The ultrastructure of gametogenesis of cryptosporidium baileyi (eimeriorina; cryptosporidiidae) in the respiratory tract of broiler chickens (Gallus domesticus).

The ultrastructural features of sexual development of Cryptosporidium baileyi in the respiratory tract of experimentally infected broiler chickens were studied using transmission electron microscopy. Sexual stages of C. baileyi were seen attached to the tracheal epithelium and free in the tracheal lumen. These stages included intracellular type III merozoite-like stages, microgamonts, microgametes, macrogamonts, thin-walled oocysts, and thick-walled oocysts. These stages were developmentally similar to those observed for other Cryptosporidium species. All of the above stages were observed during each study day. Thin-walled oocysts, microgamonts, and microgametes were seen less frequently than other sexual stages. Microgamonts, macrogamonts, and oocysts attached to the epithelium were all contained in a host cell membrane or within a parasitophorous vacuole. Thin-walled oocysts of C. baileyi were observed for the first time on an ultrastructural level in the respiratory tract of chickens.     

The life cycle of Cryptosporidium baileyi n. sp. (Apicomplexa, Cryptosporidiidae) infecting chickens

The life cycle and morphology of a previously undescribed species of Cryptosporidium isolated from commercial broiler chickens is described. The prepatent period for Cryptosporidium baileyi n. sp. was three days post oral inoculation (PI) of oocysts, and the patent period was days 4-24 PI for chickens inoculated at two days of age and days 4-14 for chickens inoculated at one and six months of age. During the first three days PI, most developmental stages of C. baileyi were found in the microvillous region of enterocytes of the ileum and large intestine. By day 4 PI, most parasites occurred in enterocytes of the cloaca and bursa of Fabricius (BF). Mature Type I meronts with eight merozoites first appeared 12 h PI and measured 5.0 x 4.9 micrometers. Mature Type II meronts with four merozoites and a large granular residuum first appeared 48 h PI and measured 5.1 x 5.1 micrometers. Type III meronts with eight short merozoites and a large homogeneous residuum first appeared 72 h PI and measured 5.2 x 5.1 micrometers. Microgamonts (4.0 x 4.0 micrometers) produced approximately 16 microgametes that penetrated into macrogametes (4.7 x 4.7 micrometers). Macrogametes gave rise to two types of oocysts that sporulated within the host cells. Most were thick-walled oocysts (6.3 x 5.2 micrometers), the resistant forms that passed unaltered in the feces. Some were thin-walled oocysts whose wall (membrane) readily ruptured upon release from the host cell. Sporozoites from thin-walled oocysts were observed penetrating enterocytes in mucosal smears. The presence of thin-walled, autoinfective oocysts and the recycling of Type I meronts may explain why chickens develop heavy intestinal infections lasting up to 21 days. Oocysts of C. baileyi were inoculated orally into several animals to determine its host specificity. Cryptosporidium baileyi did not produce infections in suckling mice and goats or in two-day-old or two-week-old quail. One of six 10-day-old turkeys had small numbers of asexual stages only in the BF. Four of six one-day-old turkeys developed mild infections only in the BF, and sexual stages of the parasite were observed in only one of the four. All seven one-day-old ducks and seven two-day-old geese developed heavy infections only in the BF with all known developmental stages present.     

In vitro excystation of Cryptosporidium baileyi from chickens

Release of sporozoites from the oocysts of Cryptosporidium baileyi is described from Nomarski interference-contrast microscopy. Just prior to excystation, the four sporozoites became motile and rearranged themselves within the oocyst. The sporozoites were then rapidly expelled through an opening that formed in the oocyst wall, and the residuum was either released or retained within the oocyst. Excysted sporozoites were crescent shaped and measured 5.0-9.0 microns X 1.0-1.6 micron (mean = 6.8 X 1.1 microns). Excystation occurred when sodium taurocholate or a mixture of trypsin and sodium taurocholate was present in the incubation medium. High levels of excystation occurred at 37 degrees or 40 degrees C, but excystation did not occur at 4 degrees C. The ability of biles from two avian and two mammalian hosts to produce excystation of C. baileyi was also studied. After a 2-h incubation at 40 degrees C, the percentages of excystation were 69.5% in goat bile, 45.0% in pig bile, 33.0% in chicken bile, and 34.5% in turkey bile.     

