1. Provision of light and dark periods can influence broiler behaviour and impact bird welfare. Determining how offering light in different patterns, such as intermittent (INT) lighting, impacts birds is necessary to determine ideal management practices. The objective of this research was to establish the impact of 9 h of darkness (D) provided in one (1 × 9D), two (2 × 4.5D) and three (3 × 3D) periods on Ross 308 male broiler behaviour.2. Each treatment was replicated three times and behaviour was recorded over 24 h at 32-34 d in one pen per room using infrared cameras. Behaviour was assessed via instantaneous scan sampling at 10 min intervals.3. Birds in the INT treatments spent a lower percentage of time preening. Broilers spent most of their time resting during scotoperiods. The INT lighting schedule birds spent a higher percentage of time feeding and drinking and less time in comfort and exploratory behaviours. Broilers appeared to anticipate all scotoperiods and increased their feeding activity at the beginning of each photoperiod, regardless of period duration.4. Providing 9 h of darkness over 24 h in one, two or three scotoperiods had minor impacts on behaviour. Birds prioritised resting during scotoperiods, while during the shorter photoperiods between scotoperiods birds on INT lighting schedules prioritised nutritive behaviours. Broilers appeared to anticipate the beginning of each scotoperiod and adjusted their feeding behaviour to compensate for time off feed during scotoperiods.
1. This study evaluated whether lunar periodicity was associated with variation in productive traits and mortality in commercial broiler breeder hens. Production records from Cobb 500 heavy breeder hens (n = 17,548), collected between 2016 and 2021 on a commercial farm, were analysed.2. The synodic lunar cycle was divided into eight consecutive phases of approximately 3.7 days each. Two production seasons were defined according to rainfall patterns: December-April (wet season) and May-November (dry season). In addition, three laying periods were considered: early production (weeks 26-28), peak production (weeks 29-34) and late production (weeks 35-56).3. The lunar cycle significantly influenced the number of eggs laid, laying rate, percentage of hatching eggs and the number of cracked eggs (p < 0.01). The number of double-yolk eggs was not affected. Egg production decreased towards the middle of the lunar cycle and increased towards the final phases, with higher production around the new moon compared to the full moon.4. Significant interactions were observed between lunar phase and both production season and laying period. Mortality showed variation across the lunar cycle, with the highest values occurring around phase 6.5. These findings suggested that lunar periodicity may be associated with short-term variation in productive traits and mortality in commercial broiler breeder flocks, highlighting the potential relevance of lunar-associated environmental rhythms in avian biology.
1. In this study, genome-wide population structure, genetic differentiation and homozygosity patterns were investigated between Silkie (SLK) and White Leghorn (WLH) chickens, using high-density autosomal SNP genotypes. These breeds were selected as they have markedly different breed histories and productive performances.2. Principal component analysis revealed complete genetic separation between the two breeds, explaining 75.82% of total genomic variance and indicating strong divergence. Genome-wide differentiation showed heterogeneous patterns across autosomes. The top 1% of windows (FST ≥ 0.7467) were used as an empirical threshold for prioritising regions showing elevated differentiation.3. The study identified 20 protein-coding positional candidate genes, including TRHDE, GABBR2, SEMA3A, SEMA5A, IGF1, SOCS2, AR and NLGN4, which have roles in neuroendocrine, behavioural, growth and reproduction.4. Breed-specific runs of homozygosity (ROH) revealed marked differences in autozygosity, with Silkie chickens showing substantially higher genomic inbreeding coefficients (F) of ROH (mean FROH = 0.396) than White Leghorns (mean FROH = 0.175). Island analysis identified 30 islands in Silkie and 19 in White Leghorn chickens, predominantly located on macrochromosomes. There were breed-specific and partially overlapping differentiated genomic intervals, highlighting concurrent differentiation and homozygosity in the two breeds.5. The results showed substantial genome-wide differentiation between Silkie and White Leghorn chickens. This provided a population-genomic framework for prioritising candidate regions for maternal behaviour, reproductive physiology and egg production.
