Chicken at a drinker

Increased stress on modern broilers could be putting the eating quality of poultrymeat in jeopardy. As such, the industry needs to pay more attention to the effects of nutrition and housing to ensure birds are not being compromised.

Addressing a DSM conference at Morely Hayes in Derbyshire, Malcolm Mitchell, a professor at Scotland’s Rural College who specialises in understanding stress in commercial livestock said genetic selection of modern broilers had focused on growth rates and meat quality.

However, high growth-rate birds were more susceptible to stress, which resulted in muscle damage and tougher meat.

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“Genetic selection has reduced the time it takes to get a 2kg body mass,” he told delegates. “But when we produce the animals, we are not aware of the responses and mechanisms we might have compromised.”

Prof Mitchell said more research was needed to ensure poultry production systems were perfectly tailored to birds’ needs and not putting avoidable stress on their bodies.

“All the stressors accompanying high growth-rates result in muscle damage,” he said. “Modern meat birds are more stress susceptible, particularly to heat.”

Research had shown that heat stress in fast-growing chickens continued for a day, compared with just a few hours on slow-growing birds. Stress was further exacerbated by things like transportation

“All the stressors accompanying high growth-rates result in muscle damage.” Professor Malcolm Mitchell, Scotland’s Rural College

“Just by being a broiler chicken, you have a much greater degree of muscle damage,” he added.

“And it is during muscle repair that cells can become fibrosis, which results in tough meat.”

A better understanding of the impacts of nutrition and housing was vital to ensuring birds were reared in the optimum conditions and that good meat quality was maintained, Prof Mitchell said.

For example, scientists had discovered that birds given a restricted diet had smaller muscle fibres which were less susceptible to damage and tough meat, he said. Yet birds were still selected for bigger muscles.

There was also little understanding of how birds’ behaviour was altered in different production systems, and whether they experienced negative sensations such as muscle soreness.

“We need to look further at the consequences for the birds,” he added.

“If we don’t, theremay be a price to pay for the successes we have had in broiler production.”