Molecular characterization of major histocompatibility complex (B) haplotypes in broiler chickens

In Leghorn (laying) chickens, susceptibility to a number of infectious diseases is strongly associated with the major histocompatibility ( B ) complex. Nucleotide sequence data have been published for six class I ( B-F ) alleles and for class II ( B-Lβ ) alleles or isotypes from 17 Leghorn haplotypes. It is not known if classical B-L or B-F alleles in broilers are identical, at the sequence level, to any Leghorn alleles. This report describes molecular and immunogenetic characterization of two haplotypes from commercial broiler breeder chickens that were originally identified by serology as a single haplotype, but were differentiated serologically in the present work. The two haplotypes, designated B ^A4 and B ^A4variant, shared identical B-G restriction fragment length polymorphism patterns, but differed in one B-Lβ fragment that cosegregated with the serological B haplotype. Furthermore, the nucleotide sequences of the highly variable exons of an expressed B-LβII family gene and B-F gene from the two haplotypes were markedly different from each other. Both the B-LβII family and B-F gene sequences from the B ^A4 haplotype were identical to the sequences obtained from the reference B ²¹ haplotype in Leghorns; however, in the B ^A4 haplotype the B-Lβ ²¹ and B-F ²¹ alleles were in linkage with B-G alleles that were not G ²¹. The nucleotide sequences from B ^A4variant were unique among the reported chicken B-LβII family and B-F alleles.     

Decreased glycogen mobilization during ochratoxicosis in broiler chickens.

Graded doses of pure ochratoxin A (0, 0.5, 1.0, 2.0, 4.0, and 8.0 microgram of toxin per g of feed) were incorporated into a commercial diet which was fed to chickens from hatching to 3 weeks of age, at which time the experiments were terminated. Liver glycogen levels were elevated significantly (P less than 0.05) by 4.0 and 8.0 microgram/g but not lower doses. Glucagon stimulation of glycogen mobilization was inhibited at the same concentrations. Histopathological examination revealed cytoplasmic but not nuclear deposits of glycogen in cells at the periphery of liver lobes. These data demonstrated that ochratoxin inhibited glycogenolysis. Impaired ability to generate glucose from glycogen could account for the increased susceptibility to cold stress previously reported to occur in ochratoxicosis. Based on present and prior observations, it seems possible that ochratoxin induces a syndrome which mimics the glycogen storage disease of type X which is caused by a deficiency in the cyclic AMP-dependent enzyme of the glycogenolytic enzymatic cascade.     

Inheritance of fertility in broiler chickens

Background

The fertility of a chicken''s egg is a trait which depends on both the hen that lays the egg and on her mate. It is also known that fertility of an individual changes over the laying period.

Methods

Longitudinal models including both random genetic and permanent environmental effects of both the female and her male mate were used to model the proportion of fertile eggs in a pedigree broiler population over the ages 29-54 weeks.

Results

Both the male and the female contribute to variation in fertility. Estimates of heritability of weekly records were typically 7% for female and 10% for male contributions to fertility. Repeatability estimates ranged from 24 to 33%, respectively. The estimated genetic variance remained almost constant for both sexes over the laying period and the genetic correlations between different ages were close to 1.0. The permanent environment components increased substantially towards the end of the analyzed period, and correlations between permanent environment effects at different ages declined with increasing age difference The heritability of mean fertility over the whole laying period was estimated at 13% for females and 17% for males. A small positive correlation between genetic effects for male and female fertility was found.

Conclusion

Opportunities to improve fertility in broiler stocks by selection on both sexes exist and should have an impact throughout the laying period.     

