Consumer preference for poultry meat from free-range birds is not justified by scientific evidence. Inconsistency in results among studies on the effects of access to pasture on performance, carcass composition, and meat quality has led to a meta-analysis to quantify effects. After identification of studies where response variables were directly compared between birds with and without access to pasture, standardized effect sizes were used to calculate differences. The effect size for growth combined according to a fixed effect model did not present heterogeneity (P = 0.116). However, with feed intake and feed efficiency, variability among studies (heterogeneity with P-values of below 0.10) was influenced by more than sampling error. Carcass yield was the only carcass component that showed heterogeneity (P = 0.008), whereas numerous response variables related to meat quality were not homogenous. The use of subgroup analysis and meta-regression to evaluate the sources of heterogeneity was limited by ill-defined explanatory variables and few values available within response variables. Consequently, between-study variability was accounted for by use of random effects models to combine effect sizes. According to these, few response variables were influenced by pasture access. Fat concentrations in breast (mean effect size = -0.500; 95% CI = -0.825 to -0.175; 11 studies; 14 comparisons), thigh (mean effect size = -0.908; 95% CI = -1.710 to -0.105; 4 studies; 5 comparisons) and drum (mean effect size = -1.223; 95% CI = -2.210 to -0.237; 3 studies; 3 comparisons) muscles were decreased in free-range birds. Access to pasture increased (P < 0.05) or tended to increase (P < 0.10) protein concentrations in the respective commercial cuts. It is concluded that factors other than enhanced meat quality could be responsible for consumer preference for meat from free-range poultry.

• MeSH
• chov zvířat metody   MeSH
• kur domácí růst a vývoj   fyziologie   MeSH
• maso analýza   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• metaanalýza MeSH
• práce podpořená grantem MeSH

Mathematical modelling of the relationships between mineral inputs and outputs would enable the prediction of mineral requirements of poultry under a wide range of conditions. To establish the feasibility of possible modelling of mineral requirements, the current study aimed to describe the individual mineral concentrations of whole bodies of quail over the life cycle from hatching to 70 days of age. Quail were reared indoors without any restrictions that could limit growth. Sampling of birds (n = 6-18) was carried out at 0, 3, 7, 14, 21, 35, 49 and 70 days after hatching. Freeze-dried samples of whole bodies (digestive contents removed) were analysed for ash, and macrominerals (calcium, magnesium, phosphorus, potassium, sodium) and microminerals (copper, iron, manganese, nickel, selenium, zinc). Ash concentration followed a curvilinear trend, with a maximum of 101.7 g/kg dry matter at 32.77 days. Individual mineral concentrations, expressed as a proportion of ash, were fluctuating over time, with the most prominent changes at 3 days and again at either 14 or 21 days. Dissimilar patterns in individual mineral concentrations resulted that ratios between minerals followed inconsistent patterns over time. Although mineral contents in absolute quantities can be described through modelling over the entire life cycle of the bird, it can be concluded that variable concentrations of individual minerals could complicate further model development.

• MeSH
• biologické modely MeSH
• Coturnix fyziologie   MeSH
• minerály chemie   MeSH
• složení těla fyziologie   MeSH
• stárnutí fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Conclusions from narrative qualitative reviews on differences in total tract digestibilities between goats and sheep did not account for variability among studies. Therefore meta-analytic techniques were used to describe the magnitude of these differences with numerical values. A unitless effect size (Hedges' g) was applied within studies to measure differences in digestibilities of dry matter (DM; 104 comparisons), organic matter (OM; 93 comparisons), crude protein (CP; 85 comparisons), neutral detergent fibre (NDF; 74 comparisons), acid detergent fibre (ADF; 59 comparisons), cellulose (24 comparisons), hemicellulose (18 comparisons) and gross energy (GE; 29 comparisons). The absence and inability to describe independent factors which contributed to variation among studies necessitated the use of frequentist random effects and hierarchical Bayesian models in the calculation of summary statistics across studies. Digestibilities of DM, OM, CP, NDF, ADF and hemicellulose were higher (p < 0.05) in goats than sheep when all-forage diets were fed. When concentrates were included in the diets, there were no such differences. Differences between goats and sheep in DM intake were found to be non-significant. Differences in nutrient digestibilities of forages as sole feed implies that species-specific values have to be used in feed formulation and feeding strategies. However, caution is needed when extrapolating results from stall-feeding, which is how digestibility data are usually measured, to grazing conditions.

• MeSH
• Bayesova věta MeSH
• dietní proteiny MeSH
• druhová specificita MeSH
• energetický metabolismus MeSH
• fyziologie výživy zvířat * MeSH
• gastrointestinální trakt fyziologie   MeSH
• kozy fyziologie   MeSH
• krmivo pro zvířata analýza   MeSH
• ovce fyziologie   MeSH
• potravní vláknina MeSH
• trávení fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• metaanalýza MeSH
• práce podpořená grantem MeSH

