The effect of dietary phytate and phytase on carbohydrase activity and hexose transport was investigated in broiler chickens. Diets containing phytate P (2.2 or 4.4 g/kg) with different phytase dose rates (0, 500, or 1,000 phytase units/kg) were fed to 504 female Cobb chicks for 3 wk. Diets containing high phytate concentrations depressed (P < 0.05) BW and G:F, whereas phytase supplementation improved (P < 0.05) the performance of birds. In the duodenum, phytate decreased (P < 0.05) the activities of disaccharidases, Na(+)K(+)-ATPase, and glucose concentrations by 5 to 11%, but phytase enhanced (P < 0.05) the concentrations of amylase, sucrase, maltase, Na(+)K(+)-ATPase, and glucose by 5 to 30%. In the jejunum, phytate decreased (P < 0.05) the concentrations of amylase, sucrase, Na(+)K(+)-ATPase, and glucose by 10 to 22%, and phytase alleviated the negative effect of phytate on the above variables. Ingestion of diets containing phytate also decreased (P < 0.05) serum amylase activity and glucose concentration, and phytase enhanced (P < 0.05) serum concentrations of amylase, sucrase, maltase, Na(+)K(+)-ATPase, and glucose. There were also interactions (P < 0.05) between phytate and phytase on the concentrations of serum amylase, duodenal amylase, sucrase, and jejunal glucose. Enzymatic analysis at a molecular level showed that neither phytate nor phytase influenced the mRNA expression of sucrase-isomaltase in the small intestine. Also, the investigation into the sodium glucose cotransporter gene may challenge the mechanism by which phytate interferes with glucose utilization, as partly indicated by bird performance, and transmembrane transport because diets containing increased phytate upregulated (P < 0.05) the mRNA expression of the sodium glucose cotransporter gene in duodenum and did not influence it in the jejunum. These results indicate that phytate can impair endogenous carbohydrase activity and digestive competence, and phytase can ameliorate these effects for chickens.

The aim of this study was to investigate the protective effect of glutamine (Gln) on the intestinal morphology, intestinal inflammatory response, and barrier integrity in broilers exposed to high ambient temperature. Three-hundred-sixty 21-d-old Arbor Acres broilers (half male and half female) were randomly allocated to 4 treatment groups in a completely randomized design, each of which included 6 replicates with 15 birds per replicate, for 21 d. The 4 treatment groups were as follows: the control group, in which birds were kept in a thermoneutral room at 22 ± 1°C (no stress, NS; fed a basal diet); the heat stress group (36 ± 1°C for 10 h/d from 08:00 to 18:00 h and 22 ± 1°C for the remaining time, heat stress (HT); fed a basal diet); and heat stress + Gln group (0.5 and 1.0% Gln, respectively). Compared to the NS group, broilers in the HT group had lower villus height (P < 0.05), higher crypt depth (P < 0.05), higher D-lactic acid and diamine oxidase (DAO) activity (P < 0.05), higher soluble intercellular adhesion molecule-1 (sICAM-1) concentration (P < 0.05), higher tumor necrosis factor (TNF)-α/interleukin (IL)-10 (P < 0.05), and lower tight junction protein expression levels (P < 0.05). Compared with birds in the HT, birds in the HT + Gln group exhibited increased villus height (P < 0.05), decreased D-lactate and DAO activity (P < 0.05), decreased sICAM-1 concentration (P < 0.05), and mediate the secretion of cytokines (P < 0.05), as well as increased zonula occludens-1 (ZO-1), claudin-1, and occludin mRNA expression levels (P < 0.05). In conclusion, these results indicate that supplementation with Gln was effective in partially ameliorating the adverse effects of heat stress on intestinal barrier function in broilers by promoting epithelial cell proliferation and renewal, modifying the function of the intestinal mucosa barrier, and regulating the secretion of cytokines.