Genome-wide expression analysis of roxarsone-stimulated growth of broiler chickens (Gallus gallus)

Roxarsone is a commonly used additive in chicken (Gallus gallus) industry. However, little is known on the intrinsic molecular mechanism via which the growth performance of birds improves. This study was therefore performed to investigate the expression profiles of genes induced by roxarsone. Fifty-six broiler chickens were divided into two groups, namely treated and untreated with roxarsone. The treated group was provided a diet of 45.4 mg/kg roxarsone medication and the other group acted as control. Data analysis showed that roxarsone consistently and significantly (P < 0.05) increased chicken growth performance. In addition to this a significant (P < 0.05) increase of arsenic residue in liver has been seen. Microarray expression analysis of 8935 genes in liver showed that 22 genes (10 up- and 12 down-regulated) had altered expression throughout the experimental periods. Two novel genes (GenBank accession no. GU724343 and GU724344) were cloned through rapid amplification of cDNA ends (RACE). Gene GU724343 was predicted to encode an unidentified protein and the second gene GU724344 was presumed to encode a new member of immunoglobulin-like receptor (CHIR) family. Our results suggested for the first time that the role of roxarsone could be mainly to modify the expression levels of cell growth, immunity/defense and energy metabolism associated genes, as a result promoting animal growth. Further research on these genes should help to increase the knowledge of improving animal productivity safely and effectively.     

Bone response of broiler chickens (Gallus gallus domesticus) induced by corticosterone

Experiments were conducted with chickens exposed to corticosterone (CORT), with the aim of determining its effects on bone characteristics. At 7 d of age, the experimental birds were injected daily with CORT (4 mg/kg of body mass) for 1 week. CORT administration significantly decreased the body weight while increasing relative liver weight of the chickens and the bone parameters were also decreased. Histology and immunohistochemistry of type X collagen revealed that CORT reduced the lengths of proliferative and prehypertrophic zone in growth plate and the number of positive chondrocytes in the prehypertrophic zone. In conclusion exposure to CORT depressed the growth performance and retarded the longitudinal growth of the long bones by inhibiting the proliferation and differentiation of chondrocytes in growth plate in broilers.     

Diversity and prevalence of Arcobacter spp. in broiler chickens

Ninety-nine strains of Arcobacter spp., isolated from 10 chicken carcasses purchased from a supermarket and 15 chicken carcasses collected from a poultry abattoir, were speciated using a variety of phenotypic identification methods. All were tested using API Campy test strips and the 16-test (Preston) identification scheme developed for campylobacters. Fifty strains were selected for examination using a more comprehensive probabilistic identification scheme, and the identity of representative strains confirmed by protein profiling using SDS-PAGE. All 25 carcasses yielded Arcobacter butzleri . Three supermarket and 10 abattoir carcasses also carried A. cryaerophilus , and two abattoir carcasses carried A. skirrowii . The API Campy scheme proved unsatisfactory for identifying these strains: only 20 of 99 strains were accurately identified, all of which were A. cryaerophilus , the only Arcobacter sp. included in the database. Moreover, 76 of 99 strains were misidentified. The 16-test scheme identified all the arcobacter strains as A. cryaerophilus, since neither A. butzleri nor A. skirrowii had been described when the scheme was developed. The computer-assisted probabilistic scheme succeeded in identifying all but one strain, the identity of which was clarified by the use of SDS-PAGE. To our knowledge this is the first time that arcobacters other than A. butzleri have been reported in poultry meat or any other food of animal origin. Their high prevalence in poultry products may be of significance to public health.     

Eimeria Spp.: Influence of coccidia on digestion (amylolytic activity) in broiler chickens

Loss in pancreatic weight and an overall decrease in amylolytic activity in the pancreas were seen in broiler chickens infected with Eimeria acervulina, E. maxima, and E. necatrix. Only E. acervulina and E. maxima reduced amylolytic activity in the surface mucosa of the regions they infected. Surface-bound amylolytic activity decreased as the severity of infection (as measured by lesion score) with E. acervulina increased. This decrease in activity was not related to the decreased feed consumption in infected birds. Little decrease in amylase activity was found in the lumenal contents with the exception of E. acervulina in the jejunum. When the effect of pH on enzyme activity was studied in vitro, a marked reduction in amylolytic activity was observed as the pH went below 5.0.     

