In vitro evaluation of the effect of yogurt acid whey fractions on iron bioavailability.

A side effect of the raised consumption of Greek yogurt is the generation of massive amounts of yogurt acid whey (YAW). The dairy industry has tried several methods for handling these quantities, which constitute an environmental problem. Although the protein content of YAW is relatively low, given the huge amounts of produced YAW, the final protein amount in the produced YAW should not be underestimated. Taking into consideration the increased interest for bioactive peptides and the increased demand for dietary proteins, combined with protein and peptides content of YAW, efforts should be made toward reintroducing the latter in the food supply chain. In this context and in view of the prevalent dietary iron deficiency problem, the objective of the present study was the investigation of YAW fractions' effect on Fe bioavailability. With this purpose, an in vitro digest approach, following the INFOGEST protocol, was coupled with the Caco2 cell model. To evaluate whether YAW digest fractions exert positive, negative or neutral effect on Fe bioavailability, they were compared with the ones derived from milk, a well-studied food in this context. Milk and YAW showed the same effectiveness on both Fe bioavailability and the expression of relative genes (DCYTB, DMT1, FPN1, and HEPH). Focusing further on YAW fractions, by comparison with their blank digest control counterparts, it resulted that YAW 3- to 10-kDa digests fraction had a superior effect over the 0- to 3-kDa fraction on Fe-uptake, which was accompanied by a similar effect on the expression of Fe metabolism-related genes (DCYTB, FPN1, and HEPH). Finally, although the 3- to 10-kDa fraction of bovine YAW digests resulted in a nonsignificant increased Fe uptake, compared with the ovine and caprine YAW, the expression of DCYTB and FPN1 genes underlined this difference by showing a similar pattern with statistically significant higher expression of bovine compared with ovine and bovine compared with both ovine and caprine, respectively. The present study deals with the novel concept that YAW may contain factors affecting Fe bioavailability. The results show that it does not exert any negative effect and support the extensive investigation for specific peptides with positive effect as well as that YAW proteins should be further assessed on the prospect that they can be used in human nutrition.

Evaluation of a Natural Phytogenic Formulation as an Alternative to Pharmaceutical Zinc Oxide in the Diet of Weaned Piglets.

A natural phytogenic formulation (NPF) was tested as an alternative to pharmaceutical zinc oxide (ZnO) in weaned piglets with respect to growth performance, apparent total tract digestibility and faecal microbiota composition and metabolic activity. Two dietary NPF levels (NPF: 1000 and 2000 mg/kg diet) were compared to a positive control (ZnO: 3000 mg ZnO/kg diet) and a negative control (CON: no added ZnO or NPF) using 84 weaned piglets from 29 d to 78 d (days of age). Feed conversion ratio was improved (p < 0.05) in ZnO and NPF piglets were compared to CON at 50 d. Dry matter, organic matter and crude protein (p < 0.05) digestibility was improved in NPF piglets compared to CON at 57 d. Compared to CON, NPF inclusion reduced E. coli (p < 0.05) and increased C. leptum subgroup (p < 0.01) at 57 d and 78 d, and reduced C. perfringens subgroup (p < 0.05; at 78 d). The ZnO reduced (p < 0.001) E. coli and C. perfringens subgroup (p < 0.01) compared to CON at 78 d. Moreover, ZnO and NPF reduced molar ratios of branched chain volatile fatty acids (p < 0.05) compared to CON, while NPF also increased butyric acid (p < 0.05) at 78 d. In conclusion, the NPF appeared to be a promising alternative to pharmaceutical doses of ZnO.

Dietary probiotic form modulates broiler gut microbiota indices and expression of gut barrier genes including essential components for gut homeostasis.

