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1.
The aim of this study was to estimate direct and maternal genetic parameters for calving difficulty score, stillbirth, and birth weight at first and later parities for Charolais and Hereford cattle in Sweden. Calving traits have long been recorded for pure-bred beef cattle in Sweden, but only birth weight has been used in the selection in order to avoid calving difficulties. Linear animal model analyses included records on birth weight for 60,309 Charolais and 30,789 Hereford calves born from 1980 to 1999, and calving traits for 74,538 Charolais and 37,077 Hereford calves born from 1980 to 2001. The frequencies of difficult calvings and stillbirths were approximately 6% at first and 1 to 2% at later parities for both breeds. Fewer than half the stillborn calves were born from difficult calvings. Heritabilities estimated for birth weight in different univariate and bivariate analyses for Charolais and Hereford calves born at first and later parities ranged from 0.44 to 0.51 for direct effects and 0.06 to 0.15 for maternal effects. Heritabilities on the observable scale for calving difficulty score of Charolais and Hereford, scored in three classes, ranged from 0.11 to 0.16 for direct and 0.07 to 0.12 for maternal effects at first parity, and lower at later parities. All estimated heritabilities for stillbirth were very low (0.002 to 0.016 on the observable scale). Direct-maternal genetic correlations were negative, with few exceptions. Genetic correlations between the traits and between parities within traits were generally moderate to high and positive. Calving difficulty score should be included in the genetic evaluation of beef breeds in Sweden, whereas progeny groups in Swedish beef populations are too small for stillbirth to be considered directly.  相似文献   

2.
Estimates of heritabilities and genetic correlations were obtained for weaning weight records of 23,681 crossbred steers and heifers and carcass records from 4,094 crossbred steers using animal models. Carcass traits included hot carcass weight; retail product percentage; fat percentage; bone percentage; ribeye area; adjusted fat thickness; marbling score, Warner-Bratzler shear force and kidney, pelvic and heart fat percentage. Weaning weight was modeled with fixed effects of age of dam, sex, breed combination, and birth year, with calendar birth day as a covariate and random direct and maternal genetic and maternal permanent environmental effects. The models for carcass traits included fixed effects of age of dam, line, and birth year, with covariates for weaning and slaughter ages and random direct and maternal effects. Direct and maternal heritabilities for weaning weight were 0.4 +/- 0.02 and 0.19 +/- 0.02, respectively. The estimate of direct-maternal genetic correlation for weaning weight was negative (-0.18 +/- 0.08). Heritabilities for carcass traits of steers were moderate to high (0.34 to 0.60). Estimates of genetic correlations between direct genetic effects for weaning weight and carcass traits were small except with hot carcass weight (0.70), ribeye area (0.29), and adjusted fat thickness (0.26). The largest estimates of genetic correlations between maternal genetic effects for weaning weight and direct genetic effects for carcass traits were found for hot carcass weight (0.61), retail product percentage (-0.33), fat percentage (0.33), ribeye area (0.29), marbling score (0.28) and adjusted fat thickness (0.25), indicating that maternal effects for weaning weight may be correlated with genotype for propensity to fatten in steers.  相似文献   

3.
Heritability of 2-yr-old heifer calving difficulty score was estimated in nine purebred and three composite populations with a total of 5,986 calving difficulty scores from 520 sires and 388 maternal grandsires. Estimates were 0.43 for direct (calf) genetic effects and 0.23 for maternal (heifer) genetic effects. The correlation between direct and maternal effects was -0.26. Direct effects were strongly positively correlated with birth weight and moderately correlated with 200-d weight and postweaning gain. Smaller negative correlations of maternal calving difficulty with direct effects of birth weight, weaning weight, and postweaning gain were estimated. Calving difficulty was scored from 1 to 7. Predicted heritabilities using seven optimal scores were similar to those using four scores. The predicted heritability using only two categories was reduced 23%. Phenotypic and direct genetic variance increased with increasing average population calving difficulty score. The estimated direct and maternal heritabilities for 2-yr-old calving difficulty score were larger than many literature estimates. These estimates suggested substantial variance for direct and maternal genetic effects. The direct effects of 2-yr-old calving difficulty score seemed to be much more closely tied to birth weight than were maternal effects.  相似文献   

