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Author Topic: How is litter size decided?  (Read 10560 times)

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hope

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How is litter size decided?
« on: November 13, 2006, 07:39:53 AM »

I have recently got a very good male from a very good breeder because he is a prolific breeder who has a tendency to sire litters of triplets & has sired  so many kits in a short space of time that the line would have been overpopulated if they kept him longer. :2funny:
Of course, I am absolutley over the moon  :::grins::
Anyway, I have been thinking about him throwing the litters of triplets despite being with 4 different females  at any given time & was wondering if any of you  who have kept records for years  have noticed whether certain males produce the same size litters & how do you think litter size is decided?
I have one female who is 12 now & retired here but my friend kept her for years & she told me she only ever had one litter a year containg a single kit & she did the same here producing a single kit a year so I am interested to know what you think?
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Re: How is litter size decided?
« Reply #1 on: November 13, 2006, 08:18:42 AM »

::silly::It takes two to tango.   :D

It depends on both ... how fertile the female is and the sperm count of the male ... and whether she beats him up the first time ... and if he goes back for more.   Or he is fast enough to get away before she can beat him up.   

If a female only drops one good egg that will = only one kit or identical twins.

If the male does not have a good sperm count ...  ::shrug::

If one or both are infertile ...  ::shrug::

Multiple kits in a litter lets you know the potential is there due to the genes, but does not always carry through.

Many breeders will not even consider breeding a single "only kit" for this reason.

 ::wave::
Jo Ann
« Last Edit: November 16, 2006, 05:58:50 AM by Jo Ann »
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Re: How is litter size decided?
« Reply #2 on: November 13, 2006, 04:08:46 PM »

The males need to have a good sex drive and a good sperm count but the female determines how many eggs there are to fertilize and therefore how many babies can be had in a litter.  As Joann said many breeders believe that females born to mothers who have large liters will be more likely to have large liters. 

As far as having lots of babies; some males just have a greater sex drive.  I have two males that will keep every girl pregnant.  Each female will get pregnant within the first month they are open to him without fail!  Other males are more laid back and their girls can go months without getting pregnant.  ::)
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RMC

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Re: How is litter size decided?
« Reply #3 on: November 13, 2006, 07:22:24 PM »

Litter size potential  is determined largely by genetics. and yes tendancy's for larg litters is a inherited. Yes sperm count,egg count, how active a breeder the male is will influence litter size .But all these are geneticly influenced. Just as tenedancy's for twins,high%of girls ,or high %of males born run in human families. the same can be said for chins as well.
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ChinchillAZ

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Re: How is litter size decided?
« Reply #4 on: November 13, 2006, 10:48:10 PM »

I don't know how much I believe that...  Granted, I only have 8 breeding pairs and only 5 of these pairs has had multiple litters, but I have not found the number of kits to be consistant and they are always with the same mate.

Clyde (Standard) and Avra (BV) produced triplets with their first litter, but then had single kits for their next four litters.
Z (Mosaic) and Mabel (BV) produced triplet with their first litter and had a single kit in their second litter.
Koontz (Dark Ebony) and Bonnie (Standard) produced twins with their first litter, triplets with their second litter, and twins for their next two litters.
Kent (Standard) and Kalli (Mosaic) produced twins for their first three litters, then had a litter of triplets, and most recently had a single kit.
Harold (Beige) and Henna (Dark Tan) produced twins in their first three litters, then had a litter of triplets, and most recently had another litter of twins.

I had two Ebonies in breeding previously.  They produced twins for their first three litters and then had a single kit for their last two litters.

I'm not saying that genetics don't play a role of any kind, but I think there are some things you can't just predict.

I recently read something that Gary Neubauer had said about how you'll have more females born if you keep the chinchillas in a colder climate and that, if they are in a warmer climate, they will produce mostly males.  I was very interested in this theory.  A friend of mine who also happens to be a breeder told me that she has only had one male born and all the rest of the kits have been female.  The first thing I asked her was what temperature she kept her house at and she told me that she kept the thermostat at 75, which is the same temperature I keep my home.  I guess some theories just don't always prove true, even if they are most of the time.  *shrugs*

RMC

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Re: How is litter size decided?
« Reply #5 on: November 14, 2006, 12:17:26 AM »

Every time a person gives birth from a family that is prone to have twins aren't twins either. But that doesn't change the fact that if you are from a family that has had twins with out fertility treatment you have a much higher probability to have twins.
Most of the longtime breeders. track litter size and they say that litter size is influenced by genetics. You have a slightly higher then 50% chance in any pregnancy to give birth to a boy. but that doesn't mean that if you have 10 kids you will have 5 boys and 5 girls,actually the chances of that are very slim. But that doesn't change the fact that if 10,000 kids are born just over 50% will be male.
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chinclub

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Re: How is litter size decided?
« Reply #6 on: November 14, 2006, 06:28:42 AM »

you'll have more females born if you keep the chinchillas in a colder climate and that, if they are in a warmer climate, they will produce mostly males. 


