An experiment was conducted to determine the effects of period on the performance, immunity, and some stress indicators of broilers fed 2 levels of protein and stocked at a normal or high stocking density. Experimental treatments consisted of a 2 × 2 × 2 factorial arrangement with 2 levels of prebiotic (with or without prebiotic), 2 levels of dietary CP [NRC-recommended or low CP level (85% of NRC-recommended level)], and 2 levels of stocking density (10 birds/m(2) as the normal density or 16 birds/m(2) as the high density), for a total of 8 treatments. Each treatment had 5 replicates (cages). Birds were reared in 3-tiered battery cages with wire floors in an open-sided housing system under natural tropical conditions. Housing and general management practices were similar for all treatment groups. Starter and finisher diets in mash form were fed from 1 to 21 d and 22 to 42 d of age, respectively. Supplementation with a prebiotic had no significant effect on performance, immunity, and stress indicators (blood glucose, cholesterol, corticosterone, and heterophil:lymphocyte ratio). Protein level significantly influenced broiler performance but did not affect immunity or stress indicators (except for cholesterol level). The normal stocking density resulted in better FCR and also higher antibody titer against Newcastle disease compared with the high stocking density. However, density had no significant effect on blood levels of glucose, cholesterol, corticosterone, and the heterophil:lymphocyte ratio. Significant interactions between protein level and stocking density were observed for BW gain and final BW. The results indicated that, under the conditions of this experiment, dietary addition of a prebiotic had no significant effect on the performance, immunity, and stress indicators of broilers.

Among the bacterial fermentation end products in the chicken cecum, butyrate is of particular importance because of its nutritional properties for the epithelial cell and pathogen inhibitory effects in the gut. An in vitro experiment, operated with batch bioreactor, was conducted to quantify butyric-producing bacteria in a simulated broiler cecum supplemented with Lactobacillus salivarius ssp. salicinius JCM 1230 and Lactobacillus agilis JCM 1048 during 24 h of incubation. Selected bacterial species were determined by real-time PCR and short-chain fatty acids and lactate concentrations were monitored. The results showed that after 24 h of incubation, Lactobacillus supplementation significantly increased the number of lactobacilli, bifidobacteria and Faecalibacterium prausnitzii in medium containing cecal content and lactobacilli supplementation (Cc + L) compared with the control (Cc). Addition of lactobacilli did not alter Escherichia coli and Clostridium butyricum, whereas it significantly (P < 0.05) reduced Salmonella in treatment Cc + L compared with the Cc treatment. Propionate and butyrate formation were significantly (P < 0.05) increased in treatment Cc + L as compared with the Cc treatment. Lactate was only detected in treatment containing 2 Lactobacillus strains. After 24 h of incubation, acetate concentration significantly (P < 0.05) decreased in all treatments. It was suggested that lactate produced by Lactobacillus in the cecal content improved the growth of butyric producers such as F. prausnitzii, which significantly increased butyrate accumulation. Additionally, the results showed that butyrate and propionate inhibited Salmonella without influencing the E. coli profile.

In order to investigate the effects of the dietary supplementation of organic acids, prebiotics and probiotics on broiler chickens, a total of 288 day-old male Cobb chicks were allocated in a completely randomized design according to a 2 × 4 factorial, consisting of two levels of crude protein (recommended or low (85% of recommended)) and a four feed-additive programme. The basal diet without any feed additive served as control and one of the following additives, organic acids, a prebiotic and a probiotic, were added to the basal diet to form the other treatments. Starter and finisher diets were offered from 1 to 21 d and 22 to 42 d of age, respectively. The birds were reared in an open-sided house system under natural tropical conditions with the same housing and general management practices. Lowering the dietary protein level significantly decreased bird performance throughout the experiment. Additives had no significant effects on body weight, body weight gain and feed intake. Dietary supplementation with the prebiotic resulted in significant improvements in feed efficiency during 22 -42 d and 1 -42 d of age. At 21 and 42 d of age birds fed the diets containing the prebiotic had the longest duodenal villi compared to the other treatments. Jejunum villi, and duodenum and jejunum crypt depth were not influenced by additives. At 21 d of age the dietary addition of the prebiotic and organic acids significantly increased the antibody titres against Newcastle disease compared to the control group. It could be concluded that under the condition of the current study, the prebiotic affected performance, small intestinal morphology and immunity of broiler chickens significantly. ______________________________________________________________________________

Aim:  To assess the probiotic effects of Lactobacillus agilis JCM 1048 and L. salivarius ssp. salicinius JCM 1230 and the pH on the cecal microflora of chicken and metabolic end products. Methods and Results:  An in vitro system, operated with batch bioreactor, was used for this assessment. Selected bacterial species were monitored at two pH values, over 24 h of batch culture incubation. The concentration of short chain fatty acids (SCFA) and lactate in the fermented material was also determined. The addition of L. agilis JCM 1048 and L. salivarius ssp. salicinius JCM 1230 into vessel 2 (Cc + P) increased the total anaerobes, lactobacilli and bifidobacteria after 24 h incubation. Moreover, lactobacilli supplementation decreased the total aerobes and streptococci, but it did not have any effects on coliforms. The supplementation of lactobacilli in vessel 2 (Cc + P) was found to significantly increase the production of lactate, propionate and butyrate. Furthermore, pH did not alter the formation of butyrate, whereas the production of acetate and propionate was significantly decreased at pH = 5·8. Conclusions:  L. agilis JCM 1048 and L. salivarius ssp. salicinius JCM 1230, as probiotic bacteria, have the ability to re‐establish proper microbial balance by the formation of lactate as well as propionate, and stimulate butyrate‐producing bacteria to produce butyrate in the chicken cecum. Significance and Impact of the Study:  This study was the first to report this under in vitro conditions, highlighting the probiotic roles of the two Lactobacillus strains in broiler cecal fermentation at different initial pH. These useful data can be helpful in improving the fermentation process in chicken cecum.

