The Effect of Chick Methionine Status on Broiler Performance and Physiological Response to Acute and Chronic Heat Stress

Abstract

and Implications An experiment was conducted to test methionine source and concentration on the growth performance and physiological responses of heat-stressed broiler chickens. Birds were fed either DL methionine or 2-hydroxy-4methylthiobutanoic acid (HMB) at two concentrations (adequate: starter 0.94%, grower 0.84% or superadequate: adequate concentrations +20% methionine) over a six day period at normal or elevated environmental temperatures. Heat treatment was initiated at 21 days of age within controlled environmental chambers. Blood samples were taken 6 hours and 6 days post treatment to determine the effects of acute and chronic heat stress on various blood parameters. Heat treatment significantly impaired growth performance over the 6 day period. There were no effects of methionine source or concentration on the growth performance of broilers within any of the environmental treatments. Blood parameters changed during acute heat stress, but normalized over chronic heat exposure. Birds were apparently able to adapt blood chemistry to heat exposure subsequent to chronic heat stress, but were still negatively affected from a performance standpoint.

Effect of Dietary Lead on Intestinal Nutrient Transporters mRNA Expression in Broiler Chickens

“…Furthermore, our result showed that Pb-induced oxidative stress negatively affected the feed efficiency. While this effect is in part attributable to the Pb-induced decrease in feed intake, it may also be directly related to associate metabolic and endocrine responses, as indicated by paired feeding studies [ 27 , 54 , 55 ]. Bolek and Persia [ 55 ] used a heat stress model in chicken and reported that approximately 54% of the reduced BWG was due to the effects of stress itself and the remaining BWG reduction was associated with reduced feed intake.…”

“…While this effect is in part attributable to the Pb-induced decrease in feed intake, it may also be directly related to associate metabolic and endocrine responses, as indicated by paired feeding studies [ 27 , 54 , 55 ]. Bolek and Persia [ 55 ] used a heat stress model in chicken and reported that approximately 54% of the reduced BWG was due to the effects of stress itself and the remaining BWG reduction was associated with reduced feed intake. It has been shown that chickens under heat stress have lower plasma thyroid hormones, weight, and length of the jejunum and higher corticosterone and apical SGLT1 expression than pair-fed groups [ 27 ].…”