Dietary Probiotics Modulate Gut Barrier and Immune-Related Gene Expression and Histomorphology in Broiler Chickens under Non- and Pathogen-Challenged Conditions: A Meta-Analysis

Data published in the literature about the favorable effects of dietary probiotics on gut health in broiler chickens are inconsistent. To obtain a more comprehensive understanding, we conducted a meta-analysis to assess the effects of probiotics on the gut barrier and immune-related gene expression, histomorphology, and growth in chickens that were either challenged or non-challenged with pathogens. From the 54 articles published between 2012 and 2022, subsets of data, separately for non-challenged and challenged conditions, for response variables were created. The mean dietary probiotic concentrations ranged from 4.7 to 6.2 and 4.7 to 7.2 log₁₀ colony-forming unit/kg under non-challenged and challenged conditions, respectively. Probiotics increased the expression of genes for mucins and tight junction proteins in the jejunum and ileum at weeks 3 and 6. The stimulatory effect of probiotics on tight junction protein expression was partly stronger in challenged than in non-challenged birds. Meta-regressions also showed an anti-inflammatory effect of probiotics under challenged conditions by modulating the expression of cytokines. Probiotics improved villus height at certain ages in the small intestine while not influencing growth performance. Dietary metabolizable energy, crude protein, and days post-infection modified the effects of probiotics on the observed variables. Overall, meta-regressions support the beneficial effects of probiotics on gut integrity and structure in chickens.

Effect of botanical composition of free-range areas on production results and selected meat quality parameters of organic Yellowleg Partridge chickens

The aim of the conducted research was to assess the impact of the botanical composition of free-range areas on the production results and selected quality parameters of the meat of fattening chickens of the Polish Yellowleg Partridge (Ż-33) breed in organic farming. Three hundred mixed-sex Ż-33 chicks were assigned to three groups: RP1 – free-range area with natural meadow vegetation, RP2 – free-range area sown with a mixture of plants containing ingredients stimulating growth, RP3 – free-range area sown with a mixture of plants rich in carotene. During the experiment, the production results (the weight of the birds, feed consumption, feed conversion ratio per g of weight gain, and mortality) were monitored. Observations were also performed on the behaviour in the free-range areas. On the 140th day of the experiment, a simplified slaughter analysis was carried out, the meat pH was measured, the colour of the muscles was also determined, as well as the water holding capacity and drip loss of the meat. In the meat samples, the content of nutrients and fatty acids was determined, and the peroxidizability index (PI) was calculated. Birds feeding in the RP2 free-range areas were characterised by higher body weight, better feed conversion, and higher dressing percentage compared to birds having access to the RP1 and RP3 free-range areas. On the other hand, the RP3 group Ż-33 chickens were characterised by a higher share of leg muscles and a tendency towards lower fat content in the carcass. It was also found that the meat of birds from the RP2 and RP3 groups was characterised by a higher pH24 compared to Ż-33 chickens from the RP1 group. Access to the RP2 free-range area modified the fatty acid profile, mainly in the leg muscles, reducing the palmitic acid and MUFA content and increasing the PUFA content. It can therefore be assumed that the plant species sown in the RP2 free-range area positively influenced the production results and the quality of the meat of fattening chickens feeding on them. It is therefore appropriate to carry out further studies on the type of vegetation sown in free-range areas in order to improve the efficiency and quality of the meat of organic fattening chickens.

