Module 6- poultry Flashcards
photoperiod
period of time when a bird receives illumination = daylength
what type of breeders are most type of birds
seasonal, long day
long day breeders
become reproductively active as days are getting longer
when is molt triggered?why
fall, they replace their plate feathers so they are ready for a fall migration
longer vs shorter wavelength colours
longer-red/orange
shorter-blues/greens
do longer or shorter wavelengths have better egg production?why?
longer b/c it stimulates the extra retinal receptors
why can birds see extra colours
they have 1 extra cone in their eye
light perception pathway
light hits photoreceptors (pineal, eye, or hypothalamus) -> takes energy from photons to convert it into a neural signal -> sent to hypothalamus -> stimulates GnRH -> releases LH & FSH from pituitary gland
how does melatonin work in photoperiods
produced by pineal gland & eye which acts like a time signal to the body to help regulate the circadian rhythm
when & where is melatonin produced
pineal gland & eye, synthesized at night
T or F: melatonin is not required for birds to respond to photoperiod
T
how many locations does the hypothalamus have for photoreceptors
3
critical daylength in chickens
when photosensitivity starts & triggers bird to become reproductively active
- 11-12 hours
commerical photoperiod
14-16 hours
internal circadian rhythm occurs on a ( ) time frame
24 hour
what is released when birds are photostimulated
LH
what occurs if birds fail to continue to be stimulated by increasing day length?
GnRH is not released & birds come out of lay
when can birds be photostimulated again after photorefractory period
next spring b/c need period of days to be photostimulated
what age are birds photostimulated in commerical laying hens?
18/19 weeks
T or F: turkeys have much steeper refractory period
T
what age does force moulting occur
70-80 weeks
why is molting birds illegal in canada
b/c of animal welfare concerns b/c need to take food & water away
molting process
deprive feed & water, use 6 hours of light / day = stresses birds = come out of lay = can photostimulate after 2 weeks of no eggs
what ovary is the rudimentary vs function
left= functional
right=rudimentary
what occurs if left ovary is damaged
right ovary can develop into ovotestis = cannot produce fertilized egg
when do oocytes begin to develop
at sexual maturity when bird is photostimulated
T or F: birds produce tons of follicles but only a small fraction will be ovulated
T
what occurs as follicles begin to mature
rich white yolk becomes incorporated = allows formation of small white follicles that develop into small yellow follicles
what is rich white yolk high in
protein
how many grams of VLDL are incorporated every day into follicles
19g
what happens to the remaining follicles that are not ovulated
undergo atresia
what type of yolks are selected to enter the follicular hierarchy
yellow, 1 per day, 5-7 total
what occurs when follicles are developing in follicular hierarchy
estrogen is produced = production of VLDL & vitellogenin
vitellogenin
transports nutrients from bird into egg
how many mm are follicles in diameter at ovulation
30-40mm
what is follicular hierarchy determined by? F1 vs F5
size, F1= biggest & next to be ovulated, F5 was smallest & last to be recruited
what is recruited from small yellow
large white follicles
T or F: large white & yellow are similar in composition
T
granulosis cell layer
large rectangular cells in follicles
what prevents materials from passing through cell layer
tight junctions
occludin
regulator of cell junctions
more occludin = stronger barrier = less gets through
effects of high activin A vs high inhibin A
activin-upregulates occludin
inhibin=downregulates occludin = less responsiveness to FSH
what is the key component to recruitment of follicles into hierarchy? why?
FSH, b/c primordial follicles become responsive to FSH & start to get recruited into follicle hierarchy = reduce sensitivity to FSH & switch to LH sensitivity
what does a defective follicular hierarchy mean? what causes it?
less organized
more than one follicle released at a time
cause- overweight in boiler breeder hens
T or F: twins cannot occur b/c not enough room in egg
T
testosterone function
stimulate comb growth & female specific plumage
estrogen function
stimulate separation of pubic bones & development of medullary bone
what can be used to indicate how close a pullet is to onset of lay
comb development
what is the production of the medullary bone stimulated by
estrogen
medullary bone
reserve of calcium
what 2 things can occur if a bird does not have enough calcium
osteoporosis & cage layer fatigue
cage layer fatigue
will not stand & will be culled
skeletal changes as bird becomes sexually mature
widening of pubic bones for egg to pass through
what bone drops down as bird approaches lay
cleal bone
what 2 changes in hormones occur as the follicles grow?
1) oestrogen declines
2) progesterone increases (F1 has the most)
what does the follicle rupture at ovulation to release the ovum into oviduct?
stigma- non-vascularized tissue
post-ovulatory follicle
produce prostaglandins, P1 is most recently ovulated
what are 3 possible functions of post-ovulatory follicles
1) recruitment of small yellow follicle into follicular hierarchy
2) triggers smooth muscle contractions for oviposition
3) nesting behaviour
infundibulum functions (2)
1) site of fertilization & sperm storage tubules
2) secrete vitelline membrane
internal infundibulum layer
malfunctioned follicles are released into abdomen instead of infundibulum
vitelline
outer layer of yolk, surrounds yolk to keep it separate from the rest
magnum function
deposits first 3 layers of albumen
- inner thick
-inner thin
-outer thick
chalazae cord function
helps with placement inside the egg
isthmus function
2 shell membranes placed
- air cell forms
how can old egg be indicated by air cell
more evaporated = larger air cells
shell gland
puts final layer of albumen down
- outer thin layer= pumps egg into outer shell egg shape
where does the egg spend most of its time
shell gland
what % of egg weight is from the shell
12%
what is 98% of the egg made of
calcium carbonate
how many grams of calcium in a 60 gram egg
7 grams
what do pores in the egg do
allow for gas exchange so embryo is not suffocated
2 layers of shell gland
1) mammillary layer: knob structures
2) spongy layer: column formation
T or F: shell pigment is a heritable trait & you can select for it
T
porphyrins
derived from haemoglobin metabolism = brown egg shell
oocyanin
product of bile formation = blue/green eggs
bird that lays blue/green eggs
araucana
physical vs chemical barriers of shell cuticle
physical- plugs pores to avoid contamination
chemical-proteins with antimicrobial factors
cuticle purpose & function
final layer that gets put into egg before oviposition- acts as a protective layer to reduce evaporation & contamination of the egg by partially blocking pores
T or F: older birds have less protection of their egg cuticles
T
CFIA egg wash instructions
pre-rinse 30 degrees C & detergent wash of 45 degrees C
should egg wash detergent have high or low pH
high
do eggs need to be washed?
yes, and need to be placed into fridge to prevent bacterial growth
germinal disk
part of ovum that will be fertilized
shell gland vagina function
similar to cervix
1) sphincter like muscle
2) major sperm storage tubules
after insemination, approx. 75% will contain an average of ( ) sperm per tubule
400
sperm host glands
folding of epithelium to form pocket to store sperm
