What determines the sex of a fawn?

I have somewhat always been fascinated by this phenomenon and read several research articles from A&M, as well as a few other biologists on the subject.



Research indicates that it is possible to manipulate the fetal sex ratio through herd density and nutrition, as the explanation claims it is mother natures way of balance. I don't have enough active brain cells to completely understand the reasoning behind it, but that's what they claim.



I did do a little experimenting last fall of my own and so far (it just may be dumb luck) with eleven fawns born - only three were doe. I still have one doe that has not had fawns yet. She could easily give me three doe fawns and make it eight buck and six doe. I hope she gives me doe fawns as I have two of them sold from her. The way it looks thought, one lucky fellow might end up with two buck fawns in place of doe...



I will be trying the same methods this fall in order to see if we can get majority buck fawns again - before I will be convinced it works.



I honestly think it was just dumb luck is all....







.

Take a coin and flip it heads or tails. Do this ten times. Let this represent what a particular doe may throw say.. over a period of five years. Now let's say you do this combination another ten times to represent the other ten does you breed over the next five years. If you chart the info I would bet there were does that were buck heavy and some that were doe heavy.

I think it is hard not to consider sex-influencing behaviors because of the possible benefits of mastering or unlocking the code but because many of us breed say less than 20 does per year it is hard to get 50% metrics on a consistant basis. you don't see much chatter from larger farms about lopsided sexes so that is my hillbilly evidence to support my claim!



That being said, maybe post you ratio or number of buck fawns to the number of doe fawns. So far I am three buck fawns to one doe fawn or 3:1. Others share your numbers so far.

Rusty,

So far out of 6 doe live bred, 5 of them had a total of 11 fawns - 8 bucks fawns & 3 doe fawns.



I still have one doe left that didn't fawn. The way it looks, she will be having triplets again this year. I try to shoot for 15-20 fawns a year, with a group of 10 or more buck fawns as the goal.





I think it was just dumb luck, this year....





.

Renee ithink you hit the nail on the head thats how i've always under stood it to be. Its all just a matter of who gets in first. Scientific studies show this to be a fact however scientific studies could be wrong as they often are.

DC

IF putting the does in a confined space with limited buck activity gives you more buck fawns, then wouldn't breeding them on the second cycle do the same thing? I know this is theory, but When I put CIDRS in last year I had two does in heat (out of 5). 1 has fawned and given me 2 buck fawns. Now I had trouble with 2 of the 5 and I pulled the CIDRS early and put them in with the breeder buck. They both had twins 1 boy 1 girl each. This would mean that my theory is wrong, but the one doe has thrown twin girls the past 2 years. Next week when I get the rest of my AI done I will see what my ratio is. Has anyone else had a higher ration of boys to girls out of their second cycle breedings?

I believe under normal conditions the does ovum or egg can and will recieve either an X or Y sperm but I still think there are some ,maybe few in numbers but some that adapt to only recieve one or the other . I know when I was talking to a few old dairy buddies they said conception was lower in using sexed semen because some cows just wouldn't except some semen that was sexed . I do believe there are some females who's ovum or eggs adapt to recieve one or the other in a Y or X sperm and these cows if bred to the wrong sexed semen will not concieve . I'll see if I can't get some literature from the company Genex .. Now keep in mind this is in cattle not deer but I'm thinking it could also hold true in Cervids too ! Just a thought !!

I got to thinking about the discussion on this topic and thought of those who might like to read a little further on the subject.



With this, I am not implying anyone is right or wrong, just offering some further information for consideration.



---------------



Sex Ratio Variation in Odocoileus: A Critical Review, by Louis J. Verme © 1983.





Abstract



Literature on deer (Odocoileus) reproduction was reviewed to elucidate the relationship between a doe's nutritional state when bred and sex of progeny conceived. Available data revealed a correlation (P < 0.01) between progeny sex ratio and fecundity rate of does older than 1 year. Percentage of male fawns progressively declined with increasing maternal age and litter size. These findings support the hypothesis that undernourished does tend to produce a surplus of males, whereas more females are born to mothers in good vigor at estrus. Population characteristics and biosocial factors also influence sex ratio outcome, however. The theoretical aspects of sex ratio variation and its herd management implications are discussed.



You can view the abstract and introduction by clicking this link



--------



Sex Ratio of White-Tailed Deer and the Estrus Cycle, by Louis J. Verme and John J. Ozoga © 1981



You can view the abstract and introduction by clicking this link



---------







Both of these articles are copyright protected and will require a purchase, or a visit to a participating Library or University, in order to read the full versions.







