REPRO ENDOCRINOLOGY POUL 4060
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This 7 page Class Notes was uploaded by Mrs. Jamil Schuppe on Saturday September 12, 2015. The Class Notes belongs to POUL 4060 at University of Georgia taught by Davis in Fall. Since its upload, it has received 56 views. For similar materials see /class/202331/poul-4060-university-of-georgia in Animal Science at University of Georgia.
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Date Created: 09/12/15
Final Review for POUL4060 o The oviduct and its different parts 0 Stressed the tissue layer wise is the same from start to finish I Some sections have more muscle than others and some have more sepatile abilities than others 0 nfindibulum Captures the ovulated egg I Middle is where you have fertilization and secondary storage of sperm I Bottom is the first part of the I Secretes albumin I Outerperivatelum layer I 20 minutes in this area 0 Magnum I Albumin is produced 0 Move into the isthmus 0 Where the shell membrane is made 0 Seed for the crystal to grow in producing the shell 0 Uterus shell gland I Here we produce the shell I The uteral vaginal junction 0 Primary storage site for sperm 0 Vagina where the egg will pass 2 tissue types Entire length of tract made of these two cells 0 Tubular gland cells 0 Sperm are stored 0 Where some albumin is made 0 Lining the lumen of the oviduct will be things that have cilia I One with cilia don t do much no secretary abilites I No ciliated are goblet cells 0 Goblets 0 Make part of the albumin Shell membranes aids in crystal formation Albumin formation and ways they prevent bacterial invasion 0 Secreted as 1 homogenous mixture and seperates as egg travels dwon the oviduct 0 Proteins that are hydrophobic make the thick albumin 0 Hydrophilic proteins make the thin albumin 0 Serves as a protector from bacterial invasion o Yolk Has the lipid minerals etc that will enable the bacteria to survive I Would love to get there due to all the nutritious material 0 Proteins have a specific function I Lysozymes will kill gram positive bacteria 0 Hurt gram negative I Ovomusin 0 Thick gell like protein 0 Gives it the thickness 0 Makes it hard for bacteria to swim through I Protease inhibitors 0 Proteins are only food source 0 Protease breaks down protein 0 Proteins you are trying to breakdown are inhibiting that process 0 Bacteria starve to death I Egg shell membranes don t offer much protection 0 Very porous to allow gas exchange 0 Main purpose is for it to become the air pocket 0 Place for the shell shell formed outside the 0 Have the shell reaction in mind when coming to the final 0 Capitalvs income breeders o Precocious eggs larger and more yolk fat and protein I Investment is in the egg I Use body reserves capital acquired prior to reproduction and use that to make the eggs Eat like crazy while laying eggs high protein and high fat foods so that she can deliver that fat and protein into the eggs income I Most birds do a combination of both I Makes a fully functional offspring 0 Factors limiting clutch size 0 Kiwi females produces an egg that is 2530 of her body weight clutch size will be 1 o How many eggs can a parent incubatephysically cover and provide heat for 0 Egg storage eggs can only sit in the nest for about 4 days without incubation before their viability starts to go down I About 45 each day after the 4 h day 0 Could incubate 20 eggs but egg 1 has over a 50 chance of not being viable I No since laying eggs that many eggs 0 Prolactin o Promotes parentalincubation behavior take care of the offspring o Produced by the pituitary gland under stimulation of VIP from the hypothalamus VIP initially stimulated slowlyby increasing day length days get longer and VIP goes up stepwise graph vipprolactin on x daylight on y light causes Gth and lh and fsh and ovary is stimulated to produce follicles which produce estrogen follicles grow gt F1 follicle source of progesterone for ovulation will produce an egg and take another level up maximum level if only 1 egg produced or a slow increase in levels at laying period your levels increase at highest level when last egg laid this levels knocks out FSH and LH levels so you can go into taking care of the eggs instead of making the eggs switches to incubation Based on sight feedback makes them incubate visual stimuli produces VIP and VIP makes them want to take care of the eggs 0 Once you start incubating it will be better if you don t leave the nest just sit there until the egg hatches eggs will cool and you have to reheat the eggs more energy with more eggs you have more difficult to heat at the beginning than at the end e penguins stay and lose V2 their body weight until egg hatches no food for 120 days 0 Brood patch on chest no feathers so that you can transfer heat Normal homeostasis is overridden cold based visodialation will protect you and maintain body heat opposite with birds when birds since cold an increased blood supply is sent to the brood patch so that more heat can be sent to the egg 0 Behavior parent sacrifices itself in order to provide and incubate the egg 0 Incubation o 2 key components Water loss too much water in the egg lose that water creates the air cell need to lose roughly 1115 o if you don t lose enough the chicks are wet and mushy if they survive the hatching may not survive because the air cell is not there 0 too much water loss egg is dry and the embryo will not have enough fluid will be dehydrated and its kidneys wont develop normally 0 decrease humidity to water 0 Increase humidity to lose too much water temperature to be 94100 degrees 0 more flexibility with cooling 0 if embryo is too hot minutes to hours at high temps will