The images posted shows Duramycin 10...
If you look on the first page as I stated 1 Tablespoon per gallon for the 800mg dosage rate...
http://www.durvet.com/dl/Durvet-Poultry-Brochure.pdf
Sorry missed that, page 12 of the linked PDF shows 3/4 Teaspoon per Gallon for the regular strength vitamin and electrolyte powder...
It says oxytetracycline, not Duramycin 10 or tetracycline. Easy to be confused. Glad you looked up the vitamin/electrolyte dosage.