4.
The aim of the present investigation was to study the genetic relationships between pelt quality traits (shade of fleece, size of curl, score for fleece colour, score for curl, score for quality of hair, score for thickness of fleece, sum of pelt scores, and overall score) on one hand and maternal ability, live weight, and carcass traits on the other hand for the Gotland sheep breed. Data were received from the Swedish Sheep Recording Scheme and included observations on 4-month weight (4MW) and pelt quality for 51,402 lambs and on weight (CW), fatness (FAT), and fleshiness (FLESH) of the carcass for 12,440 lambs. The lambs were born during the period 1991–2003. When maternal genetic and permanent environmental effects were included in the model direct heritabilities for the pelt quality traits varied between 0.16 and 0.25. Maternal heritabilities (0.01 to 0.05) and common environmental variances as a fraction of the total phenotypic variances (0.07 to 0.10) were low. Maternal heritabilities were higher for 4MW (0.11) and CW (0.12) than for the pelt quality traits. Direct-maternal genetic correlations were both for the pelt quality traits and for 4MW and CW generally negative and low to medium high. Direct genetic correlations between pelt quality traits on one hand and 4MW, CW, FAT or FLESH on the other hand were low (− 0.16 to 0.12). Maternal genetic correlations between pelt quality traits and 4MW or CW were positive and high (0.38 to 0.96). It was concluded that breeding for increased growth and improved carcass quality would not influence pelt quality negatively or vice versa. If maternal genetic effects are considered for 4MW and CW in the breeding program for the Gotland sheep breed, selection for maternal effects on 4MW and CW will have positive effects both on lamb weight and pelt quality.  相似文献   

5.
The first objective of this study was to test the ability of systems of weighing and classifying bovine carcasses used in commercial abattoirs in Ireland to provide information that can be used for the purposes of genetic evaluation of carcass weight, carcass fatness class, and carcass conformation class. Secondly, the study aimed to test whether genetic and phenotypic variances differed by breed of sire. Variance components for carcass traits were estimated for crosses between dairy cows and 8 breeds of sire commonly found in the Irish cattle population. These 8 breeds were Aberdeen Angus, Belgian Blue, Charolais, Friesian, Hereford, Holstein, Limousin, and Simmental. A multivariate animal model was used to estimate genetic parameters within the Holstein sire breed group. Univariate analyses were used to estimate variance components for the remaining 7 sire breed groups. Multivariate sire models were used to formally test differences in genetic variances in sire breed groups. Field data on 64,443 animals, which were slaughtered in commercial abattoirs between the ages of 300 and 875 d, were analyzed in 8 analyses. Carcass fat class and carcass conformation class were measured using the European Union beef carcass classification system (EUROP) scale. For all 3 traits, the sire breed group with the greatest genetic variance had a value of more than 8 times the sire breed group with least genetic variance. Heritabilities ranged from zero to moderate for carcass fatness class (0.00 to 0.40), from low to moderate for carcass conformation class (0.04 to 0.36), and from low to high for carcass weight (0.06 to 0.65). Carcass weight was the most heritable (0.26) of the 3 traits. Carcass conformation class and carcass fatness class were equally heritable (0.17). Genetic and phenotypic correlations were all positive in the Holstein sire breed group. The genetic correlations varied from 0.11 for the relationship between carcass weight and carcass fatness class to 0.44 for the relationship between carcass conformation class and carcass fatness class. Carcass weight and classification data collected in Irish abattoirs are useful for the purposes of genetic evaluation for beef traits of Irish cattle. There were significantly different variance components across the sire breed groups.  相似文献   