Cassava (Manihot esculenta) leaf and tuber concentrate in diets for broiler chickens

Experiment 1 was conducted to determine the nutritive quality of cassava tuber leaf concentrate prepared either by mixing cassava tubers and leaves together before grinding or grinding them separately before mixing. Three mixing proportions of 50:50, 60:40 and 80:20 were used. Samples were subjected to either sundrying or oven drying. Physical examination of samples, proximate analysis and cyanide content of each of the samples were determined. In experiment 2 the sample of highest nutritive value was selected for inclusion in four diets at levels of 0%, 10%, 20% and 30% respectively. A total of 120 day-old broilers were divided into four groups and each group further into three subgroups. The four experimental diets were fed to each of the groups for a period of 9 weeks. Growth parameters, carcass characteristics and haematological parameters were also determined. Results showed that in experiment 1 the grinding together of cassava tubers and leaves in the proportion of 50:50 before sun-drying gave the best texture, highest CP content with low HCN content. Inclusion of 10% cassava concentrate gave good performance in terms of growth and feed conversion, with no detrimental effects on haematological parameters and carcass characteristics.     

Colonization of broiler chickens by waterborne Campylobacter jejuni.

Chickens on a broiler farm in southern England were found to be colonized with Campylobacter jejuni of a single serotype, Lior 1 Penner 4. The farm was the sole supplier of a local slaughterhouse associated with a campylobacter outbreak in 1984 caused by this serotype. The serotype persisted on the farm for at least 18 months after the outbreak; its prevalence in the human population served by the farm remained high until it disappeared from the farm in 1986. The possible sources and routes of transmission of C. jejuni to the broilers on the farm were investigated. The results showed that vertical transmission, feed, litter, small mammals, and environmental or airborne cross-contamination between sheds or successive crops could be excluded as persistent sources of C. jejuni. The predominant source of C. jejuni on the farm was shown to be the water supply. Direct microscopy and fluorescent antibody methods revealed presumptive campylobacters throughout the farm's water system. Campylobacter-free chickens raised in an animal house and given water from the farm supply became colonized with the serotype of C. jejuni endemic on the farm (Lior 1 Penner 4). An intervention program based on water chlorination, shed drinking system cleaning and disinfection, and withdrawal of furazolidone from feed reduced the proportion of birds colonized with campylobacter from 81 to 7% and was associated with a 1,000- to 10,000-fold reduction in campylobacters recoverable from the carcasses. Two months after the end of the intervention program colonization of the birds returned to high levels (84%), indicating that there was a temporal association between intervention and reduced colonization with C. jejuni. Investigations continue to establish the general applicability of these findings.     

Oxidative stress induced by corticosterone administration in broiler chickens (Gallus gallus domesticus) 2. Short-term effect

Two trials were conducted to evaluate the effects of short-term administration of corticosterone (CORT) on the induction of oxidative injury in broiler chickens (Gallus gallus domesticus). Twelve broiler chickens of 30 and of 40 days of age were respectively employed in Trial 1 and 2. Half of the chickens were administered subcutaneously with CORT (4 mg/kg body weight [BW] in corn oil), while another half served as controls (corn oil) in each trail. In Trial 1, a blood sample was obtained from each chicken immediately before administration and at 1 and 3 h after injection. In Trial 2, the liver and heart were obtained after 3 h of CORT exposure. Short-term administration of CORT resulted in enhanced proteolysis and gluconeogenesis. There were no obvious changes in lipid peroxidation status of the heart and liver, whereas a decrease in lipid peroxidation in the plasma was observed after acute CORT exposure. The significantly increased plasma nonenzymatic antioxidants (uric acid [UA] and total antioxidant capacity) in concert with the enhanced enzymatic antioxidant activity (SOD in heart) during short-term CORT administration indicate preventive changes to counteract the oxidative injury, and these may be tissue specific.     

