Reading

• Chapters10 and 11
• Additional diagrams or pictures not found in text

Lecture a:

Reproductive Behavior

• provides an opportunity for copulation
• social bonding

Precopulatory Stage

• Search for sexual partner
  • in female limited to estrus
  • in male can occur at any time
  • involves all of the senses
    • sight
    • smell
    • hearing
    • tactile
• Courtship
  • species specific events
  • sniffing of the vulva by male
  • urination by the female
  • flemen lip curl
  • chin resting on female rump
  • increased phonation
  • male checks for female lordosis
  • human - eye contact, touching, detection of pheremones
• Sexual arousal
  • Female - lordosis, present hindquaters to male
  • Male - erection, penile protrusion

Copulatory Behavior

• Mounting
• Intromission
• Ejaculation
• Varies among species
  • short copulators (1 - 3 seconds)
    • bull
    • ram
  • sustained copulator (5 - 20 minutes)
    • boar
  • intermediate (20 to 60 seconds)
    • stallion

Postcopulatory Behavior

• Male
  • Dismounting
  • Refractory period
    • period of time during which copulation will not take place
    • dependent on:
      • species
      • sexual rest prior to copulation
      • age of male
      • degree of female novelty
      • number of previous ejaculates
    • for semen collection try to minimize
  • Memory
    • a bad experience will carry over

Endocrine Effects on Sexual Behavior

• Prenatal steroid exposure
  • feminization
  • masculinization
• Postnatal Behavior
  • castrated female
    • no steroids - no estrous behavior
    • plus estradiol - estrous behavior
    • plus progesterone and estradiol - maxium estrous behavior
    • plus testosterone - male-like behavior
  • castrated male
  • no steroids - decreased sexual behavior
  • plus testosterone - sex behavior restored
  • plus dihydrotestosterone - decreased sex behavior
  • plus estradiol - sex behavior restored
• Aromatization
  • testosterone can be converted to estradiol by aromatase
  • dihydrotestosterone can not
• both male and female sexual behavior is dependent on estradiol receptors in brain

Control of Reproductive Behavior

• Sensory
• Hypothalamus
• Midbrain
• Medulla
• Spinal Chord

Sensory Inputs for Reproductive Behavior

• specific importance varies with species
• olfaction
  • pheromone
    • volatile substance which elicite specific behavior in the recipient
  • males produce
    • boars
    • humans
  • females produce during estrus
    • dogs and rats can sense cow pheromones
  • flehmen response
• Auditory
  • cows bellow
  • sows grunt
  • good for long-range signaling
• Visual
  • posturing
  • males observing other males or females mounting
  • valuable for close encounters
• Tactile
  • biting on neck or whithers of mare
  • chin resting on cow
  • boar nudging of sow flank
  • final stimulus before copulation
  • leads to erection

Erection, Emission, Ejaculation

• erection
  • vasodilatation (simtulate parasympathetic), inhibit vasoconstriction (inhibit sympathetic nerves), relax retractor penis muscle, contraction of ischiocavernosus muscle (parasympathetic)
  • non-erect, helicline arterioles smooth muslce, corpus spongiosum smooth muscle contract via effects of norepinephrine (NE) from sympathetic nerves
    • NE release, NE binding to Na channel, Na ions enter, cell depolarizes, action potential, ca channels open, muscle contracts arteriole constricts, low blood flow
  • errection - Nitric Oxide (NO) released from parasympathetic nerves and arteriole endothelial cells cause relaxation of artery and arteriole smooth muscle
    • NO released, guanylate cyclase stimulated, cGMP increases, K channel opens, K ion leave cell, hyperpolarizes cell, ca channels close, muscle relaxes, arteriole dialates, high blood flow
    • viagra (Sildenafil Citrate) is an inhibitor of the posphodiesterase that breaks down cGMP, therefore increased amounts of cGMP are present leading to maintaining of erection.
• emission
  • contraction of cauda epididymis, vas deferens
    • oxytocin from posterior pituitary
    • sympathetic neurons
  • release of accessory gland fluid
    • sympathetic neurons
• ejaculation
  • contraction of smooth and striated muscles

Homosexual Behavior

• common in farm animals
• useful to detect when females in heat
  • selection by man may have enhanced this
• can collect bulls off of other bulls as mounts

Maternal Behavior

• Prepartum
  • high estrogen,low progesterone
  • prolaction (cross blood brain barrier)
• Postpartun
  • Prolactin - lactation, parental care, alloparental care
  • Ocytocin - secreted by hypothalamus into cerebrum, social bonding, ie maternal behavior
  • Opiods - decreases in these promote social bonding
  • Serotonin - low leves associated with increased maternal behavior, opposite with infant rejection
    

Lecture b:

Age When Semen Can Be Collected

• Bull 12 months
• Boar 6 - 8 months
• Ram 6 - 9 months
• Stallion 20 - 24 months
• Dog 8 - 12 months

