It is true that there are slightly more males born than females in humans and in dogs. There are many theories as to why, but no proven facts. According to Phyllis A. Holst, MS, DVM, (Canine Reproduction, page 94), there are 55% male pups to 45% female pups whelped. I've always thought that perhaps the weight of an X sperm is heavier than the weight of a Y sperm since there is a big difference in the size of the sex chromosome (the only chromosome size difference between the two types of sperm). This would make the X sperm slower than the lighter Y sperm and give the boys a better chance in the race to the egg. Just my own thoughts here and you can take it for whatever it it worth. All the best, Susan Cochran
----- Original Message ----- From: "Patricia Ide" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, December 22, 2001 8:25 PM Subject: Re: [CKCS-L] Female puppies > Actually, a genetic roll of the dice determines the sex of a fetus. The > female has two X chromosomes. The sperm donor, or sire, has only one X and a > Y that is only half the size or so of the X. Nature rolls the dice at > conception and decides which of the two female X's and which of the two male, > an X or a Y, will combine in the ova to produce the fetus. If it is XX it's > a female and if it is XY it is a male. Mendel's Law says that that, out of > 100 puppies bred, approximately half should be male and half should be > female. In humans there are slightly more males (1%) born than females but > more females grow up. I have never heard this said about dogs. If it is > true, then it would be only one percent more. If you have bred one hundred > pups, you might like to check your records to see if this supposition proves > to be correct. > > Pat Ide > > ========================================================= > "Magic Commands": > to stop receiving mail for awhile, click here and send the email: > mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20NOMAIL > to start it up gain click here: > mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20MAIL > > E-mail [EMAIL PROTECTED] for assistance. > Search the Archives... http://apple.ease.lsoft.com/archives/ckcs-l.html > > All e-mail sent through CKCS-L is Copyright 1999 by its original author. ========================================================= "Magic Commands": to stop receiving mail for awhile, click here and send the email: mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20NOMAIL to start it up gain click here: mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20MAIL E-mail [EMAIL PROTECTED] for assistance. Search the Archives... http://apple.ease.lsoft.com/archives/ckcs-l.html All e-mail sent through CKCS-L is Copyright 1999 by its original author.
