Evaluation models and genetic parameters for calving difficulty in beef cattle

Calving difficulty was analyzed under threshold and linear models considering either a fixed or random herd-year effect. The aim of the study was to compare models for predicting breeding values according to the size of herd-year groups. When simulating data sets with small herds, in order to obtain...

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Bibliographic Details
Published in:Journal of animal science 2003-04, Vol.81 (4), p.933-938
Main Authors: Phocas, F, Laloe, D
Format: Article
Language:English
Subjects:
Animal Husbandry - methods
Animal productions
Animals
beef cattle
Biological and medical sciences
Breeding
Breeding of animals
calving
Cattle
Cattle - genetics
Cattle - physiology
Charolais
data collection
Dystocia - genetics
Dystocia - veterinary
Female
Fundamental and applied biological sciences. Psychology
genetic correlation
Genetics
herds
heritability
Linear Models
maternal effect
Models, Biological
Models, Genetic
Models, Statistical
Monte Carlo Method
Mother. Fetoplacental unit. Mammary gland. Milk
Parturition - genetics
Phenotype
prediction
Predictive Value of Tests
Pregnancy
Pregnancy. Parturition. Lactation
sires
Statistical methods
Terrestrial animal productions
Vertebrates
Vertebrates: reproduction
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Summary:Calving difficulty was analyzed under threshold and linear models considering either a fixed or random herd-year effect. The aim of the study was to compare models for predicting breeding values according to the size of herd-year groups. When simulating data sets with small herds, in order to obtain an unbiased evaluation under a nonrandom and negative association of sire and herd effects, the best model for a practical evaluation was the fixed linear model. Field data included 246,576 records of the largest Charolais herds in France. Models were compared using the correlations of estimated breeding values between the different models. Although the best model from a theoretical point of view was a threshold model with a fixed herd-year effect, a linear model with a fixed herd-year effect was the best choice from a practical point of view for predicting direct effects for calving difficulty in beef cattle and was a sufficient choice for predicting the associated maternal effects for data set with large herds. Correlations between direct estimated breeding values under the reference model and the fixed linear model and the random threshold model were 0.94 and 0.91, respectively. Correlations between the corresponding maternal estimated breeding values were 0.94 and 0.98. Heritabilities of direct effects were 0.27 and 0.14 under fixed threshold and fixed linear models, respectively. The corresponding heritabilities of maternal effects were 0.18 and 0.13, and the genetic correlation between direct and maternal effects were −0.36 and −0.34, respectively.
ISSN:0021-8812
1525-3163
DOI:10.2527/2003.814933x