The probiotic form (PF) type and its dietary administration in combination or not with avilamycin (AV) were investigated for their effects on broiler gut microbiota and expression of genes relevant for gut barrier and gut homeostasis. Depending on PF type (i.e. no addition, viable, inactivated) and AV addition (no/yes), 450 one-day-old Cobb male broilers were allocated in 6 treatments (CON, CON + A, ViP, ViP + A, InP and InP + A) according to a 3 × 2 factorial arrangement with 5 replicates of 15 broilers each for 42 days. Significant interactions (PPF × AV  ≤ 0.05) between PF and AV administration were shown for the ileal mucosa-associated bacteria, the caecal digesta Lactobacillus spp., the molar ratio of the sum of valeric, hexanoic and heptanoic acids and the gene expressions of ileal and caecal IgA and ileal claudin 1. Avilamycin suppressed ileal digesta Lactobacillus spp. (PAV  < 0.001) and caecal digesta Clostridium perfringens subgroup (PAV  = 0.018) and modulated the intestinal fermentation intensity and pattern. The viable PF had the higher levels of ileal digesta Bacteroides spp. (PPF  = 0.021) and caecal digesta Lactobacillus spp. (PPF  = 0.038) compared with the other two PF. Probiotic form modulated the microbial metabolic activity in the ileum and caeca with the viable PF being the most noteworthy in terms of effects regarded as beneficial. Furthermore, the viable PF resulted in reduced expression of caecal Toll-like receptors TLR2B (PPF  = 0.026) and TLR4 (PPF  = 0.011) and transcription factor NFΚΒ1 (PPF  = 0.002), which could be considered as essential for limiting inflammation and preserving gut homeostasis. In conclusion, under non-challenge conditions, probiotic function was shown to depend on PF type and to a lesser degree on co-administration with AV. The importance of probiotic viability for the beneficial modulation of important gut components towards a reduced state of physiological inflammation has been highlighted.

Diet supplementation with an organic acids-based formulation affects gut microbiota and expression of gut barrier genes in broilers.

This study was designed to study the effect of diet supplementation with an organic acids-based formulation (OABF) on luminal- and mucosa-associated bacteria, concentration of volatile fatty acids (VFA), microbial glycolytic enzyme activity and expression of mucin 2 (MUC2), immunoglobulin A (IgA) and tight junction protein, i.e., zonula occludens-1 (ZO1), zonula occludens-2 (ZO2), claudin-1 (CLDN1), claudin-5 (CLDN5) and occludin (OCLN), genes at the ileal and cecal level. A 2 × 2 factorial design was used having OABF inclusion and avilamycin as main factors. Subsequently, 544 day-old male Cobb broilers were allocated in the following 4 treatments, each with 8 replicates: no additions (CON), 1 g OABF/kg diet (OA), 2.5 mg avilamycin/kg diet (AV) and combination of OA and AV (OAAV). The trial lasted for 42 days. In the ileum, OAAV resulted in lower mucosa-associated total bacteria levels (P O × A = 0.028) compared with AV. In addition, ileal digesta levels of Clostridium perfringens subgroup were decreased by avilamycin (P A = 0.045). Inclusion of OABF stimulated the activity of microbial glycolytic enzymes, whereas avilamycin resulted in lower acetate (P A = 0.021) and higher butyrate (P A = 0.010) molar ratios. Expression of ZO1 and CLDN5 was down-regulated by both OABF (P O = 0.016 and P O = 0.003, respectively) and avilamycin (P A = 0.016 and P A = 0.001, respectively). In addition, CLDN1 was down-regulated in AV compared with CON (P O × A = 0.012). Furthermore, OABF down-regulated MUC2 (P O = 0.027), whereas avilamycin down-regulated nuclear factor kappa B subunit 1 (NFKB1) (P A = 0.024), toll-like receptor 2 family member B (TLR2B) (P A = 0.011) and toll-like receptor 4 (TLR4) (P A = 0.014) expression. In the ceca, OABF inclusion increased digesta levels of Clostridium coccoides (P O = 0.018) and Clostridium leptum (P O = 0.040) subgroups, while it up-regulated MUC2 expression (P O = 0.014). Avilamycin (P A = 0.044) and interaction (P O × A < 0.001) effects for IgA expression were noted, with CON having higher IgA expression compared with AV. In conclusion, new findings regarding OABF inclusion effects on an array of relevant biomarkers for broiler gut ecology have been reported and discussed in parallel with avilamycin effects used as a positive control. This new knowledge is expected to provide a response baseline for follow up trials under various stress and challenge conditions.

