Immune responses to dietary β-glucan in broiler chicks during an Eimeria challenge

Abstract

Escalating consumer concerns regarding pathogen resistance have placed the poultry industry under mounting pressure to eliminate the use of chemotherapeutic agents as feed additives. One possible alternative receiving increased attention is the use of immunomodulators such as β-glucan. A study was conducted to investigate the effects of a yeast-derived β-glucan (Auxoferm YGT) on broiler chick performance, lesion scores, and immune-related gene expression during a mixed Eimeria infection. Day-old chicks were fed diets containing 0, 0.02, or 0.1% YGT. On d 8 posthatch, one-half of the replicate pens were challenged with a mixed inoculum of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Measurements were taken and samples collected on d 4, 10, 14, and 21 posthatch. Dietary supplementation had no effect on performance or mortality. On d 14, 3 birds per pen (n = 24/treatment) were scored for intestinal coccidia lesions. Gross lesion severity was significantly reduced in birds supplemented with 0.1% YGT. On d 10, inducible nitric oxide synthase (iNOS) expression was downregulated in the jejunum of challenged birds fed 0.1% YGT. Expression of iNOS in the ileum was downregulated in the nonchallenged birds, but upregulated in the challenged birds fed 0.1% YGT on d 14. Interleukin (IL)-18 was upregulated in the jejunum of 0.1% YGT-treated birds. Interferon (IFN)-γ expression was decreased in challenged and nonchallenged birds fed 0.1% YGT. The IL-4 expression was downregulated in the nonchallenged birds with 0.1% YGT diet supplementation. The IL-13 and mucin-1 levels were also reduced due to β-glucan supplementation. Mucin-2 expression was increased in the nonchallenged birds, but decreased in the infected birds fed 0.1% YGT. These results suggest that although Auxoferm YGT at doses of 0.02 and 0.1% does not influence performance, it significantly reduces lesion severity and is capable of altering immune-related gene expression profiles, favoring an enhanced T helper type-1 cell response during coccidiosis.

Molecular cloning and expression of two β-defensin and two mucin genes in common carp (Cyprinus carpio L.) and their up-regulation after β-glucan feeding

“…Accurate assembly of the mucin genes is difficult due to the large size of the central tandem repeats [39], which is probably why attempts to fully sequence the mucin genes in this study were unsuccessful. Carp mucin sequences had high homology to two mammalian and avian gel forming mucins:Muc2 and Muc5B.…”

“…Consistent, but not significant, down-regulation of Muc2 in the intestine and gills was seen in the glucan fed fish, while Muc5B was significantly increased in skin, with slight up-regulation in gills. An up-regulation of Muc2 expression after b-glucan feeding was described in the intestine of chicken [39] and pigs [40], and an increased expression of Muc2 and Mub5B has been observed in mammals after bacterial [35,41e43] and nematode infections [44].…”

Hops β-acids and zinc bacitracin affect the performance and intestinal microbiota of broilers challenged with Eimeria acervulina and Eimeria tenella

“…The present study has been conducted using an experimental protocol similar to that of some recent reports (Cox et al, 2010;Orengo et al, 2012;Kim et al, 2013;Scheurer et al, 2013). In this study, the birds were inoculated with E. acervulina and E. tenella, while Kim et al (2013) showed that E. maxima was more effective in reducing weight gain than E. tenella.…”

Beta-Glucans as Immunomodulators in Poultry: Use and Potential Applications

“…In a subsequent study involving a mixed Eimeria infection at 8 days of age, intestinal iNOS expression was down-regulated in the ileums of 0.1% b-glucan fed birds in the absence of a challenge, but upregulated in the challenged, b-glucan treated birds. These results suggest a dynamic function of bglucans dependent on the disease status (Cox et al, 2010b).…”