cattle.

The objective of this study was to estimate genetic parameters for the weights of different wholesale cuts, using an experimental and a commercial data set. The experimental and commercial data sets included 413 and 635 crossbred Belgian Blue, Charolais, Limousin, Angus, Holstein, and Simmental animals, respectively. Univariate analyses using a mixed linear animal model with relationships were undertaken to estimate the heritability of cold carcass weight, carcass conformation and fat, and the cut weights, whereas a series of bivariate analyses was used to estimate the phenotypic and genetic correlations between carcass weight, carcass conformation, carcass fat, and the major primal cuts. Heritability estimates for cold carcass weight in both data sets were moderate (>0.48), whereas heritability estimates for carcass conformation and fat grading were greater in the commercial data set (>0.63) than in the experimental study (>0.33). Across both data sets, heritability estimates for wholesale cut weight in the forequarter varied from 0.03 to 0.79, whereas heritability estimates of carcass cut weight in the hindquarter varied from 0.14 to 0.86. Heritability estimates for cut weights expressed as a proportion of the entire carcass weight varied from 0.04 to 0.91. Genetic correlations were strong among the different carcass cut weights within the experimental and the commercial studies. Genetic correlations between the weights of selected carcass cuts and carcass weight were moderate to high (minimum 0.45; maximum 0.88) in both data sets. Positive genetic correlations were observed in the commercial data set between the different wholesale cut weights and carcass conformation, whereas these were positive and negative in the experimental data set. Selection for increased carcass weight will, on average, increase the weight of each cut. However, the genetic correlations were less than unity, suggesting a benefit of more direct selection on high value cuts.

Genetic parameters for traits evaluated at field tests of 3- and 4-year-old Swedish Warmblood horses.

There are two types of 1-day field tests available for young Swedish Warmblood sport horses; one test for 3-year olds and one more advanced test for 4-year olds. Conformation, gaits and jumping ability are evaluated at both tests. Studies on various genetic parameters were based on about 20 000 tested horses. The data for 4-year olds consisted of 30 years of testing. The aims of the study were to estimate genetic parameters for results from different time periods, and to estimate heritabilities for, and genetic correlations between, traits scored in the two tests. The judgement of traits was shown to have been changed during the 30 years of testing, resulting in changes in higher heritabilities in, and stronger genetic correlations between, later time periods. In the first time period, records showed higher residual and lower genetic variances than in the subsequent time periods. Genetic correlations between traits recorded in the first and last time period deviated considerably from unity. Further studies are needed to investigate how to treat data from the early period in genetic evaluations. Heritabilities were moderate to high for conformation traits (0.24 to 0.58) at both types of tests, except for correctness of legs (0.08). The heritabilities for gait traits were also moderate to high (0.37 to 0.53). For jumping traits, the heritabilities ranged between 0.17 and 0.33. The highly positive genetic correlations (0.82 to 0.99) between corresponding traits tested at the simpler test for 3-year olds and at the ridden test of 4-year olds implied that it would be desirable to include the test results of 3-year olds into the genetic evaluation as breeding values for Swedish Warmbloods for many years has only been based on results from 4-year olds.

Population parameters for birth and ewe fleece weight at different parities in Baluchi sheep.

