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To the rat breeders:

Danaish72

Danaish72

New member
A quick question for those who breed rats: What's the average litter size for your breeders? My rat had her second litter this week and it was just 6 babies; I was under the impression that they had something like 10-12 babies per litter. Any ideas on the small litter size? I've been over their diet and husbandry and everything seems pretty typical to me.
Thanks,
Danaish
 
I keep a small colony of 1.3 rats. They are all on the same diet, and relatively the same age. One of my females is a couple of weeks older then the other two. The two youngest got pregnant first, one had 8, the other had 7 babies in their first litters. My oldest female had 14 in her first litter. Nothing in their diet has changed, they all eat the same, they live together. I just think some females have the tendency to have more babies. Maybe large litters are just luck, like twins or triplets. I don't know the rats background, so I can't say if one rat came from a larger litter than another. It varies, maybe she will have more next time. Is she an older rat, or a very young rat? Did she breed as soon as she was of the age to breed? My oldest rat, who had the largest litter, didn't even get pregnant until AFTER the younger rats gave birth. Maybe her age has something to do with it. I don't know, but I've decided to keep my future breeding females away from a male until they reach adulthood. The average litter size is just that, an average. Some rats are going to have larger litters, and some will have smaller litters, most will be within the average range. But not every rat is going to give birth to same average of babies. I do know that my rats with the smaller litters gave birth to MUCH larger babies. It took the babies in the 14 litter a few days to get up to the size the others were at birth. I don't mind having smaller litters, my snow and amel are eating large rat pinks, so it was easy, I didn't have to wait before culling.
 
I don't breed rats, but I breed mice, and I imagine they are at least reasonably similar...??

Anyhow...I have a 1.4 colony consisting of 3 sisters that were not quite mature when I started the colony(actually, I bought them the day they were weaned) along with a PEW that was mature(probably a month older than the sisters) and a mature male. The PEW got pregnant first, and gave me a litter of 5. Two of the sisters were pregnant when the PEW gave birth. The 2 sisters have just given birth 2 days ago...The first sister produced 11 pinks(her first litter!), and the second sister produced 8 pinks. The third sister is currently pregnant and so is the PEW, again, so only time will tell if the sisters will all have consistantly higher numbers or if the PEW will increase her numbers with experience...

I would also be curious if the male's "performance" during each copulation might impact the number of babies? Perhaps a higher count of sperm released or something? I don't know...

Like someone said above...the "avergae" is simply that...an average. Not all females will achieve those numbers, and some will surpass...
 
Thanks for all your replies guys. I hadn't considered genetics at all and I'd imagine the pet store rat lines could be inbred, so maybe there's an inbreeding depression or something of that nature. It had also been dark and cold around these parts until just recently so perhaps they'll perk up with this nice spring weather.
Thanks for your input,
Danaish
 
well, my female averages 8 per litter, but her last one was 13!! so im not really sure
 
I don't know about rats, but among mice the size of the litter is somewhat based on general health, a little bit on luck, and younger mice often produce slightly smaller litters than they later will, but there is definitely a genetic component too. Some strains of mice simply produce large litters, and some produce smaller litters.

I wonder if anyone has specifically developed large-littered rats or mice for feeding purposes. I know in the pet fancies, the propensity for certain litter sizes in certain strains are noted, but not generally bred for, as the emphasis tends to be on health, temperament, and type, rather than suitability for feeding. But for feeding, it seems like large-litter-producing mice and rats would be useful.

Anyway, hope that helps. Good luck getting larger litters!
 
I don't think it has to do so much with health. I have three females sharing a cage with their little rat hubby, same food, water, space, etc. One female had 7, the next had 8, and the last had 14 on their 1st litters. The one that had 7 last time, just gave birth to 8 babies this afternoon, one stillborn. The female that had 8 last time has looked like she swallowed a tennis ball for three days and I'm thinking she could explode any time now, who knows how many she will have. I'm just waiting to see if the third female indeed has a large litter again. If so, I'll be raising three of the females from her, and getting them a boyfriend so I can retire my current breeders. Then I should have an idea if it's a genetic thing, or partially at least.
 
Generally, my rats have litters in the 8-10 range. Some are larger; the biggest one mine have given me, was 15. I have one that is kind of disappointing me now because she only had three, but she is older in age and this will be her last breeding.
I always like to keep 1-2 females out of a good-sized litter to raise up and breed. I am no genetics expert, but it seems like rats from larger litters would give you more babies.. but their health and prenatal care also seems to play a role in that too.
One note about larger litters: it is even more important to keep water bottles filled for the moms. I know that this is important regardless, but it seems to me that moms with larger litters tend to drink more (I guess they need rehydration after all of that nursing..) But I like to place the moms' water bottles and feed close to the nest to minimize their need to travel around a lot, as larger litters seem very stressful and the mom can lose weight fast.
 
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