This study found that mares that were in low glycemic feeding conditions and/or losing physical condition - 97% of them conceived fillies.
Mares who were eating high glycemic foods and/or gaining condition at time of conception, conceived colts.
This study is thus suggesting that someone like me, who always wants fillies, should be bringing my mares in at the end of winter, healthy (obviously), but on the lean side and kept on a low glycemic index feeding regimen while being bred and for the first few months of pregnancy.
A high glucose environment apparently kills female embryos!
This was discussed earlier this year on this board at this location.
One also has to look at the fact that the research was conducted in wild horses, which - being managed by nature alone - tend to have higher conception rates and better reproductive function than human-managed horses (in the wild, mares with poor reproductive function tend not to reproduce, and hence the poor reproductive ability - whatever it is - is not passed on to the next generation). This leads to the question as to what will happen to conception rates if one reduces nutritional levels in the human-managed herds that typically will have poorer reproductive function than wild horses, particularly with reference to reproductive conformation. Thinner mares with poor reproductive conformation will tend to have lower conception rates as a result of (a) greater pathogenic presence in the uterus; and (b) reduced uterine immune function. In other words, although the research demonstrated a slant in one direction or another (dependent upon nutritional plane) in the wild horse, the end result of allowing mares to get thinner prior to breeding with the intention of increasing a colt/filly ratio may actually be no foal at all, or at the best, greater costs to achieve that foal...
I did a search, but guess I didn't look far enough back.
I wouldn't want any of my mares as thin... that's just far too risky when one wants health of mare as number one priority, conception as the number two priority, and sex of foal would be a distant third in priority. I just found it interesting that one of the researchers was narrowing down the topic to the prevalence of glucose in the mare's system as possibly being a dominant feature in colt births.
Personally, I haven't found my mares behaving at all in line with what this research found.
I am curious, can one see a physical difference in the in male / female sperm as in humans? and life span of male vs female sperm? And I am also curious as the study didnt mention the stallions condition, possibly relating to the gender of the sperm he produces?
I know that the stallions genetics predispose him to making either more fillies or more colts, but have no idea about the condition. And there are "sperm separators" that can separate the sperm into male and female, so that you can AI your mare with male only or female only sperm. It's a really expensive procedure yet, and that's all I know about that......~Forrest
Diana, I talked to XY, Inc. already about this particular technology, and they're not ready to do this on a commercial basis yet. If they were, all of my purchased semen would be going through them to give me straight XX's.
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