6.
The aim of the study was to obtain estimates of genetic correlations between direct and maternal calving performance of heifers and cows and beef production traits in Piemontese cattle. Beef production traits were daily gain, live fleshiness, and bone thinness measured on 1,602 young bulls tested at a central station. Live fleshiness (six traits) and bone thinness were subjectively scored by classifiers using a nine-point linear grid. Data on calving performance were calving difficulty scores (five classes from unassisted to embryotomy) routinely recorded in the farms. Calving performance of heifers and cows were considered different traits. A total of 30,763 and 80,474 calving scores in first and later parities, respectively, were used to estimate covariance components with beef traits. Data were analyzed using bivariate linear animal models, including direct genetic effects for calving performance and beef traits and maternal genetic effects only for calving performance. Due to the nature of the data structure, which involved traits measured in different environments and on different animals, covariances were estimated mostly through pedigree information. Genetic correlations of daily gain were positive with direct calving performance (0.43 in heifers and 0.50 in cows) and negative with maternal calving performance (-0.23 and -0.28 for heifers and cows, respectively). Live fleshiness traits were moderately correlated with maternal calving performance in both parities, ranging from 0.06 to 0.33. Correlations between live fleshiness traits and direct calving performance were low to moderate and positive in the first parity, but trivial in later parities. Bone thinness was negatively correlated with direct calving performance (-0.17 and -0.38 in heifers and cows, respectively), but it was positively correlated to maternal calving performance (0.31 and 0.40). Estimated residual correlations were close to zero. Results indicate that, due to the existence of antagonistic relationships between the investigated traits, specific selection strategies need to be studied.  相似文献   

7.
Data from a two-breed group diallel experiment involving double-muscled (DM) and normal (N) cattle were analyzed to evaluate the importance of heterosis, maternal and direct effects for reproduction and growth traits. The DM cattle were from a composite of primarily Angus, Charolais, Galloway and Hereford breeds, and N cattle were crossbred cattle with at least 50% Hereford breeding. The data comprised a total of 491 matings and 389 calvings in four breeding seasons. Records on calving performance, calving date, calf crop born and weaned, sex ratio of progeny and weight of calves were analyzed using least squares procedures. Significant heterosis of 5 to 12% was observed for all the calf crop and growth traits, except for birth weight. Heterosis resulted in 24% reduction in the incidence of dystocia and perinatal calf mortality (P less than .05). The significant heterosis was due mainly to poor production in DM X DM crosses. The DM cows were superior (P less than .05) to N cows in reciprocal crossing (maternal effect) for all the calf crop traits, but had higher incidence of calving difficulty and a higher proportion of male progeny. Significant direct effect was observed for all the traits except calving date and sex ratio among progeny. The N sires were superior for all the calf crop traits and caused less incidence of dystocia and perinatal mortality compared with the DM sires. Significant differences were obtained between the straightbreds for all the traits except calving date. The N straightbreds were superior to the DM straightbreds for all the significant traits.  相似文献   

8.
Possibilities to include carcass traits recorded at commercial slaughterhouses in the genetic evaluation of sheep in Sweden were investigated by estimating direct and maternal genetic parameters for 4‐month weight (4MW), carcass weight (CW), carcass fatness grade (FAT), and carcass fleshiness (FLESH) using multiple‐trait animal models. Data included two sets of breeds, the so‐called white breeds (Swedish landrace breeds, Texel, Dorset, Oxford Down, Suffolk, East Friesian Milk Sheep, and Swedish crossbred) and the Gotland breed. There were 30 625 observations on 4MW and 5062 observations on carcass traits for the white breeds. For the Gotland breed the numbers were 43 642 and 7893, respectively. The results showed that it is feasible to use field‐recorded carcass traits in the genetic evaluation. To consider the effects of selection and to utilize all information in an optimal way multiple trait animal models should be used. Direct and maternal heritabilities for 4MW and CW varied between 0.04 and 0.18 and heritabilities for FAT and FLESH between 0.21 and 0.29. Direct and maternal genetic correlations between 4MW and CW were high (0.61–0.97). Genetic correlations were higher between the weights and FLESH (0.11–0.62) than between the weights and FAT (?0.23 to 0.40). Genetic correlations between FAT and FLESH were moderate (0.38–0.45). Heritabilities for CW were higher if 4MW was included in the analyses and the effect of selection on 4MW was stronger for CW than for FAT or FLESH. The importance of maternal effects on carcass traits was discussed.  相似文献   

