Hi All, Could anyone tell me what factors/which parent influence litter sizes and sex ratios? Are bigger litters born on average earlier?
Thanks
Angela

The bitch has control over litter size, i.e. how many eggs are released, fertilized, implant (not all fertilized eggs implant) and grow to term etc...
The male has the sole influence over sex.
In my experience, bigger litters have arrisen from mating every day for 3 consecutive days. Average litters have been produced in 2 matings 48-72 hours apart. The reason for this was probably more viable sperm available at exactly the right time. Having said that, with the amount of sperm released, you are going to have a lot of wastage either way.

Agree with Themutts...female dictates numbers, male dictates sex.

However i think the number of matings is not relevant to litter size just the timing, obviously more matings would cover more days but one single mating at the right time will produce a big litter if the bitch has lots of viable eggs...talking from recent personal experience, my girl just had her litter after 1 tie on day 11...resulting in 13 puppies born 4 days early!

We are breeding our bitch at her next season and the dog we are using fit's her pedigree so well, he is a stunning boy with a great nature, he has 28CC's and 19 RCC's........... but he has had 15  litters of one or two pup's and only had two litters of three, our breed usually has between five to seven in a litter.  We will still use him, although i am a bit wary of having a singlton and needing a section due to lack of hormones!!!!!!!!  So to be honest can we be sure that it is always the bitch who determines the size of litter?

As long as he's been fertility tested and is producing the normal amount of healthy sperm then yes.

> So to be honest can we be sure that it is always the bitch who determines the size of litter?

yes!

Sire can have around 4billion sperm on average, but its down to the bitch to produce viable eggs..

Can understand what you are saying but.............the owners of stud dog insist that the visiting bitches are blood tested so they are at the correct time for mating so surley all of these bitches can't be producing only one or two eggs and some of them have been mated previously and since and had normal sized litters!!!!!!!!!!!! He has been fertility tested as semen has been sent abroad, we will still use him as he is a superb example of our breed but his breeders will tell you that he only produces small or single litters

Some bitches are just not that fertile.. and only produce two or 3 viable eggs..

My boy has produced a litter of 14 to one girl, other girls have produced average sized litters to him.. and another girl produced 1 pup, came back for a free return and produced 3 pups.. one girl did not become pregnant, came back following season and produced a litter of 8 pups..

Sorry.. its down to the girl to produce the eggs..

Sorry didn't reply earlier been busy :-), that has answered my question then, my girl has just had a litter of 9 (5 days early, which is very big for her breed) after 1 x 10min tie again day 11 with an 8 yr old dog we I have 8 bitches & 1 dog, so dog has determined sex and she has determined size of litter, I would say he knew exactly when to put the effort in LOL, lot to be said for using a experienced dog on a maiden bitch (thanks CDers :-))

I had always understood this to be the case but one of my girls has made me think twice.

She has had in total 4 litters by 2 different dogs (litters 1 and 2 by one and litters 3 and 4 by another).

Litter 1 - 5 dogs and 1 bitch (born last)

Litter 2 - 6 dogs

Litter 3 - 5 dogs and 1 bitch (born last)

LItter 4 - 6 dogs

Ive just put it down to the fact that she prefers boys :-)

My bitch has had 2 litters...2 different dogs...3 pups each litter

Litter 1
2 dogs and 1 bitch

Litter 2
3 bitches

If I remember correctly it is all down to chromosomes X & Y - think I am correct in saying in the human the female carries only the X and the male X & Y therefore if at conception there results a X X pair the result will be female if X Y it will be male. Do not know if it is the same with dogs but would think this is likely and if it is there is no way the bitch could influence the sex as she only carries the X chromosome. As to the number it stands to reason that as in a fertile male there will be thousands of sperm deposited at a successful mating it must be down to the bitch and her condition or stage in her cycle that rules the number in a litter plus or minus the norm, if anything in nature can be said to be normal

I have heard that is a bitch is mated early in her season you are likely to get more girls. Old hunting dog men used to say it...
I have always thought it to be old wives tale but just googled it and there might actually be some sense behind it.
http://wiki.answers.com/Q/Is_there_a_difference_in_how_long_XY-chromosome_sperm_for_boys_and_XX_sperm_for_girls_live

e.g mated early so some of the Y-sperm has died before the eggs are ready and more X-sperm is still alive to fertilise the eggs...
Well at least there is some science behind what the old men said, whether it actually works in reality or is just old wives tale made from this kind of finding, who knows!
Saying this, I doubt many of these people would have read scientific findings but relied on what they have seen and learned over the years...