Oxidative stress induced by corticosterone administration in broiler chickens (Gallus gallus domesticus) 1. Chronic exposure

Two trials were conducted to evaluate the effects of short-term administration of corticosterone (CORT) on the induction of oxidative injury in broiler chickens (Gallus gallus domesticus). Twelve broiler chickens of 30 and of 40 days of age were respectively employed in Trial 1 and 2. Half of the chickens were administered subcutaneously with CORT (4 mg/kg body weight [BW] in corn oil), while another half served as controls (corn oil) in each trail. In Trial 1, a blood sample was obtained from each chicken immediately before administration and at 1 and 3 h after injection. In Trial 2, the liver and heart were obtained after 3 h of CORT exposure. Short-term administration of CORT resulted in enhanced proteolysis and gluconeogenesis. There were no obvious changes in lipid peroxidation status of the heart and liver, whereas a decrease in lipid peroxidation in the plasma was observed after acute CORT exposure. The significantly increased plasma nonenzymatic antioxidants (uric acid [UA] and total antioxidant capacity) in concert with the enhanced enzymatic antioxidant activity (SOD in heart) during short-term CORT administration indicate preventive changes to counteract the oxidative injury, and these may be tissue specific.     

Intestinl fragility during ochratoxicosis and aflatoxicosis in broiler chickens.

Graded concentrations of dietary ochratoxin (0, 0.5, 1.0, 2.0, 4.0, and 8.0 microgram/g) and aflatoxin (0, 0.625, 1.25, 2.5, 5.0, and 10.0 microgram/g) were fed to broiler chicks from hatching to 3 weeks of age. The breaking strength of the large intestines was decreased significantly (P < 0.05) by ochratoxin (2, 4, and 8 microgram/g), but not by aflatoxin. This fragility was accompanied by an increase in the weight of the large intestine relative to body weight of birds fed ochratoxin (4.0 and 8.0 microgram/g), whereas aflatoxin had no significant (P < 0.05) effect on this parameter. Lipid content of the large intestine was decreased significantly (P < 0.05) by aflatoxin (10.0 microgram/g) and increased by ochratoxin (8.0 microgram/g). Microscopic examination of cross sections of large intestines stained for collagen gave the impression of a great decrease in collagen content of birds fed ochratoxin, but not aflatoxin. The radial length of the collagenous longitudinal folds of the large intestine was decreased significantly (P < 0.05) by ochratoxin (2.0, 4.0, and 8.0 microgram/g). These observations, plus a field case characterized by intestinal ruptures causing carcass condemnations on the processing line and by the occurrence of aflatoxin and ochratoxin in the chicken feed, suggest a novel way in which mycotoxins cause economic loss to agriculture.     

Percent G+C profiling accurately reveals diet-related differences in the gastrointestinal microbial community of broiler chickens.

Broiler chickens from eight commercial farms in Southern Finland were analyzed for the structure of their gastrointestinal microbial community by a nonselective DNA-based method, percent G+C-based profiling. The bacteriological impact of the feed source and in-farm whole-wheat amendment of the diet was assessed by percent G+C profiling. Also, a phylogenetic 16S rRNA gene (rDNA)-based study was carried out to aid in interpretation of the percent G+C profiles. This survey showed that most of the 16S rDNA sequences found could not be assigned to any previously known bacterial genus or they represented an unknown species of one of the taxonomically heterogeneous genera, such as Ruminococcus or Clostridium. The data from bacterial community profiling were analyzed by t-test, multiple linear regression, and principal-component statistical approaches. The percent G+C profiling method with appropriate statistical analyses detected microbial community differences smaller than 10% within each 5% increment of the percent G+C profiles. Diet turned out to be the strongest determinant of the cecal bacterial community structure. Both the source of feed and local feed amendment changed the bacteriological profile significantly, whereas profiles of individual farms with identical feed regimens hardly differed from each other. This suggests that the management of typical Finnish farms is relatively uniform or that hygiene on the farm, in fact, has little impact on the structure of the cecal bacterial community. Therefore, feed compounders should have a significant role in the modulation of gut microflora and consequently in prevention of gastrointestinal disorders in farm animals.     

