English to Russian Science Livestock / Animal Husbandry

Помогите, пожалуйста. Никак не могу подобрать слово. Вот несколько примеров, где встречается этот термин:
The first phase of nutritional damage was considered to be a reduction in amino acid availability,... which would reduce ***animal performance*** when the available amino acid supply fell below the animal's requirements.
During early stages of heat damage, Maillard reactions may result in decreased ***(animal) performance*** due to reduced amino acid availability...
Caloric intake of rats decreased when fed proteins heated for short periods of time and this decrease appeared to be responsible for some, at least, of the poor ***performance*** of rats.
After extensive autoclaving, severe reductions in ***performance** and intake were considered to be a result of both reduced intake and reduced digestibility of the protein.
Это все из обзора исследований влияния нагрева белка с углеводами или без них, на его усвоение животными. Заранее благодарю.