Effect of Breed and Diet on Carcass Parameters and Meat Quality of Spent Hens

Two spent hen breeds (Mos and Isa Brown) fed with three different diets [commercial feeding (CF); corn, pea, and triticale (CPT); and corn and wheat (CW)] were studied to assess their laying performance, carcass characteristics, and meat quality parameters (breast and drumstick). A total of 48 hens reared in a traditional free-range system were used. Birds were slaughtered at 72 weeks of age after the moulting in an accredited abattoir, and measurements (for each bird) of carcass and meat started at 24 h post-mortem. The results demonstrated a breed and diet effect (P<0.05) on laying performance, carcass, and meat quality. The Mos breed showed lower laying performance, higher live weight (P<0.001), carcass weight (P<0.001), dressing percentage (P<0.001), and carcass fat (P<0.001) than Isa Brown. The breed also affected physicochemical parameters of drumstick and breast (P<0.05). Concerning the diet effect, spent hens fed with commercial feeding showed heavier live weight (P<0.01) and carcass weight (P<0.01). Diet significantly affected most of meat quality parameters, CPT being the formulation that most affected (P<0.05) drumstick composition, while in the breast was CF (P<0.001). Significant (P≤0.005) effects on breast colour, cooking loss and hardness were observed in animals fed with alternative diets to CF. Regarding nutritional quality, no breed or diet effect (P<0.05) was observed in MUFA s, PUFA s and n-6 contents of meat. Overall, both breeds showed a high protein and low-fat content in the breast, showing these hens as an opportunity for the development of meat products as well as an economic purpose for spent hens that reach the end of their productive lives.

An index to measure the activity attitude of broilers in extensive system

In organic poultry production it is important to rear animals with a dynamic attitude to take advantage of outdoor areas. Farmers are reluctant to use such strains due to their lower productivity and older slaughtering age. However, fast growing lines grown in organic system often suffer poor health and welfare conditions. The kinetic metabolism of chickens is correlated with different types of muscle fiber: type I (in red muscles or oxidative) for prolonged and moderate movement and type II (in white muscles or glycogenic) for fast movements. Red muscle metabolism produces energy mainly by β-oxidation of Highly Unsaturated n-3 Fatty Acids (HUFA). Accordingly, kinetic activity causes higher consume of HUFA in red muscles than in white muscles, so the ratio between n-3 HUFA and their precursor C18:3 n-3 (ALA) is likely to be smaller in red than in white muscles. However, these ratios are highly affected by the environment. To reduce the effect of environmental variables, we propose an "Activity index" as the difference between n-3 HUFA/ALA in white and red muscle within the same bird. This index, measured after slaughtering, should represent the activity performed by the chicken during its life. Given that birds in good health had the possibility of moving, the "Activity index" would measure the activity actually performed by the animals. Should birds of a given strain show a higher activity level, this would be an indication of the suitability of that strain to outdoor systems. This work verified the application of this "Activity index" on 90 birds from 6 genetic strains with known kinetic behavior reared in an experimental farm. The "Activity index" was also tested on chicken strains collected form commercial organic farms. The results confirmed that strains recognized for higher kinetic attitude actually walked more and their behavior was clearly detected by the "Activity index" estimated from their muscles.

Evaluation of access to different legume pastures on performance and welfare of broiler chickens during dry season under tropical environment

There have been a plethora of studies on the effects of access to runs on chickens’ welfare and behavioural repertoire with a paucity of information on the comparative advantage of various legume pasture and deep litter system. A total of 200‐day‐old unsexed Marshall Broiler chicks were weighed and assigned randomly into five experimental groups, viz. deep litter without access to run (DL), deep litter with access to Stylosanthes hamata (SH), Stylosanthes guanensis (SG), Mucuna pruriens (MP) and free run (FR) during dry season. Each treatment had 4 replicates of 10 birds. Data were collected on growth performance, behaviour, tonic immobility (TI), gait score and blood parameters. The data obtained were subjected to One‐Way Analysis of Variance in a Completely Randomized Design. Results showed that the final body weight of birds in SH was significantly higher (p ˂ .05) than those of SH, MP, FR and DL which were comparable. The feed intake of the birds of DL, SH and FR was higher than those of the other treatment groups. The feed conversion ratio (FCR) of the birds on legume pastures was lower than those without access to pasture. The birds of SH, SG and MP spent higher (p ˂ .05) time drinking, preening, dust‐bathing, spot pecking and walking standing behaviours while those in DL and FR spent more (p ˂ .05) time feeding. Generally, the gait score of the birds on the different legume pastures was similar but better than those without access to pasture. Tonic immobility of the DL birds was longer than that of FR whose duration was longer than those of the birds on the pastures. The study concluded that access to different legume pastures, particularly Stylosanthes hamata, improved the welfare of broiler chickens without adverse effect on the performance of the birds.