1. The aim of this study was a detailed evaluation of the influence of genotype and sex on carcass traits and meat quality (chemical composition, physicochemical properties, texture and structure) of spent hens (parent stock of laying hens after the reproductive period).2. After slaughter (83 weeks of age), the eviscerated carcass weight and the proportion of carcass components were determined. Analyses were performed for 24 h post-mortem pH (pH24), electrical conductivity (EC24), cooking loss, colour parameters (L*, a* and b*) and composition of breast and leg muscles. Texture and microstructure analysis of the pectoralis major muscle was conducted.3. Genotype significantly influenced carcass weight (Hy-Line Brown 1.775 kg vs. Isa Brown 1.564 kg), breast muscle, abdominal fat, skin with subcutaneous fat, wings and carcass remainders. Genotype affected the water and fat content in both breast and leg muscles and protein in breast muscles. Differences between the genotypes were seen for pH and cooking loss in leg muscles and in the electrical conductivity in breast muscles (Hy-Line Brown 9.68 mS/cm vs. Isa Brown 7.12 mS/cm) and leg muscles. Breed influenced lightness (L*) of both muscles and redness (a*) in breast muscles. Shear force of pectoralis major was significantly different as was the thickness of the perimysium and endomysium, depending on genotype.4. Sex influenced carcass weight, the proportion of breast muscles and leg muscles, abdominal fat, skin with subcutaneous fat and neck weight. It affected water, protein, fat and collagen content in both breast and leg muscles, as well as the pH of breast muscles and EC of both breast and leg muscles. Sex also affected the redness (a*) of the breast and leg muscles. Analysis of the pectoralis major muscle texture and structure revealed sex-related differences in most evaluated traits, except for vertical fibre diameter (V).5. Meat from spent breeder hens can be successfully used in meat processing, especially where mechanical or thermal treatment helps minimise quality differences due to age. Higher protein and relatively low fat content in the muscles of older hens may even be technologically advantageous. For consumers, this offers a cheaper alternative to more expensive broiler meat, provided it is properly prepared.
1. The present study investigated the extent and impact of a Z-linked genetic effect on sexual size dimorphism. It estimated genetic parameters for the body weights of layer chickens during the period of 7 to 84 d, using random regression model.2. Body weights of 5,296 birds were measured at four different ages. Two random regression models that described the weight of individual birds, with and without a Z-chromosome relationship matrix, were compared. The fixed effects covariate included the coefficients of genetic group and inbreeding (both quadratic effects). Heterogeneous residual variances were modelled by grouping the test period into seven subgroups. A sixth-order polynomial was used to model the mean weight of the population.3. Covariance components were estimated using the AIREML method. Models were compared using Akaike information criterion, Bayesian information criterion and residual values. The models including quadratic and cubic polynomials for additive direct and permanent environmental effects, respectively, and linear polynomials for Z-linked genetic effects were the best.4. According to the best model, autosome heritability was estimated in the range of 0.19-0.38 with a decrease from 7 to 20 d of age and a subsequent fluctuation around 0.22 to the end of the trajectory. The Z-linked heritability increased from 0.14 at 7 d to 0.50 at 56 d and then declined moderately to 0.40 at 84 d.5. Permanent environmental variance increased with age. However, the maximum proportion emerged at 16 d of age. The estimate of Z-linked genetic correlations between weeks was high at over 0.82.6. The results illustrated the potential of a Z-linked relationship matrix for genetic evaluations of body weight in poultry, using random regression models.
1. Despite the pivotal role of the hypothalamic-pituitary-gonadal (HPG) axis in avian reproduction, the underlying molecular mechanisms that govern sexual maturity and spermatogenesis in roosters are not well elucidated. This study aimed to explore gene expression changes in the HPG axis using Wenchang cockerels.2. Phenotypic results showed significant testicular growth from 18 to 20 weeks of age. Transcriptome analyses identified 2,154 differentially expressed genes (DEG) in testes, which was markedly higher than those identified in hypothalamus (52 DEG) and pituitary (27 DEG).3. Functional enrichment analysis showed neuroactive ligand-receptor interactions and hormone transport pathways in the hypothalamus and pituitary and ciliary motility and spermatogenesis pathways in the testes.4. Protein-protein interaction (PPI) networks analysis pinpointed key hub genes, such as BDNF, NPTX2, TEKT2, TEKT3, CFAP52, and MNS1, associated with spermatogenesis and sperm motility.5. This research gave insights into the genetic regulatory networks within the HPG axis that orchestrate testicular development and maturation in roosters, paving the way for potential applications in the molecular breeding of breeding roosters for reproductive optimisation.
