Breeding And Reproduction Flashcards
Polyoestrous
Cycles all year round e.g. Cows
Seasonal polyoestrous
Regular cycles during a certain time of year
Long day- horses
Short day- sheep
Mono oestrous
1 oestrous in a year eg bitches
Seasonal effects on male reproduction
Low testosterone production
Reduced sperm motility
Behavioural factors
Seasonal affects on female reproduction
Many females have a breeding season
E.g. Horses, come into season during spring summer, will become receptive to male, GnRH pulsing impulses starts ovulation.
Sheep have an autumnal breeding season.
Mechanism by which seasonal breeding is effected?
Melatonin!
Declining daylight leads to increasing melatonin but species response is different.
Depressed reproduction in long day breeders e.g. horses.
Short day breeders eg sheep require declining photoperiod , increasing, melatonin to stimulate GnRH.
3 ways in which seasonality can be used to manipulate breeding
Expose animals to artificially lengthened or shortened days e.g. Cover cage, turn lights out (hens)
Change latitude - shuttle stallions
Give melatonin- implants to advance cyclicity in ewes
Give 3 non reproductive examples of the importance of seasonal effects for husbandry
Body weight
Behaviour
Appetite
State oestrous detection aids for a variety of species
Visual signs- bulling, ride marks, bulling string (cows)
Tail paint/ chalk, mount indicators (cows and sheep)
Pedometers (cows)
Follicle observation in mares - 35mm, tear dropped, soft, thick wall
Vaginal cytology in bitches. Pro oestrous, cells become cornified.
Reasons for manipulation of oestrous
Poor oestrous detection
Synchronisation
Enable AI at same time
Trigger post partum resumption
Explain effects of commonly used hormones on oestrous cycle
Luteal phase?
Follicular waves?
Arrest?
Control luteal phase? Shorten- prostaglandins. Lengthen- progesterone
Manipulate follicular waves? To start-PMSG or eCG. Stimulate ovulation? GnRH or hCG
Temporary arrest ? Progesterone
Cause of anoestrous?
Pregnancy Lactation Season Stress Negative energy balance
Describe one possible protocol to achieve oestrous synchronisation in cattle
Fixed time AI cows- ovsynch Day0 GnRH, synchronise new wave emergence Day 7 PGFa causes luteolysis Day 9 GnRH control time of ovulation Day 10 AI
Use of exogenous progesterone
Intra vaginal devices eg PRIDs and CIDRs
When removed all will start cycling at same time, can AI at same time.
Give PGFa 24 hrs before removal to remove an CL
AI 56 hours after removal
What are the three stages of spermatogenesis?
1 proliferation. Mitosis. SPERMATOCYTOGENESIS. Stem cell renewal
- Meiotic. SPERMATIDOGENESIS. Primary spermatocytes. Haploid
- Differentiation. SPERMIOGENESIS. No further cell division. Spermatozoa
Goals of spermatogenesis
Generate spermatozoa
Create and replenish supply of stem cells
Create genetic diversity
Stages from spermatogonia- spermatozoa
Spermatogonia (in basal compartment)
Spermatocytes (cross sperm testis barrier)
Spermatids (in luminal compartment)
Spermatozoa
How is stem cell stock replaced?
Some spermatogonia don’t continue process to become spermatozoa, some will regenerate back to stem cells
Spermatozoa features
Head
Tail
Head? Nucleus and acrosome and nuclear cap
Shape varies
Acrosome contains hydrolytic enzymes required for penetration of zone pellucida
Tail? Self powered flagellum
Middle piece contains mitochondria for energy
Spermatogenic wave
Regina along seminiferous tubules are at different stages of development
Get continual trickle release
Endocrine regulation of males
Hypothalamus- GnRH -> Ant Pit- LH and FSH
LH-> leydig cells- testosterone -> Sertoli cells
FSH-> sertoli cells —> produces testicular fluid
All effected by negative feedback
Spermatozoa?
Produced/matured/stored
Produced in Testis
Matured in head and body of epididymis (develop motile capacity)
Stored in tail of epididymis
Compensate effect?
Problems which can be compensated with large numbers eg motility
What are spermatozoa very sensitive too?
Temperature
Water- spermicidal
Bright light
Sperm testis barrier?
Stops immune system getting into adluminal compartment
After meiosis spermatogonia are genetically different than body cells so immune system will destroy them
Advantages of AI
Large genetic pool Known traits Bio security No male needed-safer for stockman Vastly multiplies genes from exceptional males
Disadvantages of AI
Need good oestrous detection
Correct straw storage
Need training
Can be costly esp for sexed semen
Methods of pregnancy diagnosis
Ultrasonography- transrectally around 20 days
Palpating- abdominal and foetal ballot, take care
Radiography- skeletons need to be calcified. Avoid in first two trimesters, risk to foetus
Explain the AM PM rule
Oestrous on average lasts 9-14 hours in cows and ovulation occurred around 12-18 hours after end of oestrus. If oestrous is seen in morning, AI that afternoon. If oestrous seen in afternoon, AI following morning.
