British Poultry Science最新文献

1. Genetic improvement and widespread use of artificial selection may have impacted the genetic make-up of Indian chicken breeds. The genetic architecture of contemporary chicken population of India needs to be assessed for future improvement and conservation programmes. This study utilised whole-genome sequences in 180 chicken samples from 16 indigenous breeds, along with the Red Jungle Fowl and the commercial White Leghorn.2. A panel of 76 978 genome-wide single-nucleotide polymorphisms (SNP) was selected for comparative genome analysis after stringent screening. Breeds originating from the eastern regions of India exhibited higher genomic diversity, indicative of a rich repository of distinct germplasm. Conversely, the Uttara breed, from the northern hilly areas, display considerable genetic differentiation with diminished diversity compared to others, underscoring conservation concerns. The average coefficient (F_IS) of 0.084 caution the need to mitigate risks associated with inbreeding.3. The study revealed that the analysis of 76 978 genome-wide SNP will serve as a cornerstone in refining conservation strategies, to design interventions with greater precision.4. The contribution of Red Jungle Fowl to the gene pool of all native breeds was supported by this study. Genetic structuring indicated a relationship among breeds based on geographical proximity, underscored by varying levels of admixture.

1. The proliferation of granulosa cells is vital for the development and recruitment of hen ovarian prehierarchical follicles (PF). The RAB23 protein is a member of the Rab family, belonging to the GTPase family. This study studied the regulatory roles of the RAB23 gene in PF.2. The expression of RAB23 was significantly increased in granulosa cells (GC) during PF growth and was highest in GC at 6-8 mm diameter (p < 0.05). The RAB23 protein was mainly expressed in the GC, oocytes (OC) as well as somatic cells (SC) of the PF.3. The mRNA expression of FSHR, CCND1,CYP11A1, StAR and HSD3B1 was significantly increased in the siRNA RAB23 group (p < 0.05). Additionally, protein expression of FSHR, CCND1, CYP11A1, HSD3B1 was significantly increased (p < 0.05) after GC were transfected with RAB23-specific siRNA. Protein expression of StAR in the siRNA RAB23 group was numerically higher than that in the positive control (PC) and negative control (NC) groups. The GC proliferation rate and progesterone synthesis of the prehierarchical follicles in hen ovaries were markedly increased in vitro (p < 0.05).4.This study revealed that RAB23 might play an inhibitory role in GC proliferation and progesterone synthesis during the prehierarchical follicles development in vitro.

1. The production of chicken meat has resulted in high volumes of byproducts, such as feathers, bones, skin, viscera, and feet. The structure of feathers is one of the most complex among vertebrates, with a central axis and lateral filamentary structures, providing rigidity, lightness, and flexibility. Chicken feathers are composed of proteins, lipids, and water, with the highest protein content, especially keratin, which is responsible for the material's rigidity.2. Industries still make little use of feathers, which are generally intended for the production of flour or organic fertilisers. These are low added value products, and discarded feathers can harm the environment.3. Keratin extraction techniques and resulting protein hydrolysates have been studied in chicken feathers. Acid, alkaline or enzymatic hydrolysis is the most commonly used method for obtaining molecules with functional properties such as antioxidant, antimicrobial, antihypertensive and antidiabetic activity.4. The development of keratin-based biodegradable films represents an area of interest for reducing the economic and environmental impacts caused by inappropriate disposal of feathers.

1. Two experiments were conducted, the first was to investigate the effect of increasing digesta viscosity by dietary carboxymethyl cellulose (CMC) on the growth performance and intestinal morphology and characteristics of healthy birds. The second experiment evaluated the impact of increased digesta viscosity in birds during an Eimeria spp. challenge.2. In experiment 1, a corn-soybean meal-based basal diet was supplemented with 0, 10 or 20 g/kg CMC at the expense of cornstarch and offered to seven birds in each of eight replicate cages per diet from d 8 to 22 post hatching.3. Increasing digesta viscosity due to dietary CMC linearly reduced (p < 0.05) body weight (BW) gain and the apparent ileal digestibility of nutrients. The relative lengths of the duodenum, jejunum and ileum linearly increased (p < 0.01) with dietary CMC inclusion.4. In experiment 2, on d 14, 256 broiler chickens were randomly assigned to eight replicate cages in a 2 × 2 factorial arrangement of treatments with two CMC concentrations (0 or 10 g CMC/kg of diet), with or without an Eimeria challenge. On d 15, birds in the challenge groups were orally gavaged with a 1 ml solution containing 25,000, 25,000 or 125,000 oocysts of E. maxima, E. tenella and E. acervulina; or 1% PBS, respectively.5. Increasing digesta viscosity in Eimeria-challenged birds decreased the total tract digestibility of dry matter and gross energy (p < 0.05). The ileal gene expression of glucose transporters was upregulated (p < 0.05) in challenged birds that received the CMC-supplemented diet.6. In summary, increased digesta viscosity induced changes in the expression of nutrient transporter genes and decreased nutrient utilisation in Eimeria-challenged birds.