There is a scarcity of information on the comparative advantage of various legume pasture. Stylosanthes hamata improved the welfare of broiler chickens without adverse effect on the performance of the birds.

Effects of season, genotype, and rearing system on broiler chickens raised in different semi-intensive systems: performance, mortality, and slaughter results

This study aimed to determine the effects of chicken genotype (fast-growing and slow-growing), various semi-intensive production systems (extensive indoor, free-range, and traditional free-range), and season (spring and summer) on animal performance, mortality, growth curve, and slaughter results under semi-environmentally controlled conditions in a subtropical region. Production systems were applied in conformity with the EU standards. While the summer experiment improved performance during brooding (1st-28th days), hot conditions led to a decline in performance during the growing period. In addition, negative effects were determined for all parameters of Gompertz growth curve in summer (P < 0.05, for all). In spring, fast-growing showed 36% higher final live weights than slow-growing, and this difference decreased in summer (16% for extensive indoor and 25% for free-range) (P < 0.05, for all). Fast-growing in extensive indoor and free-range displayed similar weight gains in the growing period, whereas grazing ones consumed less feed (P < 0.05) and thus showed better (P < 0.05) feed conversion. The same situation was true for slow-growing in spring. The mortality was approximately 1% in all groups in spring, while it was 17.36 and 18.06% for fast-growing in extensive indoor and free-range and 1.39, 2.78, and 4.29 for slow-growing in extensive indoor, free-range, and traditional free-range in summer. It is advantageous to choose fast-growing if short-term (56 days) fattening especially under optimum conditions is to be preferred. If the growing period coincides with summer, slow-growing should definitely be preferred and the fattening period should be extended to 82 days. Grazing improved feed conversion (P < 0.05) by reducing cereal-based diet consumption in both genotypes but did not affect carcass yield. However, grazing had a positive effect on fleshing.

Lipid Assessment, Cholesterol and Fatty Acid Profile of meat from broilers raised in four different rearing systems

Evaluated lipid and cholesterol concentration and fatty acid profile of raw breast, thigh and drumstick meat from broilers raised in different rearing systems. Were used 200 male broiler carcasses from four different rearing systems (n=50 from conventional intensive; n=50 from organic; n=50 from free-range; and n=50 from antibiotic-free) distributed in a completely randomized design with four rearing systems and 50 replications (carcasses). Breast meat from conventional broilers showed higher lipid (1.47) and cholesterol (34.13) concentration. Thigh and drumstick meat from free-range broilers had higher lipid (7.53/4.73) and cholesterol (45.55/53.65) concentration. Fat contained in breast, thigh and drumstick meat from free-range broilers showed higher levels of polyunsaturated fatty acids. Fat from breast and thigh meat from free-range broilers showed higher total concentration of ω3 and ω6 fatty acids. Fat from thigh meat from organic broilers showed higher levels of EPA (C20:5n3) and DHA (C22:6n3). Fat from drumstick meat from free-range broilers showed higher total concentration of ω3 and ω6 fatty acids. Meat from chickens raised in alternative rearing systems offers less risk to cardiovascular health because it presents lower concentrations of lipids and cholesterol, greater amounts of polyunsaturated fatty acids, which are beneficial for human health.

Effects of Supplementing Drinking Water with Mixed Herb Extract or Outdoor Access on Meat Quality Characteristics in Broiler Chickens

