Broiler industry has been bridging the gap between the supply and demand of high quality protein foods such as meat for the ever increasing human population worldwide. However, the overall expenditure on broiler diets remains between 60-80 percent of the total cost of broiler production. Therefore, the broiler industry has been striving to reduce the cost of production through improved feed utilisation by the broilers. For this purpose, exogenous enzymes have been claimed to improve the utilization of feeds by maximising the conversion of dietary nutrients into broiler meat, for example. Enzymes not only help in formulating more balanced diets for broilers by increasing the choice of ingredients such as cereals and other agro-industrial by-products but also by increasing their efficiency of utilisation by enhancing the digestibility of fibrous materials. The enzymes can also be beneficial as growth promoters instead of antibiotics which are banned in the European Union. Enzymes have been tried alone and in combinations with other additives such as organic acids to maintain health and production of broilers. Although the role of enzymes in improving feed utilisation, growth, meat quality and economics has been well reported, their quality, consistency and reproducibility have been questioned by many researchers. This article reviews the role of enzymes alongside organic acids in broiler diets and their future potential to maintain bird health and efficient broiler production which has desirable impacts on the environment.
Direct-fed microbials (DFMs) are live microorganisms which confer a health benefit to the host. The mode of action of DFMs involves multiple mechanisms, including direct inhibition of enteric pathogens and indirectly through competitive exclusion of pathogens by the normal gut microbiota. Additionally, recent basic research efforts have focused on the effects of DFMs on promoting host immunity and on the complex interactions between the gut microflora and immune system development. This review will summarize the latest developments in DFM studies with particular emphasis on the underlying mechanisms of immune enhancement.
The WW domain containing E3 ubiquitin protein ligase 1 (WWP1), an enzyme to degrade unneeded or damaged proteins, was recently identified as the responsible for chicken muscular dystrophy. Despite of intensive studies on oncogenic characters, the role of WWP1 to muscular diseases has not yet been fully understood. Since it is generally known that the switching of myosin heavy chain (MyHC) isoforms from neonatal isoform to adult one is inhibited in chicken muscular dystrophy, we transfected either of wild and mutated types of WWP1 gene into C2C12 cells to monitor the expression pattern of muscle-differentiation markers including MyHCs by real-time PCR. Excessive WWP1 expression enhanced the expression of the MyHC Ia gene but lowered the expression of the MyHC IIb gene. On the other hand, mutated WWP1 gene transfected into myoblasts was distinct from these cases in that the MyHC gene or genes expression inhibited the normal myoblast differentiation. The present data suggest that WWP1 promotes myoblast differentiation from embryonic into fast twitch phase while a mutation in WWP1 results to retain slow and fast twitch isoforms characteristic of dystrophic fast twitch muscles.
Characterization of the genetic diversity of indigenous animal populations is a prerequisite for providing needed information for the conservation of useful genotypes against future uncertainties in the face of daunting global challenges such as climate change, emerging diseases, population growth, and rising consumer demands. In this study, a total of 232 helmeted guineafowls (Numida meleagris) sampled from three populations in Ghana, one population in Benin and two populations in Japan were genotyped across six autosomal microsatellite loci. Three vulturine guineafowls (Acryllium vulturinum) were included as outgroup. A total of 66 alleles were observed with an average of 11.0 alleles per locus. The indigenous West African populations (Ghana and Benin) were more genetically diverse (Na=9.8; Ho=0.457) but less differentiated (FST=0.162) compared to the non-indigenous populations in Japan (Na=4.2; Ho=0.236; FST=0.389). The information from this study would be useful for selection and improvement programs necessary for the sustainable exploitation of this agriculturally and commercially important species as a suitable alternative to chicken.