1. Shiga toxin-producing Escherichia coli (STEC) strains are associated with disease outbreaks which cause a public health problem. The aim of this study was to determine the frequency of STEC strains, their virulence factors, phylogenetic groups and antimicrobial resistance profiles in broiler chickens.2. A total of 222 E.coli isolates were collected from the caecum of chickens intended to be slaughtered. Antibiotic susceptibility was tested against 21 antimicrobial agents and ESBL phenotype was assessed by double-disk synergy test. The presence of STEC virulence genes stx1, stx2,eaeA and ehxA was detected by PCR. The identification of STEC serogroups was realised by PCR amplification. Additive virulence genes, phylogenetic groups and integrons were examined among the STEC isolates.3. Out of 222 E.coli isolates, 72 (32%) were identified as STEC strains and the most predominant serogroups were O103, O145 and O157. Shiga toxin gene 1 (stx1) was found in 84.7% (61/72) of the STEC strains, and eae and stx2 were detected in 38.8% and 13.8%, respectively. The ESBL phenotype was documented in 48.6% (35/72) of isolates. Most of the isolates (90.3%) carried class 1 integron with the gene cassette encoding resistance to trimethoprim (dfrA) and streptomycin (aadA) in 31.9% of the isolates. Class 2 integron was identified in 36.1% of isolates.4. Broilers can be considered as a reservoir of STEC strains which have high virulence factors and integrons that might be transmitted to other chickens, environments and humans. It is important to undertake surveillance and efficient control measures in slaughterhouses and farms to control measures of STEC bacteria.

1. It was assumed that the concentrations of arsenic (As), chromium (Cr), cobalt (Co), lead (Pb), manganese (Mn) and mercury (Hg) in the meat, kidney and liver of cattle, broilers and goats within Quetta city potentially exceeded the permissible limits for heavy metal content. Risk assessment of these heavy metals on human health were estimated based on daily intake (EDI), target hazard quotient (THQ) and hazard index (HI).2. Samples of the meat, liver and kidney of cattle, broilers and goats were collected from butcher shops and slaughterhouses in 20 different areas of Quetta city. Overall, 180 samples were analysed, each for six heavy metals. After acid digestion of meat samples, heavy metals analysis was carried out via atomic absorption spectroscopy.3. The results varied in levels depending upon the species and organ type. The average concentrations of As, Pb and Hg were within the established reference limits of the Australia New Zealand Food Authority (ANZFA 2015) and the European Commission (EC, 2006), although some samples exceeded these limits. Compared with the kidney and meat, the liver was the primary tissue for Cr, Pb and Hg bioaccumulation. Metals concentration were mostly within the normal range in samples from cattle and goats, while the Mn concentration was elevated in broilers.4. The estimated daily intake (EDI) revealed that the intake of As, Co, Pb and Hg was mainly derived from goat and cattle products, whereas broiler samples were more contaminated with Cr and Mn. The EDIs of Cr and Hg in adults exceeded the oral reference dose, referring to potential adverse effects. The EDIs for Co and Mn were low, suggesting that additional intake sources were necessary. Except for As, none of the determined elements had a target hazard quotient (THQ) above 1.

1. This study investigated the effects of incorporating yellow mealworm (Tenebrio molitor) larval meal as a partial and/or complete substitute for soybean meal on carcass and meat quality in slow-growing chickens.2. A total of 256 one-day-old male broilers were randomly allocated to 1 of 32 experimental units distributed among four treatments (n = 8): the control treatment (C), where soybean (SB) meal was the protein source, and three experimental treatments, in which SB meal was replaced by Tenebrio molitor (TM) larval meal at levels of 50% (T1), 75% (T2) and 100% (T3), respectively. Three different feed phases (1-29; 29-57 and 57-92 d of age) were used for each treatment. All chickens were slaughtered at 92 d of age, with eight animals per treatment randomly selected to assess carcass and meat quality. Near-infrared reflectance spectroscopy (NIR) was used to classify meat quality.3. Carcass traits were not significantly different between treatments, except for head and thigh weight, which were higher in the control group (p < 0.01). In terms of physicochemical characteristics, treatment T2 showed less yellowness (p < 0.05), while water and cooking losses were lower in treatments T1 and T2 (p < 0.01). Meat from both T1 and T2 groups had lower shear forces (p < 0.01), higher moisture content (p < 0.01) and less protein (p < 0.05) compared to treatments C andT3. Birds fed T3 had the highest meat ash content (p < 0.01). Chickens consuming TM had higher monounsaturated fatty acid (MUFA) levels and lower polyunsaturated fatty acid (PUFA) and n-6 acidsPUFA (p < 0.01).4. Substitution of SB with TM is a protein alternative for slow-growing chickens that supports carcass and meat quality comparable to those fed a conventional diet.

