Weird sex odds in litters?

Breeding related topics, including the care of pregnant and nursing does, kitten questions and subjects like inbreeding and outcrossing.
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artgecko
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Weird sex odds in litters?

Post by artgecko » Fri Oct 02, 2015 9:07 pm

Does anyone have experience with weird sex odds in their litters? I'm new to breeding and just now have my two first litters on the ground (3 and 4 weeks old). I found out that I am terrible at sexing pups young, but now that they are older I've discovered something odd.. Both litters have far more females than males. 4 week old litter: 10 pups 2.8 3 week old litter: 11 pups: 1.10
Both litters were sired by the same buck to does from the same lines, but not litter mates.

I was wondering what your thoughts and experiences were on this topic. Is 2 litters too few to determine if my buck just throws more does? Or could this be related to something else (someone has suggested temperature to me)?

I'm not extremely disappointed with all the does, but I was hoping to select both bucks and does as possible breeders and 3 bucks is not many to choose from.

I also got a bonus surprise with the younger litter... 4 of the 11 turned out recessive hairless which neither I, nor the breeder I got the parents from, were expecting.

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cyber ratty
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Re: Weird sex odds in litters?

Post by cyber ratty » Sat Oct 03, 2015 9:19 am

Two litters is far too few to expect them to match the expected stats. Over time they will even out, but any individual litter can easily be biased towards one sex or the other. I have two litters now aged 6 and 5 weeks, the first of 11 kittens had only 3 does, the second of 10 kittens, had only 3 bucks.

There are various theories about causes, including the number of bucks versus does in the rattery, but it is generally acknowledged that the bias is most likely to be opposite the breeder's own needs or those of their waiting list. :P

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[cub]
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Re: Weird sex odds in litters?

Post by [cub] » Sat Oct 03, 2015 12:59 pm

I know almost nothing about breeding but I do know a thing or two about numbers, and two litters is way too few to draw any general conclusions about anything. You expect 50/50 (or whatever the actual sex ratio is for rats) overall in the long term, but 50/50 (or even close to it) every single time would actually be really weird!

Best of luck with your breeding project. :luck:
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artgecko
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Re: Weird sex odds in litters?

Post by artgecko » Sat Oct 03, 2015 1:35 pm

Thanks! I figured two litters would be too few to draw conclusions. I will probably end up rebreeding my best female to the same male to attempt to get more bucks to choose from as holdbacks. I'm also hoping that my sexing skills stink enough that I"ve missed some males in her litter that haven't "developed" yet.

and lol about the odds being opposite of what you want.. That sounds about right. :D

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