the success rate I was referring to was the percentage of female progeny over male by using sex sorted semen as apposed to non-sorted. Not the actual percentage of pregnancies.
[QUOTE=Bats79;5725577]
the success rate I was referring to was the percentage of female progeny over male by using sex sorted semen as apposed to non-sorted. Not the actual percentage of pregnancies.[/QUOTE]
There’s not much point in sorting them if the resulting pregnancy rate sucks!! 
The actual “sort success” rate however is approximately the same for both species at 90-95%.
Regards to all,
Update
IIRC in human repro it was once thought that the XY sperm being slightly smaller were faster but the XX sperm had longer lives so that if humans had intercourse around the time of ovulation or slightly later the chances of a boy were higher. If intercourse took place well beforeovulation some of the XY’s had died off and the XX’s had the advantage.
Also vaginal pH (forget which like vinegar and which liked baking soda) matters
See earlier post. ONCE is the operative word. Neither of these theories have stood up to testing. From ACOG: “No current technique for prefertilization sex selection has been shown to be reliable.”
Link to policy statement: http://www.acog.org/from_home/publications/ethics/co360.pdf
Also, if you cross your eyes for a long time, they don’t stay that way…if you crack your knuckles, you will not get arthritis…sugar does not make children more hyperactive…teething does NOT cause a fever…your hair and fingernails do NOT grow after death (the body shrinks from water loss)…reading in low light does not ruin your eyesight…chocolate does not cause acne…
When I truly have nothing to do, I ponder the relevance of this Do some stallions consistently produce more of one sex than others? Could this mare have had any influence on the fact that she had 2 colts in a row - from completely unrelated sires?
If you flip a quarter and it keeps coming up heads, is it a special quarter? Again the reason you have to look at large numbers. If you just ponder this, AWESOME! We need more ponderers. If you base decisions on this, well…the babies will still be really cute!!!
Okay…this one made me snort. I’m ASSUMING you mean they were trying to FEED the CHILD!
Dad #1 did not want his newborn to be “traumatized” by stopping breast feeding while I d/w Mom the risks of declining meds so he took the infant from her, unbuttoned his shirt, and made a show of putting said infant on the nipple of his very hairy chest.
Dad #2 wanted to have equal “bonding time” as Mom so they rented an S&S system (a system used for newborns when Moms milk does not come in which consists of a small tube that runs down the chest next to the nipple so the infant can practice breastfeeding while getting some supplemental feeding) so that he could partake in the experience…
These are the times you REALLY learn exactly how good your poker face is…:winkgrin:
A couple of comments:
Statistics do not prove or disprove anything. What statistics do is give you the probability that the result observed occurred purely by chance. P<0.05 is a probability of less than 1 in 20 that the observed response occurred by chance. Low numbers typically are associated with poor power of test and are a primary reason for not finding differences when differences exist. Rejecting the null hypothesis (that no differences exist; i.e. concluding that the treatment caused the groups to differ) is seldom caused by having too few subjects. The most likely mistake of having too few subjects is to fail to find a difference when a difference truly exists.
While data in mice don’t translate directly to our species of interest, there are a number of well controlled studies with sufficient numbers to conclude that diet can skew the ratio of male to female offspring. Off the top of my head I seem to recall that oil vs carbohydrate as an energy source can influence sex ratio. Additionally, type of oil (specifically omega 3 vs omega 6 rich oils) can influence sex ratio. Those interested can pull these studies from Pubmed by doing an author search for R. Michael Roberts.
Here’s one of those studies done on sheep.
http://www.rbej.com/content/6/1/21
oil vs carbohydrate as an energy source can influence sex ratio. Additionally, type of oil (specifically omega 3 vs omega 6 rich oils) can influence sex ratio.
Do you remember which way it was influenced with oils and carbs?
[QUOTE=back in the saddle;5727272]
Do you remember which way it was influenced with oils and carbs?[/QUOTE]
Here ya go!