Genetic heterogeneity of residual variance in broiler chickens

Aims were to estimate the extent of genetic heterogeneity in environmental variance. Data comprised 99 535 records of 35-day body weights from broiler chickens reared in a controlled environment. Residual variance within dam families was estimated using ASREML, after fitting fixed effects such as genetic groups and hatches, for each of 377 genetically contemporary sires with a large number of progeny (> 100 males or females each). Residual variance was computed separately for male and female offspring, and after correction for sampling, strong evidence for heterogeneity was found, the standard deviation between sires in within variance amounting to 15–18% of its mean. Reanalysis using log-transformed data gave similar results, and elimination of 2–3% of outlier data reduced the heterogeneity but it was still over 10%. The correlation between estimates for males and females was low, however. The correlation between sire effects on progeny mean and residual variance for body weight was small and negative (-0.1). Using a data set bigger than any yet presented and on a trait measurable in both sexes, this study has shown evidence for heterogeneity in the residual variance, which could not be explained by segregation of major genes unless very few determined the trait.     

Effect of different selenium source (sodium selenite and selenium yeast) on broiler chickens

A feeding experiment was carried out to compare the effects of supplementing a poultry meal-based diet with selenium as sodium selenite or selenium yeast on broiler chickens. Three groups with three replicates of broiler chickens (mean weight 710 ± 5.3 g) were given a basal diet either unsupplemented (control) or supplemented with 0.2 mg Se kg⁻¹ as sodium selenite (trial 1) or selenium yeast (trial 2) respectively, for 21 days. There was significant difference (P<0.05) in Feed Conversion Ratio (FCR) of trials 1 and 2 compared with the control. However, there were no significant differences (P>0.05) in FCR between trials 1 and 2. Final weight, survival rate and Daily Gain (DG) were not affected by the dietary Se source. Chickens fed the basal diet showed lower (P<0.05) selenium content in muscle, kidney, liver and pancreas compared to that fed selenium supplements (trials 1 and 2). Furthermore, trial 2 showed the highest value (P<0.05) among these treatments. However, there was no significant difference (P>0.05) in muscle selenium content of chickens between trials 1 and 2. Glutathione peroxidase (GSH-Px) activities in broiler chickens plasma and liver of all selenium treatment groups (trials 1 and 2) were significantly different (P<0.05) from that of the control. The GSH-Px activity in plasma was higher (P<0.05) in trial 2 compared with trial 1 and the control. However, there was no difference (P>0.05) in hepatic glutathione peroxidase between trials 1 and 2 although the average value of GSH-Px activity in trial 2 presented the trend of increase.     

Feeding graded levels of dried Sea buckthorn (Hippophaes rhamnoides) berries to broiler chickens

The aim of this study was to assess the effects of graded levels (0, 3, 6, 9 and 12 g/kg) of dry Sea buckthorn (SB) berries on growth performance, gastrointestinal tract (GIT) development, jejunal histomorphology, bird antioxidant status and caecal short-chain fatty acid concentration when fed to female Ross 308 broiler chickens. In addition, expression of cytokine biomarker genes in the jejunum was evaluated. The five experimental diets were fed from 7 to 21 days age to 8 pens (two birds in each) following randomisation. Feeding SB did not influence bird growth performance (p > .05). There was a linear decrease in butyric, acetic and valeric acid concentrations in caecal digesta (p < .05) and a decrease (p < .05) in crypt depth. The expression of IFNG and CD40LG responded quadratically (p < .05), peaking at 6–9 g/kg dietary inclusion of SB, respectively. Other studied variables were not affected by dietary SB inclusion (p > .05). Feeding dry SB berries up to 12 g/kg of diet did not improve the zootechnical variables of healthy commercial-strain broilers in this study.