Growth performance, nutrient digestibility, antioxidant capacity, blood biochemical biomarkers and cytokines expression in broiler chickens fed different phytogenic levels.

The effects of inclusion levels of a phytogenic feed additive (PFA), characterized by menthol anethol and eugenol, on broiler growth performance, nutrient digestibility, biochemical biomarkers and total antioxidant capacity (TAC) of plasma and meat, as well as on the relative expression of selected cytokines, were studied in a 42-d experiment. A total of 225 one-day-old male Cobb broiler chickens were assigned into 3 treatments, with 5 replicates of 15 chickens each. Chickens were fed maize-soybean meal basal diets following a 3 phase (i.e., starter, grower and finisher) feeding program. Depending on PFA inclusion level, treatments were: no PFA (PFA-0), PFA at 100 mg/kg (PFA-100) and PFA at 150 mg/kg (PFA-150). Feed and water were available ad libitum. Feed conversion ratio (FCR) during finisher phase was improved quadratically (P < 0.05) with increasing PFA level. Overall, increasing PFA level increased body weight gain (BWG) in a linear (P < 0.05) and quadratic (P < 0.05) manner with treatments PFA-100 and PFA-150 being greater (P < 0.05) compared with PFA-0. Total tract apparent digestibility of dry matter increased linearly (P < 0.05) and quadratically (P < 0.05) with increasing PFA level. The apparent metabolizable energy corrected for nitrogen (AMEn) also increased linearly (P < 0.05). Increasing PFA level resulted in a linear (P < 0.05) increase in blood plasma TAC. Expression of pro-inflammatory cytokine interleukin -18 (IL-18) was reduced linearly (P < 0.05) in spleen with increasing PFA level. In conclusion, PFA inclusion at 100 mg/kg diet positively influenced performance, whereas PFA inclusion at 150 mg/kg resulted in a stronger improvement in AMEn and plasma TAC. Finally, PFA inclusion resulted in a pattern of reduced pro-inflammatory biomarker IL-18 at spleen. Overall, this study provides evidence for the beneficial role of PFA as a natural growth and health promoter in broiler chickens that needs to be further confirmed in field studies.

Phytogenic Administration and Reduction of Dietary Energy and Protein Levels Affects Growth Performance, Nutrient Digestibility and Antioxidant Status of Broilers.

The aim of this study was to investigate the effect of reduced dietary energy (ME) and protein (CP) levels along with administration of a phytogenic feed additive (PFA) based on oregano, anise and citrus essential oils, on broiler growth performance, nutrient digestibility, meat and blood biochemical parameters and total antioxidant capacity (TAC). Depending on dietary ME and CP level down regulation compared to a corn-soybean meal basal diet A used as positive control, three diet types [A, B(=A-3%) and C(=A-6%)] were implemented. Depending on the inclusion or not of PFA at 125 mg/kg diet, 450 1-d old, male Cobb broilers were randomly allocated in six treatments according to a 3×2 factorial arrangement with 5 replicates of 15 broilers; A: diets formulated optimally to meet broiler nutrient requirements for maximizing protein content of meat for starter, grower and finisher growth periods; APh: A+PFA; B: suboptimal in ME and CP levels by 3%; BPh: B+PFA; C: suboptimal in ME and CP levels by 6%; CPh: C+PFA. Feed conversion ratio (FCR) was improved in birds fed diet A compared to diet C during the grower period (P D =0.021) and overall (P D =0.010). Phytogenic supplementation resulted in higher (P D×Ph =0.020) total tract apparent digestibility of fat in birds fed diet C compared to diet A. Birds fed diet A had higher (P D =0.001) plasma cholesterol, compared to birds fed diet C. In addition, birds fed diets A and B had higher (P D =0.002) breast protein content compared to C. Overall, PFA inclusion reduced cholesterol (P Ph =0.002) and increased plasma TAC (P Ph <0.001). Moreover, PFA increased breast (P Ph =0.001) and thigh (P Ph =0.01) TAC. In conclusion, a reduction in dietary ME and CP levels, adversely affected the FCR, whereas PFA supplementation tended (P Ph =0.089) to compensate these effects. Moreover, the addition of PFA reduced plasma cholesterol and improved plasma and meat TAC.