The study of feral horses:
Cameron and Linklater, 2007
Extreme sex ratio variation in relation to change in condition around conception.* http://rsbl.royalsocietypublishing.org/content/3/4/395.full.pdf+html
*
A study in mice:
Fountain et al., 2008
Effects of diets enriched in omega-3 and omega-6 polyunsaturated fatty acids on offspring sex-ratio and maternal behavior in mice.
http://www.biolreprod.org/content/78/2/211.full.pdf+html
*
The aforementioned study in mice:
Alexenko te al., 2007
The contrasting effects of ad libitum and restricted feeding of a diet very high in saturated fats on sex ratio and metabolic hormones in mice.
http://www.biolreprod.org/content/77/4/599.full.pdf+html
*
The aforementioned study in sheep:
Green et al., 2008
Nutritional skewing of conceptus sex in sheep: effects of a maternal diet enriched in rumen-protected polyunsaturated fatty acids (PUFA).
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2432061/pdf/1477-7827-6-21.pdf
Low numbers, low power
From NIH:
“The ideal study for the researcher is one in which the power is high. This means that the study has a high chance of detecting a difference between groups if one exists; consequently, if the study demonstrates no difference between groups the researcher can be reasonably confident in concluding that none exists in reality. The power of a study depends on several factors (see below), but as a general rule higher power is achieved by increasing the sample size.”
I am not saying that diet or many other things may or may not affect gender in horses. I am just saying I have yet to see a study that proves it. If you know of it, please post!!! When making decisions to change or not to change my medical practice, I don’t consider studies with low numbers or inappropriate controls or those done on mice or rats or sheep…no matter how many lunches those drug reps bring…:winkgrin:
Of course, with horses and gender determination, the stakes are a lot lower (i.e. we are probably not going to knock them off by playing around with their diet). Still I think we use a lot of iffy data in the equine world when making decisions… Remember when those Cox 2 inhibitors like Viox were REALLY popular so everyone started prescribing them like crazy. Once enough people used them, it was discovered that they increased cardiovascular risk…
JAMA article: http://jama.ama-assn.org/content/296/13/1653.extract
Precisely to my point.
If a difference is observed it is not owing to too few experimental units. There may be other factors that lead to falsely concluding that a difference exists, but too few experimental units is not one of them.
I am certain that future generations will laugh at many aspects of biology and medicine that are widely accepted by our generation as fact based on having been “proven” to our satisfaction.
I confess I did not read the entire NZ study done on feral horses, but it took place over 4 years and utilized some 400 horses.
And the results were profound – only 3% of mares foaled colts when they were losing condition, whereas 80% of the mares losing condition had fillies.
Assuming the researchers did not manipulate the data, please let me know where this study is weak?
- Large population used for the study
- Took place over a fairly long period of time
- Quite definitive results (80% vs 3%).
And stuff like determining body condition and gender are pretty simple things. The only place I could find fault would be actually determining the time of conception, so you could actually determine if the mare was gaining or losing weight.
But other than that? Granted I did not take statistics in college (and always regret that)…but where are the big holes in this study?
I’m not sure anything proves anything, but this study certainly gives some fairly strong evidence to my layman’s eye.
[QUOTE=Kyzteke;5728797]
I confess I did not read the entire NZ study done on feral horses, but it took place over 4 years and utilized some 400 horses.
And the results were profound – only 3% of mares foaled colts when they were losing condition, whereas 80% of the mares losing condition had fillies.
Assuming the researchers did not manipulate the data, please let me know where this study is weak?
- Large population used for the study
- Took place over a fairly long period of time
- Quite definitive results (80% vs 3%).
And stuff like determining body condition and gender are pretty simple things. The only place I could find fault would be actually determining the time of conception, so you could actually determine if the mare was gaining or losing weight.
But other than that? Granted I did not take statistics in college (and always regret that)…but where are the big holes in this study?
I’m not sure anything proves anything, but this study certainly gives some fairly strong evidence to my layman’s eye.[/QUOTE]
One glaring problem is the study is not controlled so other factors could cause the observed change. One quick thing that comes to mind, mares losing condition are hungrier and are more likely to eat plants they wouldn’t eat when not losing condition and perhaps those plants have something that causes the change. Feed that mystical plant to fat mares and will it change the result? I could go on but hopefully this gets the non-controlled point across…
[QUOTE=Eventguy;5729064]
One glaring problem is the study is not controlled so other factors could cause the observed change. *One quick thing that comes to mind, mares losing condition are hungrier and are more likely to eat plants they wouldn’t eat when not losing condition and perhaps those plants have something that causes the change. *Feed that mystical plant to fat mares and will it change the result? *I could go on but hopefully this gets the non-controlled point across…[/QUOTE]
By this reponse it appears that you accept the conclusion that there are factors that can skew sex ratio. The true identity of the factor(s) is where you appear to disagree.
