Why infertile eggs/how to improve fertility?

[Silvergrin]

I was just wondering if anyone out there knew how/why duds/slugs/plugs are formed? Do females have a certain amount of eggs they are going to lay, fertile or not, and so the number of duds depends on how many get fertilized? Or is it bad genetics (ie, if the embryo is not viable from early on)? Or is it environmental, like if the female doesn't have the resources to fully build the egg shell? Or all of the above?

On the same vein, anyone know any methods to inprove fertility? Breeding with several males? Housing with a male perminantly instead of just for a week or two during the breeding season? Brumination times? Calcium suppliments? Just curious. My snow girl did pretty well this year, without brumination; 18 good eggs and one dud, but my blizard just laid 13 eggs, at least 4 of which look bad. All of them look a bit questionable, I think maybe it was because she was on the small side (esp. compared to my snow!)?

 

[JM :o)]

I don't have an answer for you, sorry. Thought I'd commisserate (SP?) I had a large (450 gram) first timer lay 30 eggs this year. 20 slugs and 2 of the "Good" eggs have already molded and they still have 6 weeks to go.

So if you come up with a reason, let me know!

 

[ChaosCat]

In the wild, I believe slugs are formed so that if an egg-eating predator comes along, its hoped the predator eats the slugs and not the fertile eggs. Basically, its increased chances for the healthy eggs to survive.

-cat

 

[Susan]

I can, in no way, state facts, but I'll give my opinions.

Females, if they are going to, are going to ovulate X number of eggs, no matter what. Anybody who has had a young female, that has never been brumated nor has ever even been with another snake since hatching, lay a clutch of slugs, will probably agree with this. This can also account for all the second and even third clutches laid by females. I have had all of these occur.

The number of fertile eggs and slugs in the clutch can depend on a variety of factors. These include when the female is mated (too soon or too late for optimum fertilization of the eggs), how many times the female is mated (the more sperm available, the more eggs fertilized), and the actual fertility of the male (low sperm count &/or defective sperm = less fertile eggs). I currently have a male that I highly suspect of either having a naturally low sperm count or defective sperm. He's a '97 carmot that I purchased last year. I bred him 4 times last year and 3 times this year. He has been bred to both older, known excellent females as well as first-timers. So far, his "rating" is as follows:

1st '03 mating - 3 fertile : 4 slugs all fertile eggs went bad
2nd '03 mating - 3 fertile : 8 slugs all fertile eggs went bad
3rd '03 mating - 1 fertile : 11 slugs fertile egg went bad
4th '03 mating - 1 fertile : 9 slugs fertile egg went bad
(There was a week between the first 2 matings and the last 2 matings, and a month between the 2nd and 3rd matings. Each female was mated at least twice.)

1st '04 mating - 0 fertile : 13 slugs
2nd '04 mating - 3 fertile : 6 slugs so far, 2 of 3 fertile eggs gone bad
3rd '04 mating - not due to lay for another 3 weeks
(Two weeks between first 2 pairings and a month between 2nd and 3rd. Each female was mated 2-4 times.)

If the last female lays mostly slugs, I'm borrowing a microscope from work the next time I use him and will try to get a sample to see what is wiggling in that yellow "spooge"! I have no idea what his record was like before I bought him, but I have a clue as to why he was a "surplus adult for sale".

 

[Sasheena]

When you say fertile eggs, do you mean that you candled them and saw veins, and they still went bad? or do you mean that they "looked" fertile, but eventually demonstrated themselves as being unfertilized also.

Just curious. Want to understand the differences between a fertile egg, and unfertile egg, and a slug. Seems to me that an egg won't be considered fertile until/unless the network of veins shows itself.

 

[paulh]

Fact: Vitamin deficiencies affect fertility and embryonic development in vertebrates from trout to chickens and humans. See Lee Russell McDowell's Vitamins in Animal Nutrition. I had a Burmese python that laid a clutch of fertile eggs (opened some of the eggs and found embryos). Both mother and eggs died, and I think the cause was a vitamin deficiency.

