A feeding trial was conducted to determine the effect of organic acids or probiotics alone or in combination on growth performance, nutrient digestibility, enzyme activity, intestinal morphology and gut microflora in broiler chickens (Ross308). A completely randomized design was used, with 1,440 broiler chicks across four treatments and five replications of 72 chicks each. The chicks in the control treatment were fed on a control diet (CD), whereas for the other treatment groups, the CD was supplemented with 0.2 g/kg organic acids (CDOA), probiotics (CDP) or a combination of organic acids and probiotics (CDOAP). All the chicks were fed ad libitum during the feeding trial throughout 35 days. A total of 20 chicks were randomly allotted to individual metabolic cages to measure the nutrient digestibility (35-42 days) and the digestive enzyme activities (42 days). The intestinal morphology and gut microflora of 80 chicks were examined at the end of experiment. There were no significant (p > .05) differences in the feed intake, body weight gain or feed conversion ratio of the chicks across the four dietary treatments. The crude fibre digestibility was significantly increased in chicks fed on CDOA or CDOAP relative to CD (p < .05). Nutrient utilization, in terms of digestive enzyme activities and excreta thermal property, was unchanged by any supplementation. The chicks fed on the CDOAP had significantly higher duodenal villi height and crypt depth than the chicks fed on CDOA (p < .05). This dietary treatment dramatically improved gut microflora by decreasing the population of Escherichia coli and increasing the Lactobacillus spp.:E. coli ratio. Based on our investigations, supplementation of organic acids and probiotics in chick diets can increase the ability to digest crude fibre and villus height and decrease intestinal E. coli without impairing growth performance.

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With the ban on the use of antibiotics in poultry feed, it is required to produce alternative substances to maintain poultry health and performance. The present study was carried out to investigate the effects of dietary supplementation at various levels of bamboo vinegar (BV) on performance, egg quality, and fecal bacterial population of laying ducks. One hundred and five 50-week-old crossbred laying ducks (Khaki Campbell × Native) were randomly allocated into five treatment groups, each with seven replicates of three ducks. The experimental ducks were fed a basal diet (antibiotic-free diet) supplemented with BV at the levels of 0%, 0.2%, 0.4%, 0.6%, or 0.8% of diet until 62 weeks of age. For the overall period (from 50 to 62 weeks of age), the dietary supplementation of BV at the levels of 0.4% and 0.6% of diet increased egg production and egg mass, and improved feed efficiency of laying ducks (p<0.01). Supplementation of BV at the level of 0.8% in the diet decreased feed intake (p<0.01). Egg quality parameters were not significantly affected by supplementation of BV (p>0.05). The population of fecal Escherichia coli was significantly decreased in the experimental ducks fed diet supplemented with BV at the levels of 0.4%, 0.6%, and 0.8% compared to the control group (p<0.01), while the population of Lactobacillus spp. remained unchanged. The present results indicate that a level of 0.4% BV supplementation in laying duck diet is sufficient for reducing fecal E. coli and improves productive performance of egg laying ducks.

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This experiment was conducted to investigate the effects of dietary supplementation with coated granules (CG) on performance, in vitro digestibility and the gastrointestinal functionality in laying hens. A total of 40 Hisex Brown laying hens (36 weeks of age) were randomly divided into five equal groups; one served as a control and the other four were actual experimental groups supplemented with 0.75, 1.5, 3 or 6 g CG per day. All the hens were fed restrictively with target feed intake of 100 g basal diet/hen per day. There were no differences in egg production or egg weight among the groups, but feed conversion ratio was significantly improved (linearly, p < 0.05) with the dose level of CG in diet. Dietary CG increased the jejunal weight (linear and quadratic terms, p < 0.05) but decreased the ileal weight (linearly, p < 0.05). There was mostly statistical interaction between dietary CG and specific activity of intestinal digestive enzymes with similar patterns for dietary CG treatments (p < 0.05). A positive linear correlation was observed with in vitro protein digestibility by using the crude enzyme extract from dietary CG supplementation. Dietary CG decreased the caecal Escherichia coli population while the Lactobacillus spp.: E. coli ratio increased (quadratic fit, p < 0.05). CG supplementation, on the other hand, significantly altered intestinal morphology by increasing the height of duodenal and ileal villi (linearly, p < 0.05). Also, duodenal antioxidant capacity observed via remaining reducing power improved linearly (p < 0.05). This suggests that CG, unlike garlic oils without encapsulation, may be a good candidate for feed supplementation in commercial egg production. It could be included up to 6 g CG per day without any adverse effects on performance, which may relate to improving nutrient digestibility and better utilization of limited feed intake when using a low amount of diet or other observations in this study.

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