1. This study evaluated the effects of exogenous enzyme supplementation on bone quality, locomotor ability and pectoral myopathy severity in broilers given nutrient-restricted diets.2. A total of 1,400 one-day-old male Cobb 500 broilers were distributed among seven treatments. These included a positive control (PC); NC1 (reductions of 100 kcal ME/kg, 0.18% available phosphorus and 0.20% calcium); NC2 (reductions of 1.5% crude protein, 0.18% available phosphorus and 0.20% calcium); NC3 (combined reductions of 100 kcal ME/kg, 1.5% crude protein, 0.18% available phosphorus and 0.20% calcium); and their respective enzyme-supplemented diets: NC1 + phytase + carbohydrases (CPNC1), NC2 + phytase + protease (PPNC2) and NC3 + phytase + carbohydrases + protease (CPPNC3).3. Locomotor ability was assessed using gait score, pododermatitis, angular deformities and tibial dyschondroplasia. Bone quality was evaluated using tibial morphometry, Seedor index, ash content and mechanical resistance. Pectoral myopathies (wooden breast and white striping) were assessed.4. Nutrient restriction without enzyme supplementation reduced tibial weight, length, Seedor index and bone strength (p < 0.05). Compared with nutrient-restricted diets, enzyme supplementation increased bone strength, with PPNC2 restoring mechanical resistance to values comparable to those of the PC (p < 0.001). No significant differences were observed in gait score, tibial dyschondroplasia, angular deformities, or wooden breast severity (p > 0.05). Femoral degeneration scores were lower in birds fed nutrient-restricted diets, regardless of enzyme supplementation (p = 0.037). Pododermatitis scores were lower in NC2 and CPPNC3 than in the PC (p < 0.01). White striping severity differed among treatments (p = 0.038), with lower scores in birds fed nutrient-restricted diets without enzyme supplementation, although the magnitude of these differences was small.5. Exogenous multienzyme supplementation improved bone strength in broilers fed nutrient-restricted diets without adversely affecting locomotor ability. However, it did not consistently reduce pectoral myopathy severity, reinforcing the multifactorial nature of these conditions.
1. Keel bone damage is a major welfare issue in laying hens. In this study, brown layers kept in commercial multi-tier systems were examined individually to gain information on individual health traits associated with keel bone deformations (KBD) and keel bone fractures (KBF).2. Ten laying hen flocks were assessed at six timepoints during the laying period for KBD, KBF and various health traits (n = 2900). On each visit, five hens with and three hens without keel bone damage were selected for further diagnostics (n = 462). This included X‑rays of the keel bone, post-mortem examination with histopathology (liver and intestines) and analysis of the keel bones (incineration) and tubular bones (breaking strength tests).3. Prevalence for KBD and KBF increased continuously with age (p < 0.0001) with highest mean prevalence at 65 weeks of age (KBD 47%, KBF 52%). Factors associated with KBD were presence of foot pad lesions (p = 0.0124) and lower dry matter (p = 0.0201) in dissected hens. Factors associated with KBF on-farm were higher body mass (p = 0.0239).4. After further diagnostics, KBF was associated with lower dry matter of the keel bone (p = 0.0049), lower relative calcium content of the keel bone (p = 0.0296), wing feather damage (p < 0.05) and enteritis (p = 0.0231). Overall, the occurrence of KBF was associated with KBD and vice versa (p < 0.0001). Palpated sharp bends in the keel on-farm were highly indicative for KBF (p < 0.0001).5. There might be a potential of reducing prevalence of KBF by stabilising gut health of laying hens and preventing foot and feather damage.
