Related Experiment Video
Updated: Aug 6, 2026
07:34
Probing the Limits of Egg Recognition Using Egg Rejection Experiments Along Phenotypic Gradients
Published on: August 22, 2018
Phenotypic Definition Influences Genetic Inference and Predictive Ability for Reining Performance in Quarter Horses
Mário Luiz Santana1, Annaiza Braga Bignardi1
1Grupo de Melhoramento Animal de Mato Grosso (GMAT), Instituto de Ciências Agrárias e Tecnológicas, Universidade Federal de Rondonópolis (UFR), Av. dos Estudantes, 5055, Cidade Universitária, Rondonópolis, Mato Grosso, Brazil.
Animal Science Journal = Nihon Chikusan Gakkaiho
|July 23, 2026
Summary
Genetic evaluation of reining performance in Brazilian Quarter Horses was improved using rank-based phenotypes. Blom-transformed ranks (BLOM) offered modest advantages in predictive ability, while within-group ranks (RANK) better reflected observed competitive performance.
Area of Science:
- Animal Genetics
- Equine Science
- Quantitative Genetics
Background:
- Reining performance evaluation is complex due to subjective scoring and competition structure.
- Accurate genetic parameter estimation is crucial for improving reining horse breeding programs.
Purpose of the Study:
- To estimate genetic parameters for reining performance in Brazilian Quarter Horses.
- To compare the impact of two phenotypic definitions (within-group rank and Blom-transformed rank) on genetic inference and predictive ability.
Main Methods:
- Utilized a dataset of 21,165 longitudinal reining performance records from 1,603 Brazilian Quarter Horses.
- Employed random regression models (RRM), specifically cubic RRM, for genetic analysis.
- Compared within-group rank (RANK) and Blom-transformed rank (BLOM) as phenotypic definitions.
Main Results:
- Heritability estimates for reining performance were low and age-dependent, varying from 0.01–0.17 (RANK) and 0.06–0.23 (BLOM).
- Substantial phenotypic variance was attributed to permanent environmental and rider effects.
- BLOM demonstrated superior predictive performance and stronger favorable genetic trends compared to RANK.
Conclusions:
- Both RANK and BLOM are valuable and complementary for the genetic evaluation of reining performance.
- BLOM offers modest advantages in predictive ability and genetic trend estimation.
- RANK effectively represents relative competitive performance on the observed scale.
Related Concept Videos
02:27Background and Environment Affect Phenotype
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
01:43Incomplete Dominance
Gregor Mendel's work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid cell has two variants called alleles inherited from each parent. He suggested that amongst these two alleles, one allele is dominant in character and the other recessive. The combination of alleles determines the phenotype of a gene in an organism.
01:25Inheritance
Gregor Mendel's pioneering work on the principles of inheritance fundamentally transformed our understanding of how traits are transmitted from generation to generation. His experiments with pea plants laid the groundwork for the discovery of genes, discrete units within organisms that control heredity.
Each gene exists in pairs, and the combination of these genes from both parents forms an individual's genotype. This genotype is a blueprint of potential traits. Examples of genotype traits...
Each gene exists in pairs, and the combination of these genes from both parents forms an individual's genotype. This genotype is a blueprint of potential traits. Examples of genotype traits...
01:39Epistasis
In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...
01:23Behavioral Genetics and Its Designs
Behavior genetics explores how genetic inheritance influences human behavior. It focuses on how genes, passed from parents to offspring, contribute to the development of behavioral traits and tendencies. This branch of genetics seeks to understand the complex interplay between inherited genetic factors and environmental influences in shaping our behaviors.
The primary methodologies used in behavior genetics include family studies, twin studies, and adoption studies, each providing unique...
The primary methodologies used in behavior genetics include family studies, twin studies, and adoption studies, each providing unique...
01:09Epistasis Analysis
Although Mendel chose seven unrelated traits in peas to study gene segregation, most traits involve multiple gene interactions that create a spectrum of phenotypes. When the interaction of various genes or alleles at different locations influences a phenotype, this is called epistasis. Epistasis often involves one gene masking or interfering with the expression of another (antagonistic epistasis). Epistasis often occurs when different genes are part of the same biochemical pathway. The...