Breeding/reproduction (year 2) Flashcards
what are the three goals of spermatogenesis?
produce spermatozoa
replenish supply of primordial stem cells
create genetic diversity
what are the three stages of spermatogenesis?
proliferation, meiotic, differentiation
what are the beginning and end products of proliferation?
start - spermatogonia
end - spermatocyte
what are the beginning and end products of the meiotic phase?
start - spermatocyte
end - haploid spermatid
what stages of spermatogenesis are found in the basal compartment?
spermatogonia
what stages of spermatogenesis are found in the adlumenal compartment?
spermatocyte, spermatid, spermatozoa
what are the beginning and end products of the differentiation stage of spermatogenesis?
start - spermatid
end - spermatozoa
describe the process of the proliferation phase of spermatogenesis
mitosis occurs creating genetically identical daughter cells, these cells are all joined together allowing them to divide at the same time
describe the process of the meiotic phase of spermatogenesis
creates genetic diversity by primary and then secondary spermatocytes forming haploid spermatids
what happens during the differentiation phase of spermatogenesis?
the round spermatid becomes a self propelled package of enzyme and DNA through 4 phases
what are the 4 phases of differentiation?
golgi, cap, acrosomal, maturation
what is spermiation?
the process of the sperm being released into the lumen of the seminiferous tubule
describe the morphology of a spermatozoa
head containing nucleus, acrosome and post-nuclear cap
tail which is a self-powered flagellum composed of a middle, principle and terminal piece
what is in the acrosome in the head of the spermatozoa?
hydrolytic enzymes that penetrate the zone pellucida
what is the range of spermatogenesis in most animals?
1-2 months
how do hormones regulate spermatogenesis?
hypothalamus releases GnRH which acts on the anterior pituitary to release LH and FSH
what does LH act on in the testes?
act on the leydig cells to produce testosterone
what does testosterone act on?
the Sertoli cells and also has a negative feedback effect on the hypothalamus and anterior pituitary
what does FSH act on in the testes?
the Sertoli cells
what do the Sertoli cells produce?
inhibin which has negative feedback on the anterior pituitary
where is sperm matured?
head of the epididymis
where is sperm stored?
tail of the epididymis
how long does transport through the epididymis take?
1-2 weeks
why is the sperm-testis barrier important?
spermatids are genetically unique so they will be rejected and attacked if they are accessible to the immune system
how is the appearance of sperm graded?
0 - clear water 1 - cloudy 2 - milky 3 - thin creamy 4 - creamy 5 - thick creamy
give some examples of things that may kill sperm?
water, smoke, temperature, bright light, blood, detergent
what are the three stages of parturition?
initiation of myometrial contractions
expulsion of foetus
expulsion of foetal membrane
what are species called that have singular offspring?
monotocous
what are species called that have multiple offspring?
polytocous
what are the ball park figures for how long each stage of parturition should take?
1 - 2-6 hours
2 - 30 minutes
3 - 1-6 hours for large animals
how long are the stages of parturition in the queen?
1 - 4-42 hours
2 - 30-60 minutes
3 - pass with neonate
what are the three terms used to describe the foetal disposition?
presentation
position
posture
what is described by the term presentation?
relation between the long axis of the foetus and birth canal
longitudinal or transverse
what is meant by the term position?
the relationship between the surface of the birth canal to which the foetal vertebral column is in contact
dorsal, vental, lateral
what is meant by the term posture?
the disposition of the head, neck and limbs
flexion, extension and direction
what is the term used for a normal birth?
eutocia
how may dystocia be prevented?
good selection of dam/sire
good husband and health care
name some consequences of dystocia
increase stillbirth increased neonatal mortality increased dam mortality reduced productivity of dam reduced fertility of dam
what are three reasons dystocia may occur?
insufficient expulsion force
inadequate size/shape of birth canal
size/disposition of foetus
what are the causes of foetal dystocia?
