I also figured out that the dosage rate for turkeys published on the DuraFend 0.5 % medicated feed bag would require the bird to consume approximately 35 pounds of combined regular and medicated feed in order to get a 250 mg dose. Like the apocryphal 3 cc per gallon water recommendation, that turkey feed dosage on the bag would be unlikely to be effective -- at least not if our birds need a rate of 50 mg per kg to be effective. (That's about 10 times the dosing rate for livestock, btw, but that's the number I saw over and over again when I read all the threads I could find...) I took a couple photos of the bag, so if anyone wants to see that info, I can post the pix in another post. I'm really puzzled by this, but am thinking it is because they are feeding it as a sole food source over a period 6 days, and that it may have to do with the rate of clearance/excretion/breakdown from the turkey and the need to prevent overdosing? Anyway, I humbly don't think it would work.
I assumed a 250 mg dose of fenbendazole for cost-comparison purposes, based on all the recommendations. That is 2.5 ml of 10% liquid, 2.5 g of 10% paste, and is also 1.76 ounces BY WEIGHT (or 49.6 g) of 0.5% medicated feed. That's about 1/10 of a 1 lb medicated feed bag -- looking at the volume in the bag, my peas could probably, I think, each eat that in one meal without too much trouble, if they liked it. (Thinking a nice mash with egg or some cat food...) The 1 lb bag says that it has 2.27 g/lb, (0.45 kg), so the whole entire bag has 2270 mg of fenbendazole in it, or a little less than 10 individual bird doses. (When I saw it in the store, my plan was to do the 6 day turkey thing for a repeat dose in 10 days or so, but after doing the math, I don't think that will work. It will, however, work fine, I think, for single-dosing at the higher rate.)
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Anyway, I think this is the correct math for calculating the medicated feed (grain/alfalfa/pellet/crumble) dosing -- the thing on the bag is just weird. It says to mix the 1 lb bag of medicated feed into 313 lb of regular feed and give it to growing turkeys as the sole ration for six days. As I said above, it would take 34 1/2 lb of feed mixed at that ratio to get one 250 mg dose into a bird -- my peas definitely are not each eating 34 pounds of food per week, it's just not physically possible for them to consume that much... Since I wasn't at all sure how much they do eat per day, I worked it out backwards to see how much of it is needed to get an effective 250 mg dose... straight out of the bag, that's 1.76 ounces by weight. I don't know the volume measurement though -- it needs to be weighed out. I'd have to fool with a measuring cup and scale to figure out the volume, and doubt if it would be exactly the same across the different manufacturers. It's sold by weight.