The role of supplemental glycine in establishing a subclinical necrotic enteritis challenge model in broiler chickens

Subclinical necrotic enteritis (NE) is an economically important disease in the broiler industry. With the move towards removal of antibiotics from feeds, solutions to control subclinical NE are desperately being sought. Dietary glycine has been shown to promote proliferation of Clostridium perfringens (Cp) and may thus be useful to include in a NE challenge model. A study was conducted to evaluate the effect of increased dietary glycine levels on subclinical NE. A 2 x 2 x 2 factorial arrangement of treatments was carried out using day-old male Ross 308 chicks (n = 624) allocated to 48 floor pens with 8 treatments of 6 replicates with 11 birds per treatment. Factors were: Cp challenge (C- or C+), Eimeria spp. challenge (E- or E+), and dietary glycine in the grower diet (0 or 10 g/kg). Birds had higher FCR when challenged with Eimeria (P < 0.01) or Cp (P < 0.05) on d 24 or Cp on d 35 but FCR was lower when fed glycine on d 24 (P < 0.01). Supplementation of glycine reduced feed intake on d 24 and increased weight gain on d 35 (P < 0.05). A Cp x Eimeria x glycine interaction (P < 0.05) showed a higher jejunal lesion scores in birds challenged with a combination of Cp and glycine compared with those with Eimeria and glycine or the unchallenged birds. Lesion score interactions between Cp and glycine (P < 0.05) in the ileum and Cp and Eimeria in the duodenum (P < 0.05) and ileum (P < 0.05) illustrated higher lesion scores in birds challenged with Cp without Eimeria or glycine compared to those not challenged with Cp. This study suggests that using glycine can partially replace Eimeria in a subclinical NE challenge model in promoting the intestinal lesions but not impairing chicken performance. (C) 2017, Chinese Association of Animal Science and Veterinary Medicine. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).