Reproduction Flashcards
What term is used to describe the genotype of a horse that has one dominant gene or one recessive gene, such as large “A”, small “a”?
Heterozygous
When the paired genes are not identical, the animal is said to be what?
Heterozygous
When the paired genes are identical, the animal is said to be what?
Homozygous
What is the difference between homozygous and heterozygous?
Individuals that are homozygous for a particular gene have only one allele to pass to their offspring and heterozygous individuals can pass either of the two different alleles.
How many pairs of chromosomes are located in the body cells of the horse?
32 pairs
What is the normal sex genotype for the mare and stallion?
Mare-XX Stallion-XY
How many pairs of chromosomes are responsible for the sex of the foal?
One pair
What are two types of genetic action?
Qualitative and quantitative
What are qualitative genetic actions?
A particular trait is influenced by a single pair of genes
What is quantitative gene action?
A trait is influenced by a number of genes that all have some influence on the trait
What type of gene action will result in an intermediate state between two parents?
Co-dominance
What is another word for paired genes?
Alleles
What is the heritability estimate?
The percentage of a horse’s expressed trait that is due to genetics
True or False? Black is recessive to bay
True
What is the rule of genetics regarding the mating of a chestnut stallion to a chestnut mare?
They will produce only a chestnut foal
What is the exterior opening to the mares’ reproductive canal?
Vulva
What is the part of the mare’s reproductive tract that is shaped like a catchers mitt with finger-like projections?
Infundibulum
The ovarian end of the oviduct is called what?
Infundibulum
What is the convex side of the ovary called?
Hillus
Name the three layers of the uterus.
Serous, myometrium, and endometrium
What is another term for the complete heat cycle of a mare when she is ready to conceive?
Estrus
How long does the average heat of the estrous cycle last in a mare?
5-7 days
What term describes the mare’s seasonal estrous cycle?
Polyestrous
The estrous cycle consists of two stages, one lasting 5-7 days, the other lasting 14-16 days. What are the names for these stages?
Estrus and diestrus
In mares, what are the gonads?
Ovaries
What are the ovarian hormones that control the estrous cycle?
Estrogens or progestins
What is “silent heat”?
The failure to show behavioral signs of estrus
When is a mare’s conception rate highest?
Prior to ovulation
How can a mare’s heat cycle be manipulated without the use of hormones?
Use of extended daylight
At what age does a mare’s reproductive ability decrease?
16yrs
What is the most effective method for detecting a mare in estrous?
Teasing
What is a teasing mare?
The checking of a mare for signs of estrus by watching her reaction to a stallion
When a mare is teased or subjected to urinalysis to determine if she is i estrus,a curling of the upper lip occurs. This response is called what?
The Flehmen response
What two hormones can be used to synchronize mare’s estrous cycles?
Prostaglandin and human chorionic gonadotropin
What reproductive hormones is secreted by the hypothalmus in response to enviromental cues such as day length?
Gonadotropc releasing hormone(GnRH)
What hormone stimulates the growth of follicles?
Follicle stimulating hormone or FSH
What does FSH do?
Stimulates the growth of follicles
What is the term used for a solid mass that forms in te follicle after the egg has left and produces progesterone which helps to maintain pregnancy and prevents other follicles from developing during pregnancy?
Corpus luteum
What is the average age of a filly at puberty?
12-15 months
A mare that has never been bred is called what?
Maiden