The aim of the present study was to determine the effects of supplementing drinking water with an extract of mixed herbs or housing with outdoor access on carcass traits, levels of antioxidant enzymes (SOD, CAT, GPx), reduced glutathione (GSH), malondialdehyde (MDA), and selected quality parameters of meat from broiler chickens. One-day-old Ross 308 broiler chickens were allocated to three groups: group I (control), in which birds were kept in compartments on litter and had no outdoor access; group II, in which birds were kept in compartments on litter without outdoor access and were supplemented with an extract of mixed herbs (50% Melissa officinalis L. and 50% Urtica dioica L.) at 2 ml/l of drinking water; and group III, in which birds were raised in compartments on litter and had outdoor access from day 1 of rearing. Throughout the rearing period, the broilers had free access to feed and water. On day 42, 20 birds were selected from each group, slaughtered and subjected to simplified slaughter analysis. Their breast and leg muscles were measured for pH, colour, water holding capacity (WHC) and drip loss, and analysed for the content of antioxidant enzymes (SOD, CAT, GPx), reduced glutathione (GSH), malondialdehyde (MDA) and fatty acids. The outdoor access reduced dressing percentage, both with (P≤0.01) and without giblets (P≤0.05). The supplementation of drinking water with the mixed herb extract (2 ml/l) improved the muscle antioxidant status (higher SOD, CAT and GSH content) and reduced lipid peroxidation in the leg muscles of the broilers (lower MDA level). In general, the supplementation of the diet with the mixture of herbs in the applied form and concentration, as well as the outdoor access had no effect on the other examined quality parameters of broiler meat.

Influence of free-range days on growth performance, carcass traits, meat quality, lymphoid organ indices, and blood biochemistry of Wannan Yellow chickens

This study investigated the effects of free-range days on growth performance, carcass traits, meat quality, lymphoid organ indices, and blood biochemical parameters of Wannan Yellow chickens. A total of 1,000 one-day-old male Wannan Yellow chickens were reared to 56 D. At 56 D of age, 960 birds with similar body weight (BW) were randomly allocated to free-range treatment at 56, 70, 84, and 98 D of age (assigned to free-range treatment for 42, 28, 14, and 0 D, respectively); 6 replicates with 40 chickens per treatment. In the free-range system, chickens were reared in indoor floor pens with an outdoor free-range paddock measuring 4 × 7 m (28 m2, 1.5 birds/m2). Results showed that BW of birds decreased significantly in the first 2 wk after birds were assigned to free-range treatment compared with those in the conventional treatment (P < 0.05). Average daily gain (ADG) and average daily feed intake (ADFI) decreased significantly (P < 0.05) for chickens assigned to free-range treatment from 56 to 70 D of age, while feed conversion ratio increased significantly (P < 0.05). Breast yield increased linearly with increasing free-range days (P < 0.05), whereas leg and foot yields decreased linearly (P < 0.05). Drip loss and L* value of thigh muscle decreased linearly with increasing free-range days (P < 0.05), while shear force improved linearly (P < 0.05). Additionally, the absolute thymus weight and thymus to BW ratio showed significant increasing and then decreasing quadratic responses to increasing free-range days (P < 0.05). Furthermore, serum glucose, total protein, cholesterol, and triglyceride content declined linearly, while high-density lipoprotein cholesterol (HDL-C) content increased linearly with increasing free-range days (P < 0.05). In conclusion, increasing free-range days had positive effects on breast yield, shear force, thymus weight, and HDL-C content, but negatively affected leg yield, foot yield, drip loss, L* value of thigh muscle, glucose, total protein, cholesterol, and triglyceride levels of Wannan Yellow chickens.

Visceral composition, carcass yield and meat quality parameters of free-range broilers with diets containing different levels of crushed sugarcane

ABSTRACT The aim of this study was to evaluate the visceral composition, cuts, and meat quality of two strains of free-range chickens fed diets containing crushed sugar cane. 448 chickens were distributed at 35 days of age, in two randomized blocks design, in 4x2 factorial, with four levels of replacement in the feed (0; 15; 30 and 45%) by sugarcane and two strains (Pesadão and Label Rouge), in two repetitions per block of fourteen birds per experimental unit. In 30 minutes after slaughter, the parameter a* was higher for animals of the Pesadão strain relation to the Label Rouge lineage. A quadratic effect was observed with increasing levels of sugarcane on the L* parameter of breast meat; and linear effect on parameter b* of the breast skin. Within 24 hours after slaughter, a quadratic effect of sugarcane levels was observed on the b* parameter of the breast meat. The increase in sugarcane levels linearly reduced the weight of heart, liver, chest, thigh plus drumstick, wing, carcass yield and relative heart weight of the animals. A quadratic effect was observed with increase in sugarcane levels over the relative weight of abdominal fat, the lowest fat content was observed in animals that consumed up to 30% of sugarcane in the feed. The use of sugarcane as an alternative feedstuff in up to 45% in the diet maintains the quality of meat and reduces the abdominal fat content, however, decreases the carcass yield.