Perhaps I misrepresent your view. If so, I apologize.
I agree. *There are a number of alternative explanations for the observed difference.
In my view there are likely a number of factors that influence the sex of offspring. *In most large populations there is sufficient variability in those factors to result in an overall ratio of 50:50. * In some smaller groups and in some instances one or more factors are skewed sufficiently to skew sex ratio. *The nature of those factors are not yet sufficiently defined to assign cause and effect much less to apply in a manner that yields a predictable outcome.
[QUOTE=Eventguy;5729064]
One glaring problem is the study is not controlled so other factors could cause the observed change. One quick thing that comes to mind, mares losing condition are hungrier and are more likely to eat plants they wouldn’t eat when not losing condition and perhaps those plants have something that causes the change. Feed that mystical plant to fat mares and will it change the result? I could go on but hopefully this gets the non-controlled point across…[/QUOTE]
By this reponse it appears that you accept the conclusion that there are factors that can skew sex ratio. *The true identity of the factor(s) is where you appear to disagree.
Perhaps I misrepresent your view. *If so, I apologize.
I agree. There are a number of alternative explanations for the observed difference.
In my view there are likely a number of factors that influence the sex of offspring. In most large populations there is sufficient variability in those factors to result in an overall ratio of 50:50. *In some smaller groups and in some instances one or more factors are skewed sufficiently to skew sex ratio. The nature of those factors are not yet sufficiently defined to assign cause and effect much less to apply in a manner that yields a predictable outcome.
Sorry for the random * in the preceding post. Doing this on my iPhone and either the reply box is too small or I am too verbose. Probably the later. Copying from email to reply box resulted in random *.
But was it random? It occurred in three out of four paragraphs, so statistically it was seen 75% of the time, which seems a little on the high side to be considered random.
Or is the statistical base of 4 paragraphs too small a sample group to consider this a valid evaluation?
Or perhaps you just have no control…
Regards to all,
Jos - that is a great post. Sorry for misusing the term. Something for which I have not yet perceived a pattern is not necessarily random. Point taken.
Apology accepted
I have no idea if something does or does not cause more or less of one sex to be born. I don’t accept that there are and I don’t accept that there are not factors that skew sex ratio in horses. In my mind jury is still out.
The post I was replying to asked about holes in the study cited, I was pointing out one. I am saying the study doesn’t prove that the observed change in condition is the reason for the difference in # of filly’s and # of colts born.
All of this discussion is now mute because I found some new information and we can now transform all our fillys into colts (by feeding them wrass meal, or maybe they need to eat what wrasses eat, or live underwater, hmmm gonna have to try some of these)
"Most wrasses (family Labridae) are born female, grow into sexually mature females, and have the potential to transform into functional males later in life. In many of the wrasses, sex change correlates with social hierarchy and social behavior: social structure includes a large dominant male and many smaller, subordinate females. Removing the male from the group triggers the largest female to begin transforming into a male."
This also proves my mare is a stallion in disguise, just wish those things would drop so I could geld her!
Oh, come on now!! That’s just silly! Every hungry mare is eating the same magical plant? And for 4 yrs?
What is that law in science? Can’t remember the name of it, but it basically says if there are a numerous possibilities/explanations for an occurrence, take the simplest/most likely.
Well, in this case, what is the most likely?
It’s well known that, females are tougher than men and they live longer unless they were/are killed in childbirth. So why couldn’t female embryo’s be tougher? “Female” sperm is also tougher, I think…I seem to remember something about that in the sperm sorting dept.
Occam’s Razor
This is an interesting thread, I too read the Equus article about this. My mare was just inseminated (has been at the Repro facility for 9-10 days now, so don’t know whether she has “lost codition”, though I doubt it), and she ovulated approximately 10 hours after the first insemination, and about 5-6 hours before the second (fresh semen.)
Should I be expecting a colt?
Occam’s Razor
This is an interesting thread, I too read the Equus article about this. My mare was just inseminated (has been at the Repro facility for 9-10 days now, so don’t know whether she has “lost codition”, though I doubt it), and she ovulated approximately 10 hours after the first insemination, and about 5-6 hours before the second (fresh semen.)
Should I be expecting a colt?