cause a heart attack increases its heart rate and heart tissue is permanently damaged 0 cooling days at cool temps so cool the heart will stop beating the ability to do this is greater when you are younger child in frozen lake can be under for a few hours body goes into a stasis but older people will die same thing with embryos o hatching synchronous hatch 0 all hatch within a 24 hour period typically precoccial offspring o clicking sounds further along eggs will hurry along the later eggs will hatch sooner will send messages to older egg to slow down will try to time hatch to be equal mother can influence this as well based on egg compostion and size small eggs develop quicker than large eggs after incubation of ls egg she will lay a smaller egg will also produce small eggs early and will put a great deal of lipid in that egg as well will cause the egg to stay in the egg for a few more days to delay hatch o asynchronous hatch less successful altricial species 0 all the work is after the hatch if they all hatched at the same time they would reach the llteenage years at the same time and won t have enough food stagger births to keep the workload reduced 0 most altricial species will over produce if they have enough food great but if they don t the older you are the more likely you will survive siblocide based on hierarchy no wasted energy fighting each other for dominance because the older eggs are dominant 0 insurance species will produce 2 eggs will only raise 1 will kill off the second if the 1st lives have backups just in case older eggs don t make it o embryology 0 early embryo divides exponentially totally totipotent can take any of those cells and make any body part 0 more cell mass will cause them to specialize 0 go through gastrulation make the differ derm layers that will become the different parts of the bird 0 once in those tract still totipotent but just specific for derm layer I totipotency decreases as development increases 0 need to grow in a liquid environment away from the yolk 0 extra embryonic membranes 0 yolk sac membrane 1st to develop brings 02 and nutirents to the early developing embryo 0 then form the amnion and chorion I amnion forms a sac around the embryo filled with fluid provides protection against mechanical shock allows for the free movement of the embryo critical for limb development I chorion has no function by itself will ultimately join with the alentois o chorioAlintois fuses with the choiron source for respiration delivers coZ away from the embryo brings calcium to build bones waste products deposited away from the embryo deliver water from albumin back to the embryo will be left behind after hatch unlike the yolk sac absorbed into the body to provide food and water for the 151 24 hours 0 formation of the avian circ system I 2 peak periods April 18 2011 Final May 6 in class same format as other 3 tests complete study guide given out today last few lectures will be review 80 of points of nal will be focused on last fourth of material and 20 will be pulled from previous three exams no specific details from previous sections only big facts review by going through old exams Prolactin parental behavior causes crop milk production in some birds key role in making birds incubate eggs Incubation Strategies 1 Use sun done by Megapodes Nturkeys put eggs in mounds and based on temperature different sexes yielded unusual strategy precotial babies hatch 2 Some birds don t like to take care of their babies deposit to let another bird take care of their babies prolactin highincubate any egg and feed the baby after hatch rare in most American species 100 species do this worldwide 3 Traditional method lay eggs parents incubate eggs in nest until hatch 0 Heat transfer via brood patch Heat Transfer Via brood patch under prolactin feathers in breast fall out increase in vessel number and size increased heat by blood transferred directly to eggs transfer of heat from parent s body to the eggs hardest in beginning embryo developing a long way away in yolk so parent has to heat the entire egg itself but once embryo matures it generates its own heat via metabolism and blood supply helps move heat from parent on outside of egg into and transferred within egg incubation is easier for parent as development proceeds cold vasodilation state of homeorhesis overriding normal mechanisms prolactin overrides normal mechanisms when bird senses eggs are cold increase in supply of blood to the brood patch opposite usually happens because normally in the body coldvasoconstriction Outside temperature down or increased number of eggs decrease in efficiency of heat transfer Incubation Behavior Higher energy demands associated with incubating larger clutcheslarger eggsin cold temperatures Looking for food less time at nest likely to attract attention from predators what to do to overcome this leave nest less often but when they do leave leave for longer amounts of time predators in Southern tropical areas it is warm and birds have longer lifespan and can reproduce several times in their life thus they avoid predation risk and higher chances of nest abandonment Hatching Synchronous less than 24 hrs apart All of the eggs within the nest will hatch within 24 hrs ie Wood ducks jump out of the tree at the same time so whichever duckling didn39t hatch in time to go with its siblings will not survive in the tree cavity The mom and babies never return to the nest after they leave so it s vital for all the babies to hatch together Asynchronous greater than 24 hrs can be greater than 2 weeks and this results in size hierarchy Asynchronous hatches tend to have lower edging success rates meaning that the total of surviving