Fact: Elevated temperatures reduce sperm viability.

Your guess is as good as mine as to whether either fact has a bearing on your problem. Both are fairly easy to treat if they do.

For heat sterilization, put the snakes on a day/night temperature cycle, dropping the temperature to the high 60s/low 70s F at night. I've gotten good fertility with this temp drop.

It's a fact that wild corn snakes take eggs and baby birds in season. (I've never seen a corn snake in the wild, but the local wild fox snakes have taken eggs and babies in our pigeon coops.) So for deficiencies, you might try supplementing the snakes' rodent diet with a fresh, newly-hatched baby chick once a month.

Just some things to think about. Good luck.

Paul Hollander

 

[Silvergrin]

ChaosCat -- I've heard that theory and I'm not *entirely* sure I believe it... while duds seem to have less resources invested in them (judging by their softer and thinner shells) they still seem to require a good deal of effort and it just seems like it would be better if the snake invested slightly more energy to make all fertile eggs... then if the egg preditor doesn't come they all hatch! Plus duds rot within a week, which also doesn't make sense if they're there to discourage egg predators. I haven't analyzed the chemical composition of duds, however, so maybe they actually are extremely nutritonally poor and don't require much energy to make...

Susan -- interesting! I haven't had any females lay without being with a male, but I don't have many snakes. I've certainly heard about people who have! Good luck with your eggs there :/

paulh -- Mmm, definitely something to think about. I might try the lower temperatures next season, though I'm not having particular problems with fertility. I think the vitamin thing might have more to do with it. Can I dust mice, or should I really try chicks? I'd be fine with feeding my snakelings chicks once and a while, but I have no idea where to find them.

 

[Drizzt80]

Silvergrin,
A comment/tip for vitamins . . . I don't dust my feeders as I feed in the cage, and the vitamins I use tend to be a little sticky, hence the first time I dusted pinks and mice they looked like little aspen christmas trees! I'm glad I caught it as it wouldn't have been pretty.

Now, I inject my feeders once a month, or every two months with vitamins for one feeding, and NutriBac for another. I dissolve the powder in water, and inject/feed immediately. Not sure if it's better or worse than dusting, but I've never had a snake refuse a meal this way. I have had refusals in the past with dusted food.

Just some tips that I currently use that work pretty well so far.
D80

 

[paulh]

Silvergrin: A day/night temperature cycle is all that is necessary to avoid heat sterilization. Prolonged low temperature is as bad as prolonged high temperature.

Like Drizzt80, I use a vitamin injected in the food. I've never tried NutriBac though. Generally I use a good liquid multiple vitamin that's formulated for cage birds. Unfortunately, my favorite bird viatmin has been discontinued, and I have to find a replacement this summer.

Adult corns love chicks, but they are only seasonally available here. And chicks are too big for babies and juveniles.

 

[ecreipeoj]

Everybody has made some very good points and I may repeat a few. Over heating males as Paulh has stated can ruin an entire season. I do not cycle the males with a different night time low, but I keep my males on the bottom selves of my breeding room, which is maintained at 80-82 degrees at mid height in the room. Even with a fan in the room the bottom cages are about 75 degrees in the front of the cage and less in the back. I would never have males on any kind of heat tape or in a cage that had heat tape. This is probably the number one cause of low fertility in males.

Obviously, if we do not breed the females at the correct time fertility will be low or non-existent. This is one reason that I like to hibernate my corns when perhaps it is not completely necessary. It is a great way to help with the timing of breedings. Generally, females will be receptive within 10 days after the first shed out of hibernation and usually come in about 5 - 7 days after this shed. This is taking into considering that the females are being offered a lot of food. Sheds right out of hibernation are ignored.

