1
Q
mating
A
union of male and female gametes
- requires a mating behaviour
- accomplishes delivery of sperm containing semen to a mature ova or egg
- mating occurs at peak if female fertility
- reinforce social bonds, status and pleasure
2
Q
internal fertilization
A
- sperm enter vagina
- sex act
- sexual intercourse
- coitus
- copulation
3
Q
mating behaviour
A
- when suitable partners are found, species-specific courtship behaviours can be initiated
- males of domestic species that naturally herd utilize considerable time detecting estrus within the group
- estrus females of many species produce and secrete pheromones for attracting males ( males smell the perineal region of females to detect odour)
- female pheromones can induce the flehman reaction in bulls, rams, stallions camels)
- raised head posture and elevation of the upper lip
4
Q
male sex act
A
- straightening and hardening of the penis for entry into the vagina = erection
- ## forceful expulsion of semen into the urethra and out of the penis = ejaculation
5
Q
sexual response cycle
A
- excitement phase: erection and heightened sexual awareness ( in primates at the least)
- plateau phase: intensification of above response but also including increased heart rate, blood pressure, respiratory rate and muscle tension
- orgasmic phase: ejaculation and stimulation of neural signals in pleasure centre of the brain
- resolution phase : genitalia and body systems return to a pre arousal state
6
Q
erection
A
- in species with considerable erectile tissue in penis
- body of the penis has three columns of spongelike vascular spaces along length of organ
- very little blood in these spaces in non-aroused state ( due to arterioles normally providing blood being constricted and venous drainage maximized
- in sexual arousal, arterioles dilate, erectile tissue fills with blood and erection occurs ( reductions in venous outflow enhance erection and blood filling of vascular spaces compresses veins thereby decreasing that outflow
7
Q
erectile reflex
A
- spinal reflex triggered by mechanoreceptors in the glans penis
- increased parasympathetic vasodilator activity to the penile arterioles mediated by nitric oxide
- erectile dysfunction in humans is treated by drugs that stimulate nitric oxide production
- local vascular repsonse of increased arterial inflow and mechanicallt reduced venous outflow are initiated by erection generating centre
- found in sacral region of spinal cord
- parasympathetic vasodilation causes relaxtion of penile arteriar smooth muscle by production of nitric oxide
- induces soluble guanylate cyclase in smooth muscle cells to produce cyclic guanosine monophosphate which induces relaxation
- parasympathetic control in penile arterioles is unique in vessels
- both decreased sympathetic activity and increased parasympathetic activity accomplished more rapid and greater vasodilation
8
Q
ejaculation
A
spinal reflex - same stimuli that cause erection but only when excitation intensifies to critical peak
- two phases
emission: sympathetic impulses causes sequential contraction of smooth muscle in the prostate, reproductive ducts and seminal vesicles
- devilers semen into the urethra
expulsion: filling of the urethra with semon triggering nerve impulses that activates skeletal muscles at the base of the penis
- contraction increases pressure within the penis, forcibly expelling the semen out of the penis
9
Q
orgasm
A
- pelvic and penile muscle contractions as well as systemic responses that culminate the sex act - driven by oxytocin release
- accompanied by intense pleasure in humans
10
Q
resolutions
A
- sympathetic vasoconstrictor impulses increase to slow blood inflow in penis - erection decreases
- muscle tone normalizes and cardiovascular and respiratory systems return to pre arousal activty
11
Q
female sex act
A
- excitement, platue, orgasm and resolution
- tactile stimulation of clitoris and surrounding perineal area ( pelvic floor around genitalia) is especially powerful - same spinal reflex
- parasympathetic induced vasodilation of arterioles throughout the vagina and external genetialia; erection of the clitoris
- fluid entering the vaginal lumen from congested vaginal capillaries in the primary lubricant
12
Q
plateau phase in females
A
- increased heart rate, blood pressure, respiratory rate and muscular tension
13
Q
orgasm in females
A
- sympathetic impulses trigger rythmic contraction of the pelvic muscles
- produces oxytocin
14
Q
assisted reproduction technologies
A
- reproduction animals is an energy-intensive process
- with respect to domestic species: energy inpuf for food production from animals sources is decreased by increasing the # of offspring per unit of time the breedinf female can produce in the herd
- reproductive technologies can direct the strategies used to select animals genetically for traits that benefit production
- imporved ART could help meet the challenges anticipated with increased worl population
- ART can assist in the saving of ever increasingly rare wild species
15
Q
Artificial insemination
A
- most frequently used ART
- most impact on livestock production ( predominant in dairy cows)
- dependent on semen collection, assessment and cryopreservation from male
- electroejaculation and artificial vaginal/phantom methods most common for obtaining semen from male
- dependent on ensuring appropriate numbers if capable sperm are deposited in the female reproductive tract and at the appropriate time close enough to ovulation to aid fertilization
16
Q
improvements in sperm storage