maldisposition
feto-maternal disproportion
fetal monsters
multiple births
what are the two types of abnormalities of the birth canal? give examples
skeletal - fractures, deformaties
soft tissue - excess fat, tumour, prolapse
what is primary uterine inertia?
when myometrial contractions fail to be initiated
what is secondary uterine inertia?
myometrial contraction cease after a while before parturition is complete may be due to fatigue or blockage
what is foetal programming?
environmental cues during foetal development have long term effects of the offspring
what are the modifications to the foetal circulation?
foramen ovale
ductus arteriosus
ductus venosus
what changes occur to the neonates circulation?
foramen ovale closes - increased pulmonary circulation due to increase pressure in the left atrium
ductus arteriosus closes - reflex response due to oxygenated blood
ductus venosus closes
what is the role of surfactant and when does it develop?
prevent alveolar collapse and develops in late gestation
what happens to the lung fluid at and after birth?
physically removed and absorbed
what are the physiological stimuli of breathing?
hypoxia, hypercapnia, respiratory acidosis
what are the physical stimuli of breathing in the neonate?
lower temperature, tactile stimuli (licking/rubbing), gravity
what are the differences between thermogenesis in young ruminants and foal?
ruminants - brown fat - don’t shiver as much
foal - endogenous glycogen - shiver more
what change occurs in the liver at birth?
change from blood-forming to a metabolic organ
describe the concentration of neutrophils in the neonate compared to adults
more neutrophils in the neonate
what is the percentage activity of the complement system at birth?
10-60%
when do the calves immunoglobulins first appear?
IgA and IgM - 4 days
IgG - 8 to 32 days
is cell mediated immunity present at birth?
yes T cells are present at birth
are B lymphocytes present at birth?
yes but 1/3 of the adults - this reaches full concentration at 20 days old
what type of pathogens are neonates able to respond to?
soluble protein antigens
viral, bacteria, protozoa at 15-30 days old
when are kidneys functional and what is excreted?
kidneys become functional in the second half of gestation and excrete urine into the urachus
what two spinal reflexes develop early in gestation?
withdrawal and righting
what are two reflexes that are present at birth?
suckling reflex
pupillary light reflex
when in gestation does the foetus become able to move?
mid-gestation
how would the tendons/ligaments be described in the neonate?
have tendon and ligament laxity (looseness)
what are some features that indicate prematurity?
absence of incisors
tendon laxity (unable to support weight)
floppy ears
very fine silky coat (precocial species)
what signs are used in cattle for heat detection?
stands to be mounted mounts other cows chin pressing/licking sniffing swollen vulva with discharge
which is the most important sign of detecting cows in heat and when after this should they be served?
stands to be mounted
will ovulate 30 hours after the beginning of standing heat
what oestrus detection aids are used in cattle?
tail paint/chalk mount indicators (kamar) activity monitors
at what size will the follicle of a mare ovulate?
> 35mm
what shape does the mares follicle become before ovulation?
teardrop shape within 24 hours of ovulation
will the follicle of a mare become softer or harder when approaching ovulation?
softer within 6-12 hours of ovulation
will the follicle wall of the mare become thicker or thinner when nearing ovulation?
thicker 24 hours prior to ovulation
what is used in the bitch to determine the stage of the oestrus cycle?
vaginal cytology
when the bitch is in anoestrus what cells would you expect to see?
parabasal - round with large nucleus
when the bitch is in proestrus what cells would you expect to see?
cornified - irregular shape and small nucleus
using vaginal cytology how would you tell a bitch is coming into oestrus?
number of cornified cells increase by 10% each day until oestrus where they reach 100%
when do you know a bitch has reach dioestrus using vaginal cytology?
on day one of dioestrus there is a drop in the number of cornified cell by 50%
what are the reasons for manipulating oestrus?
poor oestrus detection
synchronisation
enable AI or ET
trigger postpartum resumption
how is the luteal phase shortened?
prostaglandin (PGF2alpha)
how is the luteal phase extended??
progesterone
what can be used to recruit/grow follicles?
