According to AWI, NCC claims that their guidelines are based on scientific knowledge and the principle that chickens raised for food should be cared for in ways that prevent or minimise fear, pain, stress, and suffering. AWI charges, however, that the guidelines are based on commercial expedience and not animal welfare science. And instead of preventing or minimizing fear, pain, and distress, the guidelines actually foster these forms of animal suffering.

AWI also added that the revised guidelines fail to provide an acceptable level of welfare. For example, the guidelines allow for near-continuous, dim lighting that facilitates feed consumption and weight gain but also causes leg abnormalities and eye problems. According to AWI, confinement to a crowded and barren indoor environment prevents chickens from performing the most basic of natural behaviors, such as preening and flapping their wings, and also leads to high ammonia levels in the air and in the birds' litter, which causes skin and respiratory ailments.

The Animal Welfare Institute says that as to the slaughter of chickens, the guidelines are not in compliance with several recommendations of the World Organization for Animal Health (OIE):

• NCC allows four per cent of birds to have broken bones, while the OIE recommends a maximum of two per cent, with less than one per cent being the goal.
• NCC allows birds to be held at slaughtering facilities for up to 15 hours, while the international standard is 12 hours.
• NCC fails to limit the amount of time that chickens are forced to hang upside down on shackles, while OIE recommends a maximum of one minute.
• NCC allows birds with broken or dislocated bones to endure the painful process of shackling, while OIE recommends that injured birds be humanely killed before shackling.
• Unlike OIE, NCC doesn't set minimum electric current levels for stunning chickens, which can result in birds being immobilised by a low current—but not necessarily rendered unconscious—before they are killed.

"The guidelines are not designed to ensure welfare but rather to facilitate the raising and slaughtering of as many birds as possible, in as short a time as possible," said Dena Jones, AWI farm animal programme manager. "We urge NCC to adopt the revisions described in our letter to provide these animals a better quality of life as well as a more humane death."

Chickens raised for food in the United States have no federal legal protections against inhumane treatment on the farm or at the slaughterhouse. AWI, along with the animal advocacy organisation Farm Sanctuary, recently petitioned the US Department of Agriculture (USDA) to enact regulations requiring humane handling of chickens at slaughter.