Effect of Age on Sperm Output

• number of sperm increases in ejaculate after puberty but may take some years to reach maximal production

Semen Collection

• Sexual arousal
  • Sight, sound, smell, touch
• Best mount - Live
• Alternative mount - dummies
  • Stallion
  • Boar
  • Bull
• Sexual Preparation
  • False mounts
    • In bulls can increase sperm collected by 100%
  • Novelty
    • Change mounts, location, other males present
  • Breed and species differences
    • Beef bulls less libido than dairy bulls
    • Arab stallions more libido than Quarter horse stallions
    • Rams less libido than bulls or male goats
• Frequency of collection
  • As increase frequency/wk
    • decrease sperm/ejaculate
    • Increase sperm recovered/wk

Effect of Semen Collection Frequency on Sperm Output

Item	Dairy	Beef	Sheep	Swine	Horses
# of collections	1-6	1-6	7-25	2-5	2-6
Volume (ml)	5-8	3-6	0.8-1.2	150-300	30-100
Concentration (million/ml)	1000-2000	800-1500	2000-3000	200-300	200-400
Total sperm/ejac. (billion)	7-15	5-10	1.6-3.6	30-60	5-10
Total sperm/wk (billion)	15-40	10-30	25-40	100-150	15-30
Motile sperm(%)	50-75	40-75	60-80	50-80	40-75
Normal sperm(%)	70-95	65-90	80-95	70-90	70-90

Characteristics of Artificial Vagina

• Temperature
  • Bull, stallion, ram at 45°C
• Pressure
• Friction
  • Lubrication essential

Electroejaculation

• Useful if male won’t or can’t mount
• Get urine often
• Poorer quality ejac.
• Used in rams and beef bulls

Massage Method

• Stimulate by rectal massage
• Seminal vesicles
• Vas deferens

Semen Evaluation

• Appearance (color)
  • No debris
  • No puss
  • No urine
• Volume
• Motility
• Concentration
  • Hemocytometer, spectrophotometer
• Morphology

 

Preservation of Semen

• Extenders
  • Nutrients
    • Glucose, fructose
  • Cold shock prevention
    • Milk, skim-milk, egg yolk
  • Buffer
    • Citrate, Tris
  • Osmotic pressure
    • The buffer component
  • Inhibit bacterial growth
    • antibiotics
  • Increase volume
  • Cryoprotectant
    • glycerol
• Liquid Semen
  • Collect semen
  • Semen quality exam
  • Extend 1:3 (semen:extender)
    • Minimal extension rate
  • Cool to 5°C over 2 hours
    • OK for bull, stallion, ram
    • Boar - cool to 15°C
  • Once cooled, extend semen to final amount
    • Bovine (inseminate 0.5 ml)
    • 2 to 5 million sperm/ml
    • Equine (inseminate 1 billion sperm)
    • 25 to 50 million sperm/ml
    • If don’t cool then inseminate 500 million motile sperm
    • Swine (inseminate 1.5 to 6 billion sperm in 50 ml)
    • 30 to 120 million sperm/ml
• Frozen semen
  • Follow instruction for collecting and cooling semen
  • After cooling to 5°C, extend to 2X the final concentration desired
    • If want final concentration to be 40 million/ml then dilute to 80 million to ml at this time
  • Hold semen for 4 to 6 hours at 5°C
    • Equilibrates semen to the cold
  • Add the cryoprotectant
    • Mix extender with 2X final cryoprotectant amount, 1:1 with extended semen
    • Do this in small portions to minimize cryoprotectant toxicity
  • Package semen
    • 0.5 ml French straws
    • Ampules
  • Freeze semen
    • Liquid nitrogen vapor
    • Static
    • Mechanically controlled
    • Dry ice depressions for pellet freezing
  • Storage
    • In a liquid nitrogen tank

Liquid Nitrogen Tank

• insulated container (vacum in outer layer)
• canisters
• canes - hold straws

Temperature in Neck of Storage Tank

• as move up in the neck, temperature increases

Temperature of Straws If Low LN

• top of tank will warm when canisters and/or canes are lifted into the neck to remove straws
• straws not removed from canes will warm into a danger zone
• when cane returned to tank for 1 min. the straws will not recool and if lifted again to remove another straw, remaining straws will warm even further

Conclusions on LN Tank

• Maintain LN level as high as possible.
• Keep extra tank (narrow neck) with only nitrogen so semen storage tank can be refilled when opened.
• Enter semen storage tank only when needed
• Do not hold canes above neck of LN tank

Thawing

• Use the procedures recommended by the semen supplier!!!
  • 35°C water for 30 - 60 seconds
  • Ice water for 3 minutes
  • Pocket thaw
• Have thawing container near LN tank when removing semen

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