A comparative histological and morphometric study based on selected skeletal muscles musculus pectoralis superficialis and musculus gastrocnemius in two lines of meat-type chickens, Anak Titan and Isa 215, was performed to detect potential differences regarding the effect of three production systems (chickens raised indoors in a conventional facility, indoors with limited outdoor access and outdoors with an umbrella roof) on muscle structure. The muscle fiber size was found to be affected by the production system, while the impact of the breeding line was less apparent. Disseminated fiber degeneration occurred more frequently in both examined muscles of Isa chickens raised outdoors. Necrotic fibers were very often infiltrated by mononuclear cells and underwent phagocytosis. The intensity of abnormal changes in muscle structure, including tiny fibers, fibers with hyaline cytoplasm and fibers with central nuclei, was substantially higher in chickens having outdoor access. This trend was particularly noticeable in musculus pectoralis superficialis and within the Isa 215 line. This indicates that it is more difficult for chickens of this line to adapt to changing environmental conditions. Significant changes observed in both muscles of birds raised outdoors can be considered highly undesirable with respect to the breeding objectives and breeding strategies for meat-type chickens. Environmental factors were found to play a more important role in chickens of the highly selected Isa 215 line, thus pointing to their worse adaptability to the less stable outdoor conditions. Furthermore, the present results suggest that the indoor housing system with access to an outdoor area can be an alternative to the traditional production system with regard to Anak Titan chickens.
Mx proteins are interferon-induced proteins with potent antiviral activities. A single nucleotide substitution at position 2032 of the Mx gene for position 631 of its protein from Ser to Asn is crucial for its antiviral activities in chickens. This study developed a real-time PCR based allelic discrimination method for the rapid genotyping of the chicken Mx gene G2032A SNP. The previously described allele-specific PCR was combined with real-time PCR melting curving analysis to genotype this Mx gene SNP from a small population of White Leghorn chickens, and the genotyping assay was confirmed by direct sequencing of PCR products. Our data demonstrate that the SNP at position 2032 of the Mx gene can be identified by the characteristic melting curve of the allele-specific fragments. This real-time PCR based SNP assay is rapid, sensitive and easy to perform compared with traditional PCR method which makes it suitable for large population analysis.
The study was to research the gene expression of lipoprotein lipase (LPL) in abdomen adipose tissue, subcutaneous adipose tissue, pectoral muscle, skeletal muscles, liver, brain and spleen of geese, and the effect of insulin and glucose on gene expression of LPL was measured in primary hepatocytes of Sichuan white geese (Anser cygnoides) and Landes geese (Anser anser). We quantified gene expression by competitive reverse transcriptase PCR (RT-PCR). The results indicated: First, 0-150nM insulin could increase the mRNA level of LPL in a dose-dependent pattern, and 200nM insulin had an inhibiting effect. Second, there was a synergistic effect of insulin and glucose on LPL gene expression, and the synergistic effect of 30mM glucose and 50nM insulin was much higher than the single effect of insulin or glucose. In addition, the induction of LPL mRNA level by insulin and glucose was higher in Landes goose than the induction in Sichuan white goose. It was concluded that LPL was highly expressed in the goose liver, and the LPL gene level could be up-regulated by insulin and glucose.
Production of gene-targeted chickens is considered to be valuable for studies in both biological science and industry, but it is yet to be achieved. In this study, an insertion vector for gene targeting of chicken lens-specific gene, delta1-crystallin (d1cry), was constructed as a useful tool to evaluate homologous recombination (HR) in chickens. A promoter-less d1cry-homologous DNA and DsRed with an artificial linker sequence (linkerDsRed) were amplified by PCR from genomic DNA and pCMV-DsRed-Express, respectively. The amplified fragments were then cloned and sequenced. The homologous DNA was 7,402bp in size and contained no amber and frameshift mutations. The linkerDsRed fragment had accurate sequence without artificial errors. Floxed marker genes composed of enhanced green fluorescent protein (EGFP) gene, internal ribosome entry site (IRES) and puromycin resistance gene (Pac) regulated by CAG promoter (PCAGEIP) was constructed using standard genetic engineering methods. Finally, these DNA materials were ligated to pCC1BAC vector. The accuracy of construction was confirmed by sequencing of ligated portions, and a 20.7-kb insertion d1cry-targeting vector was accomplished. By gene targeting in the pluripotent stem cells using this vector and transplantation of the cells into recipient embryos, chicken transformation would be observed rapidly and easily by the mutant gene-derived red fluorescence in the lens at an early stage of embryogenesis.
