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LU6: REPRODUCTION & BREEDING (Factors involve in reproduction &…
LU6: REPRODUCTION & BREEDING
Female Reproductive Organs Structure
Uterus
: Implantation & pregnancy
Duplex Uteri
:
2 uterine horns, 2 cervices, & 1 vagina.
Eg: rabbits, rodents, marsupials.
Bipartite Uteri
:
Larger uterine body with smaller uterine horns ( for mare), for cow, ewe, & doe (smaller uterine horns)
.
Bicornuate Uteri
:
2 long uterine horns, common uterine body, & 1 cervix
. Eg: dogs, pigs, elephants, whales, dolphins, tarsiers, lemurs, lorises, etc.
Simplex Uteri
: No uterine horn, all uterine body. Eg: humans
Cervix
: Protects from external disturbance
Oviduct
: Transport of ovum
Vagina
: Organ of copulation
Ovary
: Produce ova & hormones
Vulva
: External opening to reproductive organs
Sign of estrus in farm animals
Cows mounted by another cows & show signs of bellowing, thin clear mucus flow out of vagina, & increased activity.
Mare
: hind legs spread, pelvis tilted, tail diverted, evert the clitoris, & express small amount of urine.
Gilt//sow
: Stand rigid with ears erect in presence of boar.
Bitch
: Sanguineous discharge from swollen vulva due to burst of blood capillary in endometrium.
Estrus cycle
Estrus
: Period of sexual receptivity.
Metestrus
: Period of corpus luteum formation.
Proestrus
:Period of follicle growth.
Diestrus
: Period of corpus luteum is fully functional.
Describe ovarian activity.
Menstrual Cycle
Characterized by obvious bleeding.
Bleeding: Result of shedding of vascularised wall of uterus.
Describe uterine events in
large apes & human
.
Factors involve in reproduction & breeding
Social Factors
Interaction between sexes by
pheromones
&
vocalization
.
Male effect
: The onset of puberty often fasten due to exposure of female to male abruptly at peripubertal period.
Interaction between females facilitates sexual development.
Presence of male enhance the signs of estrus.
Nutrition
Sufficient nutrition needed for optimum reproductive efficiency.
Insufficient nutrition cause loss of body condition postpone the beginning of puberty & recycling.
Photoperiod & breeding season
Pineal gland
: react to changes in photoperiod by increase the melatonin secretion.
Melatonin
: decides the beginning of breeding season.
Eg: sheep & goats ("short day breeder") due to :arrow_down: photoperiod while horses & cats ("long day breeder") due to :arrow_up: photoperiod.
Reproductive Senescence
Menopause
: End of ovarian activity.
Not responsive to GnRH, estrogen & progesterone secretion is diminished.
Hormonal Changes in estrous cycle
Temperature & humidity
Hot & humid environment depresses reproduction especially dairy cows & sows ( :arrow_down: estrous detection & conception).
Hormonal Control
Anterior pituitary gland releases
follicular stimulating hormone (FSH)
&
luteinizing hormone (LH)
.
FSH
: stimulates follicle to grow & produce
estrogen
.
Controlled by
hypothalamus
through
gonadotrophin releasing hormones (GnRH)
.
LH
: stimulate corpus luteum to produce
progesterone
.
Estrogen & progesterone maintains uterus & secondary sexual characters & exert feedback control over hypothalamus & pituitary gland.
Male Reproductive Organs
Accessory Organ
: Produce fluids (carries sperm to penis).
Duct
: Store & carry sperm & seminal fluids to penis.
Testis
: Produce sperm (spermatogenesis) & sex hormones (steroidogenesis).
Also controlled by hypothalamus via GnRH.
90% made up of hundred meters of
seminiferous tubules
& 10% made up connective tissues, blood vessels, &
Leydig cells
(secretes hormone).
Penis
: Deposit sperm into vagina.
Spermatogenesis
Spermatogonia
(associated with
Sertoli cells
) :arrow_right: primary (46n) & secondary (23n)
spermatocytes
:arrow_right: differentiates to
spermatids
:arrow_right:
spermatozoa
Hormonal Control
Testosterone & inhibin exert -ve feedback control over hypothalamus & anterior pituitary & regulate level of testosterone in blood.
Feedback Mechanism
: Testosterone inhibits LH secretion; Testosterone + estrogen inhibits FSH secretion.
GnRH
: stimulate anterior pituitary to secrete FSH & LH;
FSH
: stimulate Sertoli cells to produce sperm & inhibin;
LH
: stimulate Leydig cell to produce testosterone.
Male infertility
: Low sperm count due to :arrow_down: gonadotrophin stimulation, blockages in the rete testis, epidydimis // vas deferens.
Impotency
: A penis fails to become erect. Causes: physical damage, health & medication, & psychological problem. Treatment: cognitive behavioral therapy & medicine.
Birth Control of farm animals & pet
Chemical castration
Immunization
Neutering & Spaying
Reproductive Adaptation
Fish Reproduction
Hermaphroditism (both female & male sexes)
Synchronous hermaphroditism
(1 ovary, 1 testis)
Asynchronous hermaphroditism
(switch to female or male sex) Eg: clownfish, wrasses//gobies)
Unisexuality // parthenogenesis
Bisexuality // gonochorism
Freshwater fish
demersal eggs, long incubation period, small no. of eggs spawn, larger & less vulnerable larvae. Direct insemination (save sperms).
To protect eggs against risk of freezing // low salinity of surface water.
Marine fish
Bouyant // pelagic eggs, short incubation period, large no.of eggs spawn, vulnerable larvae.
Marine animals: use asexual & sexual modes of reproduction, mostly invertebrates are hermaphrodite, have direct sex change.
Birds Reproductive Adaptation
Consist
1 left ovary
,
1 left oviduct
. Benefits: reduce female body size // weight, & :arrow_up: survival chances of fragile eggs.
Ovary enlarge significantly as it approach breeding season & male testes are paired but appeared absent through out the year.
Most male birds have
cloacal proturberance
to keep sperm at optimum temperature.
Most birds lacks a penis, so, brief copulation act known as "cloacal kiss".
Articials
less productive than precocials;
Uniparental
less productive than biparental;
Non-migrants
less productive than migrants;
Pelagic sea birds
less productive than birds feeding at other habitats
Female: need large amount of energy for eggs production, so less time & energy for nest building, & subsequent parental caring.
Egg yolk provide nutrient for embryo. Albumen acts as primary water supply & act as shock cushion.
