The effect of microbial challenge on the intestinal proteome of broiler chickens

Background: In poultry production intestinal health and function is paramount to achieving efficient feed utilisation and growth. Uncovering the localised molecular mechanisms that occur during the early and important periods of growth that allow birds to grow optimally is important for this species. The exposure of young chicks to used litter from older flocks, containing mixed microbial populations, is a widely utilised model in poultry research. It rarely causes mortality but effects an immunogenic stimulation sufficient enough to cause reduced and uneven growth that is reflective of a challenging growing environment. Methods: A mixed microbial challenge was delivered as used litter containing Campylobacter jejuni and coccidial oocysts to 120 male Ross 308 broiler chicks, randomly divided into two groups: control and challenged. On day 12, 15, 18 and 22 (pre- and 3, 6 and 10 days post-addition of the used litter) the proximal jejunum was recovered from 6 replicates per group and differentially abundant proteins identified between groups and over time using 2D DiGE. Results: The abundance of cytoskeletal proteins of the chicken small intestinal proteome, particularly actin and actin associated proteins, increased over time in both challenged and control birds. Villin-1, an actin associated anti-apoptotic protein, was reduced in abundance in the challenged birds indicating that many of the changes in cytoskeletal protein abundance in the challenged birds were as a result of an increased rate of apoptosis. A number of heat shock proteins decreased in abundance over time in the intestine and this was more pronounced in the challenged birds. Conclusions: The small intestinal proteome sampled from 12 to 22 days of age showed considerable developmental change, comparable to other species indicating that many of the changes in protein abundance in the small intestine are conserved among vertebrates. Identifying and distinguishing the changes in proteins abundance and molecular pathways that occur as a result of normal growth from those that occur as a result of a challenging microbial environment is important in this major food producing animal

The nutritional value of new varieties of high-yielding triticale: Nutrient composition and in vitro digestibility

Ten high-yielding cultivars of triticale obtained from a breeding group at the University of New England, harvested in 2008 and 2009, were assessed for nutrient composition and nutrient digestibility. The cultivars tested were AT528, H20, H127, H128, H157, H249, H418, H426, JRCT74 and Tahara. Their nutrient characteristics, including dry matter, crude protein, crude fat, ash and gross energy, starch content and composition, and concentrations of non-starch polysaccharides, minerals, phytate-P content and amino acids, were determined. The in vitro digestibility and viscosity during digestion were also measured. There was low variability between the cultivars tested and harvest years (the difference between wet and dry conditions) had little effect on nutrient composition.Keywords: High-yielding triticale, harvest years, proximate composition, starch, non-starch polysaccharide

High levels of maize in broiler diets with or without microbial enzyme supplementation

A total of 210 day-old male Cobb broiler chickens were randomly assigned to six treatments in a 3 × 2 factorial design. The treatments consisted of three levels of maize: 250 g/kg (LM), 500 g/kg (MM) and 750 g/kg diet (HM) and two levels of enzymes: plus enzyme and no enzyme. Each treatment was replicated five times, with seven birds per replicate. Chickens were reared in multi-tiered brooder cages to 21 days of age in a climate-controlled room. Feed and water were provided ad libitum. Over the feeding period (21 d), there was an increase in feed intake as maize inclusion level (MIL) increased in diets, while supplementation with microbial enzyme improved feed intake only in the MM diet. There was an improvement in live weight (LW) in chickens with increased MIL in their diets. The microbial enzyme supplement also improved LW, but only on the MM diet. The feed conversion ratio (FCR) was improved with increase in MIL in diets, but the enzyme supplements had no effect on FCR up to day 21. At day 21 there was an increase in relative weight of the small intestine with an increase in MIL, but this was not affected by enzyme supplementation. The weight of the liver increased with increase in MIL and enzyme supplementation. At day 21 the pH of the digesta in the gizzard declined with an increase in MIL in diets. In general, there was no significant effect of MIL or enzyme supplementation on pancreatic tissue protein content, chymotrypsin amidase activity and ileal digestibility of protein, gross energy and starch at 21 days of age. The population of Clostridium perfringens decreased significantly with increase in MIL, but other microbial species were unaffected. The present findings suggest that maize could be included at much higher levels than is currently done without detrimental effects on productivity. Exogenous enzymes also resulted in a significant increase in some of these variables.Keywords: Maize inclusion, enzyme supplement, bird performance, gut microflor

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Not AvailableInadequate supply, exorbitant prices and diversion towards using cereal grains forbiofuel production, particularly maize, has led to a constant search for alternativeenergy sources for poultry and other non-ruminant species. The abundantavailability of cassava in certain regions makes it a good alternative to maizeand other cereal grains. Cassava root meal is rich in carbohydrate but low inprotein and all other nutrients, whereas, cassava leaf meal is a moderate sourceof protein. Results of studies to evaluate the replacement of cereals with cassavaproducts in poultry feed show wide variability due to differences in origin, variety,plant maturity at harvest, ecological conditions of plant growth and processingmethods. Cassava products contain a wide range of cyanogenetic glycosides,particularly linamarin and lotaustralin. The level of hydrocyanic acid releasedfrom the cyanogenetic glycosides limits the utilization of cassava, but with properprocessing, the dietary inclusion level of cassava meal can be increased for economicpoultry production. This paper reviews the nutrient composition of cassava and itsuses as a substitute for more conventional ingredients in poultry dietsNot Availabl