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PubMed1998

Economic values in broiler breeding.

The objectives of this study were to derive economic values in broiler breeding and to determine their relationship with production circumstances. Economic values were derived using a deterministic economic model based on profit equations with a fixed amount of broiler meat output of the production system. Nonintegrated and the integrated broiler production systems were studied. The difference between these originates from different definitions of cost components and scaling aspects. For each stage of an nonintegrated system, the model calculated the profit margin; for an integrated system, (total) cost prices per unit of product at each stage were calculated. The Dutch broiler performance data and prices were input into the model as the representative situation. For all traits, in the nonintegrated system, economic values were derived, expressed as Dutch guilders (Dfl) per unit of product, where the unit of product depends on the stage of the production system and equals an egg for the multiplier breeder, a day-old chick for the hatchery, and a marketable broiler for the commercial grower and processor. Resulting levels of economic values were illustrated by showing underlying cost or profit changes in the production system. For the integrated system, economic values were expressed as Dfl x marketable broiler(-1) x unit(-1). Economic values of traits in the integrated system were also derived for situations where technical parameters or prices of productive factors were changed (20% increase or decrease). A general conclusion from these sensitivity analyses is that the economic values are sensitive to production levels, product prices and feed prices; there are both linear and nonlinear relationships between economic values and production circumstances.

Agriculture↗

PubMed1991

Genetic analysis of dystocia in dairy cattle.

Breeding values and genetic parameters for dystocia were estimated in Normande and Holstein breeds. Dystocia scores were related to an underlying continuous variable via a threshold model. The underlying linear model included the effects of calving season, sex of calf by parity of dam, sire of calf, grandsire of calf, dam within maternal grandsire and herd-year effects. Typical results were found for the environmental effects, with a strong influence of dam parity on dystocia, a strong influence of sex of calf, and a small effect of calving season. Herd-year variances were 32 and 40% of the residual variance in the Normande and Holstein breeds, respectively. Heritabilities for the Normande (Holstein) breed were .08 (.07) for direct effects and .11 (.07) for maternal effects. Correlations between sire and grandsire effects were .51 and .36 for the Normande and Holstein breeds, respectively. The corresponding correlations between direct and maternal effects were .15 and -.09. The results of this study show that a complete model for dystocia including the threshold concept and maternal effects can be applied for routine evaluation of dairy AI bulls. Maternal effects are important, and they should be considered in dystocia analysis, especially if nonrandom mating is present. Selection for reducing dystocia in calf and cow effects are not antagonistic.

Animals↗

PubMed2003

A regressive model analysis of congenital sensorineural deafness in German Dalmatian dogs.

The objective of the present study was to analyze the mode of inheritance for congenital sensorineural deafness (CSD) in German Dalmatian dogs by consideration of association between phenotypic breed characteristics and CSD. Segregation analysis with regressive logistic models was employed to test for different mechanisms of genetic transmission. Data were obtained from all three Dalmatian kennel clubs associated with the German Association for Dog Breeding and Husbandry (VDH). CSD was tested by veterinary practitioners using standardized protocols for Brainstem Auditory-Evoked Response (BAER). The sample included 1899 Dalmatian dogs from 354 litters in 169 different kennels. BAER testing results were from the years 1986 to 1999. Pedigree information was available for up to seven generations. The segregation analysis showed that a mixed monogenic-polygenic model including eye color as covariate among all other tested models best explained the segregation of affected animals in the pedigrees. The recessive major gene segregated in dogs with blue and brown eye color as well as in dogs with and without pigmented coat patches. Models which took into account the occurrence of patches, percentage of puppies tested per litter, or inbreeding coefficient gave no better adjustment to the most general (saturated) model. A procedure for the simultaneous prediction of breeding values and the estimation of genotype probabilities for CSD is expected to improve breeding programs significantly.

Animals↗

PubMed2005

Semiparametric animal models via penalized splines as alternatives to models with contemporary groups.

