Feed transit time is the amount of time feed components are retained in the gastrointestinal tract and is often measured by giving a known amount of marker-containing diet and determining the first appearance of the marker in the faeces. Most markers used in digestibility studies are insoluble substances such as Cr203 and acid-insoluble ash which must be incorporated into the diets in substantial quantities for sufficient accuracy in subsequent determinations. Feeding birds a marker-containing diet in a given amount of time is difficult and inaccurate, and force-feeding birds using the Sibbald technique is tedious and not suitable for young broilers. The current paper describes a new fat-soluble marker, a long-chain alkane (C36H74), which can be easily and accurately administered to chickens orally.

A total of 294 one-day old Cobb broiler chickens were used to investigate the effects of four lactobacillus strains on production performance. The chicks were assigned randomly to six groups with 7 replicates of 7 chicks per treatment. The six dietary treatments were: (i) basal diet (negative control, Tl); (ii) basal diet with added Zinc-bacitracin (ZnB, 50 ppm, T2), iii) one of four strains of Lactobacillus (tentatively identified as L. johnsonii, L. crispatus, L. salivarius and unidentified Lactobacillus sp., T3, 4, 5 and 6). The probiotic strains were selected from 235 lactobacilli isolates based on their in vitro antagonistic effect against Clostridium perfringens and Escherichia coli. Results showed that the addition of probiotic Lactobacillus spp. to the feed did not significantly improve body weight gain, feed intake and feed conversion ratio of broiler chickens raised in cages during the 6-wk experimental period.

Coccidial co-infection, dietary inclusion of viscous grains and ingredients of animal origin protein are considered important predisposing factors for onset of necrotic enteritis (NE). High dietary glycine levels has been shown to increase the intestinal 'C. perfringens' population in broilers (Dahiya et al. 2005). As the causative agent for NE, the spore germination of 'C. perfringens' can be activated by the spore cortex-lytic enzyme (SCLE) coded by SleC thus to cause gastrointestinal disease. Investigations have shown that glycine forms a conjugated compound with bile salts playing a critical role in Clostridial germination (Sorg and Sonenshein 2008). This compound is recognized by the germinant receptor, CspC and is responsible for cleaving the N-terminal propeptide of SleC, expressing mature SCLE to activate its hydrolase activity. The current study assessed the impact of a high dietary glycine inclusion on performance of broilers under subclinical necrotic enteritis challenge.

We investigated the pattern of non-starch polysaccharide (NSP) digestion along the gut of pigs fed two different wheats, which were offered with or without xylanase supplementation. The two wheats used were pre-characterised before the experiment on the basis of low and normal feed intake of young pigs. Wheat type significantly influenced feed intake and growth rate in the first 7 days, however, by day 14 the only significant effect of wheat type was on growth rate. Xylanase supplementation increased the growth performance of pigs fed the poor quality wheat to a level similar to those fed the normal wheat. It also increased the daily gain of pigs fed the normal wheat. Wheat type had no significant effect on the digestibility of dry matter (DM), energy, free sugars or the different fractions of NSP in the duodenum, ileum or in the faeces. The duodenal gross energy digestibility values for the low and high performance diets were −27.4 and −47.5%, respectively, and xylanase supplementation significantly increased the digestibility of energy back to positive levels. Dry matter digestibility values followed a similar pattern. In the duodenum, xylanase increased (P < 0.05) the digestibility values of both soluble and insoluble NSP, whereas in the ileum, xylanase had a significant effect only on the digestibility of the soluble NSP fraction. Xylanase did not affect free sugar digestibility. The reduction in soluble NSP level coincided with a marked reduction in the amount of fucose, a prominent component of mucosal polysaccharides. This suggests that soluble NSP substantially increase endogenous losses. The absence of differences in the digestibility of the measured NSP between the two wheat samples suggests that the structures of the NSP, rather than just their amount and solubility, are important for the anti-nutritional properties of NSP in pig diets.