I never use multiple males because I want to know exactly which male is the father of the hatchlings. A male in good condition can fertilize several females very well. I have bred as many as 10 females to one male before and had nearly perfect fertilization, but I was able to have them spread out quite a bit. I like to give the males a days rest between breedings if possible. Generally, if a female is receptive, the male will breed with her almost immediately when he is put in her cage. I usually check my pairings every 5 - 10 minutes to see if they are hooked up. I was surprised to find that they hook up very quickly and the deed is done a lot quicker than you might think. After a successful mating, I take the male out of the cage and give him the days rest.

It is my opinion that one good mating is all that you need to get great fertility in your clutches. Now that I have said that, I do put the males back with the females just to make sure, but you would be surprised at how many times I put the males back with the females only a few days later and they don’t do anything at all. It is already a done deal. The eggs usually come around 35- 40 days give or take a day or two after the first breeding. It is amazing how many times I have looked back after I have gotten a clutch of eggs and found the very first breeding of a female to be within this time period.

Experience helps a lot too. I can tell when a female is receptive, but I still miss a few. I can feel the follicles in females, but two times this year I was waiting for the first shed and the females seemed to go past the follicle stage and I could feel what I thought were eggs or plugs. I thought I had missed them entirely, but put them with a male anyway. They did produce a few fertile eggs, but many more plugs, so I feel that I bad timing was the cause of the low fertility in these females. Breeding the females after the first shed is only a guide that I have to keep reminding myself of.

Another thing, that nobody has mentioned is there are medical reasons why we can get low fertility. The most common is protozoans. They are extremely common and anybody can get them very easily. I routinely treat all of my breeders with Flagel right out of hibernation and the females after they lay their first clutches. I also treat all of the males before they start breeding the females for the second clutches. This also helps keep their appetites very good which helps considerably with second clutches. I also routinely worm all of my breeders twice a year with Ivermectin. I breed all of my own rodents and wild ones get in some times and since my colony of snakes is fairly good sized it is impossible to keep them in a totally sterile closed laboratory type condition.

It may seem odd to you that I treat my breeding colony routinely with Flagel and Ivermetin. You may think that perhaps it is not necessary or that I am not as sanitary as I could be. I keep my colony in very clean conditions and I am very careful not to spread things around. This is one reason I really like taking care of everything myself. I know exactly what has been done. In all other breeding programs of just about any animal, regular treatments for common reoccurring problems are done as a preventive measure.

 

[Silvergrin]

Drizzt80 -- injecting is a good idea! Where do you find syringes?

paulh -- Where do you usually find chicks? Do you go to a farm, or is there some sort of feeder animal breeder near you? I've seen them available for order from frozen feeder shippers. My snakes seem quite healthy so I'm not *too* worried about nutrition, but I'd like to give them a treat once and a while.

ecreipeoj -- doesn't seem odd to me to treat your colony with Flagel and Ivermetin. Sounds like a good idea if your colony isn't isolated! I might do a treatment next season, just in case, since I just got some new animals (they're isolated from the rest, but I've never treated any of them. De-worming for all!).

 

[Susan]

I hadn't thought of temperature being the cause of the low fertility of my problem male, but all my other males, which are kept at the same temps as the problem male, are fertilizing eggs left and right. I'll try keeping him just a bit cooler, just in case he's more sensitive.

Silvergrin - I only had one female lay without being with a male, ever. It was last year, when she was 2 yrs old, never brumated and kept alone in her tupperware on the shelf with all the other sub-adults and hatchlings. And she is also the one that was bred to my problem male and produced all slugs (13 total). Just coincidence or related?

Sasheena - I consider all eggs that look fertile at laying (not obvious slugs) to actually be fertile. I open as many of these as possible when they go bad, and, unless it is just too early to tell otherwise, I've found embryos in all of them. There are the occasional egg that looks half-way between being fertile and a slug. I always questionmark these. Most turn out to be infertile, but not all. I have had hatchlings come out of these questionable eggs. I've attached a pic of what I consider an entirely fertile clutch. One egg did go bad about 2 weeks into incubation. I found evidence of veins and what seemed to be the remains od a tiny embryo inside. Some embryos do die early in development. The egg that went bad was the fourth one up from the left.