9.
Reproductive data were collected on 4,595 cow exposures and subsequent calvings over four generations in a rotational crossbreeding study involving Angus, Brahman, Charolais and Hereford breeds. Direct and maternal additive (Ig and Mg) and nonadditive (Ih and Mh) genetic effects were estimated for calving rate, calf survival, weaning rate, calving assistance and calf birth date. Genetic effects were estimated by regressing individual animal response on the proportion of genes from breed of origin and gene combinations expected for the four breeds in offspring and in dams. Breed direct and maternal additive and nonadditive genetic effects were expressed as a deviation from the least squares mean. Brahman Ig effects decreased calving and weaning rate (-9.5 +/- 4.0 and -11.8 +/- 4.4%) but Mh effects for weaning rate that included Brahman were positive, ranging from 16.5 +/- 6.7% for Angus-Brahman to 27.8 +/- 6.9% for Brahman-Hereford. The Brahman Ig effect delayed calf birth date (9.8 +/- 2.1 d; P less than .01), whereas Angus and Hereford Ig effects influenced earlier calf birth dates (-4.3 +/- 1.9 and -4.1 +/- 1.9 d; P less than .05). Brahman combination Mh effects also influenced earlier calf birth dates (P less than .01). The Charolais Ig effect for calving assistance was positive (4.3 +/- 1.9%; P less than .05), whereas Angus-Brahman and Brahman-Charolais Mh effects for calving assistance were negative (-6.5 +/- 3.2 and -7.0 +/- 3.2%; P less than .05) and more desirable. Predicted reproductive traits for rotational mating systems were intermediate between predicted reproductive traits for two- and three-breed terminal crosses. Predicted calving and weaning rates were maximized when Brahaman first-cross and Charolais-Hereford cows were used in three-breed cross mating systems.  相似文献   

10.
There is limited genetic information relating calving difficulty and body weights to other productive and reproductive traits. Such information is useful for specifying selection criteria and for predicting economic consequences of selection. Genetic, maternal, and environmental covariances of six productive and reproductive measurements with calving difficulty, birth weight, 200-d weight, and 168-d postweaning gain were estimated in 12 experimental populations of cattle. Calf (direct) genetic effects resulting in longer gestation length were associated with increased calving difficulty and birth weight. Maternal genetic effects of increased gestation length and heavier birth weight were significantly associated. Lighter birth weight and reduced calving difficulty were associated with earlier heifer age at puberty. Increases in direct genetic effects of calving difficulty, 200-d weight, and postweaning gain were associated with a small increase in direct effect of scrotal circumference. Increased direct genetic effects of scrotal circumference were correlated with maternal effects decreasing calving difficulty and increasing 200-d weight. Direct effects of the skeletal measurements, yearling hip height, and heifer pelvic area were positively correlated with direct effects of calving difficulty, birth weight, 200-d weight, and postweaning gain, positively correlated with maternal effects for birth weight and 200-d weight, and negatively correlated with maternal calving difficulty. Percentage of retail product was positively associated with calving difficulty and negatively associated with 168-d gain. Predicted genetic change in calving difficulty resulting from one standard deviation of selection for either calving difficulty score or birth weight was much larger than for any other traits. Selection for 200-d weight, 168-d postweaning gain, hip height, pelvic area, or scrotal circumference was predicted to have opposite effects on direct and maternal calving difficulty. Estimated genetic correlations indicate some small to moderate relationships between calving difficulty and the measured productive and reproductive traits. However, selection for reduced calving difficulty should be based on calving difficulty score and(or) birth weight because of their superiority in predicted genetic change.  相似文献   

