Exam 5: Puberty, Estrous, and Repro Behavior Flashcards
Is puberty a process or an event?
Process
What is puberty?
Acquisition of reproductive competence
When does puberty occur?
When there is secretion of GnRH in appropriate frequency and quantity to stimulate gonadotropin release by the pituitary
What are the hypothalamic differences between a male and female?
The hypothalamus is inherently female with a tonic and surge center. Male only has a tonic center
Testosterone from fetal testis defeminizes hypothalamus and eliminates GnRH surge center
Testosterone is converted to E2 in the brain so it can defeminize the brain
Alfa-fetoprotein in females binds E2 and prevents crossing of blood-brain barrier
What are the definitions of puberty in females?
Age at first estrus or heat
Age at first ovulation
Age at which pregnancy can be maintained without deleterious effects
Is it easy of difficult to detect the age at first heat/estrus in females?
Easy
Is it easy of difficult to detect the age at first ovulation in females?
Difficult
Describe detecting the age at which pregnancy can be maintained without deleterious effects
Most practical
At time of 65% adult body weight
What are the definitions of puberty in males in chronological order?
Age of expression of behavioral traits Age at first ejaculation Age when sperm appear in the ejaculate Age when sperm appear in the urine Age when ejaculate contains a threshold number of sperm
What is puberty influenced by?
Plane of nutrition or “fatness”
Threshold body size and composition
Exposure to environmental and social cues
Genetics
What can puberty be influenced by in terms of genetics?
Breed variations and scrotal circumference in bulls and early puberty
What are examples of environmental and social cues?
Season of birth in seasonal breeders
Photoperiod in seasonal breeders
Presence or absence of opposite sex
Density of same sex groups
What species are effected by season of birth in seasonal breeders?
Sheep, goats, cats
What species are effected by photoperiod in seasonal breeders?
Sheep, goats, cats
What species are effected by the presence or absence of opposite sex?
Ewe, sow, cow, rodents
Describe the impact of density of same sex groups
Small groups reach puberty later
Large groups reach puberty sooner
What holds up puberty?
Failure of hypothalamus to produce sufficient quantities of GnRH to cause gonoadotropin release
Describe the prepubertal female
Tonic center in hypo release small quantities of GnRH at low frequency
Provides insufficient stimulation of pituitary
The minimal follicular development cannot release enough E2 to trigger surge center to release large amount of GnRH
What happens at the pubertal transition?
At low level of E2, the tonic center is very sensitive to neg. feedback on GnRH
Negative feedback is slowly lost which results in higher and higher level of GnRh which leads to more E2
Eventually the E2 is high enough to cause surge center to discharge large quantities of GnRH resulting in ovulation and puberty ensues
Describe the prepubertal male
Small amounts of testosterone/estradiol have negative feedback at hypothalamus
GnRH neurons become less sensitive to T and E2 as puberty approaches
More T and E2 are required to inhibit GnRH neurons
The decreased sensitivity leads to a negative feedback of T
Hypothalamus can now produce more GnRH and subsequently more FSH/LH is produced
What is the bovine age at puberty?
11 mos
What is the equine age at puberty?
14 mos
What is the ovine age at puberty?
7 mos
What is the porcine age at puberty?
7 mos
What is the canine age at puberty?
9 mos, but can be 24 mos in large breeds
What is the feline age at puberty?
9 mos, but can be as short as 4 months
What is estrus?
Noun
The period of sexual receptivity commonly referred to as “heat” when the female will stand for breeding
What does the estrous cycle begin and end with?
Begins with estrus and ends at the onset of subsequent estrus
What does the estrous cycle provide females with?
Repeated chances to become pregnant
What can cause interruption in cyclicity?
Pregnancy Nursing Changes in photoperiod Inadequate nutrition Stress Pathology
What can interruption in cyclicity cause?
Anestrus
What is the general sequence of events for the female?
Puberty Cyclicity starts Breeding Pregnancy Parturition Uterine involution Lactation Resumption of cyclicity Repeat at cyclicity
When are breeding seasons initiated?
When the environment will allow for best survival of young
How can breeding seasons be altered?
By selecting more prolific animals and providing better environment
What are the types of cyclicity?
Polyestrus
Seasonally polyestrus
Monoestrus
Describe polyestrus
Cow, swine, rodents
Multiple periods of estrus each year
What species are seasonally polyestrus?
Sheep, goat (short day breeders)
Horse, cat (long day breeders)
Describe monoestrus
Dog
One period of estrus each year
What are the major phases of estrous cycle?
