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.

Effect of fermented tomato pomace on the growth performance, antioxidant capacity, and intestinal microflora in broiler chickens.

Solid-state fermentation is a useful method for the utilization of the agri-industrial residues. This study was conducted to investigate the effects of tomato pomace (TP) and Aspergillus niger-fermented tomato pomace (FTP) on the growth performance, some carcass traits, antioxidant status, and intestinal microflora in broiler chickens. A total of 140 Ross 308 one-day-old male chicks were allocated to one of four treatment groups consisting of five replicates of seven chicks each. Chicks were fed ad libitum with the corn-soybean based basal diet (control), the basal diet supplemented with 0.25 g/kg synthetic antioxidant, 10 g/kg TP or 10 g/kg FTP for 42 days. Dietary TP increased serum glutathione peroxidase (GPx) and superoxide dismutase (SOD) but did not affect the growth performance. Dietary inclusion of FTP improved the feed conversion ratio and raised serum GPx and SOD. Carcass traits, malondialdehyde level, pH, and color of breast meat and cecal microflora were not affected by dietary treatments. The results of the study showed that TP can be used as a natural antioxidant in broiler diets without a detrimental effect on growth performance. Dietary FTP can be suggested as an alternative to synthetic antioxidants with beneficial effects on growth performance and antioxidant capacity.

The effects of infused olive leaf offered with drinking water on growth performance, ileum histomorphologic characteristics, and some cecal microorganism counts of broiler chickens.

The aim of the study was to investigate the effects of infused olive leaves (IOL) in drinking water on the growth performance, carcass characteristics, ileal histomorphology, and cecal microorganisms of broiler chickens. A total of 210 day-old male broiler chicks were randomly divided into 5 treatment groups with 6 replicates and 7 chicks in each replicate. All chicks received a corn-soybean-based diet and drinking water with or without IOL ad libitum for 42 days. Treatments were drinking water without any additives (control group), drinking water including IOL of 5 m/L (IOL5), 10 m/L (IOL10), 15 ml/L (IOL15), and 20 ml/L (IOL20). The addition of IOL to drinking water did not affect the growth performance, water intake, carcass parameters, weights of inner organs, and digestive tract weight and length. The Escherichia coli and Lactobacillus spp. counts in the cecum were also not influenced by IOL supplementation in drinking water. However, chickens receiving IOL5, IOL10, or IOL15 had higher villus length in the ileum compared with birds in the control group. Crypt depth was lower in chickens from the IOL20 group compared with birds in the other treatment groups. In addition, broilers offered IOL15 or IOL20 had a higher villus length to crypt depth ratio in the ileum than chickens in the control group. However, treatments had no influence on the lamina muscularis mucosae layer of the ileum in broiler chickens. The results showed that drinking water including IOL at 15 and 20 ml/L improved ileal histomorphology without any detrimental effect on growth performance, carcass traits, and cecal microorganisms in broiler chickens.

Effect of chamomile (Matricaria chamomilla L.), linden (Tilia cordata Mill.), and green tea (Camellia sinensis L.) aqueous extract administration in the drinking water during pre-slaughter feed withdrawal period in broiler chickens.