11.
This study estimated genetic and phenotypic parameters and annual trends for growth and fertility traits of Charolais and Hereford cattle in Kenya. Traits considered were birth weight (BW, kg), pre-weaning average daily gain (ADG, kg/day) and weaning weight (WW, kg); calving interval (CI, days) and age at first calving (AFC, days). Direct heritability estimates for growth traits were 0.36 and 0.21; 0.25 and 0.10; 0.23 and 0.13 for BW, ADG and WW in Charolais and Hereford, respectively. Maternal heritability estimates were 0.11 and 0.01; 0.18 and 0.00; 0.17 and 0.17 for BW, ADG and WW in Charolais and Hereford, respectively. Direct-maternal genetic correlations ranged between −0.46 and 1.00; −0.51 and −1.00; −0.47 and −0.39 for BW, ADG and WW in Charolais and Hereford, respectively. Genetic correlations ranged from −0.99 to unity and −1.00 to unity for growth and fertility traits respectively. Prospects for improvement of growth and fertility traits exist.  相似文献   

12.
Data collected from steer and bull progeny, fed to a constant final feedlot weight over 11 yr, were used to estimate heterosis in post-weaning feedlot growth and carcass traits in two-way and three-way rotational crossing systems and a breed composite from crossing Hereford, Angus and Charolais breeds. Steer and bull progeny from matings of beef x Brown Swiss-cross sires and dams also were compared with the straight beef breeds and beef crosses. Growth traits evaluated were initial weight on test, 112-d weight, total feedlot average daily gain and total days from initial to final weight. Carcass traits included hot carcass weight, dressing percentage, rib eye area, 12th-rib fat thickness, kidney, pelvic and heart fat, yield grade and marbling score. Heterosis estimates for calves of all crossing systems were significant for initial and 112-d weight and for saving of days in the feedlot, but not for average daily feedlot gain. Heterosis estimates were small and nonsignificant for most carcass traits except for fat traits in specific crosses. Males from Hereford and Angus sires mated to Angus x Hereford dams had higher (P less than .10) backfat than did the parental average. Male progeny from Charolais ranked higher (P less than .10 to P less than .01) than calves from Hereford and Angus sires for most growth traits. Progeny from Charolais sires were more desirable (P less than .10 to P less than .01) for traits related to cutability, but they had less (P less than .05 to P less than .01) marbling than calves of Angus sires.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
Birth, weaning, feedlot and carcass traits were evaluated on 1,181 calves sired by Charolais and Limousin bulls out of eight crossbred dam groups (Hereford X Angus, Angus X Hereford, Simmental X Angus, Simmental X Hereford, Brown Swiss X Angus, Brown Swiss X Hereford, Jersey X Angus, Jersey X Hereford). Calves were born in the spring over a 4-yr period during which dams ranged from 3 to 8 yr of age. Charolais-cross calves were 2.7 kg heavier (P less than .01) at birth and had a 9.9% higher (P less than .01) incidence of difficult calvings and 4.6% greater (P less than .05) preweaning death loss than did Limousin crosses. Charolais-sired calves out-gained Limousin-sired calves by 31 g/d (P less than .01) from birth to weaning and were 9 kg heavier (P less than .01) at weaning. After weaning, calves were self-fed a finishing diet and slaughtered as each animal attained an estimated carcass grade of low Choice. Charolais-cross calves gained 60 g/d faster (P less than .01) than Limousin crosses, were fed 6.8 fewer d and were 17.3 kg heavier (P less than .01) at slaughter. Feed efficiency was similar for both sire breeds. On a grade-equivalent basis, Charolais crosses produced 7 kg heavier (P less than .01) carcass and had 22 g more carcass weight per day of age (P less than .01). Charolais crosses had slightly less internal and external fat. Dressing percentage was higher for Limousin cross calves (64.6 vs 63.9%, P less than .01). Longissimus muscle area and carcass cutability were similar for crosses of both sire breeds.  相似文献   