1. The following study investigated the regulation of Intramuscular fat (IMF) deposition at different developmental stages in Jingyuan chickens. Pectoral muscles from hens at 42, 126 and 180 days of age were analysed using transcriptome sequencing and weighted gene co‑expression network analysis (WGCNA).2. A total of 1187, 1377 and 617 differentially expressed genes (DEGs) were identified in the three pairwise comparisons, respectively. Among these, MAPK8, ACSL4 and ACACB are known to be involved in IMF synthesis and metabolism through energy and amino acid metabolic pathways.3. The WGCNA data identified three modules (MEyellow, MEbrown, MEdarkred) that were significantly correlated with IMF content and age (p < 0.05). Functional analysis indicated that FOXO6, PTEN and EGFR were enriched in both FoxO and GnRH signalling pathways. This suggested potential roles in IMF deposition. Further investigation of DEG and the three modules revealed AGXT2 and LAMB1 as candidate genes that could influence IMF deposition in muscle.4. The data represents a transcriptomic resource for IMF deposition in Jingyuan chicken breast muscle. The results identified candidate genes for future molecular breeding aimed at improving meat quality.
1. This study evaluated the genetic variation of growth curve parameters in Japanese quail using nonlinear mixed-effects models based on the Gompertz model.2. Two three-parameter mixed-effects models were fitted to longitudinal body weight data to estimate biologically meaningful parameters: initial weight (W0), growth rate (k), upper asymptotic weight (A) and inflection point age (Ti). These individual-specific parameter estimates were subjected to genetic analysis using a quadrivariate animal model with appropriate fixed and random effects.3. Results showed a satisfactory model fit (CV(RMSE) ≈6%). Females had greater mature size and later maturation, whereas males showed faster early growth. Heritability estimates were moderate, with the highest value observed for asymptotic weight (h2 = 0.35). Genetic correlations indicated important trade-offs between growth rate and final size (rG(k,A) = -0.46) and a near-complete negative association between k and Ti (rG = -0.98).4. The k-means clustering analysis distinguished three growth profiles, corresponding to fast-maturing light quails, intermediate birds and slow-growing heavy individuals. These findings demonstrated the utility of growth curve modelling in genetic evaluations and offer pathways for targeted selection strategies in quail breeding programmes.
1. This study examined the dynamics of the 2019-2023 avian influenza (AI) outbreak on large-scale poultry farms in Russia and explored the management factors associated with morbidity levels.2. Six industrial poultry farms were included in the study, with repeated observations taken annually. Data on AI morbidity and mortality, biosecurity practices, vaccination coverage and virus sub-type distribution were collected from veterinary surveillance reports and farm health records. Descriptive statistics were used to summarise morbidity and mortality levels across intervention periods. Welch's t-tests and non-parametric tests were used to compare morbidity and mortality rates before and after the introduction of enhanced control measures in 2021.3. Correlation analysis evaluated the relationship between morbidity and mortality. Linear regression models examined the associations between management factors and morbidity levels. Temporal changes in virus sub-type distribution were analysed using chi-squared tests.4. Morbidity rate fell from 11.6% prior to the intervention period (2019-2020) to 8.9% following the implementation of enhanced control measures (2022-2023), while the mean mortality rate decreased from 5.8% to 4.2%. Regression analysis revealed a significant association between higher vaccination coverage and lower morbidity levels.5. Biosecurity indicators were significantly related to morbidity variation across farms. Temporal analysis revealed significant changes in the distribution of sub-types, with H5N1, H5N8 and H9N2 detected throughout the observation period.6. These results suggested that integrated disease control strategies are associated with improved management of AI in large-scale poultry production systems. The observed reductions likely reflected a combination of farm-level interventions and broader national and ecological trends.