Contemporary groups (CG) are used in genetic evaluation to account for systematic environmental effects of management, nutritional level, or any other differentially expressed group effect; however, because the functional form of the distribution of those effects is unknown, CG serve as an approximation to a time-varying mean. Conversely, in semiparametric models, there is no need to assume any functional form for the time-varying effects. In this research, we present a semiparametric animal model (AMS) using the covariate day of birth (DOB) by means of penalized splines (P-splines), as an alternative to fitting CG. In the AMS, the functionality of the data on DOB is expressed by means of a Basic segmented polynomial line (B-spline) basis, and proper covariance matrices are used to reflect the serial correlation among the points of support (or knots) at different times. Three different covariance matrices that reflect either short- or long-range dependences among knots are discussed. Different models were fitted to birth weight data from Polled Hereford calves. Models compared were an animal model with CG, an animal model with CG and the covariate DOB nested within CG (CG + DOB), and P-splines with the first difference penalty matrix and three different AMS with 20, 40, 60, 80, or 120 knots. Models were compared using a modified Akaike information criterion (AICC), which was calculated as a byproduct of the estimation of variance components by REML using the expectation maximization algorithm. All three AMS had smaller (better) values of AICC than the regular model with CG, while producing almost the same ranking of predicted breeding values and similar average predicted error variance. In all AMS, the inference and all measures of comparison were similar when the number of knots was equal > or = 40. The model CG + DOB had analogous performance to the AMS, but at the expense of using more parameters. It is concluded that the use of penalized regression splines using a B-spline basis with proper covariance matrices is a competitive method to the fitting of CG into animal models for genetic evaluation, without having to assume any functional form for the covariate DOB.

Animals↗

PubMed2000

[Diseases with relevance to protection of animals with an example of the musculoskeletal system of dogs].

Protection of animals needs major concern in breeding programmes especially if inherited diseases occur which cause pain, suffering and/or damages for the animals. Dogs breeders and people keeping dogs as well as veterinarians should be informed about the etiology on sequels of diseases which cause pain to the animals and from which the animals have to be protected in order to make them more conscious on these problems and to achieve changes in dog breeding programmes. The information system "Inherited Diseases of the Musculoskeletal System of Dogs" should display the already published knowledge about etiology, pathogenesis, appearance, therapy and genetics of these diseases. This information system was built up in such a way that it can be used by students as a learning programme to understand the basic relationships among animal protection, diseases, and dog breeding. The user is also supplied with support for breeding decisions as well as for interpretation of breeding values and genotype probabilities. Additionally, information can be obtained on all in the German Association for Dog Breeding (VDH) represented breeds and breeding clubs. Actions to reduce genetically caused diseases required for members of dog breeding clubs are also available. The information system ist programmed by using HTML (Hyper Text Markup Language). Publication is possible on CD-ROM and on Internet. The supplied hyperlinks allow to make use of other publications on the world wide web related to dog and diseases of dogs.

Animal Welfare↗

PubMed1986

Heritability and repeatability of Hereford show-ring placing and associated correlations with individual performance measurements and expected progeny differences.

Data associated with 1,531 Herefords shown at the National Western Stock Show at Denver from 1978 to 1984 were used to estimate heritability and repeatability of show-ring placing (SRP) and genetic, environmental and phenotypic correlations. The correlations were those between: SRP and individual measurements (IM) taken at the time of show and available to the judges, SRP and parents' SRP and IM, male SRP and their individual expected progeny difference values (EPD) and SRP and sire EPD. The IM were height, weight, backfat, weight per day of age and scrotal circumference. The estimation procedures were symmetric differences squared, analysis of variance and parent-offspring regression and correlation. Three similar estimates of SRP heritability averaged .39. Three similar estimates of SRP repeatability averaged .33 and suggested little effective selection for SRP based on first record and low permanent environmental variance. The phenotypic correlations indicated an individual's height (.63) had the most influence on its SRP followed by weight (.43). Genetic and environmental correlations between height and SRP averaged (three estimates) .78 and .37, respectively. Dam SRP, height and backfat had higher correlations with offspring SRP than those of the sire. Male SRP was moderately correlated with EPD values for weaning (.25) and yearling (.38) height and weaning (.33) and yearling (.32) weight. The correlations between SRP and sire EPD values were: .27 (birth weight), .16 (weaning weight), .33 (weaning height), .10 (yearling weight), .23 (yearling height) and .07 (maternal breeding value). The results did not support SRP as a criterion for improving growth performance traits.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2003

Short communication: Validation of two animal models for estimation of genetic trends for female fertility in Norwegian dairy cattle.

Two animal models were compared with respect to potential bias in genetic trend estimates for female fertility and for their predictive ability. In addition to either a fixed effect for month of first insemination or for month-year of first insemination, the models had fixed effects of age and double insemination and random effects of herd-year and animal. The model with a fixed effect of month of first insemination had a larger positive genetic trend for 56-d nonreturn rate in virgin heifers (0.16% yr), smaller downward bias, and somewhat higher predictive ability. These results demonstrate the importance of verifying models to be used in the calculation of breeding values.