Feed withdrawal (FW) and other pre-slaughter stressors have detrimental effects on the meat quality of broiler chickens. Herbal extracts can be used for their sedative effects to reduce the harmful impacts of pre-slaughter stress on broiler chickens. This study aimed to investigate the effect of chamomile (CAE), linden (LAE), and green tea (GAE) aqueous extracts (AE) in drinking water during the pre-slaughter FW period on the meat and liver quality, serum corticosterone level, and some cecal microorganisms of broilers. A total of 450 male and female 42-day-old chickens were allocated to a completely randomized design with five treatment groups and two sexes in six replicates, 12 birds (six male and six female) for each replicate. Treatment groups were chickens offered ad libitum feed and drinking water (control, CT), broilers exposed to FW for 10 h before the slaughter with unsupplemented drinking water (FW), with drinking water supplemented 50 ml/L CAE, LAE, and GAE. Chickens that experienced FW had lower (P < 0.001) slaughter body weight, carcass, gastrointestinal tract (GIT) and inner organ weights, and GIT length (P = 0.002). However, the dressing percentage was higher (P < 0.001) in FW and AE groups than CT group. The FW increased (P < 0.001) the ultimate pH of thigh meat compared with the CT group. The FW also decreased (P = 0.026) the lightness (L*) value of thigh meat of broilers, although CAE and LAE did not change the L* value compared with the CT group. Similarly, the redness (a*) value of thigh meat was lower (P = 0.003) in chickens exposed to FW but was not affected by GAE administration. However, FW or AE did not impact the serum corticosterone level and cecal microbial loads in broiler chickens. The obtained result showed that CAE, LAE, or GAE can be used in drinking water to reduce the harmful effects of FW on the meat quality of broiler chickens.

Effect of raw and fermented pomegranate pomace on performance, antioxidant activity, intestinal microbiota and morphology in broiler chickens.

The present study was conducted to investigate the effects of raw (PP) and fermented pomegranate pomace (FP) on performance, antioxidant activity, caecal microbiota and ileal morphology in broiler chickens. A total of 175 male broiler chicks were allocated to five treatment groups with five replicates and seven birds per replicate in a completely randomised design. Dietary treatments included a soy-corn based diet (control), diets supplemented with PP at 5 (5PP) and 10 g/kg (10PP), and diets supplemented with FP at 5 (5FP) and 10 g/kg (10FP). Dietary PP and FP did not change the body weight and feed conversion ratio. Moreover, dietary PP and FP did not alter the serum glutathione peroxidase, superoxide dismutase, and catalase levels but decreased malondialdehyde (p < 0.05) in breast meat. Caecal Clostridium perfringens count was decreased in broiler chickens of groups 10PP, 5FP and 10FP (p < 0.05). However, PP and FP had detrimental effects on the ileum morphology of broiler chicks. The villus height was decreased in the 10PP, 5FP and 10FP groups compared with the control group (p < 0.01). Crypt depth was higher in the 5PP and 10FP groups than control and 10PP groups (p < 0.01). The villus height to crypt depth ratio was also decreased in 5PP, 5FP, and 10FP groups (p < 0.01). These results suggest that PP and FP have the potential to be used in broiler diets as antioxidant and antimicrobial agents. However, detailed studies should be conducted to investigate the underlying reasons for the detrimental effects on ileal morphology.

Effect of Raw and Fermented Grape Pomace on the Growth Performance, Antioxidant Status, Intestinal Morphology, and Selected Bacterial Species in Broiler Chicks.

The effects of raw (GP) and fermented grape pomace (FGP) on the growth performance, some carcass parameters, antioxidant status, intestinal morphology, and selected bacterial species in broiler chicken were investigated in this study. Grape pomace was fermented with Aspergillus niger for 7 d. In total, 140 one-day-old male chicks (Ross 308) were randomly assigned to four treatment groups, with five replicates and seven birds each. Chickens were fed either a basal diet (CON) or the basal diet supplemented with 0.25 g/kg synthetic antioxidants (5% butylated hydroxytoluene, 1% butylated hydroxyanisole, and 11% ethoxyquin) (AO), or 15 g/kg GP (GP), or 15 g/kg FGP (FGP) for 42 d. Dietary GP raised serum glutathione peroxidase (p = 0.031) and superoxide dismutase (p = 0.021) levels, increased ileum lamina muscularis thickness (p = 0.016), and did not affect selected bacterial species in the cecum of broiler chickens. Dietary FGP improved body weight (p = 0.003), increased the serum catalase level (p = 0.032), and decreased the cecal Clostridium perfringens count (p = 0.033) but did not affect the ileal morphology of broiler chickens. The carcass parameters, malondialdehyde level, pH, and color of the breast meat of chickens were not changed by either GP or FGP supplementation. Chickens fed with the synthetic antioxidants had similar growth performance with the chickens fed with FGP but had better body weight (p = 0.003) and feed conversion ratio (p = 0.045) compared with the chickens fed with GP. The obtained results showed that FGP can be used as an alternative to synthetic antioxidants in broiler diets.

