This study was conducted to determine whether avilamycin, which is used as a growth promoter in broiler chickens, would affect the structure of the bacterial community within the jejunal intestinal tract. Sixty chickens were assigned to 2 groups: a control group and an avilamycin-treated group. The jejunal tissue from 4 chicks randomly sampled on d 1, 3, 7, 21, and 42 from each treatment group were investigated for changes in villus height, total mesophilic bacteria, lactic acid bacteria, and the structure of the microbial community using PCR-denaturant gradient gel electrophoresis. Supplementation with avilamycin had no effect on villus height and total bacterial count in either the mesophile or lactic acid bacteria. Based on PCR-denaturant gradient gel electrophoresis analysis, 3 bacterial groups were identified in both groups of chicks: gram-positive bacteria having low contents of guanine and cytosine, gamma proteobacteria, and actinobacteria. The abundance of Weisella, Enterococcus faecium, and Pediococcus acidophilus found only in the control group indicated that avilamycin did affect their growth and led to low microbial diversity among the low guanine and cytosine group compared with the control group. In contrast, however, avilamycin treatment was associated with higher microbial diversity among the gamma proteobacteria group in respect of the various Pseudomonas species. This finding should increase awareness of the potential effects of antibiotic use and particularly avilamycin in commercial poultry production in tropical areas.

Two experiments were conducted to study the effect of corn extrusion and feed form on feed quality and growth performance of broilers. In experiment 1, whole corn was extruded at a water flow rate of 16, 19, and 22 L/h. The experimental design was a completely randomized design with 3 replications for each treatment. The extrusion process significantly decreased (P < 0.01) ether extract, crude fiber, and moisture content of corn. Increased water flow significantly decreased enzyme susceptibility from 56 to 47% (P < 0.01), but increased the bulk density of extrudate from 134 to 224 g/L (P < 0.01). However, there was a trend for lower total energy consumption (P < 0.01) and extruding production rate (P < 0.05) when corn was processed at the water flow of 22 L/h. In Exp. 2, 1,600 broilers (initially BW of 41 g) were used to determine the effect of extrudate and feed form on the growth performance in poultry during a 42-d growth assay. There were 50 chicks per pen and 8 pens per treatment. Treatments were arranged in a 2 x 2 factorial arrangement with the main effect of feed form and the main effect of 25% processed corn inclusion. Treatments were 1) conventional corn mash, 2) conventional corn pelleted feed, 3) +25% extruded corn mash, and 4) +25% extruded corn pelleted feed. Chicks fed pelleted feed, regardless of processing of corn, had a greater BW and feed conversion than those fed mash feed diet (P < 0.001). Extruded corn mash decreased the growth performance. Results suggested that optimal growth rate and feed conversion of birds raised in a tropical environment given extruded corn might be achieved by steam pelleting.

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Two experiments were conducted to determine physical and chemical properties of vermicelli waste (VW) and effect of VW inclusion levels on growth performance of broilers. In experiment 1, VW samples were randomly collected from vermicelli industry in Thailand to analyze nutritional composition. Vermicelli waste contained 9.96% moisture, 12.06% CP, 32.30% crude fiber (CF), and 0.57% ether extract (EE), as DM basis. The ratio of insoluble:soluble non-starch polysaccharide (NSP) was 43.4:8.9. A total of 120 chicks (6 pens per treatment and 10 chicks per pen) were fed a corn-soybean meal-based diet or 20% VW substituted diet to determine the apparent metabolizable energy corrected for nitrogen retention (AMEn) of VW. The AMEn of VW was 1,844.7±130.71 kcal/kg. In experiment 2, a total of 1,200 chicks were randomly allotted to 1 of 4 dietary treatments for 42-d growth assay. There were 300 chicks with 6 pens per treatment and 50 chicks per pen. The dietary treatments contained 0%, 5%, 10%, or 15% VW, respectively. All diets were formulated to be isocaloric and isonitrogenous. From 0 to 18 d of age chicks fed VW diets had higher (p<0.001) feed conversion ratio (FCR) compared with those fed the control diet. No difference was observed during grower and finisher phase (19 to 42 d). Chicks fed VW diets had lower relative weight of abdominal fat (p<0.001) but higher relative weight of gizzard (p<0.05) than those of chicks fed the control diet. Increasing VW inclusion levels increased ileal digesta viscosity (p<0.05) and intestinal villus height of chicks (p< 0.001). For apparent total tract digestibility assay, there were 4 metabolic cages of 6 chicks that were fed experimental treatment diets (the same as in the growth assay) in a 10-d total excreta collection. Increasing VW inclusion levels linearly decreased (p<0.05) apparent total tract digestibility of DM and CF.

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