Animals↗

PubMed1989

[Study on BLUP with reduced animal model in evaluation of performance tested males].

This study is computed in best linear unbiased prediction (BLUP) with the reduced animal model. BLUP is a powerful method to evaluate genetic value of animals, but the computation is sometimes costly because of the large set of equations to be solved. Equivalent linear models with a reduced number of elements of breeding values can reduce computations substantially. Using a general animal model and a reduced animal model predictions of additive genetic merit are described for the case of sire and maternal grandsire. A simple numerical example is used to illustrate the identity of the two solutions. The reduced animal model can be useful for evaluation of males that have been performance-tested and have, in some case, progeny that have been tested as is the case with beef cattle.

Animals↗

PubMed2001

Repeat breeding and subsequent reproductive performance in Swedish Landrace and Swedish Yorkshire sows.

The objective of the present study was to analyse the association between repeat breeding (RB) in gilts/sows and their subsequent reproductive performance as well as the impact of interactions between repeat breeding and factors like parity number, boar breed, season and mating type (MT) on subsequent reproductive performance in Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed included 7040 sows (3654 L and 3386 Y), farrowing during January 1994 until December 1999 in 11 L and 8 Y nucleus herds. The study was assigned as a cohort design and the aim was to study gilts/sows from their first mating as gilts until mating after third parity. Analysis of variance was applied to continuous data and logistic regression was applied to categorical data. Percentages of litters as a result of repeat breeding in sow parities 1-3 were 6.1, 12.0 and 6.3% for L sows and 6.7, 13.1 and 7.4% for Y sows. For parity 3, the incidence of litters resulting from repeat breeding was significantly higher (P<0.001) in Y than in L sows. The proportion of irregular return to oestrus (>24 days after first mating) was higher (P<0.01) in primiparous sows than in multiparous sows (69% versus 61%). On average, litters resulting from repeat breeding were larger (P<0.001) than litters resulting from non-repeat breeding (NR) (about 0.5 piglets per litter) in both L and Y sows. For Y sows, if the previous litter was a result of repeat breeding, the subsequent reproductive cycle had 2.7% higher RR (P<0.05) and 2.4% lower FR (N.S.) compared with sows that were not repeat bred. The same trend was found in L sows (1.4% higher RR and 1.3% lower FR) but the differences were not significant. Among the sows removed from the herds, about 24% of L and 28% of Y were culled due to reproductive problems (gilts not included). In addition, a number of sows from these nucleus herds were also culled due to low breeding value and poor conformation.

Animals↗

PubMed2005

Up hill, down dale: quantitative genetics of curvaceous traits.

'Repeated' measurements for a trait and individual, taken along some continuous scale such as time, can be thought of as representing points on a curve, where both means and covariances along the trajectory can change, gradually and continually. Such traits are commonly referred to as 'function-valued' (FV) traits. This review shows that standard quantitative genetic concepts extend readily to FV traits, with individual statistics, such as estimated breeding values and selection response, replaced by corresponding curves, modelled by respective functions. Covariance functions are introduced as the FV equivalent to matrices of covariances. Considering the class of functions represented by a regression on the continuous covariable, FV traits can be analysed within the linear mixed model framework commonly employed in quantitative genetics, giving rise to the so-called random regression model. Estimation of covariance functions, either indirectly from estimated covariances or directly from the data using restricted maximum likelihood or Bayesian analysis, is considered. It is shown that direct estimation of the leading principal components of covariance functions is feasible and advantageous. Extensions to multi-dimensional analyses are discussed.

Analysis of Variance↗

PubMed2002

Morphological and hormonal parameters in two species of macaques: impact of seasonal breeding.

To compare physiological and developmental differences between two cogeneric species that differ by seasonal vs. aseasonal breeding, values for morphological measurements, testicular volume, serum testosterone, estradiol, and dehydroepiandrosterone-sulfate levels were obtained from 53 rhesus during the early breeding season, as well as 41 pig-tailed macaque males maintained at the Tulane Primate Center. The two species exhibited similar body size, testosterone, and estradiol levels, but differed substantially in testicular volume (3.00 +/- 1.7 vs. 1.72 +/- 1.3 cc), abdominal skinfold measures (15.7 +/- 9.2 vs. 9.0 +/- 7.7 mm), and DHEA-S levels (18.0 +/- 11.7 vs. 7.6 +/- 5.4 microg/dl). Significant interaction effects for species by age group were found for weight, tricep circumference, length, and estradiol level. In addition, length was more closely related to testicular volume among rhesus compared to pig-tailed macaques, suggesting different developmental patterns between the species. Predictors of hormonal levels differed between the two species. In the rhesus, estradiol levels were related to testicular volume and testosterone levels while there were no anthropometric predictors of testosterone or DHEA-S. For the pig-tailed macaques, testicular volume was related to tricep circumference, testosterone to triceps skinfold and testicular volume, and estradiol to weight. It is argued that rhesus have larger testes for body size and more abdominal fat deposits during the early breeding season relative to pig-tailed macaques reflecting the increased demands of sperm competition in a seasonally breeding species. Hormonal differences associated with the difference in breeding system appear to be primarily related to adrenal rather than testicular activity.

