Methionine toxicity in chicks and poults

Area of Science:

• Animal Nutrition
• Poultry Science
• Biochemistry

Background:

• DL-methionine is an essential amino acid crucial for poultry growth.
• Methionine and its analogues can exhibit toxicity at high dietary levels.
• Understanding the metabolic interactions of methionine is vital for optimizing poultry feed formulations.

Purpose of the Study:

• To investigate the effects of high DL-methionine and homocystine supplementation on poult growth.
• To determine the efficacy of glycine and betaine in alleviating the growth depression caused by these amino acids.
• To explore the potential link between methionine toxicity and folic acid deficiency symptoms.

Main Methods:

• Feeding experiments were conducted with poults using diets supplemented with DL-methionine or homocystine.
• Glycine and betaine were added to the diets to assess their alleviating effects.
• Observations included growth performance and clinical signs, such as cervical paralysis.

Main Results:

• DL-methionine at 2% caused significant growth depression, which was ameliorated by glycine.
• Homocystine also depressed growth, but to a lesser extent than methionine, and was alleviated by glycine.
• Betaine alleviated homocystine-induced growth depression but not that of methionine.
• Methionine-fed poults exhibited cervical paralysis, unresponsive to folic acid supplementation.

Conclusions:

• Glycine can counteract the growth-depressing effects of both DL-methionine and homocystine in poults.
• Betaine shows specific efficacy in mitigating homocystine toxicity, but not methionine toxicity.
• The cervical paralysis observed in methionine-fed poults is distinct from folic acid deficiency, despite superficial similarities.