Where is semen deposited during AI
Through cervix into uterine horns
State drugs that could be used to control parturition
Sow- PGF2a around day 114, give birth within 36 hrs, CL dependent
Cow- PGF and corticosteroids opens birth canal and primes neonate, can get long, medium and short acting.
State drugs that couples be used to temporarily suppress reproductive function
Delvosteron- progesterogen. Cats dogs and ferrets. One injection at start of proestrus
Oxytocin- mare. Give week or two after ovulation to extend CL life
Tardak in male dog to suppress of hyper sexuality
Drugs that can be used to treat misalliance
When you don’t want animal to carry on pregnancy
Mare- fluprostenol (PGF) at day 35
Cow- PGF2a between day 6 and 150
Bitch- do not use prostaglandins. CL quite resistant. Use oestradiol benzoate. Day 3 and 5
Reasons for embryo transfer
Multiply superior genetics especially with species with long gestations
Reasons for in vitro methods of reproduction
Genetic diversification
Rare semen can be used on multiple females
Reasons for controlling litter size
Dairy and horse- twins undesirable
Describe what anatomical and physiological changes take place to life ex uterine with regard to cardiovascular system?
Closure of foramen ovale- starts lung circulation, increase pressure in left atrium
Closure of ductus arteriosus- reflex response to oxygenated blood
Umbilical vessels. Veins collapse and arteries contact
Describe what anatomical and physiological changes take place to life ex uterine with regard to respiration
Alveoli. Altricial young still developing post partum
Surfactant- prevent alveoli collapse, develops late gestation
Lung fluid- physical removal during parturition
List four natural stimuli of respiration and how these may be utilised to resuscitate a neonate
Physiological
-hypoxia, respiratory acidosis
Physical
Lower temp - rub with towel to dry and raise temp
Tactile- rubbing, tickling nose
Gravity- gently tip upside down
Outline capabilities and development of immune system
Full capabilities only after birth, more neutrophils than adults
T cells all at birth
B cells 1/3 of adult at birth
Ability to respond to antigens at birth
Viruses, bacteria and Protozoa until 14-30 days
But often not a full response
State a breed or species specific example of thermoregulation
Ruminants have a supply of brown fat
Foals use endogenous glycogen
Describe the capabilities and adaptations with regard to GI tract
Gut flora takes several weeks to become established
Live changes from a blood forming organ to a metabolic organ
Describe the capabilities and adaptations with regard to renal function
Kidneys functional from second half of gestation. Urine excreted via urachus
Post partum higher glomerular filtration rate
High levels of renin and aldosterone
Large volume of hypotonic urine
Describe the capabilities and adaptations with regard to neurological system
Spinal reflexes developed early eg withdrawal and righting
Skin sensation developed
Suckling reflex present
Describe the capabilities and adaptations with regard to musculoskeletal adaptations
Foetal movements mid gestation
Bones well ossified
Wide stance and exaggerated gait
Tendon and ligament laxity
List 2 body features that may indicate prematurity
Silky coat
No incisors
Over extended limbs
Floppy ears
Describe normal stages of parturition
Complex cascade of endocrine events initiated by foetus
Initiation of my one trial contractions
Expulsion of foetus
Expulsion of foetal membrane
What is foetal disposition?
Spatial arrangement of the foetus in relation to pelvis and birth Canal
Can be normal or abnormal
Three terms used to describe disposition?
Presentation
Position
Posture
Foetal presentation?
Can be anterior, posterior or transverse
Foetal position
Can be dorsal, ventral or lateral
Foetal posture?
Disposition of the head, neck and limbs
Eg flexed, extended and direction
Common causes of dystocia
Expulsive forces insufficient
Birth canal of inadequate size or shape
Size or disposition of foetus means it’s unable to pass through birth canal
Foetal dystocia
Maldisposition
Feto-maternal disproportion
Foetal monsters
Multiple births
Maternal dystocia
Abnormalities of birth canal- skeletal or soft tissue
Incompetence of cervical dilation
Uterine torsion
Expulsive deficiency
Uterine inertia
A) primary uterine inertia
Deficiency of contractile potential of myometrium
B) secondary uterine inertia
Inertia of exhaustion
List economic, health and welfare implications of dystocia
Increased stillbirth and mortality of offspring
Increased dam mortality
Reduced productivity of dam
Less offspring less profit
Outline care of neonate after dystocia
Do not rupture umbilical cord- will rupture naturally. When does dip naval
Remove foetal membranes and ensure is breathing
Colostrum!
Outline care of dam after dystocia
Always check for another foetus
Check for injury to reproductive tract
Pain relief
Good nursing care
