British Poultry Science最新文献

1. Melan-A (MLANA) plays a key role in the development of the melanosome, making it a strong candidate for the pigmentation phenotype observed in animals. The main purpose of this study was to analyse the relationship between MLANA gene polymorphisms and tyrosinase (TYR) enzyme activity in skin tissues and melanin content in dorsal down feathers of Chinese yellow quail.2. The coding sequence region of MLANA mRNA was cloned and sequenced to detect polymorphisms. The melanin content in down feathers of 266 Chinese yellow quails was analysed by spectrophotometry, and TYR enzyme activity was measured in dorsal skin tissues. The expression of MLANA mRNA in skin tissues of individuals with different genotypes was analysed using RT-qPCR.3. One non-synonymous single nucleotide polymorphisms (NSSNP; c.218T/A) was identified, which resulted in a Leu36Val mutation in the transmembrane helix region of the MLANA protein. This NSSNP significantly reduced the expression level of MLANA mRNA and TYR enzyme activity in dorsal skin tissues, leading to a significant reduction in melanin content in down feathers.4. The c.218T/A locus of the MLANA gene is closely related to the pigmentation TYR of the down feathers in Chinese yellow quail and can be used as a molecular marker locus for breeding pure feather colour in quail.

1. Clustered regularly interspaced short palindromic repeats (CRISPR)-associated proteins (Cas) systems have been highlighted for their potential applications in controlling the spread of mobile genetic elements, including antimicrobial resistance (AMR) genes. This study investigated the characteristics of CRISPR-Cas systems in E. faecalis from commercial broiler farms and assessed the impact of these systems on AMR.2. All E. faecalis isolates contained CRISPR2, and CRISPR1-Cas and CRISPR3-Cas were identified in 84 (56.4%) and 144 (96.6%) isolates. A combination of CRISPR2 and CRISPR3-Cas and a combination of CRISPR1-Cas, CRISPR2 and CRISPR3-Cas were each identified in 27 (96.4%) farms.3. There were significant differences between CRISPR-Cas systems for phenotypic AMR: CRISPR1-Cas and CRISPR3-Cas. The E. faecalis isolates without CRISPR1-Cas showed higher resistance to most antimicrobials and had a higher prevalence of multidrug resistance (MDR) than those with CRISPR1-Cas. However, the resistance rate against most antimicrobials and the prevalence of MDR did not differ significantly depending on the presence or absence of CRISPR3-Cas.4. The E. faecalis isolates without CRISPR1-Cas harboured higher levels of all AMR genes, except for tetL, than those with CRISPR1-Cas. However, the E. faecalis isolates with CRISPR3-Cas showed a significant lower prevalence of tetL gene and a significantly higher prevalence of fexA and poxtA genes.5. In the distribution of rep families, the rep₉ family was predominant, followed by rep₁, rep₇, rep₂ and rep₈ families. Only prevalence of the rep₇ family was significantly higher in the E. faecalis isolates without CRISPR1-Cas (15.4%) than in those with CRISPR1-Cas (0%).6. This study is the first report on the characteristics of CRISPR-Cas systems in E. faecalis isolated from commercial broiler farm environments, and the results supported the hypothesis that the development of antimicrobial strategies requires an understanding of the distinctive capabilities between CRISPR1-Cas and CRISPR3-Cas and their underlying resistance mechanisms.

1. This study evaluated the effect of acidified drinking water on the gastrointestinal function and intestinal health of broilers.2. A total of 630 one-day-old male broilers (Arbor Acre) were randomly assigned to one of three treatment groups: drinking water treatment (CON), drinking water + 0.5 ml Selko pH®/L (Selko pH), or + 0.85 ml Forticoat®/L (Forticoat) treated groups. Performance data, gut and digesta samples were collected from the broilers at the age of 21 and 42 d.3. The results showed that acidifying drinking water had no significant effect on body weight or average daily gain (ADG). However, addition of Forticoat significantly increased (p < 0.05) feed conversion ratio (FCR) throughout the experimental period and significantly increased (p < 0.05) pepsin activity on d 21. The Selko pH supplemented drinking water significantly increased (p < 0.05) the relative length of the duodenum and jejunum on d 21. The relative length of the jejunum and caecum on d 42 compared to birds receiving CON. The addition of the Forticoat to drinking water significantly increased (p < 0.05) the relative length of the jejunum and caecum on d 42 than for samples from birds in the CON group. In the caecal chyme, abundance of Blautia, Bifidobasterium, Faecalibacterium, Limosilactobacillus and Akkermania spp. on d 21 were significantly higher (p < 0.05) in the caecum of birds receiving Selko pH than those in CON group and the number of Escherichia Shigella in Selko pH and Forticoat group were significantly lower (p < 0.05).4. Overall, adding Seiko pH and Forticoat to drinking water improved pepsin activity, reduced the number of caecal pathogens, increased the number of beneficial bacteria and improved intestinal health in broilers.

