Poor Ca:P Ratio of Blackworms

[Jasper]

From the caudata live food nutritional values website, blackworms have a Ca:P ratio of only 0.12. To prevent MBD, a recommended ratio is around 2:1. This is substantially higher than the majority of the common feeder foods. On the other hand, silkworms are being advertised at Silkworms - The Benefits of feeding your reptile and pet the silkworm with values of 0.5:0.6 which = 0.83, which is substantially higher than black worms, which incidentally have been successfully used as the sole food source to adult hood. With that being said, either the chart is wrong, or MBD does not affect newts as long as some calcium is apparent.

Nutritionally, silkworms seem to be the better option compared to most feeder foods, except for earthworms/nightcrawlers. I am looking to replace black worms with silkworms, but I will also be alternating between Repashy's Superfly cultured fruit flies, which have a supplemented >2:1 ratio. Are silkworms fine as a staple, due to the higher calcium, protein, fat, etc, as well as being easier to obtain in general?

Does anyone have any insight about this?

[Coastal Groovin]

I'm confused. How are you going to replace a small aquatic worm that has the thickness of piece of thread with a silkworm that live totally on land and are almost immediately bigger than a black worm from the start? Within days of hatching silkworms are already to big to feed to the animals that feed on black worms. Also raising enough silkworms to replace black worms is next to impossible or would take every waking moment to achieve.

[Rodrigo]

Blackworms are not used as the sole food, and if they are, they end up causing trouble. Some species are more susceptible to calcium deficiencies than others, and variation inside populations should also be expected, but all newts are susceptible and inadequate diets will produce problems sooner or later. I suspect that the hardness of the water also plays a role and that animals in hard waters may tolerate poorer dietary intakes for longer.
Silkworms are still not optimal in calcium content and also they are too rich in fat to be an adequate staple.

[Jasper]

Thanks for the replies!

I think you are assuming the blackworms are for tiny aquatic larva, but in my case, the ¼” to ½” are perfectly fine for 2-3 inch efts. For silkworms, being fed to survive rather than to thrive keeps it at a smaller size. In this way, all nutrients are essentially still there, but worst case scenario(providing they are still alive) is that they are at lesser amounts (except for perhaps protein, which remains the same). This method is especially successful in reducing fat content, as this is the first to go.

As for raising silkworms, I find them substantially easier to keep alive rather than to cultivate when compared to blackworms. I have been buying an ounce of blackworms every week, and have the majority of them die by the time the week is over. I don’t want to feed dead blackworms, even if recently dead, to my newts, so I tend to just dump them and buy more. Of course, the blackworms have been put in the fridge and washed daily to remove dead individuals. Yet, they still perish this way.

Hm. Water hardness is an interesting explanation for why MBD doesn’t seem to affect some individuals. It could very much be true. As for blackworms being the main staple, I do know that it does work succesfully. If you also look at the main foods that are fed during the juvenile stage, they all have horrible Ca:P ratios, which worries me. I am not looking to solely feed silkworms, just to use them as a replacement for blackworms. Perhaps some tropical woodlice would be the perfect way to increase calcium intake.

Theoretically speaking, silkworms are more appealing visually compared to blackworms (at least on land) due to their vigorous movements. If this encourages the shyer efts to eat, the higher nutritional values should promote faster growth. In my case there are older fatties who relish blackworms and will eat in front of me, and the slim, younger shy ones that only eat one worm every few days when I’m not around. I was hoping that by feeding silkworms, the one that gets eaten is substantially better than eating that one blackworm, which would inevitably promote growth for the little ones.

[Chris Michaels]

Growth rates are also important. If animals are growing slowly (usually because of cool temepratures and smaller food input), they will show fewer negative effects of a low Ca:P ratio, as their calcium demand for skeletal growth is lower.

C

[Jasper]

Originally Posted by froggy

Growth rates are also important. If animals are growing slowly (usually because of cool temepratures and smaller food input), they will show fewer negative effects of a low Ca:P ratio, as their calcium demand for skeletal growth is lower.

C

That is also true. However, I do know someone personally that has had great success with feeding only blackworms in the juvenile stage. Another factor may be that since growth rate is so slow, the small amounts of calcium are actually meeting the demands of growth.

There is also a lot we don't know. For example, vitamin D is crucial for the proper absorption of calcium, yet newts generally avoid the sun and have evolved various sun-blocking chemicals on their skin. In captivity, many newts are raised in basements, with absolutely no sunlight. Feeder foods also do not get this vitamin from the food they eat, and so newts do not get any through food. Without it, much of the calcium eaten is excreted by the kidneys as waste. Additionally, vitamin A, found in the carotenoids used to supplement reptiles, is found, in turn, to suppress the absorption of vitamin D.

There is also no set ratio for Ca:P required by caudates. The recommended value is 2:1, but I have also seen 1.2:1 being recommended for newts. These values seem anecdotal. At those values, you may not experience any problems, but perhaps at 0.5:1, you won't as well.

Of course, I'm not going to risk it, but it is interesting talking about it nevertheless. Also, I found this:

"Silkworms

Silkworms are widely accepted as being the best livefood for reptiles. They are high in protein, low in fat, (half as much fat as there is protein) have a very good Ca:P ratio compared to any other feeder insect, and their soft bodies do not cause any digestive problems as you may get with mealworms. Silkworms also contain an enzyme known as Serrapeptase which is often used as a supplement because to its many therapeutic properties.


Dry Mass
30-35%a
Protein
53%^^
48%^^^
63.8%"
Fat
26%^^
27%^^^
10.6%"
Ca:P ratio
0.83:1""
0.8:1"
kcal/g
6.74^^^

High in Protein and relatively low in fat. Best Ca:P ratio out of all livefood listed.
"