1. The primary aim of this study was to conduct a cost-benefit analysis of Ethiopian indigenous chickens and to estimate the economic weights of key performance traits. Data were collected through structured questionnaires administered to smallholder poultry farmers and subsequently analysed using R statistical software.2. Data were analysed using a bio-economic model integrating biological performance parameters with economic parameters to assess the profitability and efficiency of production systems. It was applied to a standardised flock of 100 indigenous chickens (IC) to evaluate economic performance across systems for egg number (EN), body weight (BW), age at first egg (AFE) and survival rate (SV).3. The study revealed that production in Shambu and Fincha districts was predominantly based on a free-range production system (FRS), whereas production in Shagar City was mainly a semi-intensive system (SIS). The FRS generated a total income of US$1,687.28, while the SIS produced a significantly higher return of US$9,082.85. In both production systems, feed costs accounted for the largest share of production expenses, 61.21% (US$2,709.41) in FRS and 62.94% (US$18,346.63) in SIS followed by fixed costs, which represented 24.04% (US$1,064.28) and 24.27% (US$1,632.88), respectively.4. The major sources of income in both systems were the sale of surplus grower females and cockerels. Specifically, revenues for FRS and SIS were US$46.15 and US$162.80 from eggs; US$2,254.63 and US$3,044.84 from surplus females; US$3,529.42 and US$5,348.27 from surplus cockerels; and US$226.54 and US$236.04 from culled breeding stock, respectively. Under SIS, a 1% improvement in performance through selection and management would increase profits by 6.35 from EN, 54.75 from BW, 20.67 from AFE and 145.42 US$.5. The results suggested that meat-oriented production from indigenous chickens generates higher economic returns than egg production under the two systems. However, economic weights derived from marginal profit and genetic variance, integrating both market values and biological performance indicators, assigned the highest priority to EN (36.46), followed by BW (34.37), AFE (23.91) and SV (5.26).
1. Using phenotypic and pedigree data, genetic parameters were estimated for 12 357 Rhode Island Red-I (RIRI), 13 674 Barred Rock-I (BARI) and 8 481 Colombian Rock (COL) pure line hens. The study focused on age at first egg (AFE), body weight at first egg (BWFE), total egg number by 36 weeks (EN) and average egg weight at 36 weeks (EW).2. The heritability estimates for RIRI, BARI and COL lines were 0.41 ± 0.030, 0.47 ± 0.025 and 0.40 ± 0.025 for AFE, 0.33 ± 0.025, 0.49 ± 0.025 and 0.58 ± 0.030 for BWFE, 0.44 ± 0.025, 0.33 ± 0.025 and 0.44 ± 0.025 for EN and 0.41 ± 0.021, 0.40 ± 0.025 and 0.32 ± 0.025 for EW, respectively.3. The genetic correlations ranged from -0.81 ± 0.013 to 0.86 ± 0.034, while phenotypic correlations ranged from -0.64 ± 0.025 to 0.80 ± 0.013 for the emphasised traits. The strongest genetic and phenotypic correlations were observed between AFE and BWFE in the COL line.4. The selection programme aimed to reduce AFE, optimise BWFE and improve EN and EW, with varying degrees of response observed across breeds. Genetic trends showed significant decreases in AFE and BWFE and positive gains in EN and EW across all breeds. Phenotypic trends were generally consistent with genetic trends for AFE and BWFE, while greater divergence was observed for EN and EW, especially in the COL breed.5. The results suggested that successful layer breeding requires balancing genetic selection with environmental management and implementing breed-specific strategies.
1. The following research evaluated and compared estimates of genetic parameters of productive and welfare traits of quail in collective cages, testing for inclusion of indirect genetic effects (IGE).2. Data came from two trials, along two generations of pedigreed quail, housed in collective cages, with one male and three females in each cage. Each bird's body weight variation, survival time, aggressiveness, pecking wounds and any feather damage was recorded.3. Three mixed models were tested to obtain genetic parameters. The first was a classical model with no IGE, the second included IGE and the last modelling cage effect was random.4. Heritability estimates were of low magnitude ranging from 0.03 to 0.15, except for survival time, which reached 0.34. Including IGE results in variance redistribution for all traits and heritable variance increases exceeding the value of unity and IGE accounted for most of the heritable variance. Therefore, including these effects is recommended in genetic analysis under collective housing.
