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The present study evaluated the impacts of Bacillus subtilis (BAS) inclusion in broiler diets with standard nutrient content or nutrient deficiency (ND) on growth performance (GP) and nutrient digestibility. The 42 d experiment consisted of 6 experimental diets, a diet with standard nutrient content, and 2 diets with different levels of energy and protein deficiency, without or with BAS. At the end of experiment, apparent ileal digestibility coefficients (AIDC) of starch, crude protein (CP), and gross energy (GE) were determined. Furthermore, impacts of BAS supplementation in standard diets on gut histomorphology, bacterial metabolic activity, and composition were evaluated. Performance and AIDC data were subjected to ANOVA using GLM procedure with a 3 (nutrient levels) × 2 (BAS presence/absences) factorial arrangement of treatments. Gut histomorphology and microbiology data, obtained from broilers fed standard diets without (S) and with BAS (SB), were assessed by an independent Student's t -test. The ND in diets was effective enough to cause nutritional stress and negatively affect performance. Inclusion of BAS in both types of diet improved GP, which was due to the fact that adding BAS in these diets led to improvements in AIDC of CP, starch, and GE (P ≤ 0.05). Comparing only 2 experimental groups, S and SB, revealed no impact on bacterial composition and metabolism in the ileum and cecum, except a reduction in ileal lactobacilli number for SB group. Adding BAS to standard diet reduced crypt depth (CD) and increased villus length to CD ratio in the duodenum, whereas it had no impact on other histomorphological variables in the duodenum, jejunum, and ileum. In conclusion, supplementation of broiler diets with probiotic BAS can positively affect growth performance and nutrient digestibility and this positive impact might even be more pronounced in nutrient-deficient diets. However, the extent of the alleviating ability of BAS in nutrient-deficient diets as well as the biological mechanisms for such a phenomenon needs to be studied further. [ABSTRACT FROM AUTHOR]

Various milling methods result in different particle size distributions and, in combination with mash and thermal treatment (expandate) of the feed, may have an impact on nutrient digestibility, pH of the digesta and subsequently the performance of an animal. Since this aspect has not been widely considered in laying hens, the objective of the present study was to investigate the effects of milling method, expansion, and particle size of feed on performance, apparent ileal nutrient digestibility, and pH of digesta in laying hens. Twelve variants of the same diet were produced. Four different milling techniques (hammer mill, roller mill, disc mill, and wedge-shaped disc mill) were used to grind the feed cereals. Coarse feed was obtained from all four mills. Additionally, fine feed was obtained from the hammer mill and the roller mill. Each of the six feed variants was offered as mash or expandate, resulting in a total of 12 treatments. The duration of the experimental period was 21 days. A total of 576 layers, each 19 weeks of age, were used in eight replicates. The statistical analysis for the four milling methods and two thermal treatments was performed using a 4 × 2 factorial arrangement. The effect of particle size was investigated using a 2 × 2 × 2 factorial arrangement including the coarse and fine particle sizes that were produced with the hammer mill and the roller mill as well as the mash and expandate. The animal performance and the pH of the digesta were not affected by the treatments. Ileal digestibility of starch was significantly improved by feeding mash compared to expandate (P = 0.013) and by feeding coarse compared to fine feed (P = 0.028). Based on this study, the tested milling methods can be used for the production of feed for laying hens without affecting performance and digestibility of nutrients. [ABSTRACT FROM AUTHOR]

• Broiler chickens received reduced nutrient diets had reduced performance. • Negative control diets formulated based on phytase nutrients matrix value negatively influenced tibia and toe ash contents, serum, and tibia P contents as well as ileal P, Ca and CP digestibility. • Phytase addition to the negative control diets had improved feed conversion ratio and increased tibia and toe ash contents. • Inclusion of benzoic acid to the basal diets did not influence the tibia ash, tibia Ca and P contents but increased toe ash content and improved feed conversion ratio. • Adding phytase to the benzoic acid contained diet had improved broiler chickens,s performance during the starter period. This study was conducted to investigate the effects of phytase (Phy), benzoic acid (BA) and their interactions on growth performance, nutrients digestibility and tibia mineralization in broiler chickens fed standard or nutrient,s deficient diets. A total of 768 one-d-old male chicks were divided into 8 treatments for 42 d. The treatments were as follows:positive control (PC), PC diet with 0.5 g/kg of BA, PC diet with 500 FTU/kg of Phy, PC diet with 0.5 g/kg of BA and 500 FTU/kg of Phy, negative control diet (NC) with a nutrient deficiency (ND) equal to matrix value of 500 FTU/kg of Phy, NC diet with 0.5 g/kg of BA, NC diet with 500 FTU/kg of Phy, and NC diet with 0.5 g/kg of BA and 500 FTU/kg of Phy. Broiler chickens received NC diets had lower body weight gain (BWG), feed intake (FI) and higher feed conversion ratio (FCR) in the entire experiment (P ≤ 0.05). Dietary ND negatively influenced tibia and toe ash contents, serum, and tibia P contents as well as ileal P, Ca and CP digestibility at d 28 (P ≤ 0.05). FCR of d 1 to 11 and d 12 to 24 improved when Phy was added to NC rather than PC diets (P ≤ 0.05). Phy supplementation did not affect serum P and Ca content at d 28 (P > 0.05), but reduced serum alkaline phosphatase content in broiler chickens fed PC diets (P ≤ 0.05). Phy supplementation increased tibia and toe ash contents at d 28, especially in broiler chickens fed NC diets (P ≤ 0.05). Inclusion of BA did not influence (P > 0.05) tibia ash, tibia Ca and P contents at d 28, but increased toe ash content (P ≤ 0.05).The interaction between BA and the dietary nutrient level was significant for FCR of d 25–42 and d 1–42 (P ≤ 0.05). Broiler chickens fed PC diets with BA had better FCR compared with those fed PC diets without BA atd 25–42 (P ≤ 0.05). Adding Phy to the diets containing BA improved BWG and FI atd 1–11(P ≤ 0.05). In conclusion, Phy was effective in improving some growth performance traits, and bone mineralization especially when added to NC diets. However, BA had a positive effect on FCR of broiler chickens fed PC diets and had no impact on ileal nutrients digestibility, but improved toe ash content. [ABSTRACT FROM AUTHOR]