I think this really hits the nail on the head. For decades the common nutrition mantra was 'eating fats makes you fat' and 'eating a high cholesterol diet give you high cholesterol.' The studies behind those were flimsy at best and mostly financed/promoted by people who profited from it ... especially those selling high sugar and highly processed food. But, if you repeat a lie often enough, it becomes 'fact.' (Especially if you help write the textbooks!)Not all fats are harmfull. It seems that saturated fats can be a problem if eaten in excess but other types of fat are in fact required for health.
It would be informative if for every case of fatty liver syndrome/water belly detailed information on the keeping conditions of the birds was well documented.
I buy into the idea that quality saturated fats such as butter and coconut oil are very healthy options. Pardon me if I share too many Mercola articles in a day ... but this one has some great info on fats and take particular aim at Linoleic Acid as being worse for your diet than sugars.
Back to your point, Shadrach ... if would be VERY interesting to see which fats lead to fatty liver syndrome. As, I'm doubtful that they were healthy fats.