Grapes have high amounts of phenolic compounds, which can modulate the gut activity as well as modify the structure and function of the gastrointestinal tract. The microbiological activity of avoparcin, grape pomace concentrate, and grape seed extract was evaluated in an in vitro study. An in vivo experiment was also conducted to study the effect of the inclusion of grape pomace concentrate and grape seed extract in the diet of broiler chicks on performance, intestinal microflora (by cultured and terminal restriction fragment length polymorphism methodology), and gut morphology at 21 d of age. Dietary treatments included an antibiotic-free diet (CON), a positive control (AVP; 50 mg/kg of avoparcin), and antibiotic-free diets containing grape pomace concentrate (GPC; 60 g/kg) or grape seed extract (GSE; 7.2 g/kg). Performance was not affected by dietary treatment except in the case of birds fed the GSE diet, which showed decreased weight gain. In the ileal content, birds fed CON and GSE diets had the highest populations of Lactobacillus. Compared with the CON diet, the AVP, GPC, and GSE diets increased the populations of Enterococcus and decreased the counts of Clostridium in the ileal content. In the cecal digesta, birds fed GPC and GSE diets had higher populations of Escherichia coli, Lactobacillus, Enterococcus, and Clostridium than birds in any other treatment group. Animals fed GPC and GSE diets showed a higher biodiversity degree than those fed control diets. The frequency of detection of several potential phenol-degrading bacteria as well as unidentified and uncultured organisms was increased in animals fed GPC and GSE diets. Birds fed the CON diet had longer villi and deeper crypt depth than birds in any other treatment group. The highest villi height:crypt depth ratio corresponded to birds fed GPC and AVP diets and the lowest to those fed CON and GSE diets. In conclusion, dietary polyphenol-rich grape products modify the gut morphology and intestinal microflora and increase the biodiversity degree of intestinal bacteria in broiler chicks.

Polyphenols are chemically and biologically active compounds. Grape seed extracts (GSEs) have been widely used as a human food supplement for health promotion and disease prevention. However, there is little information regarding its application in animal feeds. An experiment was conducted to investigate the effect of inclusion of GSE at 0.025, 0.25, 2.5 and 5.0 g/kg in a wheat soya bean control diet on growth performance, protein and amino acid (AA) digestibility and plasma lipid and mineral concentrations in broiler chickens at 21 days of age. Performance was not affected by dietary treatment except in the case of birds fed the diet with the highest GSE concentration, which showed a worsening of weight gain and feed conversion. Apparent ileal digestibility (AID) of protein was significantly reduced in the birds fed the highest concentration of GSE, which also had a reduction on the AID of arginine, histidine, phenylalanine, cystine, glutamic acid and proline compared with those fed control diet. The inclusion of graded concentration of GSE in the chicken diets caused a significant linear decrease in the concentrations of plasma copper, iron and zinc. Plasma cholesterol, triglycerides and lipoproteins (high-density lipoprotein, low-density lipoprotein and very-low-density lipoprotein) concentrations were not affected by dietary GSE. In conclusion, this study demonstrated that incorporation of GSE in chicken diets up to 2.5 g/kg had no adverse effect on growth performance or protein and AA digestibility. Feed conversion was reduced and growth rate was retarded, when chickens were fed 5 g/kg of GSE. This study also indicated that grape polyphenols reduce the free plasma minerals.

The effect of neutral detergent-soluble fiber level on gut barrier function and intestinal microbiota was examined in weaned rabbits. A control diet (AH) containing 103 g of neutral detergent-soluble fiber/ kg of DM included alfalfa hay as main source of fiber. Another diet (B-AP) was formulated by replacing half of the alfalfa hay with a mixture of beet and apple pulp resulting in 131 g of soluble fiber/kg of DM. A third diet (OH) was obtained by substituting half of the alfalfa hay with a mix of oat hulls and a soybean protein concentrate and contained 79 g of soluble fiber/kg of DM. Rabbits weaned at 25 d and slaughtered at 35 d were used to determine ileal digestibility, jejunal morphology, sucrase activity, lamina propria lymphocytes, and intestinal microbiota. Suckling 35-d-old rabbits were used to assess mucosa morphology. Mortality (from weaning to 63 d of age) was also determined. Villous height of the jejunal mucosa increased with soluble fiber (P = 0.001). Rabbits fed with the greatest level of soluble fiber (BA-P diet) showed the highest villous height/ crypt depth ratio (8.14; P = 0.001), sucrase specific activity (8,671 μmol of glucose/g of protein; P = 0.019), and the greatest ileal starch digestibility (96.8%; P = 0.002). The opposite effects were observed in rabbits fed decreased levels of soluble fiber (AH and OH diets; 4.70, 5,848 μmol of glucose/g of protein, as average, respectively). The lowest ileal starch digestibility was detected for animals fed OH diet (93.2%). Suckling rabbits of the same age showed a lower villous height/crypt depth ratio (6.70) compared with the B-AP diet group, but this ratio was higher than the AH or OH diet groups. Lower levels of soluble fiber tended (P = 0.074) to increase the cellular immune response (CD8+ lymphocytes). Diet affected IL-2 production (CD25+, P = 0.029; CD5+CD25+, P = 0.057), with no clear relationship between soluble fiber and IL-2. The intestinal microbiota biodiversity was not affected by diets (P ≥ 0.38). Rabbits fed the B-AP and AH diets had a reduced cecal frequency of detection compatible with Campylobacter spp. (20.3 vs. 37.8, P = 0.074), and Clostridium perfringens (4.3 vs. 17.6%, P = 0.047), compared with the OH diet group. Moreover, the mortality rates decreased from 14.4 (OH diet) to 5.1% (B-AP diet) with the increased presence of soluble fiber in the diet. In conclusion, increased levels of dietary soluble fiber improve mucosal integrity and functionality. Copyright © 2007. . Copyright 2007 Journal of Animal Science