The theory is that because male sperm swim faster, if you mate your bitch when the eggs are ripe for fertilisation (ie because you have been guided by progesterone testing or in my case ovulation scan) you will get more male puppies. By the same token, if you mate a day or so before the eggs are ripe, you will get more female pups since the female sperm live longer so that by the time the eggs are ready to be fertilised, most of the male sperm have died off.
I was wondering if anyone had noticed any kind of patterns in relation to the sex of puppies and timing of mating ?
My most recent two litters have been conceived when I know my bitches eggs were ripe as took them for mating two days after ovulation had taken place. One litter - 4 boys 2 girls, other one,  5 boys. Not ideal for a breeder, especially as I do not keep boys at all. Could be coincidence, but I am inclined to think not.

** Thread title worded wrongly, sorry, I didn't mean at time of ovulation, I meant when eggs are ripe !**

Over the years I have been lucky (I keep only girls) enough to have more bitches than dogs overall in my litters, I have had my most recent litter of all girls (5 bitches and 1 stillborn male) from early mating based on whelping date she was mated at ovulation, but I have similar with very late single mating from a bitch going 5 days early so obviously mated toward the end of the fertile period, result 6 bitches and 3 dogs, my biggest litter to date.

Thing is the theory may be correct as to how many eggs of which sex fertilise, but there are many more fertilised eggs than ever implant, and I suspect the ones implanted are likely to be more random.

Both of my girls who were mated late have had more girls. The first litter a day 24 mating she had 6 bitches. The other girl was taken to be mated despite the test saying wait a few days as we could only take her that day she had 7 girls and 1 boy.

Spoke to a vet many years ago who had studied what clients had and he said mate them late to get girls.

Thanks and yes, I see your point re which ones actually implant, that part of it is undoubtedly down to chance. Still, I think it might be worth me taking my bitches a couple of days earlier in the future, just to see what happens :-).

It seems though that some think late matings will get you more girls, so i don't think there is much in it with species with multiple births.

I have a girl that is mated on days 11 12 13
first mating 6girls 2boys.
second mating 6boys 3 girls
Third mating 3girls 3boys.
all mated on same days but different stud dogs

Basically proves that over numbers of litters it works out about 50/50

Minnie Mouses you know which days the matings took place each time, but do you know at what stage re ovulation your girl was at both times ?
The concept of male sperm swimming faster and female sperm living longer is I believe, a biological fact, but whether in reality it has all that much bearing on resulting pups (or babies of other species, including humans I am unsure). That said, I do know that my own daughters were conceived earlier in my cycle than my sons LOL.

i think it would be more likley that some dogs just produce more male sperm than female and others more female than male sperm

Wouldn't have thought so, since for survival we do need a fairly equal number of males and females and should think this is pretty uniform amongst all species. But who knows lol.

This is actually a proven theory in humans and one that I can vouch for.  When we were'trying'(I hate that term!) for our last baby, I wanted a girl because I so wanted my first daughter to have a sister in her life.  We researched and found a fabulous book all about the subject.  You need to find ovulation and then avoid intercourse though ovulation about 7 days either side.  If you don't concieve, you bring it closer slowly.  Basically, they say, the 'fresher' the egg, the more chance it will be male as only the strongest (female) sperm survive longer.  I now have a second daughter thanks to this.
Don't know how bothered I would be about the pups sex though.  I think a nice even litter is usually best.

A nice even litter is good I agree, but if like me you don't keep boys, to get litters of boys or predominantly boys isn't great. And I can vouch for the theory too as mentioned in previous post :-)

Cavlover the second mating was 2 days after ovulation only 1 mating. The third mating was 2 days after ovulation 1 mating both days were day 13 the first was on day12 had the blood test done for the last 2.