1. The aim of this study was to estimate heritability and genetic correlations, first among behavioural responses of juvenile South African Black ostriches towards humans and secondly with slaughter weight and skin traits.2. Behavioural traits, such as willingness of the birds to approach humans, keeping a distance from the human observer and allowing touch interactions by a human were recorded (n = 1012 birds). In addition, slaughter weight, skin size, scores for nodule size, nodule shape and the presence of hair follicles were recorded.3. Single- and multi-trait animal model analyses performed on the data using ASReml4 revealed high heritability estimates of 0.44 for allowing touch interactions and 0.48 for both willingness to approach and keeping a distance from the human observer. In addition, significant genetic correlations among behavioural response traits were estimated, ranging from -0.99 between keeping a distance and willingness to approach the human observer, to 0.87 between allowing touch interactions and willingness to approach the human observer.4. In contrast, genetic correlations of behavioural response traits with most slaughter and skin traits were low, variable, and not significant. The exception was hair follicle score, which appeared to be unfavourably correlated with key behavioural traits.5. This study suggested that the temperament of ostriches could be improved by selection of birds that demonstrate willingness to associate with humans without compromising slaughter weight or skin traits.

1. Dietary electrolyte balance (DEB) has been used to minimise problems in broiler chickens raised in warm climates. However, there is a need to determine the most appropriate DEB levels in these animals2. This study evaluated the influence of five DEB levels (110, 175, 240, 305 and 370 mEq/kg) on water intake (WI), zootechnical performance (feed intake, weight gain and feed conversion ratio), tibiotarsus bone variables (fresh bone weight, dry bone weight, bone length, mineral matter, Seedor index and bone strength) and intestinal histomorphometry (villus height (VH) and width (VW), crypt height (CH) and width (CW), internal and external muscularis) on broilers in two developmental phases (1-21 and 22-42 d of age). Additionally, the haematological profile (blood count and serum biochemistry), carcass yield, cuts and abdominal fat were assessed.3. Applying 370 mEq/kg DEB increased WI, VW in the jejunum and ileum and number of haemocytes at 21 d, while WI and VW in the duodenum and ileum at 42 d. In contrast, 110 mEq/kg increased chlorine concentrations at 21 d and leukocyte and heterophil numbers at 42 d.4. In summary, the 370 mEq/kg level was the most appropriate for broiler homoeostasis raised under natural heat stress, as the best results were found on WI and VW variables. Therefore, this DEB level was recommended in broilers aged 21 or 42 d.

1. This study determined the effective indicators and proteins involved in long-duration fertility (DF) in chickens.2. Three lines of Chinese Xinhua chickens (900) were compared using seven phenotypic trait indicators, and the best was determined based on repeatability value. Subsequently, differential expression analysis, functional annotation and protein-protein interaction (PPI) network analyses were performed to investigate the pathways and hub proteins. Finally, qPCR analysis was conducted to validate the expression of identified hub proteins, and functional annotation with previously published genes was performed to explain how hub proteins work to maintain the trait.3. The study found that the number of fertilised eggs (FN) and maximum fertilised eggs (MCF) were the most repeatable among the seven indicators. It identified 231 differentially expressed proteins, with 144 being down-regulated and 87 being up-regulated. The differentially expressed proteins exhibited high clustering within various cellular compartments, including the cytosol and cytoplasm and GTP binding. Multiple pathways were identified, including tight and adherens junctions, TGF-beta signalling, autophagy-animal, regulation of actin cytoskeleton and the ribosome that may regulate the trait. Three hub proteins, KRAS, RPL5 (p < 0.001), and HSPA4 (p < 0.01), were significantly differentially expressed between high and low DF groups.4. This study identified FN and MCF as effective indicators for addressing DF. As it is a quantitative trait, KRAS, HSPA4, and RPL5 are potential hub proteins that work with other genes to maintain the trait.