UNLABELLED: ZUSAMMENFASSUNG: Populationsparameter für Geburts- und Vließgewicht von Baluchi Schafen Das Datenmarterial stammt von zwei Herden einer Schafzuchtstation in NO Iran aus den Jahren 1966-1989. Die Tiere waren unselektiert und stammten aus zufällig verteilten Paarungen. Es wurden Geburtsgewicht und Vließgewicht bei verschiedenen Altersstufen erhoben und Varianzkomponenten mittels Restringierter Maximaler Likelihood mit einem bivariaten Tiermodell mit fixen Wirkungen von Jahr, Geschlecht, Geburtstyp und Parität sowie Zufallswirkungen für additiven Genotyp des Lammes (direkt) und des Mutterschafes (maternal), gemeinsamer Umwelt (ausgenommen Vließgewicht) und Resteinfluß geschätzt. Direkte und maternale genetische Korrelationen zwischen Leistungen verschiedener Paritäten wurden berechnet. In Herde 1 scheinen Varianzen und Heritabilitätswerte für Lammgewicht bis Parität 5 zuzunehmen, kaum aber in Herde 2. Die durchschnittlichen Heritabilitätswerte, direkt, maternal und gesamt waren 0.12, 0.11 und 0.26, die genetische Korrelation zwischen direkten und maternalen Wirkungen 0.42. Bei Vließgewicht waren in Herde 1 keine Veränderungen der Varianzen und Heritabilitätswerte mit Alter zu erkennen, aber bei Herde 2 nahmen phänotypische und Umweltvarianz mit Alter leicht zu. Durchschnittliche direkte, maternale und Gesamtheritabilität waren 0.19, 0.04 und 0.22, die genetische Korrelation zwischen direkten und maternalen Wirkungen geringgradig positiv in Herde 1, aber mit Alter zunehmend negativ in Herde 2. Die genetischen Korrelationen für direkte Wirkungen auf Geburtsgewicht waren hoch zwischen Paritäten 1 bis 5, aber niedriger bei Parität 6 und jene zwischen maternal bedingten Wirkungen zeigten ähnliche Trends. In Herde 2 waren Werte mit Parität 6 ähnlich wie die zwischen den übrigen Paritäten. Die die Vließgewichte betreffenden direkt genetischen Korrelationen zwischen Paritäten waren in beiden Herden ähnlich (0.73-0.92), jene, die maternale Wirkungen betreffen, deutlich geringer, besonders soweit sie Paritäten 5 und 6 betroffen haben und zeigten besonders bei Herde 2 starke Schwankungen (-0.54 bis 0.74). SUMMARY: Direct and maternal performance of ewes at different parities were examined in Baluchi sheep. The data set was collected during the period 1966-1989 from two flocks at a sheep breeding station in the north-east of Iran. The animals included in the data set were unselected and randomly mated. The traits analysed were birth weight of lamb and fleece weight at different parities of the ewe. Variance components were estimated using Restricted Maximum Likelihood with a bivariate animal model including fixed effects of year, sex, type of birth and parity, and random effects of additive genotype of lamb (direct genetic effect), additive genotype of ewe (maternal genetic effect) and common environment (excluded for ewe fleece weight), and random residual effect. Direct and maternal genetic correlations between different parities were estimated. There was evidence of increasing phenotypic and genetic variances and heritabilities from parity 5 for birth weight of lamb in flock 1, but only evidence of a slightly increasing age trend for the environmental and phenotypic variance in flock 2. The average heritabilities over flocks and parities were 0.12, 0.11 and 0.26 for the direct, maternal and total heritability, respectively, while the average genetic correlation between direct and maternal effects for this trait was 0.42. There were no indications of any age changes in variances or heritabilities for ewe fleece weight in flock 1, but indications of slightly increasing age trends for the environmental and phenotypic variance. The average heritabilities over flocks and parities were 0.19, 0.04 and 0.22 for the direct, maternal and total heritability, respectively, while the average genetic correlation between direct and maternal effects was slightly positive in flock 1 but increasingly negative with age of the ewe in flock 2. Direct genetic correlations between parities 1-5 were very high for birth weight of lambs (on average 0.96) in contrast to the markedly lower correlations of parities 1-5 with parity 6 (on average 0.67) in flock 1 with a similar pattern for the maternal genetic correlations. In flock 2, these correlations were also high but without the marked decrease between parities 1-5 with parity 6 that was found in flock 1. Direct genetic correlations between the various parities for ewe fleece weight were similar for the two flocks, ranging from 0.73 to 0.92 and without any obvious differences between the various combinations of parities. However, the maternal were markedly lower than the direct genetic correlations, especially for the combinations of parity 5 and 6 with the earlier parities, and most pronounced in flock 2 fluctuating from -0.54 to 0.79. To obtain reliable estimates of breeding values for birth weight of lamb, it is recommended that the prediction should include not only earlier but also later parities (ages) of the ewe.

Genetic effects on stillbirth and calving difficulty in Swedish Holsteins at first and second calving.

In Swedish Holstein dairy cattle, genetic effects on stillbirth and calving difficulty were studied in 411,409 first- and 281,193 second-calvers. A linear single-trait sire-maternal grandsire model and a threshold model using a Gibbs sampling technique were used to analyse calving data from 1985 to 1996. In first calving when using the linear model, the heritability of stillbirth on the visible scale was 4% for the direct effect and 3% for the maternal effect. For calving difficulty it was 6% and 5% for direct and maternal effects, respectively. In second calving the corresponding heritabilities for the two traits were considerably lower, less than 1%. Adjusting for calving difficulty in linear analysis of stillbirth halved the heritabilities for the direct and maternal effects in first calving. When using a threshold model, heritabilities for stillbirth in first-calvers were 12% and 8% for direct and maternal effects, respectively, and for calving difficulty they were 17% and 12%. At second calving corresponding heritabilities were 2 to 4% for stillbirth and 4 to 7% for calving difficulty. The correlation between direct and maternal effects was around -0.1, irrespective of whether the linear or the threshold model was used for first-calvers. The genetic correlations between bulls' EBV from first and second calving were 0.4 to 0.5 for direct and maternal effects in stillbirth, whereas they were 0.6 to 0.7 for calving difficulty. In first-calvers there was a substantial genetic variation in both traits, expressed by differences between breeding values of bulls, despite fairly low heritability. The results obtained in this study suggest that first-parity records should preferably be used for genetic evaluation of bulls for calving performance. In such routine evaluations both stillbirth and calving difficulty, and both direct and maternal effects, should be included.