Traits in horses can be dominant or not, impacting breeding outcomes.
Dominant traits tend to prevail in offspring.
Incomplete dominance can occur, where traits blend together (e.g., red and white to produce roan horses).
Genetic disorders exist within horse breeds, affected by recessive genes.
HYPP (Hyperkalemic Periodic Paralysis): A disorder in horses where potassium cannot move in and out of cells effectively.
Symptoms include muscle spasms and weakness triggered by stress or exercise.
This disorder is associated with the "Impressive" bloodline of Quarter Horses.
Inbreeding increases the likelihood of expressing recessive genes that lead to disorders.
Breeding requires understanding the risks of genetic abnormalities and disorders.
Altering breeding pairs (i.e., outcrossing) is one method to reduce risks of inherited disorders.
Record keeping is vital to track bloodlines and potential hereditary issues.
Genetic mapping in horses has improved understanding of hereditary traits.
Researchers can identify specific segments in DNA associated with traits through genomics.
Genetic testing (e.g., through hair and blood samples) provides breeding insights and helps predict outcomes:
Certain traits can be tied to genetic markers or "snips" in the DNA sequence.
Male hormones (mainly testosterone) are crucial for sperm production and overall behavior.
Testicles produce sperm and hormones and must remain at a cooler temperature than the body.
Cremaster Muscle: Regulates the position of testicles based on temperature, drawing them closer in cold and further away in heat.
Male puberty occurs around 15 months of age, but optimal breeding usually starts around 3 years.
A typical ejaculation contains millions of sperm necessary for successful fertilization.
Sperm undergo different stages of development:
Meiosis: Process of halving chromosome numbers to create gametes (sperm).
Spermatogenesis: Final stage of sperm maturation, including developing tails and heads.
Sperm travels from testicles through the epididymis and vas deferens.
Sperm can remain viable in the female reproductive tract for days, helping ensure successful fertilization within a narrow window.
Genetic abnormalities can lead to severe health issues or fail to produce viable offspring (e.g., failed pregnancies).
Abnormalities can stem from recessive traits when inbreeding occurs.
As awareness of breeding implications grows, ethical breeding practices are increasingly emphasized.