 

[Drizzt80]

Silvergrin, I work for a petstore on the side of my regular job, and I get syringes through there. We give initial vaccinations to our kittens and puppies, so I have access to them through there. I would check with a veterinarian to see if they would sell you syringes. The ones I get are smaller, only 3cc so it takes quite a few syringe-fulls to get 40 mice injected. I am trying to talk the boss into asking the vets for a larger syringe. Also, be sure to get a larger gauge needle, as vitamins don't tend to dissolve completely within the water, and the sediment plugs up smaller gauge needles.

Joe, what amount of Ivermectin and/or Flagel do you give your snakes? What is the dosage per weight (g)?

Thanks,
D80

 

[ecreipeoj]

The dose I use for Ivermectin is the same as all other animals and the recommended dose by the manufacture. It is one milliliter per 110 lbs. There are not many snakes that big!, but it is very easy to figure out the dose for smaller snakes. I use one milliliter syringes which have divisions of 100 on them. 1/100 or .01 milliliter per pound. I am sure there is a metric term for this dose, but I was born a few years too early and would have to look it up. There are smaller syringes that are ½ mil which makes it easier to see the smaller doses. It is possible to treat smaller snakes by diluting the IV in water. 1 part IV and 9 parts water works for me. I have only done this for mites. IV kill just about every internal and external parasite. It is a wonderful drug and I use it on all of my animals.

Ivermectin is very safe. It is safe up to 10 times the recommended dose in mammals, but the most that I have ever given a snake is three times the dose. You may wonder why I would do this. Many years ago a very resistant strain of mites popped up from shows and the recommended dose would not kill them, but three times the dose did. I haven’t had mites since I quit going to a lot of shows about 5 years ago but if any of you do get mites. Ivermectin is a fantastic way to get rid of mites from your entire colony. It is especially helpful for people who have a good sized colony. Treat the entire colony and clean everything. Retreat in 7 days and your mites are gone.

The Flagel dose for reptiles is 50 mg per kilo, which I have use a lot and never had any problems. I have actually given corns twice the recommended dose and they had no side effects. High mountain kings can be over dosed with Flagel. I am very careful to follow the recommended dose with them. I have accidentally overdosed a high mountain king and they had the shakes for a few weeks, but got over it and have been good breeders for years since.

The dose is 25 - 30 mg per pound which is easier for me to work with. Flagel comes in 250 mg tablets usually and with a sharp knife you can cut them in half and get 125 mg, in half again and you have 60 mg and one more time you get down to 30 mg. I usually treat adult corns or good sized ones with 60 mg and half grown ones with 30 mg. Crush the Flagel into powder and put it into something like a 3 mil syringe with 1.5 mil of water. Let it dissolve and squirt it down their throat with a short 3 inch catheter attached. Repeat in 7 days if you are having a problem. Flagel will fix most regurge problems too.

I have bought snakes from many very well known breeders and just about every one of them had some protozoans. Many started regurging soon after I got them. Flagel fixed them right up. I believe Flagel has some anti-bacterial properties as well. I am not a vet so I can not get very technical, but these things have worked for me. I do not think that very many people have a “closed” breeding facility. There are many ways for things to get into your colony. Flies are terrible or very good at moving things around. I keep no pest strips hanging in all of my rooms.

Back to infertility problems. Excessive heat does cause temporary infertility in male snakes. How hot they have to get and for how long I really don’t know. I have heard of some peoples air conditioners going off and their room got up to 90 for a day or two and they did not get one fertile egg that year, so 90 degrees will do it for a short length of time. I find male snakes on pretty hot pavement all the time, so it probably doesn’t hurt them for the short term, or they know when to get off. There is just no reason to take a chance. If we are talking about adult corns, after hibernation there is no real reason to get adult male corns over 75 degrees. They will eat and do fine at that temperature. They do not need to be power fed like the females and only need to be maintained. Many older breeders will not eat at all when the girls are receptive anyway. I only feed my males every 7 - 10 days, unless they are still growing and at 75 degrees they seem to do fine. I keep the younger males a little higher in the room and feed them on the same schedule as the females every 5 days. I don’t know what the magic temperature is to make males have infertility problems, but is seems like most people that have been around a while do not want their males to get over 82 degrees if at all possible.