Phytobiotics represent a wide range of bioactive compounds that can be extracted from various plant sources. In recent years, some interesting and novel applications of phytobiotics in the production and wellbeing of monogastric animals have emerged, and these aspects are reviewed in the present paper. Recent studies at the University of New England indicate that water—soluble carbohydrate extracts from some Australian and New Zealand native plants can be used as potential phytobiotic compounds to modify the gut microflora in broiler chickens. Compared with other in—feed antibiotic alternatives, the evaluation of phytobiotics is still in its infancy and their potential use needs to be investigated with broader emphasis.

Necrotic enteritis (NE) causes significant economic losses in the broiler chicken industry, especially in birds raised without in-feed antibiotics. A standardized blend of plant-derived isoquinoline alkaloids (IQA) derived from Macleaya cordata has shown to have anti-inflammatory potency and promoted animal productivity. This study investigated the effects of IQA supplementation on broiler chickens under NE challenge. A 2 × 2 factorial arrangement of treatments was employed with factors: NE challenge (no or yes), and additives (no additive or IQA at 0.15 g/kg) in starter, grower, and finisher diets. Birds were challenged with Eimeria spp. on d 9 and 10⁸ to 10⁹Clostridium perfringens on d 14. Each treatment had 7 replicate floor pens with 17 birds each. NE challenge negatively affected growth performance, livability, and carcass traits. Regardless of challenge, IQA increased feed intake and gain on d 24 (P < 0.05) and 35 (P < 0.01) and improved FCR (P < 0.05), flock uniformity (P < 0.01) and breast meat yield (P < 0.001) on d 35. Supplementation of IQA also reduced lesions in the duodenum (P < 0.05), jejunum (P < 0.001), and ileum (P < 0.001). This study suggests that IQA may protect broilers from NE indicating its role as a promising antibiotic alternative.

The effect of a non-starch polysaccharide-degrading enzyme product (A vizyme, TX) on the performance of 4 week old broiler chickens fed wheats with high and low-AME values was studied. Supplementation with the enzyme increased the AME (MJ/kg dry matter) of a low-ME wheat from 12.02 to 14.94 and of a normal wheat from 14.52 to 14.83. This coincided with a significant fall in the digesta viscosity and marked increases in the apparent starch and protein digestibility in the small intestine. The performance of the birds fed the low-ME wheat with the enzyme was as good as those fed the maize control diet.

Previous research showed that mannanoligosaccharide (MOS) supplementation of broiler diets tended to reduce the number of coliform bacteria in the intestine of broiler chickens (Yang et al., 2006). The effects of MOS on the populations of mucosa-associated bacteria were further examined using an 'E. coli' challenge model.

Two enzyme assays, the radial diffusion and the dye-release methods, were modified and tested for their suitability in measuring β-glucanase activity in poultry feed. Enzymes A and B were incorporated into a barley-based broiler starter diet at three levels (500, 1000 and 2000 g/t). The measured β-glucanase activities were 35 U/g and 49 u/g for Enzymes A and B, respectively. A comparison of enzyme recovery rates from samples containing known amounts of the enzyme and from a buffer solution containing the same amount of the enzyme revealed that a fixed percentage of the enzyme bound to feed components in a dose responsive manner. Thus, enzyme recovery rates for the feed samples were not complete and varied between 66% and 97% for the radial diffusion assay and between 76% and 91% for the dyerelease assay. The two assays largely agreed with each other although at low enzyme concentrations, the dye-release assays gave higher recovery rates with lower standard errors. It may be concluded that both assays are useful in determining β-glucanase activity in feed and digesta samples, but the radial diffusion assay is cheaper to perform.

An experiment was conducted to determine the effect of sorghum particle size and milling type on broiler performance and feed apparent metabolisable energy (AME). Results show that AME was improved by feeding a pelleted diet containing whole sorghum, but the best performance (lowest FCR) was elicited by feeding a rolled sorghum diet at a common commercial grind size. Feed particle size may influence the rate of excretion of different fractions of the digesta and AME of a feed. AME may not be an accurate indicator of the nutritive value of grain as the same feed can have a different AME values based on physical structure.