Think that as in humans some male dogs produce more of one sex than another, how many times have you heard for a family of all one sex and the final baby being the longed for opposite sex. I have wondered if the male does at times produce more X than Y or if at times the X will be fitter quicker and more viable than the Y and then another time it will be the Y but I have no proof of this although it may be out there somewhere.

Do not think the old hunting men had it right either, if you mate a bitch before her eggs are ready then there will be no pups resulting, sperm lives for a short while and if it does not meet a ripe egg it dies. Whereas if the eggs are ready sperm have an equal chance of  reaching them, although we can check when a bitch ovulates it is not possible to time the exact moment egg meets sperm and to mate before the bitch is ready is not only against nature but likely to result in no whelps rather than female whelps.

But some bitches will stand very early, before or when they are ovulating?
X sperm lives longer, there could be a chance of more of them being alive when the eggs ripen?
I did always think these men are talking rubbish but they definitely believed it made a difference and having looked in to it little bit more, it could just be possible.
They wanted girls so would try to mate their bitches as early as they would stand...

Y sperm lifes fast and dies young, they move quicker than X(being lighter/smaller) but do not tolerate the acid enviroment as well as the larger X sperm...
I have learned looking in to this :)

Think you would be in danger of the bitch missing altogether if you try this, a viable egg must be available within a relatively short time regardless of what the sperm is carrying, to try to manipulate the outcome by this method is asking for disaster. Even if you know the time of ovulation you would not know when the eggs were in the right place for fertilisation or if the womb was ready to receive them, no good fertilising early with X sperm if they do not implant.

Maybe these hunters did get many disasters and bitches missing...who knows!
I have no idea what the success rate was or if they indeed had more girls this way but they seemed to think it is "wisdom" worth sharing and was widely believed in those circles.
I Just remember listening to the advise and thinking that is rubbish and I was only young girl :)

I doubt they would have been ovulation testing so would have not had no idea where the bitch is in their cycle except the behavior of the pair. (if indeed you could test? This is some 15-20 years ago!)
They would have probably laughed at such idea anyway, that animals would not know when to mate...

It was just an idea on why some bitched could keep having certain sex with different males/have mainly one sex in a litter, could be something to do with the time they are standing and being mated... or just pot luck!

I have just used a friends dog who had sired 4 litters, previously (including to my girls daughter and full sister).

Each produced just 2 bitches each and they were convinced he had a propensity for males.

First litter 2 dogs 2 bitches, second 5 dogs 2  bitches, third 4 dogs 2 bitches, then 0 dogs 2 bitches, and mine is 1 dog and 4 bitches.  Sex ratio over enough numbers will nearly  always be 50/50.

Very possibly there could be a single sex bias with only one mating poorly timed.

I have also heard it said that as a dog ages his sperm quality decreases and that the female sperm are stronger and likely to be more viable than his male sperm, so later in life he may produce more bitches?????

I have used young maiden dogs and had prevalence bitches and veteran males and got more males, so I doubt it is statistically significant re fertilisation.

No - we were more convinced he had a propensity for producing just the two females, regardless of how many males there were in the litter. :-)  He broke his duck this last time... :-)

But it is notable how the numbers of male and female offspring have evened out over time.

i have just had my first litter form my large breed bitch but not that large a girl. its the boys third litter, he has made 10 and 7 in last two, well my girl had 15 pups. she sadly lost three, it gets better the total count was 2 girls 13 boys!!!

I have had 2 litters of 9. The first litter the mating was late - day 17 and produced 5 girls and 4 boys. The second from her daughter the mating was later - day 19 and she produced 6 girls and 3 boys