Effect of dietary raw and fermented sour cherry kernel (Prunus cerasus L.) on growth performance, carcass traits, and meat quality in broiler chickens.

Sour cherry kernels are waste products of the fruit juice industry. Solid-state fermentation has great potential for recycling the agro-industrial residues. In the present study, the effect of raw sour cherry kernel (RC) and fermented sour cherry kernel (FC) by Aspergillus niger on growth performance, carcass traits and meat quality in broiler chickens was investigated. A total of 343 one-day-old male broilers (Ross 308) were randomly allocated to 7 treatments with 7 replicates for each treatment and 7 birds in each replicate. The chicks were fed on a basal diet (control) and basal diet supplemented with RC or FC at the 1, 2, and 4% level. Dietary RC improved (P < 0.001) the feed conversion ratio (FCR) at the 1% inclusion level although chicks fed 2 and 4% RC had lower (P < 0.01) body weight (BW), body weight gain (BWG), and feed intake (FI) from day 1 to 42, compared with that of the birds in the control group. Dietary FC with 1% inclusion level increased (P ≤ 0.05) BWG from day 22 to 42 and also enhanced (P < 0.001) the FCR from day 1 to 42. However, 4% dietary FC had an adverse effect (P < 0.01) on BW, BWG, FI, and the FCR, compared with the control group. The bursa of Fabricius weight was raised (P < 0.01) as the supplemental FC level increased. Dietary RC and FC elevated gut weight (P < 0.01) and length (P ≤ 0.05). Broilers fed on 2% FC had a higher (P ≤ 0.05) ash level and a lower (P ≤ 0.05) b* value in thigh meat, compared with the 2% RC group. The results indicate that FC can be used in broiler nutrition up to 2% level although RC can be added to broiler diets up to 1% level without a detrimental effect on growth performance. Dietary inclusion of 1% RC or FC can be recommended due to the positive effects on broiler chickens.

Effect of dietary raw and fermented sour cherry kernel (Prunus cerasus L.) on digestibility, intestinal morphology and caecal microflora in broiler chickens.

This study was conducted to investigate the effect of dietary raw sour cherry kernel (RC) or fermented sour cherry kernel (FC) on apparent digestibility, ileal morphology, and caecal microflora in broiler chickens. Raw sour cherry kernel was fermented by Aspergillus niger for 7 D. A total of 343 one-day-old Ross 308 male chicks were assigned to 7 dietary treatments consisting of 7 replicates of 7 broilers each. All birds were fed with a commercial diet or diets supplemented with 1%, 2%, or 4% RC or FC. The experimental period was 42 D. Apparent dry matter (DM), nitrogen and ash digestibilities were diminished (P < 0.05) by dietary RC inclusion, although dietary FC did not negatively affect (P > 0.05) nutrient digestibility. Dietary 1% FC increased (P < 0.01) the villus height to crypt depth ratio (VH:CD) compared with the other treatment groups, although RC4 reduced the villus height (VH, P < 0.001) and VH:CD (P < 0.01), compared with the control group. Dietary treatments had no effect (P > 0.05) on the crypt depth (CD). Birds fed 1% FC had the highest (P < 0.05) caecal Lactobacillus spp. counts among the treatment groups. Enterococcus spp. and Escherichia coli counts in cecum were not affected (P > 0.05) by dietary treatments. The results showed that the dietary inclusion of 1% FC improved ileal morphology and caecal microflora without any adverse effect on the apparent digestibility. These results indicate that FC has the potential to be a feed additive which improves intestinal health for broiler diets.