I've heard that a lot too, however, I don't find it to be true in my herd.  I have 100 chinchillas in breeding.  In the summer their building stays between 69-73.  In the Winter it stays in the mid 50's.  Thats almost a 20 degree difference.  I have noticed no trends of a higher number of a certain sex depending on temperature.

Does anyone know the scientific reasoning behind this theory?  ::think:: If I remember my Biology correctly doesn't the male sperm determin the sex?  Does temperature somehow cause more of one sex sperm to be created hormonally?  It would have to be triggered by some chemical change in the body because the sperm and eggs don't know the difference.  The chinchilla body temp shouldn't change with the outside air. 

I'm not saying its not possible, I would just like to know the reasoning behind it.  ::shrug::
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Re: How is litter size decided?
« Reply #7 on: November 14, 2006, 06:46:59 AM »

::silly::
 
I have found that, not that many people (newbies) understand the percentages apply to each litter separately, not with all the litters produced put together, some will think:

A pair that is made up of one standard gray and one black velvet gives them a 50-50 chance of having a black velvet or a standard gray, or one of each.  Then they make the mistake of thinking, since the pair had a black velvet this time, they will have a standard in the next litter ... nope, that's not the way it works ... the percentages start all over with each litter.

I get so many e-mails wanting to know when a certain color chin will be born ... people can not seem to understand that they are just like human babies ... you don't know what color their hair will be till they get here.  You may know the possibility is there, but you can not say for sure. 

We keep our temperature set at 66 year round and we have just about an equal number of males and females.  Some years we seem to have many more males and other years more females, but we never change the setting on the thermostat ... it stays at 66.

 ::wave::
Jo Ann
« Last Edit: November 14, 2006, 06:51:43 AM by Jo Ann »
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Debbie.nl.ca

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Re: How is litter size decided?
« Reply #8 on: November 14, 2006, 10:59:06 AM »

Quote
Every time a person gives birth from a family that is prone to have twins aren't twins either. But that doesn't change the fact that if you are from a family that has had twins with out fertility treatment you have a much higher probability to have twins.
This only holds for the females, they are the ones sending down the seeds, and no matter if the male is one of a twin he will have nothing to do with his mate having twins.
He decides the sex of the babies or chins, not the number.
Unless one sex of sperm cells swim better in a certain temperature I can't understand how it would effect breeding habits either.
There was talk about lighting playing a roll, but unless they are kept in total darkness or full light 24/7 I can't see it playing much of a roll in their breeding. As long as they can tell day from night they seem to react the same.
I see no difference in my breeders in the summer or winter, when lighting and temps. change.
I seem to have spurts of male kits born and female, then some seasons it's 50/50.
As our temperatures change drastically here with each season, and we do daylight savings time, it gets dark at 6pm now, I would think I would see some changes in the chins if there was going to be any.
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Abby W.

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Re: How is litter size decided?
« Reply #9 on: November 14, 2006, 12:14:16 PM »

Actually, I can see how temperature and lighting might affect breeding, because it affects their natural environment.  I know with some mammals, elephants for example, will produce more male or female offspring depending on the environmental conditions.  In times of plenty they will produce more males because their investment in males is less and males have the ability to produce greater number sof offspring by mating with multiple females.  But in harder times they will produce more female offspring, and will even abandon live male babies in favor of females because the females are hardier and have a greater chance of survival.  This strategy apparently maximizes the potential for an individual animal's genes will be passed on. 

So...maybe the lighting or temperature changes simulate some sort of environmental change that triggers a particular instinctive or biological response for the mothers, thus leading to a greater production of males or females, depending on the response the environment triggers.

