Effects of essential oils on egg production and feed efficiency as influenced by laying hen breed: A meta-analysis.

Background and Aim: Successful rearing of laying hens to achieve optimal egg production is an endeavor that often faces various constraints and challenges, such as infectious diseases, environmental stressors, and fluctuations in feed quality. The incorporation of essential oils (EOs) into the diet of laying hens has attracted considerable attention in recent years. Therefore, our study aimed to evaluate the efficacy of EO inclusion in laying hen diets by considering the effects of production phase and breed on performance, egg quality, serum biochemistry, gut health, and antioxidant activity. Materials and Methods: The articles were obtained from the Web of Science, Scopus, Science Direct, and PubMed using the search terms "essential oils," "laying hens," and "phytobiotics." Data from 27 articles and 71 experiments were grouped according to laying hen production phase and breed in the database. The EO levels ranged from 0 to 1000 mg/kg, with thymol and carvacrol being the major EOs. A mixed model was used to analyze the data. Random effects were applied to the treatment, and fixed effects were applied to EO level, production phase, and breed. Results: Egg production, feed intake, feed efficiency, eggshell quality, villus height, crypt depth, superoxide dismutase, and glutathione peroxidase levels increased linearly (p = 0.05) and egg weight and mass increased quadratically (p < 0.05) with increasing EO concentrations. An interaction was observed between the EO level egg production and feed conversion ratio (p = 0.05). Serum glucose, cholesterol, and malondialdehyde levels decreased with increasing EO concentrations (p < 0.05). Conclusions: The inclusion of EOs effectively increased egg production, feed efficiency, egg weight, egg mass, eggshell quality, oxidative enzymes, and intestinal health. In addition, the proportion of dietary EOs in lightweight laying hens was higher than that in semi-heavy-weight laying hens in improving egg production and feeding efficiency.

Effects of biodegradable- and non-biodegradable-rich waste separation on ash deposition behaviour during coal and refuse-derived fuel co-combustion.

The potential impact of ash deposition during the combustion of separated biodegradable- and non-biodegradable-rich waste of refuse-derived fuel (RDF) was evaluated in this study. Theoretical prediction, drop tube furnace experimental combustion, and ash observation were performed to comprehensively investigate their ash deposit behaviour. The results show that high CaO and Cl in RDFs result in severe sintering and rust in the metal surface. The high ash deposit weight and aggregated sticky particles are observed during single-firing RDFs. Furthermore, adding 5 wt% of biodegradable-rich RDF or mixed RDF to coal has a less significant effect on ash deposition. However, several aggregate particles and metal degradation are observed during the combustion of mixed coal with the addition of 5 wt% non-biodegradable-rich RDF. The high Cl in non-biodegradable-rich RDF affects the ash deposition behaviour significantly. This research provides valuable insights into optimising coal-RDF co-combustion, especially with separating biodegradable- and non-biodegradable-rich RDFs.

A Meta-analysis of Optimum Level of Dietary Nanoselenium on Performances, Blood Constituents, Antioxidant Activity, Carcass, and Giblet Weight of Broiler Chickens.

Contradictory reports regarding the effects of nanoselenium (NanoSe) on the performance of broiler chickens may occur. Therefore, the optimum supplementation of NanoSe doses needs to be determined. The current meta-analysis study was aimed at evaluating the effectiveness and the optimum doses of NanoSe supplementation in broiler diets on performance, blood constituents, carcass, and giblet weight by considering breed and sex. The database was obtained from online scientific publications by searching through search engines such as Scopus, Web of Science, Google Scholar, and PubMed by entering the keywords nanoselenium, performance, antioxidants, and broiler. A total of 25 articles were included in the meta-analysis database. The study group was treated as a random effect while NanoSe dose, breed, and sex were treated as fixed effects. Daily body weight gain, carcass weight, and breast weight increased quadratically (P < 0.05), and FCR decreased quadratically (P < 0.05) in the starter and cumulative periods with increasing NanoSe supplementation. NanoSe supplementation tended to decrease cumulative feed intake linearly (P < 0.1) and decreased (P < 0.05) abdominal fat, albumin, red blood cells, ALT, and MDA levels. In contrast, levels of total protein, globulin, glucose, AST, white blood cells, cholesterol, triglyceride, and the weight of the liver, heart, gizzard, bursa of Fabricius, thymus, and spleen were not affected by NanoSe supplementation. Increasing the dose of NanoSe increased (P < 0.05) the GSHPx enzyme and Se concentration in breast muscle and liver and tended to enhance (P < 0.01) the CAT enzyme. It is concluded that a proper dose of NanoSe supplementation in a broiler diet improves body weight gain, feed efficiency, carcass, and breast weight without adverse effects on giblets. Dietary NanoSe elevates Se concentration in the breast muscle and liver and antioxidant activity. The current meta-analysis shows that the optimum dose for body weight gain and FCR is 1 to 1.5 mg/kg.

Dietary Phytogenic Extracts Favorably Influence Productivity, Egg Quality, Blood Constituents, Antioxidant and Immunological Parameters of Laying Hens: A Meta-Analysis.

The present study aimed to assess the impact of dietary phytogenic extracts on laying hen productivity, egg quality, blood constituents, antioxidant, and immunological parameters through a meta-analytical approach. A total of 28 articles (119 data points) reporting the influence of dietary phytogenic extracts on the productive performance, egg quality, blood constituents, immunological, and antioxidant parameters of laying hens were embedded into a database. Statistical analysis was performed using a mixed model, with different studies treated as random effects and phytogenic extract levels treated as fixed effects. This meta-analysis revealed that dietary phytogenic extracts quadratically (p < 0.05) improved egg production and egg mass as well as decreased (p < 0.05) the feed conversion ratio (FCR) with no adverse effect on egg weight and egg quality. Feed intake and egg yolk percentage tended to increase linearly (p < 0.1). Total serum cholesterol and low-density lipoprotein (LDL) declined quadratically (p < 0.001 and p < 0.05, respectively), high-density lipoprotein (HDL) increased linearly (p < 0.001), and malondialdehyde (MDA) decreased linearly (p < 0.01), with increasing levels of dietary phytogenic extract. In addition, immunoglobulin G (IgG), immunoglobulin A (IgA), glutathione peroxidase (GSH-Px), and total superoxide dismutase (TSOD) increased linearly (p < 0.05) in line with the increase in dietary phytogenic extract level. It was concluded that the inclusion of phytogenic extracts in the diet of laying hens had a positive effect on productive performance, feed efficiency, egg mass, immunity, and antioxidant activity without interfering with egg quality. The optimum level of feed photogenic extract for egg production and feed efficiency was determined to be around 300 mg/kg feed.