GnRH
what can be used to trigger ovulation?
GnRH or gonadotropins
what is used to temporarily arrest the oestrus cycle?
progesterone
name some causes of anoestrus
pregnancy lactation - can depend how often offspring feeds season negative energy balance stress pathology/disease
what is a programme used to synch beef cattle <50 days postpartum and dairy cattle?
fixed time AI using ovsynch
describe fixed time AI for beef cattle <50 days postpartum and dairy cattle
GnRH on day 0 to synchronise the new follicular waves
on day 7 give PGF2alpha to cause luteolysis, this will remove the CL whether it is mature and ovulated or immature
on day 9 give another dose of GnRH to stimulate the follicle to ovulate
AI on day 10
describe the cycling heifers can be synchronised
2 doses of PGF2alpha 11 days apart and the AI at 72 and 96 hours after the second dose or once at 84 hours after the second dose
how does using two doses of PGF2alpha work in cyclicling heifers?
1st dose - CL undergo luteolysis then a new follicle will form and ovulate forming a new CL but if there is no CL present the follicle ovulates and CL forms
2nd dose - all have CL so undergo luteolysis a new follicle will form and ovulate
what programme is used for heifers and cycling beef cattle more than 50 days postpartum?
intravaginal progesterone devices such as CIDR or PRID placed in and then PGF2alpha is given just before they are removed
what is used to synchronise sheep flocks?
progesterone sponges are placed inside the vagina and PMSG is given on removal
what are the negative effects of using progesterone sponges in sheep?
lower pregnancy rate compared to normal
higher ram to ewe ratio needed
higher risk of triplets and quads
how is the oestrus cycle manipulated in gilts?
puberty is induced using a PMSG and hCG
2nd oestrus is then synchronised using PGF2alpha 18 days after the PMSG/hCG
how is oestrus activity stimulated post-farrowing?
prostaglandin 24 hours after farrowing then PMSG/hCG at weaning
what is the lifespan of fresh, chilled and frozen semen in the mare?
fresh - 72 hours
chilled - 36 hours
frozen - 12 hours
why is pregnancy diagnosis done?
check pregnancy
litter size
due date
sexing
using rectal palpation, what are you looking for to confirm a pregnancy?
enlarged horn fluid membrane slip foetus cotyledons fremitus
what is fremitus?
turbulence/vibration in the uterine artery
what happens during the membrane slip when rectally palpating an animal?
allantoic membrane slips through fingers just before the uterine wall
ultrasonography can be used, how long into gestation of cattle can you do this?
28 days
what are you looking for to confirm a pregnancy when using ultrasonography?
fluid filled sac that appears black
how can hormone assays be used to confirm pregnancy?
measure progesterone on day 0 and day 21 should stay high if she conceives
pregnancy associated proteins
eCG levels in the mare
oestrone sulphate
what are the advantages of artificial insemination?
large gene pool
known traits
biosecurity
no male needed
what are the disadvantages of artificial insemination?
oestrogen detection
handling animals
if you see a cow in oestrus one morning when should she be AIed and why?
in the afternoon - oestrus is 9-14 hours and ovulation occurs 12-18 hours after the end of oestrus
where do you deposit the semen when doing AI?
into the horn
how is sex semen separated?
X sperm contains more DNA so attracts more dye, the sperm are then deactivated by a laser
what can be used to trigger parturition in pigs?
prostaglandin on day 114 the sow will farrow within 36 hours
how is parturition/abortion triggered in cattle?
corticosteroid or prostaglandin depending on the how far into the gestation they are
use prostaglandin if more than 255 days
what is to used to treat misalliance in the mare?
progesterone (fluprostenol) on day 35
what is used to treat misalliance in the bitch?
aglepristone (progesterone antagonist) up to 45 days of gestation
what is used to treat misalliance in cattle?
prostaglandin from day 6 to 150
what drugs can be used to suppress reproduction?
progesterone, oxytocin, testosterone, GnRH vaccine