Coccidiosis is a common infectious disease in poultry, causing major economic losses. The aim of this study was first, to investigate the effects of synbiotic Biomin®IMBO on performance of broilers in normal condition (experiment 1) and secondly, to evaluate the influence of synbiotic on severity of intestinal lesion score and fecal oocyst shedding of the broilers challenged with coccidian (experiment 2). There were four dietary treatments in each experiment; basal diet (control) and basal diet +0.05, 0.1 or 0.15% synbiotic Biomin®IMBO of diet. In experiment 1,400 day-old male broiler chicks were randomly assigned to 16 pens (25 birds/pen) and were fed regular nonmedicated broiler starter (0-10d), grower (11-28d) and finisher (29-42d) diets. The measured traits were: Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) at the end of each period. In experiment 2, on 10d, four birds from each pen used in experiment 1 (totally 64 birds) were transformed to battery. On 15d, birds were inoculated esophageally with 5000 oocysts of either Eimeria acervulina or Eimeria tenella. On 6 day after postinoculation, intestinal lesion score and number of oocysts excreted for successive five days were determined. The results showed that BWG was increased significantly (P<0.05) in broilers fed diet containing 0.1 and 0.15% synbiotic, when compared to control group, from 1d to 42d. The presence of synbiotic in diet made significant improvement (P<0.05) in FCR of finisher and total experimental periods. All groups fed diets with synbiotic significantly (P<0.05) shed less oocysts than non-supplementation groups. The lowest lesions score of duodenum and cecum were observed in broiler fed diet with 0.15% synbiotic. In conclusion, it can hypothesize that synbiotic Biomin®IMBO can promote growth and have protective properties against coccidiosis in broiler diets.
Two experiments were conducted to investigate whether increasing the dietary level of sn-2 saturated fatty acids (SFA) could improve total fatty acids (TFA) and Ca digestibility, growth performance and tibia characteristics, and reduce the occurrence of leg abnormalities in broiler chickens. In experiment 1, 30 male broiler chicks were individually fed diets with either low or high levels of sn-2 SFA and one of three levels of Ca in a factorial design manner. The apparent digestibility (AD) of TFA and Ca were measured. Increasing the dietary level of sn-2 SFA increased the AD of TFA (P<0.01) and Ca (P<0.05) in the broilers. Increasing the dietary Ca decreased the AD of TFA and Ca (P<0.01). In experiment 2, four hundred male broiler chicks were fed either a low or high sn-2 SFA diet. Growth performance, tibia characteristics and the occurrences of leg abnormalities during weeks 0 to 6 were measured. Increasing dietary level of sn-2 SFA did not affect growth performance, but increased stress and Ca level in the tibias (P<0.05) and decreased the occurrence of leg abnormalities (P<0.05). These results indicated that increasing the dietary level of sn-2 SFA could improve fatty acid and Ca digestibility and tibia characteristics and reduce the occurrence of leg abnormalities in broilers.
This research was conducted to determine effects of dietary bergamot oil levels (0, 0.25, 0.50, 0.75ml/kg) on performance, egg quality, blood metabolic profile and fatty acid composition of egg yolk in laying hens. Sixty four of 67 weeks old white Lohman LSL laying hens were randomly assigned to four groups equally (n=16). Each treatment was replicated four times Dietary supplementation of bergamot oil had no significant effect on feed conversion ratio, egg weight, and egg production, shell thickness, ratio of albumen and shell. But, supplementation of bergamot oil decreased feed intake. The addition of 0.50ml/kg bergamot oil to the laying hens feed led to a significant increase in the yolk ratio. It was also observed that egg shell ratio, serum cholesterol and calcium concentration reduced significantly with supplementation of bergamot oil in laying hens diets. The highest IgG concentration was obtained from hens fed 0.25ml/kg bergamot oil. Addition of bergamot oil to feeds significantly increased eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and n-3 concentration and decreased n-6/n-3 ratio in egg yolk. The results of this research indicated that the addition of bergamot oil to the laying hens feed led to a significant decrease in the feed intake and concentrations of serum cholesterol. It was also concluded that dietary supplementation of bergamot oil significantly increased egg shell strength and, the EPA, DHA and n-3 ratio of the egg yolk.
