Tilhana
Songster
Of course they eat to fill a caloric need, that goes without saying. But that doesn't mean they necessarily stop eating once that need is fulfilled. Even if they stop eating the food that's available, they may still eat more if their favorite treats are offered. For some birds, their favorite treats will be bugs they can find on pasture all day; for others it may be grains that they usually only get in the morning; and for others it may be pieces of fruit that get thrown to them throughout the day.Most all poultry will if eat to fill a caloric need.
But my main point is that chickens with multiple food options available are not going to become deficient in protein because they've filled up on grass. My understanding of your initial argument about protein requirements in feed is that you disagree, and worry that if any part of their diet is lower in protein than the rest, they will meet their caloric needs for the day and stop eating, thereby becoming protein deficient. If that is your hypothesis, then presumably you would be against letting chickens free-range, since you can't control the nutrient ratios of what they find in the pasture? If that's not your argument, then please explain why it would be ok to let them get part of their diet from pasture, with unpredictable nutrient ratios, but not ok to also feed them a conventional grain feed that has a slightly lower protein content than their daily requirement?
I'm not sure how that bolsters yoru argument...unless a full crop offers a more powerful satiety signal than a full stomach, which may be true, I don't know. I'm just saying that many animals will continue eating if food is available, even if they're full or have met their caloric needs for the day. Dogs are another example. Presumably because many animals evolved in an environment where all foods were not always available, so they never had to learn to curb their appetites. It was more advantageous to eat the less available foods whenever they found them, regardless of their current state of hunger, because their availability is unpredictable and it's better to hoard the nutrients in anticipation of future lean times.The nutritional needs of poultry and the way they process there food is different than humans. When we eat our food goes straight to our stomach, when poultry eat there food goes to there crop and sits there for up to 12 hours getting for the most part "fermented" then the food goes to the gizzard to get ground up and later absorbed by the small intestine.