1. This study evaluated the effects of cyclic eggshell temperature between 10 and 14 d of embryogenesis on traits viz. the expression of MYOZ2, PPARγ and GPx7 in breast muscle, meat quality and incidence of white striping at slaughter age.2. Eggs were obtained from Cobb and Ross broiler breeders to investigate the response of breeds to eggshell temperature, which regulated air temperature. A total of 784 eggs were incubated at either the control eggshell temperature (37.8°C) from 0 to 18 d or exposed to cyclic high eggshell temperature (CHT) at 38.8°C for 6 h/d between 10 and 14 d of incubation. The temperature was 36.8°C between 18 and 21 d. Hatched chicks were reared under optimum rearing conditions. The birds were sampled at 19 d of incubation, at hatch and at 42 d post-hatch.3. There was no effect of eggshell temperature on yolk-free body weight and residual yolk sac weight. The CHT chicks had wider breasts on the day of hatching.4. At hatch and 42d post-hatch, PPARγ expression in Cobb-CHT was upregulated 4.78-fold and downregulated 3.28-fold, respectively, compared to the Cobb-control. At slaughter age, chickens from Ross-CHT had 1.98- and 2.33-fold upregulated PPARγ and GPX7 expressions, respectively, compared to Ross-control. The CHT increased GPx7 expression in the Cobb-CHT day-old chicks compared to the Cobb-control. On ED19, MYOZ2 expression was upregulated in Cobb and downregulated in Ross by CHT.5. The effects of breed and eggshell temperature on pH₁₅, L*, a*, expressible juice and cooking loss were not significant. The CHT increased the incidence of severe white striping lesions in Ross chickens.6. It was concluded eggshell temperature modulated embryo development, incidence of white striping and expression of related genes differently in the two commercial breeds.

1. The amount of calcium and phosphorus in the empty, feather-free bodies of Cobb 700 breed males and females was measured from hatch to 15 weeks of age.2. A four-phase ad libitum feeding programme was used to feed 400 chicks of each sex. Feeds contained commercial levels of calcium and phosphorus which met or exceeded the requirements for energy, protein and amino acids. All birds were weighed weekly. Ten birds per sex were sampled at 0, 7, 14, 28, 42, 56, 70, 84 and 105 d of age. Defeathered birds were minced, freeze-dried and then analysed for protein, ash, calcium and phosphorus content.3. Amounts of Ca in males and females at 105 d averaged 54 and 37 g, respectively, and 105 d P content in males and females averaged 35 and 27 g, respectively. The allometry of ash, Ca and P with empty, feather-free body protein was assessed. Ash was isometric with body protein, while an allometric exponent greater than 1 was established for Ca and P with body protein.4. The allometric models and means for Ca and P relative to body protein were compared with models and means found in the literature. Comparison of the Ca/protein ratios with previous data suggested that modern broilers may not reach their potential bone mineral deposition with current dietary guidelines, even when growth rates were maximised.5. Theoretical allometric relationships between Ca and P in bone and bone-free body and body protein have now been proposed. The allometric relationship between Ca and P and empty, feather-free body protein offers a suitable way to model the growth of these minerals in the broiler body.

1. In the following experiment meat quality traits of a Gushi-Anka F2 resource population were measured, and their heritability estimated. Intramuscular fat (IMF) had medium heritability (0.35) but leg muscle fibre density (LMD), leg muscle fibre diameter (LMF), breast muscle fibre density (BMD), fresh fat content (FFA), and absolute dry fat content (AFC) had low heritability (0-0.2). The IMF presented the most important genetic additive effect among the poultry meat quality-related traits studied.2. The phenotypic data of meat quality traits in the Gushi-Anka F2 resource population were combined with genotyping by sequencing (GBS) data to obtain genotype data. Six meat quality traits in 734 birds were analysed by GWAS. Based on these variants, 83 significant (-log₁₀(p) > 4.42) single nucleotide polymorphisms and four quantitative trait loci (QTL) regions corresponding to 175 genes were identified. Further linkage disequilibrium (LD) analysis was conducted on chromosome 13 (Chr13) and chromosome 27 (Chr27) QTL regions.3. Based on the transcriptome data and GWAS results, 12 shared genes - ITGB3, DNAJC27, ETV4, C7orf50, FKBP1B, G3BP1, IGF2BP1, KCNH6, LOC416263, SCARA5, SMIM5 and TBL1XR1 were identified as candidate genes influencing muscle fibre and fat traits.