This experiment was conducted to investigate and compare the efficacy of different feed additives on performance, tibial dyschondroplasia (TD) incidence and tibia characteristics of male broilers fed low-calcium diets. A completely randomized design, with six treatments and five replicates of five chicks per each was used. Experimental treatments were: (i) Basal diet containing recommended level of calcium (0.9%) as control treatment (Ctrl), (ii) low-calcium (0.67%) diet without any additive (LC), (iii) low-calcium diet + probiotic (2 g/kg diet), (iv) low-calcium diet + prebiotic (2 g/kg diet), (v) low-calcium diet + synbiotic [mix of probiotic and prebiotic (each 2 g/kg diet)], (vi) low-calcium diet + organic acid (1.5 g/kg diet). Birds were reared in an open-sided house system under natural tropical condition until 21 days of age. Feeding with low-calcium diet negatively influenced broiler performance (body weight, body weight gain and feed conversion ratio) and tibia characteristics, whereas dietary inclusion of all feed additives had beneficial effects on above-mentioned parameters and helped the birds to overcome problems related to low-calcium diets. Different treatments had no effect on TD incidence.

1. An experiment was conducted to determine the effects of supposedly unpleasant physical treatment on broiler performance, small intestinal development and ameliorating role of probiotics. 2. The following treatments were applied from day one: (1) chicks exposed to normal human contact fed basal diet (control); (2) chicks were exposed to unpleasant physical treatment and fed basal diet (UPT-BD); and (3) chicks were exposed to unpleasant physical treatment and fed basal diet supplemented with Lactobacillus (UPT-BDL). Chicks were exposed to UPT from days 1 to 21. Different segments of gastrointestinal tract were sampled at 14, 28, 35 and 42 d of age. 3. Broilers of UPT-BD had lower feed consumption compared with control group at 7 d of age. Overall, UPT-BDL birds showed higher body weight gain (BWG) and better feed conversion ratio (FCR) over the course of the experiment. 4. Birds of UPT-BD had lower concentrations of lactic, propionic and butyric acids in the caecum as compared with other groups at 14 d of age. Acetic acid concentration was profoundly decreased in both UPT groups compared to the control. 5. Duodenal villus height of UPT-BD broilers showed a slight reduction compared to the control and UPT-BDL birds at 14 d of age. Afterwards until day 42, UPT-BDL birds showed the highest villus height among treatments in different parts of the small intestine. 6. The results suggested that, even though UPT did not have significant inhibitory effects on the development of the small intestine and broiler performance, it negatively affected bacterial metabolic end products in the caecum, which could be ameliorated by the addition of Lactobacillus.

An experiment was conducted to determine the effects of different feed additives on performance, nutrient retention, gut pH, and intestinal morphology of broilers fed different levels of energy. This study was a 4 × 2 factorial arrangement of 4 feed additive programs (a basal diet without any feed additive as the control, the basal diet with added organic acid, the basal diet with added prebiotic, and the basal diet with added probiotic) with recommended levels (3,150 and 3,200 kcal of ME/kg of diet for the starter and finisher diets, respectively) or low levels (90% of recommended) of energy. A total of 640 one-day-old male and female broiler chicks were randomly assigned to 8 treatments. Each treatment consisted of 4 replicate floor pens of 20 birds each. Starter and finisher diets were fed from 1 to 21 d and 21 to 42 d of age, respectively. Dietary levels of other nutrients, housing, and general management practices were similar for all treatments. Dietary inclusion of additives had no significant effects on broiler performance, intestinal villus height, crypt depth, gut pH, and dietary AME. Birds fed the low-energy diets were heavier but had inferior FCR compared with those fed the recommended-energy diets. Prebiotic and organic acid significantly (P < 0.05) improved protein digestibility. The recommended-energy diets significantly (P < 0.05) increased AME and protein digestibility. No interactions were observed for the measured parameters.

A study was conducted to investigate the effect of two Lactobacillus strains on hypothalamus pituitary adrenal (HPA) axis activity induced by supposedly unpleasant handling (UH) of broiler chickens. The three treatments were: (1) non-handled chicks fed basal diet (control); (2) unpleasantly handled-chicks fed basal diet (UH-BD) and (3) unpleasantly handled-chicks fed basal diet supplemented with the probiotic, lactobacilli (UH-BDL). Chicks were exposed to UH from days 1 to 21. Treatment UH-BDL received probiotics in their diet for the whole experimental period. Blood corticosterone (CS) concentrations were monitored at 14, 28, 35 and 42 days of age and selected caecal bacterial groups were enumerated in 14-day old birds. Unpleasant handling significantly increased blood CS concentrations at 14 and 28 days of age. Blood CS concentration decreased with age over the course of the experimental period. Lactobacillus supplementation did not reduce blood CS concentration in broilers in the UH-BDL treatment. Moreover, the UH treatment did not alter caecal bacterial numbers in the 14-day old broilers while the probiotic numerically increased total anaerobes and lactobacilli. Overall, it seems as if the efficacy of lactobacilli to modulate stress-related high HPA-axis activity depends on gastrointestinal tract microbial alteration. However, Lactobacillus salivarius subsp. salicinius JCM 1230 and L. agilis JCM 1048 were able to reestablish a proper microbial balance in the caecum of the chickens. ________________________________________________________________________________