Rats Retain Sperm???

[Shep151]

First, a little background.

I have a colony of rats, with about 40 females to 4 males. The females are kept 4 to each male. When a female begins to look pregnant, she's pulled and put in a separate birthing bin on her lonesome, and another girl who has raised her kiddos up takes her place.

So after conception, there is NO opportunity whatsoever where the female can come in contact with a sexually mature male. When the rats reach weanling size (barely, at 30-40g) they are put in a rearing cage until it's time to pull them.

Sunday when I cleaned cages last, I noticed one girl with pups nearly ready to wean was getting big. Thinking that I was probably going to have to cull her soon for health reasons causing the "bloating" I pulled the pups and left her to her designs.

Today I check on her and she has pinks! :shrugs:

The only thought I had was retained sperm, but I'm not sure even that makes sense, since I've never heard of it in mammals.

Any rat gurus out there think maybe she ovulated and got nailed (while already carrying fetuses) right before I pulled her from the breeding colony?

And please, no responses from "super-geniuses" who have personally given CPR to mice.

 

[attackturtle]

I have seen something like this on animal planet or discovery. I wish I remember what kind of animal it was. It was a small shew I think. A male came across a nest of babies and mated all the females. They were 2-3 weeks old but the director said that in a few weeks when they were old enough, they would become pregnant.

 

[Roy Munson]

I have seen something like this on animal planet or discovery. I wish I remember what kind of animal it was. It was a small shew I think. A male came across a nest of babies and mated all the females. They were 2-3 weeks old but the director said that in a few weeks when they were old enough, they would become pregnant.

I've heard of this happening with weasels. The male sometimes impregnates the females before they're even weaned, and the females retain the sperm until they're sexually mature. I think they mature fairly quickly though-- maybe 3 months, or so.

Dunno about rats. :shrugs:

 

[Bobo's Mama]

I've had male rats and mice mate with the female a day or two before they give birth, but never in the "middle" of a pregnancy. That sure is odd, but I suppose its possible. :shrugs:

 

[cornsnakekid92]

First, a little background.

I have a colony of rats, with about 40 females to 4 males. The females are kept 4 to each male. When a female begins to look pregnant, she's pulled and put in a separate birthing bin on her lonesome, and another girl who has raised her kiddos up takes her place.

So after conception, there is NO opportunity whatsoever where the female can come in contact with a sexually mature male. When the rats reach weanling size (barely, at 30-40g) they are put in a rearing cage until it's time to pull them.

Sunday when I cleaned cages last, I noticed one girl with pups nearly ready to wean was getting big. Thinking that I was probably going to have to cull her soon for health reasons causing the "bloating" I pulled the pups and left her to her designs.

Today I check on her and she has pinks! :shrugs:

The only thought I had was retained sperm, but I'm not sure even that makes sense, since I've never heard of it in mammals.

Any rat gurus out there think maybe she ovulated and got nailed (while already carrying fetuses) right before I pulled her from the breeding colony?

And please, no responses from "super-geniuses" who have personally given CPR to mice.

That made me laugh, i am not sure of your question, but do you ever have fight when you put a new female in?

 

[Shep151]

do you ever have fight when you put a new female in?

Nothing more than dominance struggles. I've never lost any due to these, nor have they received any wounds, so I don't even bother to monitor them for "acceptance" of the new girl(s) anymore.

 

[Ratsicles]

Gerbils definetly have this ability. They will retain sperm to ensure that they dont have a litter more often than every 5 weeks.

My mice also seem to have these "miraculous" pregnancies. I know that they havent been with a male for more than 3 weeks and then they drop a litter. I tend to see this most in first time mothers though.

Bryan