Concentrations of putrescine, spermidine, and spermine in duodenum and pancreas as affected by the ratio of arginine to lysine and source of methionine in broilers under heat stress.

An experiment was designed to investigate the effect of Arg, Lys, Met, and environmental temperature on broiler performance and associated changes in duodenal and pancreatic polyamines. Two groups of 26-d-old Ross male broilers raised under thermoneutral (TN) conditions were reallocated to 4 rooms kept at heat stress (HS) or TN. Birds were fed equimolar amounts of 2-hydroxy-4-(methylthio) butanoic acid (HMB) or DL-Met (DLM) at requirement levels with Arg:Lys at 0.95 or 1.40. Twelve replicates of 4 birds were offered each diet ad libitum. Body weight gain, efficiency of dietary CP accretion (CPE), feed intake, and feed conversion ratio were ascertained from 26 to 33 d and from 34 to 47 d of age. One bird per cage was killed at 33 and 47 d, and samples of duodenum and pancreas were assayed for putrescine, spermidine, and spermine (Spm), together with estimates of duodenal villus height. From 26 to 33 d, birds fed HMB performed better than those fed DLM, but only at TN conditions. From 34 to 47 d, feeding HMB tended to optimize CPE when added to diets high in Arg. However, lower CPE was obtained when HMB was added to low-Arg diets, whereas birds fed DLM were unaffected by these treatments (P < 0.10). Methionine source, Arg:Lys, or both affected the concentrations of duodenal and pancreatic polyamines, with some changes correlating with performance variables during HS (P > 0.05). It was found that HS caused lower tissue spermidine (P < 0.001) and higher pancreatic Spm (P = 0.08) from 34 to 47 d. Putrescine concentrations were affected by diet and HS, depending on tissue and experimental period. Pancreatic Spm correlated negatively with changes in CPE influenced by Arg:Lys by Met source interaction in chronically heat-stressed birds. The possible association between polyamine metabolism and some of the effects of the Arg:Lys by Met source interaction observed in chronically stressed birds deserves further investigation.