Reproduction in birds

Question 1

Do male birds have accessory reproductive glands?

Answer 1

No

Question 2

Where do the testes lie?

Answer 2

The testis are intraabdominal and lie craniovetral to the first kidney lobe near the abdominal air sac

Question 3

Are there any fluctuations in bird sperm production?

Answer 3

Because spermatogenesis is better at a cooler temperature this means in birds it is better at night.

Question 4

Where does the ductus deferens terminate?

Answer 4

it terminates in the urodeum on a papilla

Question 5

What are the changes in reproductively active male birds?

Answer 5

In breeding birds Testes can increase 300- to 500-fold compared to that of non-breeding males, the Ductus deferens also becomes more convoluted to form a seminal glomus embedded in the cloaca wall which functions to store sperm

Question 6

Do birds have a phallus?

Answer 6

The presence of a phallus varies among species it can be present and not used for intromission or not present at all.

Question 7

In birds with a penis is the erection mechanism the same as mammals?

Answer 7

Errection is lymphatic in birds with a phallus used for intromission

Question 8

How is sperm transmitted in birds without a penis?

Answer 8

other methods of semen transfer is cloaca to cloaca contact (male inverts cloaca to expose the papilla).

Question 9

Do birds use both ovaries?

Answer 9

The left ovary is functional and the Right is only activated if left ovary removed

Question 10

What do bird ovaries look like?

Answer 10

The bird ovary looks like a bunch of grapes, the yellow part of the egg is a single cell with huge lipid inclusion

Question 11

Are avian follicles the same as mammals?

Answer 11

Birds have have rapid follicular development and their follicles also consist of oocyte, granulosa cells, theca cells.
The larger the follicle the quicker it develops

Question 12

Where do the hormones that cause nesting behaviour come from?

Answer 12

At ovulation the follicle spilts open and the egg is relased
AT this point it is a post ovulatory follicle thin walled sace with granulosa cells, this lasts around 8-10 days and non-steroid hormones are released that cause nesting behaviour

Question 13

How are progesterone and oestrogen produced in the bird?

Answer 13

In the granulosa cells cholesterol is converted to progesterone and some od this diffuses into the theca cells which convert it to oestradiol. This action of the theca cells is more before laying occurs.

Question 14

What pre-laying behaviour is caused by oestrogen?

Answer 14

Oestrogen linked preparation for laying:
Calcium ATPase is produced in the shell gland
The medullary spaces of esp the tiba are calcified
The liver produces VLDL’s which become the yolk
The oviduct enlarges

Question 15

What is the open period?

Answer 15

The window of time when LH surge can occur
Approx 8-10 hours
From the onset of darkness to 1 hour after light onset
Dusk sets the circadian clock
So, if the F1 follicle produces enough progesterone during the open period then there will be an LH surge and ovulation will occur.

Question 16

After ovulation the egg is caught by………..

Answer 16

This egg is the caught by the infundibulum which is covered in a ciliated columnar epithelium

Question 17

What are sperm storage tubule and where do they lie?

Answer 17

At the junction between the vagina and the shell gland lies sperm storage tubules, in birds sperm is viable at body temperature and can last 10-14 days so when required they are squeezed out of the sperm storage tubles, migrate and fertilise another egg.

Question 18

Describe the path of the ovulated egg

Answer 18

Infundibulum (<1 hr)
This is where the chalazae are made which anchor the yolk to the poles and ensures the embry maintains the correct orientation

Magnum (>3 hrs):
The layer of albumen is laid dowm ,this is produced in the liver and it is the moevemnt of the egg through the tract that triggers its release.

Isthmus (1 - 1 1/2 hrs):
This is where the inner and outer shell membranes are laid down

Uterus/shell gland (20 hrs):
Where the shell of calcium carbonate is added and the proteins are added to form the cuticle +/- pigment which seals the egg and protects from dehydration.

Vagina and cloaca (seconds hours):
Responsible for oviposition

Question 19

How big is a clutch of eggs?

Answer 19

Egg clutch size varies and can be anywhere from two to five plus, number of clutches varies over the breeding season and among species. There is normally a day pause between each egg.

Question 20

What are determinate and indeterminate egg layers?

Answer 20

Birds can be determinate (set number of eggs in a clutch) or indeterminate (keep laying eggs over a specified time) layers

Question 21

In the domestic hen ovulation occurs 6-8 hours after the LH surge and egg laying about 24-26 hours after ovulation. Egg laying occurs 15-75 mins after oviposition so ovulation occurs ……………. later each day.

Answer 21

1-2 hours

Question 22

State some brooding behaviours of birds

Answer 22

A brood patch where ovarian steroids cause a defeathered area that becomes edematous and highly vascularised. This increases blood flow and heat to the eggs (they also naturally increase metabolism to increase temp of eggs)
Prolactin increases nesting activity, incubation, Gonadal regression and Parental care (can occur in males or females)

Question 23

In order for there to be an LH surge the bird must be primed, what does this include?

Answer 23

eg. Nest box and full contact with a mate or there will be a low amount of LH.

Question 24

When are the two times birds “check” the light?

Answer 24

Two critical times for seasonal influence: dawn and 13-17h hours after dawn is the other photosensitive phase.

Question 25

How are birds sexed?

Answer 25

DNA (eg blood from nail clipping, eggshell or live cells plucked from the feather), surgical exploration, instrument sexing (instrument is inserted into the large intestine to observe gonad through the intestinal wall- males will have two testis and females will have one ovary however this does carry a risk of injury) or more commonly vent sexing is done.