14.
Heritabilities of and genetic correlations between additive direct and maternal genetic effects for calf market weight, and additive direct genetic effects for carcass traits, were estimated for Japanese Black cattle by REML procedures under 2-trait animal models. Data were collected from calf and carcass markets in Hyogo and Tottori prefectures and analyzed separately by prefecture. Calf market weight was measured on 42,745 and 23,566 calves in Hyogo and Tottori, respectively. Only the fattening animals with calf market weight were extracted from the carcass database and used for estimation. The carcass traits analyzed were carcass weight, ribeye area, rib thickness, subcutaneous fat thickness, yield estimate, beef marbling score, and 4 meat characters (color, brightness, firmness, and texture). Direct and maternal heritabilities for calf market weight were estimated to be 0.22 and 0.07 in Hyogo, and 0.37 and 0.15 in Tottori, respectively. The estimates of heritabilities for carcass traits were moderate to high in both prefectures. The estimates of direct-maternal genetic correlations for calf market weight were positive (0.17) in Hyogo and negative (-0.63) in Tottori. The direct effect for calf market weight was positively correlated with the direct effect for carcass weight (0.87 and 0.56 in Hyogo and Tottori, respectively) but negatively correlated with the direct effect for beef marbling score (-0.10 in both prefectures). The estimates of genetic correlations between the maternal effect for calf market weight and the direct effects for carcass traits varied from -0.13 to 0.34 in Hyogo and from -0.14 to 0.15 in Tottori. Because direct and maternal genetic effects for early growth traits can be evaluated from calf market weight data in the production system of Japanese Black cattle, this information should be incorporated into selection and mating schemes of the breed.  相似文献   

15.
The objective of this study was to investigate a potential association of an inactive myostatin allele with early calf mortality, and evaluate its effect on growth and carcass traits in a crossbred population. Animals were obtained by mating F1 cows to F1 (Belgian Blue x British Breed) or Charolais sires. Cows were obtained from mating Hereford, Angus, and MARC III (1/4 Hereford, 1/4 Angus, 1/4 Pinzgauer, and 1/4 Red Poll) dams to Hereford, Angus, Tuli, Boran, Brahman, or Belgian Blue sires. Belgian Blue was the source of the inactive myostatin allele. Myostatin genotypes were determined for all animals including those that died before weaning. Early calf mortality was examined in the F2 subpopulation (n = 154), derived from the F1 sires mated to F1 cows from Belgian Blue sires, to evaluate animals with zero, one, or two copies of inactive myostatin allele. An overall 1:2:1 ratio (homozygous active myostatin allele:heterozygous:homozygous inactive myostatin allele) was observed in the population; however, a comparison between calves dying before weaning and those alive at slaughter showed an unequal distribution across genotypes (P < 0.01). Calves with two copies of the inactive allele were more likely (P < 0.01) to die before weaning. Postweaning growth traits were evaluated in the surviving animals (n = 1,370), including birth, weaning, and live weight at slaughter, and postweaning ADG. Carcass composition traits analyzed were hot carcass weight, fat thickness, LM area, marbling score, USDA yield grade, estimated kidney, pelvic, and heart fat, retail product yield and weight, fat yield and weight, bone yield and weight, and percentage of carcasses classified as Choice. Charolais lack the inactive myostatin allele segregating in Belgian Blue; thus, in the population sired by Charolais (n = 645), only animals with zero or one copy of the inactive myostatin allele were evaluated. Animals carrying one copy were heavier at birth and at weaning, and their carcasses were leaner and more muscled. In the population sired by Belgian Blue x British Breed (n = 725), animals with two copies of inactive myostatin allele were heavier at birth, leaner, and had a higher proportion of muscle mass than animals with zero or one copies. Heterozygous animals were heaviest at weaning and had the highest live weight, whereas animals with zero copies had the highest fat content. The use of the inactive myostatin allele is an option to increase retail product yield, but considerations of conditions at calving are important to prevent mortality.  相似文献   

