Just thought I'd let everyone that is interested know that I got a prompt and detailed response to my query about Natura's policies about in vivo pet food testing.  (i.e. feed trials where the cats or dogs actually eat the food.)  They sent me 3 documents: a statement from Peter Atkins, an article written by a veterinarian technician for Natura Pet Products; and a copy of their official policies.
They ask that you do not post or forward electronic communications, but I think that they will be happy to send the same information to anyone that asks.  I found them to be very open about the testing.  They have their own facility and it looks quite nice to me and looks like a place that an animal lover would be comfortable working.  They said that they do not do any invasive surgical procedures nor any nutrient deprivation testing.  Mr. Atkin's statement said that the reason they have their own facility and do not contract any feeding studies out is that they want to be sure that cats and dogs that test their products are treated in a way that the company is comfortable with.  To start with, the cats and dogs that live there all have names instead of numbers. 
The documents they sent me had photographs of the facilities, some of the cats and dogs, and lots of details about policy.  I think it was a good sign that Natura was so open.  I'd feel comfortable asking them questions in the future if I had any.  To me humane treatment of working cats and dogs that trial pet food is the foundation of having a comfort level with a pet food manufacturer.  Not everyone feels the need to buy food that is actually feed trialed, but some people do and I think Natura's dogs and cats have better lives overall than many pets in private homes.  (And they said that they do adopt the pets out carefully at some point, and watch over them for life.)
If Natura can accomplish this, then there is no excuse for other companies close to their size or larger not to have a private facility like this.  If you are formulating a good product made from good traditional ingredients, you don't need strange or invasive testing and you can afford to run your own facility that would be considered very humane by the average pet owner.
I encourage everyone that is using a pet food that does feed trials to study the Natura program and if your own company is not up to their standards, ask them to meet their standards.  I personally have to feel that a pet food company cares about ALL cats and dogs in order for me to feel that there is a good chance that they will care about my pet.
I am going to lock this thread since I just wanted to post a report here and not start a discussion.  But do contact Natura if you are interested in their feeding trial program.  I hope that most people would feel as relieved as I was to learn about it.