Yeah, for college biology and darwinian theory!!!   :)
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RMC

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Re: How is litter size decided?
« Reply #10 on: November 14, 2006, 07:18:08 PM »

Males will effect litter size , It doesn't matter how many eggs are present if the sperm isn't viable if /when it arrives at the eggs.
sperm quality is a factor in the number of offspring born.
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hope

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Re: How is litter size decided?
« Reply #11 on: November 15, 2006, 10:15:19 AM »

Jo-Ann that is really interesting that some breeders don't breed from a single only kit because they think potentially they may only produce single litters.
so although the female determines how many eggs there are that could be fertilised the males sperm is just as important as his sperm  has to fertilise them so really everybody is right!
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Jo Ann

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Re: How is litter size decided?
« Reply #12 on: November 16, 2006, 06:57:25 AM »

::silly::
Quote
some theories just don't always prove true
That's why they are called 'theories' ... just like 'rules' are made to be broken ... nothing is a sure thing.
Quote
As our temperatures change drastically here with each season, and we do daylight savings time, it gets dark at 6pm now, I would think I would see some changes in the chins if there was going to be any.
Chins have internal 'clocks' ... don't think they go on daylight savings time ... that 's just for us humans.   :blush2:
Quote
In times of plenty they will produce more males ... But in harder times they will produce more female offspring, and will even abandon live male babies in favor of females because the females are hardier and have a greater chance of survival.
If that were true for chinchillas ... if we wanted all females, we could starve the mommas ... and if we wanted males we could stuff the mommas.  Maybe in the wild, but not in a breeding situation where they all get equal food year round ... year after year.
Quote
Jo-Ann that is really interesting that some breeders don't breed from a single only kit because they think potentially they may only produce single litters.
  ::silly::The size of litters can be genetically influenced.  If you want only a kit or two now and then, I would put two "only kits" together.  If you want large litters, I would put two chins from two different large litters together.  If it does not matter to you, then ignore the number of kits in the litter they came from.   They will not always have single kits or large litters, in every litter, but should, over time, average about the same.
Quote
so really everybody is right!
To a certain extent.   ;)
  All factors have to be considered ... including their mental state of mind ... a chin that is happy would probably take better care of her kits and maybe even have healthier kits born.  If a pair fight constantly or the female is stressed, the kits often suffer and are born smaller and weaker.
    You start with the best you can get, match up not only for genetics, but for compatibility, you take the best care of them you can and the results are usually good ... but there are always exceptions ... never say never ... be ready to make changes in your pairings, if the need arises.

 ::wave::
Jo Ann
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Re: How is litter size decided?
« Reply #13 on: November 16, 2006, 07:38:22 AM »

Very well said again Jo Ann, ::nod::
Quote
Chins have internal 'clocks' ... don't think they go on daylight savings time ... that 's just for us humans.
What I was referring to was the amount of light they get effecting breeding.
They still get the same # of day light hours I know, but as it gets so dark so early now they get more artificial lighting because I have the lights on earlier, and longer. I get the same # of births no matter what season.
They'll breed 2 twice a year like clock work if I let them.

That seems to be the standard no matter if you live in Florida or Newfoundland, and the temps are very different.
I get mostly twins, a scattered single, and only  one set of triplets,and both of the parents were from twins. ::think::
Loads to think about though ;)

I wonder if there is anyone  in Alaska keeping/breeding chins? How would months of day light then months of darkness effect them?
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Re: How is litter size decided?
« Reply #14 on: November 16, 2006, 08:04:30 AM »

::silly::
Quote
What I was referring to was the amount of light they get effecting breeding.
They still get the same # of day light hours I know, but as it gets so dark so early now they get more artificial lighting because I have the lights on earlier, and longer. I get the same # of births no matter what season.
rofl
I figured that was what you were referring to ... but ... we always have to remember we have newbies that would actually take it the other way.  ::)
Most of the time, I think they have the same internal clock today that it was in the wild (with maybe some adjustments for evolution).  {In the wild, when they were plentyful, most only had one litter a year ... they amost became extinct ... now they will often have 2 litters a year and some 3 in one year.}  Mother nature has a way of letting all the animals know when it is the normal/best  time for them to have their kits.  Just like the squirrels that gather more nuts than normal know it will be a harsh winter, or deer will come out to graze in the middle of the day when there is rain comming that night.  The animals just seem to know ... I think they got first and second dibs on looks, smarts and personality and the humans got the left-overs.   :D

 ::wave::
Jo Ann
« Last Edit: November 16, 2006, 08:10:54 AM by Jo Ann »
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