Meat quality, fatty acid profile, and sensory attributes of spent laying hens fed expeller press canola meal or a conventional diet

This study evaluated the effects of feeding an expeller press canola meal (EPCM) supplement (20%) on the carcass, meat, and sensory quality characteristics of spent laying hens. Thirty EPCM-based and thirty conventionally (soybean based) fed Lohmann Brown-Elite spent laying hens were obtained from a commercial egg farm. Carcass, portions, physical quality, proximate composition, fatty acids, and sensory quality were determined. EPCM-fed hens had higher (P ≤ 0.05) drum yield, breast bone weights and percentages, but lower (P ≤ 0.05) thigh and breast meat yields. Conventionally fed hens had higher (P ≤ 0.05) thaw losses, skin yellowness (b*), Chroma values and breast fat content with lower (P ≤ 0.05) cooking losses, skin redness (a*) and hue angle values, as well as breast Warner-Bratzler shear force values (N) (15.43 ± 0.600 vs. 12.37 ± 0.411). Palmitic acid, stearic acid, heneicosanoic acid, palmitoleic acid, saturated fatty acids (SFA) (34.0 ± 0.56 vs. 38.7 ± 0.71), n-6:n-3 polyunsaturated fatty acids (PUFA) ratio (5.5 ± 0.13 vs. 7.2 ± 0.28), atherogenic index, thrombogenic index, delta-5 desaturase, elongase index, and thiosterase index were lower (P ≤ 0.05) for EPCM-fed hen breast meat. Myristic acid, lignoceric acid, nervonic acid, alpha-linolenic acid, docosahexaenoic acid (DHA), PUFA:SFA ratio (0.7 ± 0.05 vs. 0.9 ± 0.02), n-3 PUFA (3.4 ± 0.31 vs. 5.1 ± 0.17), hypocholesterolemic:Hypercholesterolaemic, stearoyl-CoA desaturase 16, and stearoyl-CoA desaturase 18 were higher (P ≤ 0.05) for EPCM-fed hen breast meat. Metallic flavor was decreased (P ≤ 0.05) for EPCM-fed hen breast meat. Generally, effects of EPCM supplementation were observed to have an effect on the carcass, physical quality, proximate composition, fatty acids, and health indices. The sensory profiles did not differ between EPCM and conventionally fed spent laying hen breast meat (except for metallic flavor). The EPCM improved the nutritional profile of spent laying hen meat with low intramuscular fat, low n-6:n-3 PUFA ratio, and favorable lipid health indices.

Effect of strain and sex of bird on carcass and fat yield of foraging slow-growing chickens

Meat and fat yield influence the profitability of modern commercial poultry production. This study sought to determine the effect of strain and sex on carcass and fat yield of three slow-growing chicken strains reared in open and closed pens. Two hundred and fifty-eight, 20-week old PK, OV and NN chickens, weighing 1710±308.8 g, were allocated to 4 paddocks of Chloris gayana and 4 pens in a poultry house. Final body weight (BW), carcass (CW), dressed (DW) weight, cut, abdominal fat pad (AFP) yield and giblet weights were determined. As a result of this study, strain did not affect BW but influenced back, pancreas, gizzard, neck, crop and AFP weight. Sex of bird influenced BW and males were significantly heavier, yielding heavier cuts and pancreases but lighter AFP than females. It was concluded that foraging males yield heavier cuts and females are fattier than foraging males of the same strain. Evaluating fatty acid composition of meat from foraging birds could help quantify risk associated with consumption of meat from foraging slow-growing chickens.