Interesting stuff for sure...







.

I was under the same belief ...My reasoning behind it was...When there is lack of food the doe's produce bucks to disperse the young bucks further out from the herd...for less competion for food.

PaintedMeadowsBJs said:

I was under the same belief ...My reasoning behind it was...When there is lack of food the doe's produce bucks to disperse the young bucks further out from the herd...for less competion for food.

Click to expand...

I believe the same thing. It seems crazy if you just think about it on the surface with little thought, but I have a rancher friend of mine who swears that when their is a drought year more buck fawns are born.

Interesting observations.Here is my scenario last year first fawn apr 28. Bred on first cycle .This year when no fawns came till may 30 and 3 fawned on jun 2. I know they didn't get bred till second cycle.Buck to do ratio on fawns:9 buck fawns 2 doe fawns.

Kinda confirms theory on second cycle.

A few years ago I got 14 fawns and only 2 were bucks. This year , I have 12 fawns so far and only 2 are bucks. Last year it was near 50/50 but I haven't had a "buck" year for a long time. This is with many different bucks over the years . I have the book "Whitetail Deer of North America" and it states lean times for the does says to them , don't expand the population.... while times of lots of food says" extend the population with more females born. This is nature and deer are wild animals with years of evolution without human interference so I guess I feed mine too good. I tried to cut back a little last year on feed before the rut but they still looked the same and gave me an over abundance of girls. Jim

I got dibs on who will be the first feed company to offer a flush ration to produce more bucks fawns?



Seriously though, there seems to be a lot of variables in what determines the sex ratio of fawns. It's not as simple as changing the nutritional plain of the does diet, from my understanding. Some of it has to do with exactly when the doe is breed as far as timing after or during the onset of estrus.



Low buck populations with a heavy doe population would lead to doe being bred later in estrus than with a heavy population of buck - more buck can breed more doe closer to the onset of estrus. A low buck population results in a higher buck fawn ratio due to doe being bred later in estrus, statistically speaking.



Also family structure of the herd would play a role as to prevent high levels of inbreeding as bucks tend to leave the family group at around puberty or close to one year of age, unlike a doe that will spend up to three or more years in a family group. I agree some buck fawns can breed before one year of age...



Stress during estrus can also be a big factor as it causes the adrenal gland to produce higher levels of adrenaline, which suppress luteinizing hormone and other reproductive hormones including estrogen that can change the PH level and temperature of the uterus.



I do agree, most of these aspects are based on wild deer but as herd managers we could/can manipulate the scenario to our benefits, I would think.

Most people have no bucks in pen when they AI, and usually only one when backing up or live breeding. So I'm curious to how this applies to sex ratio?

Guys I agree we can somewhat regulate what we get . I can tell you back in the 90's when we were selling lots of cattle embryo's and we wanted heifers we'd breed our flush cows after 9 PM and one year useing the embryo's we couldn't sell we got 105 heifers and 7 bull calves. Now these were holstein dairy cattle and not deer but there has to be something to it. My flushing vet was Richard Schulte and it was his idea to breed several times at night but never befor 9PM and it really worked . We'd breed several times as we were trying to fertilize anywhere from 0 (bad flush) to 55 eggs(great flush) at a time . I my self would really like to see more embryo work done with deer then I would using sexed semen . Why not just put in a quick thaw embryo then mess around with sexed semen and lower conception ? If you do a search on how they sex bull semen you'll see that one draw back was the females that will adapt to only a Y or X sperm keeping conception low . Just google sexing bull semen , I tried it this morning .. Pretty interesting .. Just my opinion nothing more !!

Rusty

I had 2 does live bred.Each of them had 1 buck fawn and 1 doe fawn.Which in my opion,I think that is about the best anybody can hope for.Now I have one to carry on the gene's and one to breed with.The one doe I bred to Draxxin.He scored 151@1,he has a real good look to him,he is a Maxin son.The farmer that own's him,run's a ad in Whitetail Heartbeat mag.I only say that in case you want to see a picture of him.The other doe I bred to Evergreen,he scored [email protected] am a very happy camper with this fawning season.Liven the dream.

so far this year my ai'd does produced 11 does and 7 bucks, pretty good considering i want to keep most of these fawns. my 1st live cover pen has produced 8 bucks and only 1 doe, also pretty good. my only problem is i sold too many live cover doe fawns and now i only have 1 pen left. i've tried several things in the past, but it seems like the buck makes the most difference.