1. Following the ban on prophylactic antibiotic use in feed for poultry, interest in natural alternatives has increased, particularly plant-derived extracts. In this study, the effects of Aronia melanocarpa fruit extract (AMF) on growth performance, serum biochemistry and caecal microbiota in broilers were evaluated.2. A total of 360 male Ross-308 broiler chicks were randomly allocated to one of the four treatment groups for 35 days. These included a control group (CON) receiving the basal diet and three treatment groups supplemented with 50 mg/kg (AMF1), 100 mg/kg (AMF2) or 200 mg/kg (AMF3) of AMF extract.3. Antioxidant capacity and phenolic profile were determined by DPPH and UHPLC-ESI-MS/MS analyses. Because the ethanol extract had the highest antioxidant activity (94.5%), it was used in the experiment. Chlorogenic acid, quercetin, hesperidin and cyanidin-3-O-glucoside were the major phenolic compounds identified.4. The AMF supplementation had no significant effect on growth performance (p > 0.05). In contrast, serum triglyceride (TG), phosphorus, sodium and iron concentrations exhibited statistically significant quadratic dose - response relationships (p < 0.05). Serum TG levels were significantly reduced in the AMF3 group, whereas serum iron levels were significantly increased in the AMF1 and AMF2 groups (p < 0.05). Phosphorus and sodium levels were found to be lower in the control group compared to the other groups (p < 0.091 and p < 0.063, respectively).5. The 16S rRNA sequencing showed that low and medium dose AMF applications supported caecal microbial diversity by increasing the relative abundance of beneficial bacteria such as Bacillus spp. and Lactobacillus jensenii. The high supplementation dose led to the dominance of the Morganella morganii population.6. In conclusion, AMF can modulate the gut microbiota in broiler chickens in a dose-dependent manner without negatively affecting growth performance. Moderate inclusion rates have the potential to positively impact gut health and metabolic balance by increasing beneficial bacteria populations.
1. Calcium (Ca) is essential for avian embryonic bone mineralisation, yet its metabolic dynamics during duck embryogenesis remain unclear. This study investigated Ca mobilisation in Muscovy duck embryos.2. Eggshell (ES) and yolk samples were collected from embryonic day (ED) 16 to ED31 for analysis of ES physical properties (thickness, strength, mass ratio) and Ca levels. Serum, yolk sac membrane (YSM) and liver tissues were collected from ED16 to the day of hatch (DOH) to assess serum biochemical parameters and relative mRNA expression of genes associated with Ca transport (PLCG1, PRKCA, CALM1) and absorption (CALB1, ARNT, EP300).3. Results showed ES quality and Ca levels decreased (p < 0.01) linearly with increasing incubation days. Yolk Ca levels decreased (p < 0.01) linearly and quadratically, reaching a minimum on ED25. Serum Ca levels and alkaline phosphatase (ALP) activity increased (p < 0.01) linearly and quadratically during ED16-DOH and achieved a plateau during ED28-DOH. Expression of Ca-related genes in YSM and liver increased quadratically (p < 0.01), peaking during ED25-28.4. In conclusion, ES quality declined with reduced Ca levels during embryogenesis. Concurrently, yolk Ca levels, along with serum Ca and ALP levels, increased significantly during ED25-28, indicating peak embryonic Ca mobilisation during this period. Additionally, relative mRNA expression of Ca mobilisation-related genes in the YSM and liver exhibited a similar increasing trend. This suggested enhanced Ca mobilisation during this phase to support bone mineralisation and growth in duck embryos.
1. An experiment was conducted to evaluate the effects of different levels of dried Spirulina platensis (SP) on growth performance, caecal microflora, intestinal morphology, antioxidant status and particularly the expression of major lipogenic genes in the liver of broiler chickens.2. Three hundred Ross 308 male broiler chicks were assigned to one of five treatments with six replications and 10 birds each based on a completely randomised design. Experimental diets were maize-soy based and included 0, 0.25, 0.5, 0.75 or 1% SP and fed to birds for 42 d. Two birds per replicate were selected for the evaluation of carcass characteristics, caecal microflora, intestinal morphology, serum and liver antioxidant status and lipogenic gene expression.3. Body weight gain and feed conversion ratio were significantly improved in chickens fed a diet containing 1% SP compared to the control group (p < 0.05). Significant improvements in carcass (p < 0.05) and breast (p < 0.01) yield in the chickens fed diets containing 0.75 and 1% SP were observed compared to the control group, and, with increasing SP, abdominal fat decreased linearly (p < 0.05).4. Escherichia coli counts in the caecum of birds fed 0.75 and 1% SP decreased significantly compared to the control group (p < 0.05). Inclusion of 0.5, 0.75 and 1% SP decreased malondialdehyde level in liver (p < 0.05). Gene expression of ∆-6-desaturase and ∆-9-desaturase was higher in the birds fed 0.5% or higher SP levels compared to control group.5. This study showed that adding 1% SP to the diet of broiler chickens improved production efficiency by improving growth performance, antioxidant status and intestinal health. This level of supplementation showed significant potential in improving carcass quality and reducing abdominal fat by regulating the expression of key genes in the fatty acid metabolism pathway.