1. Poultry farming faces challenges regarding correct hygiene and nutrition. One of the challenges is gram-negative bacteria that stimulate pro-inflammatory reactions through lipopolysaccharide (LPS) and cause disease and anorexia. Liquorice, a medicinal plant containing glycyrrhizin (Glz; a saponin and emulsifier compound) as its main active ingredient, was injected into broilers to investigate any beneficial effects on feed intake in LPS-injected broilers.2. The study involved three experiments using 72 male broiler chickens in each, to examine the impact of Glz on feed intake, especially when challenged with lipopolysaccharide (LPS) by intra-peritoneal (IP) injection to cause inflammation (n = 24). Experiment 1 was conducted to examine the effects of intraperitoneal injection of Glz (12.5, 25 and 50 mg) on feed intake in chickens. In experiment 2, the effects of intracerebroventricular injections of LPS (6.25, 12.5 and 25 ng) were examined. The third experiment investigated the impact of IP injection of Glz on inflammation induced by LPS.3. Injection of Glz significantly increased feed intake in a dose-dependent manner. Whereas LPS significantly reduced the feed intake in feed-deprived chickens (p < 0.05).4. In conclusion, Glz can neutralise the feed intake reduction caused by inflammation in broilers, highlighting its potential role in modulating feed intake in broilers.

1. This study investigated the effects of different housing systems on oxidative defence mechanisms, heterophil functions, cellular immune response and cytokine production in laying hens. One hundred and twenty laying hens were allocated into one of four groups: conventional cages, furnished cages, deep litter, and free range.2. Housing system did not affect malondialdehyde concentrations and enzymatic antioxidant status. Ascorbic acid values were higher in deep-litter hens than in those in conventional cages and free range.3. Phagocytic and chemotactic activities tended to rise in the deep-litter system, and oxidative burst was higher than in furnished cages. Cytotoxic T cells were decreased in furnished cages, both cytotoxic and helper T cells decreased in deep litter compared to free range.4. The IL-2 and IL-13 expression was higher in deep litter than in conventional cages, and IL-6 expression was higher in furnished cages than in free range.5. Housing system had no significant effects on the oxidative defence system; however, they affected heterophil functions, cellular defence mechanisms and cytokine production. The results suggested that breeders need to consider the housing system's potential effects on immune defence responses while applying a breeding strategy appropriate for animal welfare and consumer demand.

1. This study evaluated the effectiveness of different types of acidifiers on reproductive performance, body weight loss and plasma biochemical indices of breeding pigeons as well as on growth performance, carcass characteristics, meat quality and plasma biochemical indices of squabs.2. In a 45 d trial, 144 pairs of European white Mimas pigeons were selected and randomly divided into three experimental groups. Three groups of pigeons were fed plain pigeon grit (NC), pigeon grit supplemented with 5% single acidifier (SAG) and pigeon grit supplemented with 5% combined acidifiers (CAG).3. Supplementing with SAG and CAG significantly increased the weight gain in male pigeons from 1-12 d of incubation. However, SAG and CAG had no significant effect on the feed intake of breeding pigeons during incubation, but significantly increased total feed intake of breeding pigeons during the lactation period. Breeder pigeons fed SAG and CAG had significantly higher egg-laying rate at 40 d. In addition, feeding SAG and CAG significantly increased growth rate and slaughter weight of squabs, but SAG reduced the diameter of pectoral muscle fibres. Biochemical indices showed that feeding SAG and CAG improved metabolism and increased the liver function of breeder pigeons and squabs.4. In conclusion, supplementing pigeon grit with acidifiers increased feed intake of breeding pigeons during lactation, protected liver function, enhanced reproductive performance and promoted the growth and development of squabs.

1. The present study assessed the effect of different antioxidants on the quality of chilled/frozen-thawed sperm of red-legged partridge.2. Sperm samples from 40 red-legged partridges were collected and extended 1:1 (v:v) with Lake and Ravie 84, supplemented with ascorbic acid or butylated hydroxytoluene (BHT) at 0, 0.2, 0.4, 0.8 mM and catalase (CAT) or superoxide dismutase (SOD) at 0, 100, 200 and 300 IU/ml. Ten sperm samples were used per concentration. Motility and viability were evaluated in fresh and after 6 h of chilling at 5°C or after freezing-thawing.3. For chilled sperm, the presence of ascorbic acid decreased viability and several motility variables; BHT 0.8 mM increased non-progressive motility (NPM, 26.7 ± 1.99 vs. 20.7 ± 2.12); CAT 200 IU/ml improved the rectilinear velocity (40.4 ± 4.63 μ/s vs. 29.9 ± 4.62 μ/s) and linear progression ratio (52.8 ± 3.11% vs. 45.4 ± 2.98%); SOD 100 IU/ml increased NPM (24.5 ± 1.21% vs. 19.3 ± 1.75%) and tended to improve total progressive motility (42.7 ± 3.33% vs. 33.2 ± 3.26%, p = 0.07). Using an extender supplemented with CAT 200 or SOD 100 did not improve the post-thawed sperm quality.4. The present work provides an advance in the optimisation of chilling and freezing protocols for red-legged partridge sperm.