The study, published in the British Journal of Nutrition’s publication Molecular Nutrition, looked at 180 chickens from the age of 1-21 days and 22-42 days. After being raised conventionally for the first 21 days, they were divided into three groups: those not given methionine, those given the recommended level of methionine and those given an excessive amount.
They were either kept at a comfortable thermal temperature or exposed to heat stress at 38°C for 24 hours.
Chickens exposed to stress and fed methionine-supplemented diets showed better results in terms of the activity of enzymes used as stress markers, said the team.
The Brazilian researchers said this could be due to an increased expression of genes related to antioxidant activity.
“These results allow us to suggest that under heat stress conditions in which the body temperature was greatest, methionine supplementation could mitigate the effects of stress, since the supplementation contributed to the increased expression of genes related to cysteine and glutathione (GSH) production as well as to the increased expression of the glutathione peroxidase 7 (GPx7) gene,” the researchers wrote.
GSH is an antioxidant system and the gene GPx7 is related to antioxidant activity.
At 42 days old the birds from both the thermal comfort and heat stress groups were slaughtered by cervical dislocation, before which rectal temperature was measured.
However, in 2013 methionine was amongst the four amino acids listed by the Norwegian Scientific Committee for Food Safety (VKM) as high-risk and linked to problems like nausea, dizziness and increased blood pressure.
High levels of methionine can be found in eggs, sesame seeds, Brazil nuts, fish, meats and cereal grains.
Source: Molecular Nutrition
Vol 113 Iss 04, pp 549-559, doi:10.1017/S0007114514003535
“Effects of methionine supplementation on the expression of oxidative stress-related genes in acute heat stress-exposed broilers”
Authors: A. Paula Del Vesco, E.Gasparino, D. de Oliveira Grieser, V. Zancanela, M. Amélia Menck Soares and A. Rodrigues de Oliveira Neto