The chicken industry pushed back this week against a growing campaign to move away from breeding larger birds that bulk up quickly, saying the “slow-growth” movement would use more energy, cost shoppers more and possibly result in less protein on people’s plates.

If even a third of the nation’s $48-billion poultry industry switched to more svelte chickens, the national flock would need to grow by 1.5 million birds to keep up with current consumption rates, according to an economic analysis released Wednesday by the National Chicken Council, a not-for-profit trade association.

That increase would require an additional 5.1 billion gallons of water and 7.6 million acres of land to raise the additional feed those chickens would need, according to the report. 

“It comes with trade-offs, and that’s what we want to get out there,” said Tom Super, spokesman for the council. “Before it becomes a domino issue like the cage-free eggs, we want our customers to have all of the information on hand while they’re making these decisions.”

The report, prepared by an industry consulting group, comes after a year marked by increased pressure from consumers, retailers and food service companies to transform practices at the nation’s factory farms, including the use of antibiotics, housing chickens in crowded cages and failing to stun birds properly before slaughter.

Last March, Whole Foods Market announced it would require its suppliers to switch back to slower-maturing breeds and to improve farm conditions by 2024 as part of the Global Animal Partnership program the retailer created to push for more humane treatment of farm animals. In November, food service titans Aramark and Compass Group agreed to follow the same standards.