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2.2.7 Fermentation characteristics of lactobacilliFermentation characteristics of each group of Lactobacillus species were performed with the Ph-48generalized PhenePlate system (BactusAB, Huddinge, Sweden). This is based on intervalmeasurements of colour changes, visualized by the pH indicator (bromothymol blue), resulting frombacterial metabolism of two sets of 46 freeze-dried substrates including low–molecular-weightcarbohydrates (mono-, di-, and trisaccharides), carbohydrate derivatives (sugar alcohols, sugar acids,and glucosides), organic acids, urea, and ornithine.2.2.8 Enzyme-linked immunosorbent assay (ELISA)Total antibody titre concentrations of IgY, IgM, and IgA in serum were determined before Cpchallenge (14 d), and at 7 d after first challenge (21 d) using a sandwich ELISA. Blood samples werecollected from the jugular vein into 7-mL serum tubes and clotted at room temperature (RT) (25˚C) for2 h, and serum was separated from the cells by centrifugation (Beckman Instruments Inc., Palo Alto,CA, USA) at 2,300 x g for 5 min and stored at -20˚C. The specific IgY antibodies against the α-toxinof Cp in blood serum were determined as described by Heier et al. (2001), with some modifications2.2.9 Bird husbandryAll birds used under Strategy A were Cobb strain, obtained from a local hatchery (Baiada hatchery,Kootingal, NSW, Australia). They were vaccinated against Marek‟s disease, infectious bronchitis, andNewcastle disease prior to collection. At 1 d of age, chicks were randomly placed in brooder cages(42 cm x 75 cm x 25 cm dimension) with wire floor and with a floor space of 0.32 m 2 /cage. The cageswere randomly assigned to one of six dietary treatments with the appropriate number of replicates pertreatment. The temperature was set at 33-34˚C during the first week and gradually decreased by 3˚Cper week until 24-25˚C was reached by the third week. Relative humidity was between 65 and 70 %.A photoperiod of 24 h from 1 to 21 d of age, and 18 h from 22 to 42 d of age was maintained. Eachpen was equipped with a feeding and water trough placed outside and also an excreta collection tray.Water and feed were provided ad libitum. Weekly BWG and FI per cage were measured and FCR,adjusted for mortality, calculated on a cage basis. Birds were observed twice daily for general health.2.3 Strategy BThree experiments were conduct to address the second strategy of this project. Some of the methodswere common to those used for strategy A, and are described in section 2.6.0. Specific methods usedfor this strategy are described in the following sections.The first of the three experiments was conducted at the Agricultural University of Norway, Ås,approximately 20km south-east of Oslo. The feeding trial work was conducted inside a temperatureand light controlled environment on campus. The experiment commenced in May 2004 and wascompleted in June 2004.Feed was processed at The Agricultural University Center for Feed Technology Ltd. (FôrTek),situated on the University campus. All sample analyses were conducted on campus. Dry feed anddigesta particle size analysis was carried out using a Mastersizer 2000 LASER diffraction particle sizeanalyser, with Sirocco 2000 and Hydro 2000G accessories (Malvern Instruments Ltd., UK) used fordry and wet samples, respectively.8