Is too much lysine is a good for animal?

Lysine HCl is an essential amino acid used in poultry diets to help ensure balanced nutrition and flock performance. But as with anything else, birds can get too much of a good thing, says Jenny Fricke, DVM, a poultry veterinarian at the University of Saskatchewan.

Fricke recently witnessed this first-hand after doing some hard detective work. She and a number of other researchers were asked to investigate why some chickens were severely underweight. The chickens were seven days old when they were brought to her and had clearly not grown as expected.

“We weighed them and they weighed half as much as they should have,” says Frick.

At first she was stumped. She cut up the poultry to look for clues – such as lesions or signs of other common poultry diseases – but came up empty. She examined samples of birds from other floors and found that many of them had become lame at 12 days old, a phenomenon she could not explain either.

Their investigations also revealed some variation in the amount of lysine combined with feed during the last delivery – a condition that causes otherwise healthy birds to eat less.

She and her colleagues chose to study 500 birds. The birds were fed in cages and their lysine supplementation increased by 2%, 4%, 6% and 8%.

The researchers noted that in many of the birds that received an increase in lysine supplementation, weight loss occurred, as did weight gain. In addition, feed consumption decreased and feed conversion rates were reduced.

“We have footage of birds trying to consume a high lysine diet,” she said, adding that the video suggests that diet palatability is also an issue because there is too much lysine in the diet.

“There are reports that birds will reduce their feed intake if you have an excess or deficiency [of lysine],” she said.

There are several important lessons for producers, she says. One, always collect a good feed sample when poultry are placed.

“You never know when you’re going to need it,” she says.

Two, stay alert.

“We don’t get these birds until they’re seven days old,” she says.

In Canada, she says, broilers usually spend 35 days on the floor. She wonders if the situation could have been reversed if someone had noticed a few days earlier that the birds weren’t eating enough feed.

“Response time is critical,” Flick adds. “On day 7, a fifth of the time these birds had been on that farm had passed. They were pretty far gone by that time.”

Thirdly, too much of anything can be a bad thing – even healthy amino acids.

“It’s important to make sure the birds have good quality amino acids in their diet, but if you consume too much of a good thing, the birds will respond appropriately and reduce their intake,” says Frick.


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