Midterm 3 - Lecture 26 Flashcards
How do chickens mate?
- vas deferens ejects semen into cloaca
- folds of female cloaca swell during mating and allow semen transfer through cloacal contact
- female everts cloaca to make better contact with ejaculate
- less “courtship” behaviour- more forced copulation
Do avians display courtship behaviours?
- not really; more forced copulation
What do sexually active male look like?
- scruffy
When are roosters most sexually active?
- at the beginning and especially end of the day
- assess mating behaviour at a time when males should be actively mating
What is fertility of the flock based on?
Activity of the roosters
When does rooster/flock fertility decline?
with age
How is rooster/flock fertility related to age?
- declines with age
- natural relationship btw bird behaviour and physiology
- rooster less interested and able to complete mating
- hen physiologically needs to be mated more often to sustain same level of fertility
How is a Rooster Spiking Program implemented?
- To keep fertility since it is almost impossible to maintain early fertility in a +40 wk old flock
- add 2% 28 wk old males to a flock at 40-45 wk of age
What does a Rooster Spiking Program achieve?
- reactivate/motivate older males
- young males will increase the overall mating frequency in the flock (second string)
- adds 3-6 chicks/hen to flock production
- old male activity declines 6-9 weeks after spiking
How is chicken and turkey breeding different?
Turkeys: AI
Chickens: natural breeding
What are 2 roles of the sperm storage tubules?
- Select sperm
- Store sperm
Where are the sperm storage tubules located? What do they do?
- located just inside the shell gland
- provide a micro-enviro in which sperm can survive and retain fertility
- play a role in sperm selection
Is sperm storage time different for different species?
yes
Why is sperm stored?
- ability to store sperm eliminates the need to synchronize mating with ovulation
- reduced mating frequency = less susceptible to predators
- fertility extended during SST
In chickens, how long is fertility extended during SST storage?
~6 days = full fertilizing capacity
10 days = ~50% eggs are fertilized
19 days = ~15% eggs are fertilized
If a hen is inseminated with 150 million sperm, what percentage makes it to the SSTs?
- 1-2% reach SSTs
- 84% lost in feces within 30 min
- 90% can’t pass through vagina
How does interaction with the hen’s tract determine sperm fate?
- sperm selection starts with interaction with luminal fluids on way to SST
- hen’s “vagina” have cilia that beat and move fluids and debris toward the cloaca
How do sperm enter SST?
motility and cilia action
What are the characteristics of the SST microenvironment?
- suppresses O2 uptake and motility = REST
- inhibits enzyme systems
- stabilizes plasma membrane
What ‘type’ of sperm are selected to be stored?
the youngest and most “fit”
How long does it take to fill SST in chickens vs turkeys?
Chicken = 1 day
Turkey = 2 day
What is the last male precedence theory?
- theory suggests that the male who completes the most recent insemination is most likely to successfully fertilize the next egg
- assumes that a fresh ejaculate will provide fit/viable sperm and preferentially fill the SST
Is the last male precedence theory true?
no
What defines which sperm fill the SST and fertilize?
- order of insemination did not dictate which sperm populated the SST
- quality of the sperm defines which wiill fill
- if inseminated by 2 males 24hrs apart, sperm from the different males were not both found in the SSTs
What is the criteria for SST selection of sperm?
- sperm with low motility are rejected
- recognition of sperm via proteins on sperm plasma membrane
- species-specific immunological barrier
What is sperm survival in SST dependent on?
- production of fatty acids by SST epithelium for energy used by sperm
- prevention of damage to the sperm plasma membrane
- removal of sperm catabolism products from the luminal fluids via membrane proteins at the blind ends of SSTs
Why must sperm in the SST remain motile?
to remain “parked” and prevent from being flushed out by release of fluid produced by SST epithelium
What is the site of fertilization?
infundibulum
Continuous Release Model
- theory suggests that some sperm are constantly being released into the oviduct
- supported by the fact that the # of sperm in the SST is reduced at a continuous rate regardless if ovulation occurs or not
- motile/fit sperm enter folds in the female tract and are moved up to the site of fertilization by localized contractions