individuals from that nest will be less in comparison with a synchronous hatch However most bird species incubate in an asynchronous manner So what is the evolutionary reason for choosing the less ef cient hatching strategy Incubation Onset Fast Onset This occurs when the parents begin to incubate as soon as the eggs are laid Slow Onset The parents do not sit on the eggs at all or incubate inconsistently Temperature may be freezing at night so the birds will be forced to sit and incubate at night even if they don t want to initiate incubation In other cases the eggs may be exposed to high temperatures during the day due to the sun beaming down so the eggs will be incubated by the sun during the day but not at night by the parents The time from the start of egg laying until the onset of incubation is longest when the hatch is synchronous so that all the eggs begin incubation at the same time when the last eggs is laid The time from first hatching to all edged is shortest with synchronous because all the hatched chicks will be the same age will be developing at the same rate and will be gone at the same time Therefore the time that the nest has babies is least with synchronous hatch Precocious chicks are synchronous for the most part Incubation Onset Precocious chicks are synchronous for the most part even though incubation will many times be initiated before the last egg is laid The chicks are able to communicate and therefore hatch together Embryo communication is done with clicking sounds or vibrations the faster the clicking the more the surrounding embryos will be accelerated and the slower the clicking the more the surrounding embryos will be delayed So the embryo in the first egg will produce faster clicking vibrations high frequency to tell its siblings to hurry up and the embryo in the last egg that was laid will be producing slower clicking sounds lower frequency to tell it s siblings to slow down In this way up to 4 days of asynchrony between the chicks can be abolished however the eggs must be touching in order for the vibrations to be carried from egg to egg Incubation Onset In addition to embryo communication precocious chicks are also synchronous due to the nutrient provisioning allocated to the eggs by the female depending on where they fall in the sequence of her clutch 2 Egg composition ie Wood duck sequence Slide 10 Small eggs are laid first and last because they development faster since the embryos are smaller Large eggs development slower since the embryos are bigger and have bigger mass Higher lipid content in early eggs may allow developed embryos from the fist eggs to delay hatch because the lipid provides extra energy for the chick to utilize while its waiting on its siblings to catch up The samll embryos in the small eggs that are laid rst require less energy for maintenance so that they can be sustained for longer by the extra lipid energy Incubation Onset Accelerate mallard ducks 13 days acceleration of the embryos in the eggs that were laid last Delay Bobwhite quail pheasants 12 days delay of the embryos that are developing in the eggs laid rst Extra day of incubation in not desirable because the nest may be found by predators and because the extra day depletes more of the energy reserve of the chicks so it is less desirable than an accelerated incubation method Incubation Onset Altricial chicks are generally asynchronous why Lack 1947 original hypothesis When a species has a food supply that is unpredictable at the time of egg laying then parents should lay an optimistic clutch If resources turn out to be scarce asynchronous hatching enables parents to reduce brood size by killing the youngest of the brood to t the available food resources to the number of chicks in the nest This was widely accepted even though not tested and eventually proven wrong in the 1980 s Today we realize there are many reasons that vary depending on the habitat and species Asynchrony Hypotheses for and against Energy constraints during lay if food is abundant the female will not have to spend time looking for food so she will be able to start incubation immediately Iffood is not as readily available the female will not be able to start incubation immediately so her brood will end up asynchronous Hormones ie Prolactin is needed to shut olT the follicular development so that the bird stops laying eggs and begins to incubate but the last egg that has ovulated will still be in the tract while she begins to incubate the other eggs This means that the last embryo is 24 hours behind the rest of the eggs in the nest Egg viability there is only so long before the embryo in the rst egg can survive The longer the it has to wait to begin incubation the lower it39s survivalhatchability rate Egg protection if the bird is in an environment where there are many predators or if you are in a colony the parents will be forced to begin incubation simply because they have to stay in the nest to protect the egg Classic example the Gentoo Penguin To avoid asynchrony the rst egg is very small while their second egg is very large so when the 2quotd chick hatches it is roughly the same size as its sibling Limiting breeding opportunities very similar to egg protection but space is not available so the parents have to stay on the nest so that they don39t lose the space for their nest Example Sand swallows Brood parasitism Birds that are paracitized by other birds need to stay in their nest to prevent nest paracitism Brood paracite birds such as the cuckoos lay their eggs in the nests of other species so that those birds will take care of their young and the cuckoos don t have to
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