200 kilograms, wow, what a pigeon--he weighs over twice what I do!!!
Sorry, just had to do that because when we figure medications for these little guys, we have to be oh-so-precise or we'll kill the bird or not heal it. That said, you no-doubt meant to say "200 g" or 200 grams, which is 0.2 kg.
So... 0.2 kg X 20 mg/kg = 4 milligrams per day. Yes, 5.6 milligrams would be a slight overdose, but not that significant for that drug, just 40%. While that sounds significant, it kinda' does depend on the drug in question. When, for example, we're dealing with anti-epileptic drugs, we have to be a lot more precise, but not really here, you're good to go. If you wanted to try and cut the pill up into 5 somewhat-equal pieces, it would go further.
Pidgey