Comparison of Carcass Characteristics, Meat Quality, and Blood Parameters of Slow and Fast Grown Female Broiler Chickens Raised in Organic or Conventional Production System

The objective of the study was to compare the carcass characteristics, meat quality, and blood parameters of slow and fast grown female broiler chickens fed in organic or conventional production system. The two genotypes tested were medium slow-growing chickens (SG, Hubbard Red JA) and commercial fast-growing chickens (FG, Ross 308). Both genotypes (each represented by 400 chickens) were divided into two sub-groups fed either organic (O) or conventional (C) systems. Chickens of each genotype and system were raised in a semi environmentally controlled poultry house until 21 d of age and were assigned to 5 pens of 40 chickens each. Then, O system chickens were transferred into an open-side poultry house with an outdoor run. At 81 d of age, 10 female chickens from each genotype and from each production system (n = 40) were randomly chosen to provide material for analysis, and were weighed and brought to the slaughterhouse to assess carcass characteristics and meat quality. The blood parameters were determined by using 5 female chickens from each genotype and from each production system (n = 20). FG had the higher live weight, along with carcass, breast, and thigh-drumstick weights compared to SG (p<0.05). FG had the higher breast yield, whereas SG had the higher thigh-drumstick yield (p<0.05). The O system resulted in a higher amount of abdominal fat (p<0.05). In addition, the O system values were higher for dry matter, crude ash, crude protein, and pH¹⁵ values in breast meat, and for crude ash, crude protein, and pH¹⁵ values in drumstick meat (p<0.05). In addition, total saturated fatty acids, total mono-unsaturated fatty acids, and total omega 3 were significantly higher in the O system than in the C system. Thus, the O system showed a positive advantage compared to the C system regarding female chicken meat quality, primarily within the ash, protein, and total omega 3 fatty acid profiles. In conclusion, the present study indicated that the main factor affecting the carcass characteristics of female chickens was genotype, whereas the organic system contributed to enhanced meat quality. These findings provide a better understanding of the relative roles of genotype and production systems in female broiler characteristics, and might aid producers in designing their facilities to optimize yield and quality while maintaining acceptable animal welfare standards.

Feeding conditions and breed affect the level of DNA methylation of the mitochondrial uncoupling protein 3 gene in chicken breast muscle

To investigate the effects of feed condition and breed on the level of DNA methylation for the uncoupling protein 3 (UCP3) gene, which is an important candidate gene for regulating intramuscular fat (IMF) content in chicken breast muscle, breast muscle of Daninghe (DNH) and Qingjiaoma (QJM) chickens under scatter-feed and captivity-feed conditions was analyzed. Using RNA sequencing, 47 and 113 candidate genes were determined to be related to feed conditions and breed, respectively, and 7 differentially expressed genes were confirmed by real-time quantitative PCR, including UCP3. The mRNA levels of UCP3 were significantly different between the 2 feed conditions. The DNA region from bp +1700 to +2459 of the UCP3 gene was studied using the bisulfite sequencing method and contained 46 methylation sites and 3 CpG islands. The results showed that the methylation level of this UCP3 region was lower in DNH chickens (0.77% to 0.88%, P = 0.012) and QJM chickens (0.88% to 0.91%, P = 0.20) under scatter-feed conditions than under captivity-feed conditions. The mean methylation level of UCP3 in DNH chickens was lower than that in QJM chickens under scatter-feed conditions (DNH to QJM, 0.77% to 0.88%, P = 0.007), which suggests that breed affects the mean methylation level of UCP3 under scatter-feed conditions. In summary, our findings suggest that feed condition and breed affect the methylation of UCP3 in chicken breast muscle.

Quantification of the effects of castration on carcass and meat quality of sheep by meta-analysis

After an extensive literature search, meta-analytic techniques (fixed effect, random effects and hierarchical Bayesian models) were applied to numerically describe sizes and precision of effects caused by castration of intact rams on several performance, carcass and meat quality response variables. According to random effects models, rams presented greater (P<0.05) average daily gain, loin muscle area (leaner carcasses) and instrumental meat tenderness (more tough), with lower feed conversion ratios, dressing percentages and backfat thickness (less carcass fat) compared to castrates. These results could be applied in further strategies on the use of castration in male sheep.