Dietary Cr supplementation has potential to decrease fat and increase lean in carcasses of growing-finishing swine. However, effects of Cr supplementation on performance and economically important carcass and meat quality characteristics varied considerably among studies. Therefore, a meta-analysis was designed to quantitatively describe effects obtained in several independent studies. To accommodate differences in methodology among studies, standardized effect sizes (Hedges's g) were calculated for results from 31 studies, in which Cr was supplemented as complexes of Cr Met chelate, Cr nanocomposite, Cr nicotinate, Cr propionate, Cr tripicolinate, or Cr yeast in diets for growing-finishing swine. Summary statistics were calculated by frequentist fixed and random effects, and hierarchical Bayesian models. With characteristics related to carcass quality, observed heterogeneity (P < 0.10) could not adequately be explained in a meta-regression by differences in initial BW and amount of Cr supplemented. Random effects and Bayesian models to summarize effect sizes for these characteristics showed similar results. According to random effects models, dietary Cr supplementation decreased (P < 0.05) 10th-rib fat thickness (mean effect size = -0.479; 95% confidence intervals = -0.680 to -0.279; 24 studies; 59 comparisons), whereas percentage carcass lean (mean effect size = 0.614; 95% confidence intervals = 0.366 to 0.863; 22 studies; 52 comparisons) and LM area (mean effect size = 0.571; 95% confidence intervals = 0.364 to 0.778; 29 studies; 72 comparisons) increased. Average daily gain and G:F, which did not present heterogeneity, were improved by Cr supplementation, whereas no effects were detected in characteristics (CIE color, drip loss, cook loss, shear force) related to meat quality. Some publication, or other small-study bias, was evident in results on growth and feed efficiency. However, directions of mean effect sizes were not changed by application of the trim-and-fill method to correct for bias.

• MeSH
• biologické modely MeSH
• chrom farmakologie   MeSH
• dieta veterinární   MeSH
• fyziologie výživy zvířat MeSH
• krmivo pro zvířata analýza   MeSH
• maso normy   MeSH
• potravní doplňky MeSH
• prasata růst a vývoj   fyziologie   MeSH
• složení těla účinky léků   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• metaanalýza MeSH
• práce podpořená grantem MeSH

Dietary vitamin E supplementation provides a feasible option to extend the shelf life of meat. However, the costs of extra supplementation necessitate an accurate level of feeding to achieve the maximum return in product quality improvement. The current study aimed to quantify the effects of total dietary vitamin E intake on muscle α-tocopherol concentration in cattle and pigs, and to relate muscle α-tocopherol concentration to lipid oxidation and color of meat. Through computerized and manual searches, 13 studies with cattle and 10 with pigs were identified that have presented data on dietary vitamin E intake and muscle α-tocopherol concentration. Treatment means from 12 studies with beef and 14 with pork were used to evaluate the effects of muscle α-tocopherol concentration on lipid oxidation, as represented by thiobarbituric acid reactive substances in meat stored or retail displayed at chilled temperatures. With CIELAB a* (redness) values as an indicator of color development, the association between muscle α-tocopherol concentration and color could be evaluated with treatment means from 8 studies with beef and 5 with pork. Different treatments applied within studies resulted in 20 to 66 values available for the respective regression analyses. Relationships could be described effectively by different forms of the Mitscherlich model, which presented an initial value for y when x = 0, an asymptotic plateau, and the rate of change of y with increasing values of x. With the inclusion of experiment as a random effect, the relationship between total dietary vitamin E intake (x, IU/d for cattle and mg/d for pigs) and muscle α-tocopherol concentration (y, µg/g of meat) reached asymptotic plateau values at 5.71 and 4.83 µg/g of meat for cattle and pigs, respectively. The fractional accumulation rate (per total dietary vitamin E intake) of muscle α-tocopherol concentration was considerably greater in pigs (0.0130) than in cattle (0.00174). The form of the relationship between muscle α-tocopherol concentration and thiobarbituric acid reactive substances in pork was influenced by a single value, whereas muscle α-tocopherol concentrations could not be related to a* values in beef. This study presented viable models that could be applied in practice to calculate the amounts of supplemental dietary vitamin E needed to obtain the maximum profit from beef and pork.

• MeSH
• alfa-tokoferol analýza   MeSH
• barva MeSH
• kosterní svaly chemie   účinky léků   MeSH
• lipidy analýza   MeSH
• maso analýza   normy   MeSH
• peroxidace lipidů účinky léků   MeSH
• potravní doplňky MeSH
• prasata MeSH
• skot MeSH
• vitamin E farmakologie   MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Research studies presented inconsistent results on the effects and action of choline in dairy cow diets. A meta-analysis was conducted to quantify the effects of dietary rumen-protected choline on production characteristics of dairy cows. Dry matter intake (kg/d), milk yield (kg/d), milk fat (% and kg/d), and milk protein (% and kg/d) were evaluated as dependent variables in models. The number of treatment means varied from 20 obtained in 7 studies for milk fat and protein contents to 34 from 11 studies (12 experiments) for milk yield. Accounting for experiment as a random effect, DMI, milk yield, milk protein content, and milk protein yield could adequately be related to levels of dietary rumen-protected choline chloride by a logistic model. Marginal responses in milk yield decreased from 131.5 to 0.037 g of milk/g of dietary rumen-protected choline chloride when supplementation increased from 6 to 50 g/d. From estimated values for the metabolizable Met supplied by diets, it appears that dietary rumen-protected choline chloride functions as a methyl donor to spare Met for milk protein synthesis. However, more accurate input data on Met status of diets are needed to confirm this. Within the range of 6 to 50 g/d of rumen-protected choline chloride, milk fat content decreased linearly at a rate of 0.00339% for a 1g/d increase in dietary rumen-protected choline chloride. This illustrates that dietary rumen-protected choline chloride has no effect on milk fat content. Numerous physiological and dietary factors probably related to responses obtained with dietary rumen-protected choline supplementation, and the precise mechanism of choline action in the lactating dairy cow warrants further investigation.

• MeSH
• bachor MeSH
• cholin farmakologie   MeSH
• krmivo pro zvířata MeSH
• laktace účinky léků   MeSH
• lipidy analýza   MeSH
• mléčné bílkoviny analýza   MeSH
• mléko chemie   sekrece   MeSH
• potravní doplňky MeSH
• skot fyziologie   MeSH
• zvířata MeSH
• Check Tag
• skot fyziologie   MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• metaanalýza MeSH
• práce podpořená grantem MeSH