A
- advances in AI use due to
- extenders - reagents to extend protection/life of semen
- improved methods for storage of sperm in liquid and frozen forms
- distribution increased geographically and temporally
- in cattle pregnancy using AI with frozen semen now are similar to those with matural mating
- sub optimal pregnancy rates still in pigs and small ruminants but advances likely to change this soon
17
Q
extenders
A
- iso osmotic (equal osmotic pressures
- good buffers ( pH 6.8-7)
- dilution shock protection (protein )
- cold shock protection (22-4C (egg yolk)) (4 to 196 C cryoprotectants)
- energy substrate (fructose)
- bacterial contamination (antibiotics)
18
Q
cryopreservation
A
- once semen mixed with extenders, semen is placed in straws
- cooled to 4C
- frozen and stored in liquid nitrogen
- can be stored for decades
19
Q
identifying estrus in females
A
- effectiveness has varied in the past
- development of estrous synchronization programs has helped a lot
- regulating luteolysis, follicular growth, ovulation means in some situations management of estrus detection is not required now
- now have timed AI schemes
20
Q
why has effectiveness of identifying estrus in species varied in the past
A
- lack of overt symptoms of estrus in the ew ( in the absence of male)
- prolonged estrus in the mare
- lack of physical access to females when extensively managed such as in beef cattle and sheep
21
Q
where should semen be deposited
A
- for optimal AI, semen is directly deposited into the uterus
- relatively simple in cattle and horses due to size of female ( rectal palpation of reproductive tract to aid placing of AI pipette through cervix
- advances have helped increase use in smaller animals
22
Q
sexed semen sorting
A
- development of flow cytometry techniques in 1980s allow separation in 1980s allow separation of X from Y bearing sperm
- based on DNA content, introduced to US for cattle AI on widescale in 2005
- approaching 90% success rate
23
Q
what are some problems with sexed semen sorting
A
- sperm damaged and yield
- loss of sperm during sorting
- lower fertility rates
- cost of flow cytometer system
24
Q
who generally uses sexed semen
A
- dairy is the biggest user
25% Australian dairy farmers
50% in UK
10-25% in canada depending on breed - beef has started to use it more
25
advantages of embryo transfer
- increase number of offspring from animals of higher genetic value (efficiency of embryo transfer still needs to increase wide genetic improvement)
- increase production of offspring in monotocous species
- circumvent seasonal reproduction
- increase number of quality offspring from animals with reproductive tract disorders
- increase number of offspring of endangered species
- enhanve genetic diversity across a wide geographical region ( by shipping embryos rather than animals
26
step 1 of successful embryo transfer
- synchronization of recipients with donor
27
step 2 of successful embryo transfer
- superovulation of donar
28
step 3 for successful embryo transfer
- inseminate donar with semen from genetically superior bull
29
step 4 for successful embryo transfer
- recovery and identification of viable embryos
30
step 5 for successful embryo transfer
- transfer of viable embryos into synchronized recipients
31
who uses embryo trasnfer
used in cattle and more limited entent currently in horses ( both helped by advances in cryopreservation techniques i e no need for recipient synchronization just after collected of embryos
32
embryo quality
- standards are set by the international embryo transfer society
- blastocyst - pulsed expansion/contraction of blastocoel
- morulae - surface clean and embryo showing compaction
33
disadvantages to embryo transfer
- in terms of numbers of offspring produced ( AI from single bull 1000000s of offspring, ET to single cow with most intensive programs 100s)
superovulation response: poot in some species like horse
- can lead to poor viability of embryos
- recovery of embryos from tract - needs surgical procedures in pigs and small ruminants
34
ET in bovine
- particularly for fertility enhancement ( most examined in dairy cows)
- effects of climate change may increase use ( heat stress when fertility is low)
- global numbers 2010 for et using vivo derived embryos 600 000
- for ivf and et 300 000
35
ART in wildlife species
- the ability to cryopreserve blood products. DNA, tissues, cells, reproductive material in wild species at san diego zoo in 1975
- this greatly assisted the expansion of possibilities for ART
- ART required significant knowledge of reproduction anatomy and physiology of a wild species to be succeeful
- largely used in mammals and birds
- limitations for other species
- will likely be the ket to stop mass extinction and irrevesible loss of keystone species
- particularly when smell numbers of founder individuals exist
- infertile due to old age
- distances between individuals is large
- being used for many species now such as rhinos and bison
36
somatic cells nuclear transfer
- enables preservation and rederivation of elite animals or endangered species
- opened novel roles for livestock breeding
- genetic manipulatio?
- first cloned animals ( amphibians in 1952)
- has been successfully used in cattle hotse pig and sheep = dolly the sheep
- practical applications are still changing
37
what are some problems with SCNT
- low efficiency of cloning (5%)
- malformations, abnormalities in cloned animals
- high cost and technologically demanding
38
Animal Physiology
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