The effects of phytate and phytase on broiler performance and cellular and humoral immunity was assessed by using 504 Cobb 500 female broilers fed nutritionally marginal diets. At 1 d of age, the chicks were randomly allocated to 6 treatments in a 2 x 3 factorial arrangement including 2 levels of phytate P (0.22 or 0.44%) and 3 dose rates of an Escherichia coli-derived phytase [0, 500, or 1,000 phytase units (FTU)/kg of feed]. Both low- and high-phytate diets were corn and soy based with the same nutritional specifications (AME 2,900 kcal/kg, CP 21.00%, Ca 0.78%, and nonphytate P0.28%), differing only in the concentration of phytate P. The immune status of birds was measured at 14, 21, and 28 d of age. The results revealed that phytase improved feed intake, BW, and feed conversion ratio (P < 0.05), whereas high dietary phytate depressed bird performance (P < 0.05). There was no interaction between phytate and phytase on bird performance. Feeding phytase increased the percentages of erythrocyte rosette-forming cells and erythrocyte-antibody complement cells by 3.03 and 1.83% at d 21, and by 2.76 and 2.20% at d 28, respectively (P < 0.05). The percentages of CD4(+)CD8(+) T lymphocyte subsets were also increased by phytase (P < 0.05), without affecting the ratio of CD4(+) and CD8(+). The levels of intestinal secretory IgA were improved with phytase at d 14, 21, and 28 (P < 0.05). Antibodies against Newcastle disease virus vaccine were enhanced at d 21 and 28 in the high-phytate diets with phytase addition (P < 0.05). Increasing the phytase dose to 1,000 FTU/kg did not improve immune function further than 500 FTU/kg. The results suggest that application of phytase in nutritionally marginal diets could enhance lymphocyte numbers and the seral and mucosal antibodies of 1- to 28-d-old broilers, suggesting that both phytate and phytase may have a role in gastrointestinal health and immune competence.

The effects of phytases on the performance of layers and the ileal nutrient digestibility of corn-, soybean-, and by-product meal-based diets were assessed with 320 Hy-Line brown layers from 23 to 28 wk of age. Layers were grouped randomly into 5 treatments, with 8 replicates per treatment and 8 layers per replicate. The 5 diets consisted of a positive control diet with adequate Ca (3.30%), total P (0.50%), and nonphytate P (NPP; 0.28%), and a negative control diet with Ca reduced by 0.12%, total P reduced by 0.14%, NPP reduced by 0.13%, and 3 phytases (phytase A derived from Aspergillus niger, and phytases B and C derived from Escherichia coli) supplemented at 300 phytase units/kg of feed, respectively. Egg production and feed intake were recorded daily, and eggshell quality and ileal nutrient digestibility were measured at the end of a 6-wk feeding period. The results revealed that the reduction of Ca and P from the positive control diet significantly depressed feed intake, egg mass, eggshell hardness, and the digestibility of N, Ca, P, and amino acids (P < 0.05). Phytase supplementation in the negative control diet improved the digestibility of P and Ca by 11.08 and 9.81% (P < 0.05), respectively, whereas it improved the digestibility of amino acids by 2 to 8% (P < 0.05). However, the digestibility of most amino acids was not restored to the levels of the positive control diet by the application of phytases. Supplementing phytases in the negative control diet improved the rate of lay, egg mass, and egshell quality to the levels of birds fed the positive control diet. These results suggest that supplementing phytases can improve the digestibility not only of Ca and P, but also of amino acids in layers fed a corn-, soybean-, and by-product-based diet.

This study aimed to investigate the effect of lactic acid bacteria (LAB) and smectite on the growth performance, nutrient digestibility and blood parameters of broilers that were fed diets contaminated with aflatoxin B (AFB ). A total of 480 newly hatched male Arbor Acres broilers were randomly allocated into four groups with six replicates of 20 chicks each. The broilers were fed diets with the AFB (40 μg/kg) challenge or without (control) it and supplemented with smectite (3.0 g/kg) or LAB (4.0 × 10 CFU/kg) based on the AFB diet. The trial lasted for 42 days. The results showed that during days 1-42 of AFB challenge, the feed intake (FI) and body weight gain (BWG) were depressed (p < .05). The inclusion of LAB and smectite increased (p < .05) the BWG by 71.58 and 41.89 g/bird, respectively, which reached the level of the control diet (p ≥ .05), but there were no differences (p ≥ .05) in performance between LAB and smectite. LAB and smectite also increased (p < .05) the apparent total tract digestibility of the crude protein. Regarding the blood parameters, AFB decreased (p < .05) the levels of red blood cell count, haematocrit, mean corpuscular volume, haemoglobin, albumin and total protein. In the meantime, the AFB increased (p < .05) leucocyte counts, urea nitrogen, cholesterol, total bilirubin, creatinine, glutamic-pyruvic transaminase, glutamic oxaloacetic transaminase and alkaline phosphatase. By contrast, LAB and smectite affected (p < .05) these parameters in the opposite direction. It can be concluded that after the AFB challenge, LAB and smectite have similar effects on the growth and health of the broilers, suggesting that LAB could be an alternative against AFB in commercial animal feeds.