16.
Selection was used to create select and control lines within 4 purebred and 3 composite cattle populations. Both lines were selected for similar direct yearling weight and maternal weaning weight EBV. Select lines were selected for lower 2-yr-old heifer calving difficulty score EBV and control lines were selected for average birth weight EBV. Select (n = 6,926) and control (n = 2,043) line calves were born from 1993 through 1999 and selection began with the 1992 mating. High replacement rates resulted in 2,188 births to select line and 598 births to control line heifers. Data used to calculate EBV came from these populations and from 15 yr of data preceding the experiment. Calving difficulty was scored from 1 (no assistance) to 7 (cesarean). Calving difficulty scores from all twins, malpresentations, and cows 3 yr old and older were eliminated. Except for the first year, when a single-trait BLUP was used, a multiple-trait BLUP was used to calculate direct and maternal EBV for calving difficulty score, birth weight, and weaning weight, and direct EBV for postweaning gain. Sires (n = 498) were selected from those born in both the preceding populations and the select and control lines. In purebred populations, some industry sires (n = 88) were introduced based on their EPD. Tests of mean select and control line EBV differences of calves born in the final 2 yr were based on population variation. Select line direct EBV were 1.06 lower for heifer calving difficulty score (P < 0.001) and 3.5 kg lower (P < 0.001) for birth weight than controls. Average differences for other EBV were small and not significant. Yearling weight EBV was intentionally increased in both select and control lines of purebred populations. Angus, Hereford, Charolais, and Gelbvieh yearling weight EBV in control lines increased by 32.4, 27.2, 21.0, and 10.5 kg, respectively, from 1991 and 1992 to 1998 and 1999 compared with an average increase of 2.7 kg in composite populations. Birth weight direct EBV in purebred control lines increased by approximately 8% of yearling weight EBV increases. Selection based on a multiple-trait BLUP was able to create lines differing in calving difficulty score and birth weight EBV, but not in weaning weight and postweaning gain EBV. Differences between lines should be useful for evaluating BLUP and other traits and for identifying potential limitations of genetically decreasing calving difficulty score and birth weight.  相似文献   

17.
The objective of this study was to quantify the effect of inbreeding on carcass quality, growth rate, live conformation measures, and calving performance in purebred populations of Charolais, Limousin, Simmental, Hereford, and Angus beef cattle using data from Irish commercial and pedigree herds. Variables analyzed are reflective of commercial farming practices. Inbreeding was included in a linear mixed model as either a class variable or a linear continuous variable. Nonlinear effects were nonsignificant across all traits. Inbred animals had decreased carcass weight and less carcass fat. The effects of inbreeding were more pronounced in the British beef breeds. Effects for carcass weight ranged from -0.87 kg (Charolais) to -1.90 kg (Hereford) per 1% increase in inbreeding. Inbred Charolais and Hereford animals were younger at slaughter by 3 and 5 d, respectively, per percentage of increase in inbreeding, whereas the effect of inbreeding on age at slaughter differed significantly with animal sex in the Limousin and Angus breeds. Inbred Limousin and Angus heifers were younger at slaughter by 5 and 7 d, respectively, per percentage of increase in inbreeding. Continental animals were more affected by inbreeding for live muscling and skeletal conformational measurements than the British breeds; inbred animals were smaller and narrower with poorer developed muscle. Calf inbreeding significantly affected perinatal mortality in Charolais, Simmental, and Hereford animals. The effects were dependent upon dam parity and calf sex; however, where significant, the association was always unfavorable. Dam inbreeding significantly affected perinatal mortality in Limousin and Hereford animals. Effects differed by parity in Limousins. Inbred first-parity Angus dams had a greater incidence of dystocia. Although the effects of inbreeding were some-times significant, they were small and are unlikely to make a large financial effect on commercial beef production in Ireland.  相似文献   

18.

