i'm not sure if it's his age - he's 3.5 years old - or if it is something else. he just seems "out of steam" these days. when he walks, when he stands (totters) or when he runs. he also ran into a cattle fence the other day and just dropped to the ground. should i give him and my other 3 adults (2 male, 2 female) ducks some niacin?