1. This study evaluated the effects of digestible sulphur amino acids to digestible lysine ratios (dSAA:dLys), applied in increasing and decreasing series, on growth performance, gene expression, plasma homocysteine and taurine and feather quality in broiler chicken.2. Two trials were conducted using 720 one-day-old broiler chicks (Ross 308) from 1 to 24 d of age in a completely randomised experiment using four treatments with nine replicates of 20 birds. Treatments consisted of dSAA:dLys ratios applied across the pre-starter (1-10 d) and starter (11-24 d) phases in a decreasing (Trial 1) or an increasing manner (Trial 2).3. In Trial 1, dSAA:dLys ratios (pre-starter/starter) were: TRT1 (84/82%), TRT2 (82/80%), TRT3 (80/78%) and TRT4 (78/76%). In Trial 2, dSAA:dLys ratios (pre-starter/starter) were: TRT1 (78/80%), TRT2 (76/78%), TRT3 (74/76%) and TRT4 (72/74%).4. In the decreasing series of the dSAA:dLys ratio, higher levels improved feed conversion ratio (FCR) at 24 d of age. The increase favoured feather structural development, providing a linear increase in primary follicle diameter, while feather weight and calamus thickness showed quadratic responses. The maxima was estimated at approximately 78% of the dSAA:dLys ratio, which indicated greater structural development in feathers near this level.5. For the increasing treatments, a linear response was observed in the length of vane 1 of the eighth primary feather and greater skin hardness was estimated at approximately 78% of the dSAA:dLys ratio. This suggested enhanced feather development and greater mechanical resistance of the skin.6. In conclusion, dSAA:dLys ratios at 78% improved feather structure and FCR in the decreasing series and maximised skin hardness in broiler chickens in the increasing series.
1. In many poultry species, the absence of pronounced sexual dimorphism or its delayed onset until adulthood complicates visual sex identification. This directly hinders effective breeding and conservation management protocols.2. Sex identification analysis of 11 poultry species was performed, based on the gene ubiquitin-associated protein 2 (UBAP2). Blood and feather samples obtained from both males and females were used for genomic DNA extraction. Subsequent PCR amplification was conducted with UBAP2 primers. The amplification outcomes were characterised using both agarose gel electrophoresis and capillary electrophoresis plots. The obtained gene fragments were sequenced to perform a phylogenetic analysis of the UBAP2 sequences across the species under study.3. The length polymorphism between UBAP2-W and UBAP2-Z homologous genes allowed clear sex discrimination by agarose gel electrophoresis in chicken, turkey, quail, chukar partridge and pheasant. However, in Muscovy duck, mule duck, goose, guinea fowl sexing was achieved using capillary electrophoresis. Duck and pigeon exhibited a single band or peak, regardless of sex.4. As sequences of species within a family were clustered together, it was predicted that those closely related to each other shared similar UBAP2 sequences. The results demonstrated that UBAP2 is an effective marker for genetic sex identification in nine poultry species.
1. This study evaluated metabolisable energy (ME) and amino acid (AA) ileal digestibility in different cereals and processing for 9 d old broilers. It compared energy estimates derived using the total collection versus the indigestible marker methods and investigated growth period-related differences in energy release and ileal AA digestibility.2. Six experimental diets were formulated as mashed diets, including a nitrogen-free control and five semi-purified diets each using maize, extruded maize, wheat, fine wheat flour, or barley as the sole source of energy and AA. A total of 480 male Ross 308 broilers, aged 5 d old, were allocated to one of the six treatments each with eight pen replicates as a randomised complete block design.3. Interactions existed (p < 0.001) between collection method and cereal ingredient on ME. The total collection method gave higher results (p < 0.05) than the indigestible marker method, particularly for barley and wheat.4. Fine wheat flour had the greatest (p < 0.05) apparent and standardised AA ileal digestibility, followed by maize, extruded maize, wheat and barley. In the grower period, ME and ileal AA digestibility improved, and these responses were dependent on cereal and processing method.