The aim of this study was to estimate genetic and phenotypic parameters for the three mortality traits crushing, stillbirth and total mortality in piglets, and their respective correlations with birth weight. Records were available from 11 016 Yorkshire piglets from 1046 first parity litters in a Swedish experimental herd. Each mortality trait was analysed jointly with birth weight, using bivariate models. Both mixed linear models and threshold models were used. The threshold models took environmental and maternal genetic effects into account, whereas the linear models also included a direct genetic effect of the piglet on its birth weight. The estimated heritabilities were low for all mortality traits (0.01-0.15), with the lowest estimate for crushing and the highest for stillbirth. The estimated environmental correlations between the different mortality traits and birth weight were negative. The estimated genetic correlations between crushing and birth weight (both direct and maternal effect) were also negative in both models, indicating that sows with low-weight piglets are more likely to crush piglets. However, the genetic correlations between stillbirth and birth weight (both direct and maternal effect) were positive. These results suggest that stillbirth and crushing are traits with different genetic backgrounds, and that genetically increasing the birth weight of the piglets may result in more stillborn piglets.  相似文献   

19.
Direct and maternal additive effects and heterosis were estimated using data from straightbred Angus, Brahman, Charolais, Hereford, and four generations of rotational crosses among these breeds. Traits of interest were birth weight, Julian day of birth, average daily gain from birth to weaning, 205-d weight, and weaning weight per cow exposed. Complete data were available on 3,445 calves produced from 4,733 matings. Discrete generations of 4-yr duration were produced from 1970 through 1988. Brahman was included in each rotational crossbreeding system. Genetic effects were estimated by regression. Direct and maternal additive effects of Brahman, Charolais, and Hereford were estimated as deviations from Angus. Direct and maternal heterosis effects were assumed proportional to expected heterozygosity. The Brahman direct additive effect resulted in later-born calves (P < 0.01). Brahman, Charolais, and Hereford direct additive effects increased birth weight, and the Brahman maternal additive effect decreased birth weight compared with Angus (P < 0.05). Charolais direct and maternal additive effects were greater than Angus for average daily gain and 205-d weight (P < 0.01). The Hereford maternal additive effects on average daily gain and 205-d weight were less than those of the other breeds (P < 0.01). Breed combinations including Brahman had greater direct heterosis for birth weight, average daily gain, and 205-d weight than other combinations (P < 0.01). Angus, Charolais, and Hereford direct additive effects on weaning weight per cow exposed were greater than Brahman (P < 0.05). Predicted average daily gain, 205-d weight, and weaning weight per cow exposed were, on average, greater in four-breed rotation systems than in three- and two-breed systems. Among two-breed rotation systems, predicted average daily gain and 205-d weaning weight were greatest for Charolais-Brahman and least for Angus-Hereford. Calves from the Angus-Charolais-Hereford system weighed less at weaning than any other three-breed combination. However, weaning weight per cow exposed from the Angus-Charolais-Hereford system was greatest among three-breed systems. Within three- and four-breed rotation systems, ranges in predicted birth and weaning weights among generations varied by up to 10.0 and 25.2 kg, respectively. The choice of breeds affects performance, and the sequence of their use may affect intergenerational variation in performance.  相似文献   

20.
The experimental design and objectives are outlined for a crossbreeding experiment with European beef breeds as sire breeds and RDM (Danish Red), SDM (Black Pied Danish) and Danish Jersey as dam breeds.Results from a calving survey of 1006 single calvings are presented. Gestation length, birth weight and calving performance were strongly influenced by breed of sire, breed of dam and sex of calf. The variation in gestation length seemed to have only a slight effect on birth weight. The variation in birth weight had a strong effect on calving performance.The ranking of the sire breeds in descending order according to the frequency of unasisted calvings (which varied from 70 to 26 percent) was as follows: Hereford, Limousin, Danish Red and White Cattle, Simmental, Blonde d'Aquitaine, Chianina, Charolais and Romagnola.  相似文献   

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