The present study was performed to demonstrate the presence of receptors for avian calcitonin (cCT) in ovarian granulosa cells of the largest follicle of laying hens and to determine the effect of cCT on LH-stimulated P4 production. The cCT binding in the granulosa cells of the largest follicle was determined using a [125I]CT binding assay. The binding properties in the granulosa cells satisfied the criteria of a receptor-ligand interaction in terms of specificity, saturation, high affinity and limited capacity. During incubation of ovarian granulosa cells in vitro, cCT alone did not affect the P4 production alone, but cCT decreased the amount of LH-stimulated P4 production and the sensitivity to LH. The present study suggests that cCT may act directly on the granulosa cell of the largest follicle via its receptor binding and inhibit P4 production in response to LH in hens.
The agouti signaling protein (ASIP)/melanocortin signaling system regulates lipid metabolism in humans but not in mice. To examine whether the system is present in adipose tissues in chickens, we performed reverse transcription-polymerase chain reaction (RT-PCR) analysis using mRNAs extracted from subcutaneous and visceral adipose tissues. This revealed that mRNAs for melanocortin 1 receptor (MC1R), MC5R, ASIP, pro-opiomelanocortin (POMC), prohormone convertase 1 (PC1) and PC2 were expressed in both adipose tissues, suggesting the presence of a local ASIP/melanocortin signaling system in these tissues in chickens. To investigate the potential biological role of this system, the adipose tissue mRNA expression of ASIP and POMC was examined under food-deprived conditions. Forty-eight-hour fasting significantly decreased body weight and reduced the cell size in adipose tissues. In addition, the plasma levels of free fatty acids were increased while those of glucose, triacylglycerols and insulin were decreased, suggesting the activation of lipolysis and gluconeogenesis in the fasted chickens. Under this condition, the mRNA expression of ASIP and POMC was decreased and increased, respectively, in subcutaneous and visceral adipose tissues. ASIP and melanocortins are lipogenic and lipolytic hormones, respectively. Therefore, these findings suggest that lipid metabolism in the adipose tissues is regulated by a local ASIP/melanocortin signaling system in chickens. This is the first report demonstrating changes in the expression of ASIP mRNA in adipose tissues in the negative-energy state in vertebrates.
The present study was conducted to determine both the site at which the eggshell matrix is produced and the critical period for its production in the oviductal uterus of the Japanese quail, Coturnix japonica. An antiserum was produced against the proteins of the 116-kDa band in electrophoretic profiles of the matrix proteins obtained from eggshells decalcified with EDTA. N-terminal amino acid sequences were very similar to those of chicken ovocleidin-116. Immunofluorescent and immunoelectron microscopic observations revealed that the 116-kDa proteins were synthesized in granular cells of the uterus mucosal epithelia, secreted between 7 and 20 h after the previous oviposition, then integrated into the structure of the eggshell matrix. Scanning electron microscopic observations revealed that 10-μm-wide posts appear on the surface of the mucosal epithelia until 21h, and disappear thereafter. The posts were less prominent in the mucosal epithelium facing the sharp end of an egg than in that facing the equator or blunt end. On the other hand, the number of pores in eggshells at the sharp end was smaller than that at the equator or blunt end. Our results indicate that air canals and/or pores are formed in the eggshell by the retreat of the posts after the establishment of eggshell.
The emergence of Salmonella enterica serovar Enteritidis (S. Enteritidis) during the past three decades as major contaminant of eggs and other poultry products caused a surge in human infections. This could have been mediated in part by emerging S. Enteritidis strains with enhanced virulence. The overall pathogenicity of Salmonella is controlled by numerous genes. To assess the role of a few specific genes thought to contribute to the pathogenicity of S. Enteritidis in egg laying hens, we conducted an experimental infection of egg-laying hens, with a wild type (WT) S. Enteritidis phage type 4 strain and three mutants (M1, M2, M3). These mutants were produced from the wild type by the inactivation of the prgH, SEN4287, and tyrR genes, respectively. We observed that the WT and the M1 mutant had shorter durations of fecal shedding and faster clearance from internal organs of the infected hens than the M2 and M3 mutants. The isolation rates of the wild type S. Enteritidis and the mutants were highest from the ceca, moderately high from the liver and spleen, and lowest from the ovaries of the infected hens. Hep-2 cells attachment assay revealed attenuated attachment for the M1 mutant while the M3 mutant seemed to have enhanced attachment. Colonization of tissues of the infected hens by M1 mutant appears to have been attenuated.