Follicular phase
Luteal phase
Describe the follicular phase
Period of CL regression to ovulation
Growing follicle is dominant structure
Estradiol is the dominant hormone
Describe the luteal phase
Period from ovulation to CL regression
CL is dominant structure
Progesterone is dominant hormone
What are the purposes of female behaviors?
Attractiveness
Proceptivity
Receptivity
What species show signs of estrus with behaviors?
Cows
Mares
Sows
What is looked at during estrus with sensory?
Visual
Olfactory
Auditory
Tactile
What happens in the hypothalamus during estrus?
E2 increases which increases nerve excitability
Neurons produce behavior specific peptides
What happens in the midbrain during estrus?
“Receiveing zone” for hypothalamic peptides
Speeds up impulses
What happens in the medulla during estrus?
Integrates postural adaptation for lordosis and mounting
What happens in the spinal cord during estrus?
Generates signals to specific muscles for lordosis and mounting
What is the behavior of the cow during search?
Increased locomotion
Increased vocalization
Twitching
Elevation of the tail
What is the behavior of the cow during courtship?
Increased grooming
Mounting attempts with other females
What is the behavior of the cow during consummation?
Homosexual mounting and standing to be mounted
What is the behavior of the mare during search?
Increased locomotion Tail erected (flagging)
What is the behavior of the mare during courtship?
Urination stance
Urination in presence of stallion
What is the behavior of the mare during comsummation?
Presents hindquarters to male
Clitoral exposure by labial eversion
Pulsatile contractions of labia
What is the behavior of the ewe during search?
Short period of restlessness
Ram “seeking”
What is the behavior of the ewe during courtship?
Urination in presence of ram
What is the behavior of the ewe during consummation?
Immobile stance
What is the behavior of the sow during search?
Mild restlessness
What is the behavior of the sow during courtship?
Immobile stance
What is the behavior of the sow during consummation?
Immobile stance
What is the behavior of the bitch during search?
Roaming
What is the behavior of the bitch during courtship?
Immobile stance
What is the behavior of the bitch during consummation?
Tail deflected to one side
Urination in presence of male
Affectionate head rubbing
What is the behavior of the queen during search?
Vocalization
What is the behavior of the queen during courtship?
Crouching
Affectionate head rubbing
Rolling
What is the behavior of the queen during consummation?
Elevation of rear quarters and hyper-extension of back (lordosis)
Presentation of vulva
Tail deviation
What is the behavior of the bull during search?
Approach sexually active group of females
Testing for lordosis
Flehmen
What is the behavior of the bull during courtship?
Nuzzling and licking of perineal region
Chin resting
Testing for lordosis
What is the behavior of the bull during consummation?
Penile protrusion with dribbling of seminal fluid with few spermatozoa
Erection and attempted mounts
What is the behavior of the stallion during search?
Visual search
Flehmen
What is the behavior of the stallion during courtship?
High degree of excitement
What is the behavior of the stallion during consummation?
Penile protrusion with no preejaculatory expulsion of seminal fluid
What is the behavior of the ram during search?
Sniffing and licking of ano-genital region
Nudging ewe
Flehmen
What is the behavior of the ram during courtship?
Neck outstretched and head held high horizontally
What is the behavior of the ram during consummation?
Repeated dorsal elevation of scrotum
Penile protrusion with no dribbling of seminal fluid
What is the behavior of the boar during search?
Moving among females
What is the behavior of the boar during courtship?
Nuzzling
Grinding of teeth
Foams at mouth
What is the behavior of the boar during consummation?
Penile protrusion
Shallow pelvic thrusts
Attempted mounting
What is the behavior of the dog during search?
Roaming around territory
What is the behavior of the dog during courtship?
Sniffing
Licking of the vulva
What is the behavior of the dog during consummation?
Erection
Protrusion of penis
Mounting
What is the behavior of the tom during search?
Prowling
What is the behavior of the tom during courtship?
Biting queen on dorsal neck
What is the behavior of the tom during consummation?
Mounting
Describe precopulatory behavior in order
Search for sexual partner Courtship Sexual arousal Erection Penile protrusion
Describe copulatory behavior in order
Mounting
Intromission
Ejaculation
Describe postcopulatory behavior in order
Dismount
Refractory period
Memory
What is needed for the precopulatory behavior of searching?
Good eyes, feet, and legs
What is needed for the precopulatory behavior of arousal?
Generally only needs a female present (teasing a stallion)