Effects of Electron-Beam Irradiation of the Diet on Microbial Population, Intestinal Morphology, Ileal Digestibility and Performance of Broilers

A total of 300 one-day old male broilers (Cobb 500) were randomly divided into four treatment groups. The groups comprised of 15 birds each, and were defined by diet and the birds in each group were fed 0 (con-trol), 3, 5, or 7 kGy electron-beam irradiated diets. A total of 5 replicates were performed. The chemical composition of the diet was not affected by irradiation. Irradiation doses of 5 and 7 kGy completely elimi-nated microbial load in diets (P < 0.05) and decreased the total aerobic and coliform counts in ileum and cecum at increasing rate at 14, 28 and 42 days of age (L: P < 0.001; Q: P < 0.0001). Total coliforms of the ileum decreased with the increased irradiation dose at 21 and 42 days of age (Q: P < 0.0001). Lactobacillus counts improved with increased EBI dose, except for lactobacillus in cecum at 42 days of age. There was a linear increase in villus height (duodenum, jejunum, and ileum) with higher irradiation doses at 21 and 42 days of age. Additionally, a linear increase and a decrease in villus height:crypt depth were observed in the jejunum at 21 and 42 days of age, respectively (P < 0.05). The villus height:crypt depth of duodenum and jejunum followed a linear increasing rate (Q: P < 0.001) with the increased irradiation dose. Feed intake, mortality (all periods), body weight gain, and feed conversion ratio were similar between treatments at 1-14 and 14-28 days of age. Body weight gain, however, increased at a rising rate (Q: P < 0.001), and feed con-version ratio decreased at a diminishing rate (Q: P < 0.01) with higher irradiation doses during 28-42 and 1-42 days of age. The ileal digestibility of dry matter, organic matter, ether extracts, gross energy, and appar-ent metabolizable energy increased with the irradiation dose (Q: P < 0.001). Our results indicated that elec-tron-beam diet irradiation reduces microbial coliform counts and supports lactic acid producers in the gas-trointestinal tract. Moreover, the ileal digestibility of nutrients, body weight gain, and feed conversion ratio improve with irradiation.