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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.

Grape pomace provides a rich source of polyphenols that have the capacity to act as powerful antioxidants. An experiment was conducted to study the effect of inclusion of grape pomace concentrate (GPC) at levels of 15, 30, and 60 g/kg and alpha-tocopheryl acetate (200 mg/kg) in broiler chicks (21 to 42 d of age) on performance; digestive organ sizes; protein; fat; hydrolyzable polyphenol and condensed tannin digestibilities; the anti-oxidant activity of diet, serum, ileal content, and excreta; and the susceptibility to oxidation of breast meat during refrigerated storage. The inclusion of GPC did not affect the performance; the apparent ileal digestibility of CP; the relative abdominal fat, liver, pancreas, and spleen weight; and the relative intestinal length. Fat digestibility was reduced in birds fed control and GPC diets compared with birds fed vitamin E. Ileal and fecal digestibility of hydrolyzable polyphenols and condensed tannins reached values in a range of 56 to 73% and 14 to 47%, respectively. The GPC diets reduced ileal and fecal digestibility of hydrolyzable polyphenols. Antioxidant activity in GPC diet, ileal content, and excreta [2, 2-azinobis (3-ethilenzotiazolin)-6-sulfonate method] and GPC diet (ferric antioxidant power method) exhibited higher scavenging free radical capacity than control and vitamin E diets. The lipid oxidation in breast meat was lower in the birds fed the supplemented vitamin E diet than the control diet after 1, 4, and 7 d of refrigerated storage. Oxidative stability in breast meat at 1, 4, and 7 d of storage was equivalent in GPC diets compared with the vitamin E diet. In conclusion, the inclusion of GPC (up to 60 g/kg) did not impair chicken growth performance, digestive organ sizes, and protein digestibility. Hydrolyzable polyphenols were more bioavailable than condensed tannins. Antioxidant activity in diet, excreta, ileal content, and breast muscle were increased in GPC diets. The GPC supplementation was equally as effective in antioxidant potential as vitamin E. On the basis of these observations, we concluded that GPC could be a new source of antioxidant in animal nutrition.

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Grape pomace (GP) is a source of polyphenols with powerful antioxidant capacity. An experiment was conducted to investigate the effect of inclusion of GP at levels of 5, 15, and 30 g/kg and alpha-tocopheryl acetate (200 mg/kg) in a corn-soybean basal diet on growth performance, protein and amino acid digestibilities; antioxidant activity of diet, serum and excreta, lipid oxidation of breast and thigh meats during refrigerated storage, and liver vitamin E concentration. Growth performance and protein and amino acid digestibilities were not affected among the different treatments. Total intake and digestibility of extractable polyphenols in the birds fed the GP diet were increased compared with birds fed supplemented and unsupplemented vitamin E diets. Antioxidant activity in vitamin E and GP diets and excreta exhibited higher scavenging free radical capacity than the control diet using 3-ethylbenzthiazoline-6-sulfonic acid and ferric reducing antioxidant power methods. Lipid oxidation (malondialdehyde concentration) in breast and thigh meats was lower in the birds fed the supplemented vitamin E diet than the control diet after 1, 4, and 7 d of refrigerated storage. Results showed a linear reduction of lipid oxidation in breast and thigh meats at 4 and 7 d with increasing content of GP in the diet. Oxidative stability in breast and thigh meats at 1, 4, and 7 d of storage was equivalent or less effective in GP diets compared with the vitamin E diet. A linear increase was observed in liver alpha-tocopherol concentration with increasing content of GP in the diet, but it was inferior to the supplemented vitamin E diet. In conclusion, the results showed that a dietary inclusion rate up to 30 g/kg of GP did not impair chickens growth performance and protein and amino acids digestibilities and increased antioxidant activity in diet and excreta. Grape pomace and vitamin E diets reduced the lipid oxidation of meat during refrigerated storage and increased liver alpha-tocopherol concentration, although these effects were greater, in some cases, by adding vitamin E to the diet.

An experiment was conducted to study the effect of microbial phytase (Natuphos 500) supplementation in chicks (0 to 6 wk of age) fed different levels of nonphytate phosphorus (nPP) on performance, mineral retention, bone and plasma minerals and serum enzyme activities. Data were analyzed as a 2 x 2 factorial arrangement with two levels of nPP for age periods of 1-d-old to 3 wk (0.35 and 0.22%) and 3 to 6 wk (0.27 and 0.14%) and two levels of phytase (0 and 500 U/kg) in each period. A positive control, adequate in nPP and Ca without phytase, was used. The low-nPP diets caused a negative effect on the performance (P < 0.05) compared to the normalnPP diet. Phytase had a favorable effect on weight gain at 3 wk (P < 0.004) and 6 wk (P < 0.0475) of age and on feed consumption only at 3 wk (P < 0.0106). Feed efficiency was not affected at any stage by addition of phytase. Performances of chicks fed with 0.35 and 0.27% nPP and phytase were comparable to those obtained with the normal-nPP diets. Decreasing nPP content in the diet increased (P < 0.0001) P retention at 3 and 6 wk of age, increased Mg retention at 6 wk, and decreased (P < 0.0001) Ca and Zn retentions at 3 and 6 wk, respectively. Phytase supplementation increased (P < 0.0001) Ca, P, Mg, and Zn retention at 3 and 6 wk of age. Likewise, the decrease in nPP content in the diet caused a significant reduction of tibia ash (P < 0.0023) and Mg content (P < 0.0001) in tibia ash and reduced liver (P < 0.0240), spleen (P < 0.0176), and tibia (P < 0.0001) weights. Similarly, Ca (P < 0.0369) and Zn (P < 0.0181) contents in tibia ash were increased in response to decreasing nPP levels in the diet. Phytase supplementation increased tibia weight (P < 0.0019), tibia ash (P < 0.0021), and Mg (P < 0.0339) and Zn (P < 0.0353) concentrations and reduced (P < 0.0161) the relative liver weight. By decreasing nPP levels in the diet, plasma Ca (P < 0.0001), Mg (P < 0.0001) and Zn (P < 0.0048) concentrations, and alkaline phosphatase (ALP) activity (P < 0.0299) increased, and plasma P content (P < 0.0001), aspartate aminotransferase (AST) activity (P < 0.0001), and total protein (TP) content (P < 0.0050) were reduced. Phytase supplementation increased plasma P level (P < 0.0001) and serum AST activity (P < 0.0049), reduced plasma Ca (P < 0.0001) and Mg (P < 0.0050) contents, and reduced serum alanine aminotransferase (ALT) (P < 0.0048), ALP (P < 0.0001) and lactate dehydrogenase (LDH) (P < 0.0192) activities. Plasma Zn was not affected by phytase supplementation. These results demonstrated that microbial phytase supplementation to low-P diets improved performance; P, Ca, Mg, and Zn use; and tibia weight and relative liver weight in broiler chickens. Likewise, serum AST, ALT, ALP, and LDH activities, as well as TP concentration, were also affected by phytase supplementation.

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