 

[Sasheena]

Susan... Thanks for your reply. I guess so far I'm pretty spoiled. Last year my two snakes (kings) laid 8 fertile eggs each, and one had a slug (obvious from the beginning) and then all the eggs that looked good and had veins (which were all but the one slug) went on to hatch. So my VERY limited experience with eggs hadn't included ones that have veins and are fertile, but then go bad! I'm keeping my fingers crossed that the eggs I have now, and that I will have in the future will all hatch out fine.

Joe... Where do you get all these meds for your snakes, including the syringes? Just curious. I got some equimectrin once, (active ingredient ivermectin) gave a little to a mouse (about a three mouse dose) and then fed the mouse to a WC Ball Python. A few days later the WC threw up a bloody mess and died instantly. But it was a BAD batch of WC balls last year, so I've heard (enough to tell me I sure am NOT going to do that again), and I lost five out of ten of the shipment, so I'm not sure if it was the meds that killed the snake, or if it was just that it was doomed anyway.

 

[ecreipeoj]

Joe... Where do you get all these meds for your snakes, including the syringes? Just curious.

I live in a cow town, so Ivermectin and syringes are available over the counter. Many people here treat their own cattle and horses on the ranches here and get the meds from the Vet so it is not too difficult to get what I need here.

Flagel and some other drugs you need to get from a Vet. I have taken a few of my snakes to the Vet over the years and he has learned that I know more about them than he does. He is pretty good about giving me what I want if I explain the problem I am having and if the medicine I am requesting will treat the problem.

It can be hard, but if you can get a good relationship going with your Vet, it makes things easier.

 

[Drizzt80]

Joe thanks for the dosage information. One more possibly stupid question. Are you injecting the Ivermectin, or giving it orally similar to the Flagel? Would you view it as possible to give either or both injected into the food similar to how I do my vitamins and NutriBac currently? I know you're not a vet, but most of my husbandry practices revolve around my personal experiences as well. I value those experiences, both good and bad, as just as valuable as what any book or vet could tell me.

Thanks,
D80

 

[ecreipeoj]

I use the injectable Ivermectin on my snakes and the oral kind on my horses and donkeys. Since they make two different kinds, it seems like they should be used the way the manufacture suggest. I like the injectable Ivermectin for the snakes because it is quick and simple. All you have to do is inject it under the skin. It is easy to do in a fold of skin in the front half of the body.

For my horses and donkeys, I put it in their grain and they eat it up. The dose you have to give them is large enough that the size of needle you have to use to inject it in them is not appreciated! I am sure that you can inject the oral Ivermectin in a food animal and give it to them that way. I actually give Flagel this way most of the time, if the snakes are eating anything at all, you can put the appropriate sized chunk of Flagel tablet in the body cavity of a food animal and they get their medicine and don‘t even know it. If you are trying to treat a snake that is regurging, this would not be a good Idea for obvious reasons. I really like giving my adult boas Flagel in this way. They can put up more of a fight than I care for when I try to stick a catheter down their throat.

 

[Susan]

Just a note ...the injectable form of ivermectin can safely be given orally at the same dosage. It tastes like doo-doo, so either use a feeding tube or, my preference, inject it into the mouse just before you feed it to your snake. At the animal hospital I work at, we've been using injectable ivermectin to treat Demodectic mange for awhile now. It's given to dogs orally on a daily basis for 2-3 months. I don't like giving injections to my snakes unless I absolutely have to.

 

[Drizzt80]

Thanks to both Joe and Susan for your information. I am in the same boat as Susan, I don't like to inject my snakes if at all avoidable.

D80