Adjuvants, Immunologic↗

PubMed1999

Evaluation of carcass, live, and real-time ultrasound measures in feedlot cattle: II. Effects of different age end points on the accuracy of predicting the percentage of retail product, retail product weight, and hot carcass weight.

Data from 970 feedlot steers and bulls were used to evaluate effects of different age end points on the accuracy of prediction models for percentage of retail product, retail product weight, and hot carcass weight. Cattle were ultrasonically scanned three to five times for fat thickness, longissimus muscle area, and percentage of intramuscular fat. Live animal measures of body weight and hip height were also taken during some of the scan sessions. Before development of prediction equations, live and ultrasound data were adjusted to four age end points using individual animal regressions. Age end points represented mean age at slaughter (448 d), mean age at the second-to-last scan before slaughter (414 d), mean age at the third-to-last scan before slaughter (382 d), and an age end point of 365 d. Ultrasound and live animal measures accounted for a large proportion of the variation in the dependent variables regardless of the age end point considered. For all three traits, final models based on independent variables adjusted to earlier ages of 365 and 382 d showed better or at least similar model R2 and root mean square errors than those based on independent variables adjusted to a mean slaughter age of 448 d. Validation of the models using independent data from 282 steers resulted in a mean across-age rank correlation coefficient of .78, .88, and .83 between actual and predicted values of the percentage of retail product, hot carcass weight, and retail product weight, respectively. Mean across-age rank correlation of breeding values for the corresponding traits were .92, .89, and .82. The results of this study suggest that live and ultrasound traits measured as early as 365 d could be used to predict end product traits as accurately as similar measures made before slaughter at age 448 d.

Aging↗

PubMed1983

Expected relative responses to selection for alternative measures of life cycle economic efficiency of pork production.

Relative genetic responses to selection for alternative measures of economic efficiency of pork production were examined. The analysis was based on results from a deterministic bio-economic model of lifecycle pork production. Alternative aggregate breeding values considered were based on cost (+)/unit of live weight or of carcass output lean for different production systems and for different breeding roles of the selected stocks. For cost/unit of lean, changes in leanness (or fatness) dominated the index. For cost/unit of live weight, however, no one trait dominated the index, and changes in growth and reproductive traits as well as the breeding role of the stock (purebred, maternal or paternal) were important in defining selection objectives. Management and production systems were less important than breeding role for cost/unit live weight output, except that importance of growth rate was increased by marketing at the mean weight reached at a fixed age rather than at a fixed weight irrespective of age. Implications of these results for goals and systems of pig improvement are discussed.

Adipose Tissue↗

PubMed2000

Possible effects of 25 years of selection and crossbreeding on the genetic merit and productivity of New Zealand dairy cattle.

A deterministic model was developed to evaluate the concurrent effects of selection and crossbreeding on the rate of genetic gain and productivity of New Zealand dairy cattle over 25 yr. Selection was based on an index, which included estimated breeding values for mature cow live weight and lactation yields of milk, fat, and protein. Mating strategies involving Holstein-Friesian, Jersey, and Ayrshire breeds were evaluated. Effects of heterosis and age were included to calculate live weight and yields of milk, fat, and protein per cow. Feed requirements were estimated for maintenance, lactation, and pregnancy and for replacement heifers. Stocking rate was calculated by assuming 12,000 kg of dry matter annually utilized per hectare. Upgrading to either Jersey or Holstein-Friesian increased the number of potential bull mothers and resulted in genetic gains of 0.27 genetic standard deviations/yr for both options. Rotational crossbreeding of Holstein-Friesian x Jersey decreased the number of potential bull mothers and resulted in a genetic gain of 0.24 genetic standard deviations/yr. Upgrading to Jersey resulted in the least increase in milk (5%) and the greatest increase in fat (16%) and protein (27%) per hectare with a small decrease in stocking rate (0.4%). Upgrading to Holstein-Friesian reduced the stocking rate by 11% and increased production of milk, fat, and protein per hectare by 10, 8, and 21%, respectively. Rotational crossbreeding of Holstein-Friesian x Jersey resulted in greater production per hectare than the intermediate production between upgrading to Jersey and upgrading to Holstein-Friesian. Crossbreeding can be used in combination with selection to exploit the effects of heterosis while maintaining genetic diversity to cover changes in market conditions.

