Litter size concerns

[Buzzard]

Okay, New at this breeding mice thing.( if you have seen my other post you'd understand). Okay After researching and reading the forums ect... My mice are having litters of only 4-6. Is this normal?? Most of my mice are younger. Do they normally have small litters the first time out?

 

[wade]

The first litter is usually small. 4-6 is smaller than normal however. I’d be patient and see if they improve on the next litter.

Keep track of which of your mice make the best mothers. Which of the males sires the most offspring. Then select new breeders from only the best of your mice. Over time you can dramatically improve the production of the colony.

 

[Russell]

4-6 is small for a first time litter, but I find that sometimes too big a first time litter the mother's milk doesn't cover for them all. But with my colony the later litters all the babies seem to get enough and grow fat and sassy. But as already stated, hold back babies from the largest litters. Feed off portions of those said larger litters too once they are sexable to enable the smaller amount of babies left to get more milk and thus grow up bigger. In my mind a bigger well grown mouse makes a better breeder than one that had to fight tooth and nail to grow up competing with so many siblings and usually wean at a smaller size. Something to think about...

Another point, although we have this mindset that outcrossing is always good, your mixing in new genetics that may are may not help at all! Plus the possibility of introducing a new strain of bacteria that could even kill off the strain you already have. It's just something I've run into while I've had mice. I have a colony that are said to have come from Gourmet Rodent when the Petco in Fargo had some in and I had asked where they came from. Anyhow, these white mice produce like crazy but when I put a different mouse in from somewhere else, about half the time the white mice will get sickly after a few weeks and even die off. So be very careful of introducing new mice to the colony! I started off with ONE trio of these white mice and from that trio comes my whole albino line that I keep seperate from my colored line in that I only let white mice breed to white mice and never take a mouse from my overstock where weanlings from all strains go into. Once they hit the overstock bin they are no longer considered for breeding. Cause I do cross the whites to the colored ones in an effort to get my colored strains to produce like the white ones. It's working, but the colored mice throw about half white mice. So I make the effort to keep the white strain pure but certainly allow the few colored strains to be outcrossed to my white strain for better production.

sorry, I see I got to rambling...oops... :nope:

 

[Buzzard]

Rambling is fine. I actually thought about something similar. As these litters grow I want to set up another 2 cages. Thought about adding a different strain. Any suggestions What strain??? Or which strains produce best/better???

 

[Buzzard]

Oh also I have a set that will be 3 weeks old this thursday... What is the proper weaning/ seperating age??? I keep reading 4 weeks but then I read some that said 5-6 weeks.

 

[hiddenhollowherp]

I would recommend 4-5 weeks. Others would disagree. Males are capable of sexual interaction around this age, and many prefer to have them seperated sooner. However, inbreeding will not have a negative effect on your mice for hundreds and hundreds of generations, so don't worry too much about it.

As for your litter sizes, my guess is that your female just has a smaller uterus. Not all uteruses (uteri?) are the same size, and it should stretch as she gives birth to more and more young. As she approaches her golden years, her litters will once again decrease in size and once this is noticable, it is time for her to retire, anywhere between 2-4 years of age. Mice have pretty short life expectancies in general.

If, after several litters, you are unsatisfied with the production of this female, it could be a genetic trait passable to her offspring, as Wade first implied. I keep breeding records and ID numbers on all of my mice to keep track of which mice came from which parents. In the long run, it's a nice thing to have around.