Animals↗

PubMed2003

Genetic relationship between body condition score, dairy character, mastitis, and diseases other than mastitis in first-parity Danish Holstein cows.

The aim of this study was to explore the possibilities of using body condition score (BCS) or dairy character (DC) as indicators of mastitis and diseases other than mastitis in first-parity Danish Holsteins. The dataset included 28,948 observations on conformation scores and 365,136 disease observations. The analysis was performed using a multitrait linear sire model. Heritability estimates for BCS and DC were moderate (0.25 and 0.22), and heritability estimates for mastitis and diseases other than mastitis were low (0.038 and 0.022). Between BCS and diseases other than mastitis, the genetic correlation was -0.22, whereas the genetic correlation was -0.16 between BCS and mastitis. The genetic correlation between DC and diseases other than mastitis was 0.43, and between DC and mastitis it was 0.27. The genetic correlation between BCS and DC was -0.61. Residual correlations were close to 0, except between BCS and DC (-0.37). Including DC as an indicator of diseases other than mastitis will increase the accuracy of the predicted breeding value for diseases, especially when the progeny group is small. Using BCS as an additional indicator of diseases did not increase the accuracy. Breeding for less DC will increase resistance to diseases.

Animals↗

PubMed2005

Genetic parameters for a maternal breeding goal in beef production.

New maternal breeding values have been developed for use in UK beef evaluations. To undertake multitrait BLUP evaluations, it is necessary to have a full covariance matrix. This study outlines the approach taken to construct the full covariance matrices for the four beef breeds that most widely contribute to suckler beef cows in the United Kingdom. The maternal traits investigated were age at first calving, calving interval, lifespan, mature cow weight, 200-d weight, and calving difficulty. Three terminal sire traits (weight at 400 d, ultrasonic fat depth, and muscle score) were included to estimate covariances between the new and existing traits. A sire-maternal-grandsire model was used for the estimation procedure in a series of bivariate and multivariate models. A weighted bending procedure was employed to construct positive definite covariance matrices. Parameter estimates broadly agreed with literature values, although for some traits, literature information was very scarce. Some differences between parameters for different breeds were evident.

Animals↗

PubMed1991

Restriction fragment length polymorphism of a bovine T-cell receptor beta gene.

Genetic polymorphism of a bovine T-cell receptor beta gene was investigated by analysing restriction fragment length polymorphism (RFLP). One locus, denoted TCRB, with four allelic variants was revealed. The relationship between alleles at the TCRB locus and bull breeding values for disease and milk production was investigated in a sample of 196 progeny-tested AI bulls of the Swedish Red and White breed. The statistical evaluation of the data revealed no convincing association between TCRB alleles and any of the traits studied.

Alleles↗

PubMed2006

Comparison of genetic gains per year for carcass traits among breeding programs in the Japanese Brown and the Japanese Black cattle.

The breeding program for beef cattle in Japan has changed dramatically over 4 decades. Visual judging was done initially, but progeny testing in test stations began in 1968. In the 1980s, the genetic evaluation program using field records, so-called on-farm progeny testing, was first adopted in Oita, Hyogo, and Kumamoto prefectures. In this study, genetic trends for carcass traits in these 3 Wagyu populations were estimated, and genetic gains per year were compared among the 3 different beef cattle breeding programs. The field carcass records used were collected between 1988 and 2003. The traits analyzed were carcass weight, LM area, rib thickness, s.c. fat thickness, and beef marbling standard number. The average breeding values of reproducing dams born the same year were used to estimate the genetic trends for the carcass traits. For comparison of the 3 breeding programs, birth years of the dams were divided into 3 periods reflecting each program. Positive genetic trends for beef marbling standard number were clearly shown in all populations. The genetic gains per year for all carcass traits were significantly enhanced by adopting the on-farm progeny testing program. These results indicate that the on-farm progeny testing program with BLUP is a very powerful approach for genetic improvement of carcass traits in Japanese Wagyu beef cattle.

Animals↗