Xinheng Zhang

Effects of outdoor access on growth performance, carcass composition, and meat characteristics of broiler chickens

The present study was conducted to investigate the effects of outdoor access on the growth performance and meat quality of broiler chickens. Thirty-five-day-old female broilers were divided into 3 groups with 6 replicates of 124 birds each: (1) birds reared indoors (control group); (2) birds reared with outdoor access since 36 d of age (35-d group); and (3) birds reared with outdoor access since 71 d of age (70-d group). The results showed that outdoor access had no effect on growth performance, carcass yield, meat yield, muscle protein content, muscle fiber characteristics, or water-holding capacity (P > 0.05). Chickens from the outdoor access groups had a better appearance and degree of evenness. Birds in the outdoor access groups had a significantly lower lung percentage than birds in the control group (P < 0.05), whereas the kidney percentage of the 35-d group was significantly lower than that of the control group (P < 0.05). The meat of chickens in the 35-d group had higher L* values than that of the control group (P < 0.05). Compared with rearing indoors, outdoor access significantly increased the shear force of the breast muscle in both the 35 d and 70-d group (P < 0.05) and decreased the fat content of the thigh muscle in the case of 35-d group (P < 0.05). Birds in the 35-d group also had lower fat content in their thigh muscles than did the birds in the 70-d group (P < 0.05). The thigh muscles of the birds in the 35-d group showed lower levels of MUFA and higher levels of PUFA than those of the control group and 70-d group (P < 0.05). In conclusion, outdoor access had no effect on growth performance and yield traits but could improve the meat quality; birds reared with outdoor access from 36 d of age had better appearance and meat quality than those with outdoor access from 71 d of age.

Effects of combinations of ochratoxin A and T-2 toxin on immune function of yellow-feathered broiler chickens

The study was to investigate the effects of combinations of ochratoxin A (OTA) and T-2 toxin on immune function of yellow-feathered broiler chickens. Three-hundred sixty 21-d-old broiler chickens were randomly assigned to 3 groups, each group consisting of 4 duplicates each with 30 chickens. The 3 groups were fed the following diets for 3 wk: C, basal diet (control, mycotoxin-free); L, basal diet + 0.25 mg/kg of OTA, 0.5 mg/kg of T-2 toxin; and H, basal diet + 0.5 mg/kg of OTA, 1 mg/kg of T-2 toxin. Body weight and feed consumption of chickens in the H group decreased significantly (P < 0.05) during the study, but their efficiency of feed utilization was not affected. The feeding of OTA-T-2 toxin diets decreased not only the relative weight of spleen, thymus, and bursa of Fabricius, but also serum concentrations of total protein, albumin, and globulin. Meanwhile, the feeding of OTA-T-2 toxin diets elevated the activities of serum gamma-glutamyltransferase, asparate aminotransferase, and alanine aminotransferase. The results of methyl thiazolyl tetrazolium reduction assay indicated that the mitogenic responses of peripheral blood lymphocytes were diminished significantly (P < 0.05 for L group; P < 0.01 for H group). Flow cytometry was employed to determine 3 indexes in peripheral blood lymphocyte of broilers, including CD4(+)/CD3(+), CD8(+)/CD3(+), and CD4(+)/CD8(+). Both toxin treatments significantly decreased (P < 0.01) CD4(+)/CD3(+) and CD4(+)/CD8(+) ratios. In summary, the combination of OTA and T-2 toxin impaired chick immune function even at combined concentrations as low as 0.25 mg/kg of OTA and 0.5 mg/kg of T-2 toxin.

Immunopathological effects of ochratoxin A and T-2 toxin combination on broilers

The purpose of this study was to investigate the immunopathological effects of combinations of ochratoxin A (OTA) and T-2 toxin on broilers. Four hundred eighty 1-d-old broilers were randomly assigned to 4 groups, each group consisting of 4 duplicates each with 30 broilers. The 4 groups were fed the following diets for 4 wk: group 1=basal diet (control, mycotoxin-free); group 2=basal diet+2,000 mg/kg of Mycofix Plus; group 3=basal diet+0.25 mg/kg of OTA and 0.5 mg/kg of T-2; and group 4=basal diet+0.25 mg/kg of OTA and 0.5 mg/kg of T-2+2,000 mg/kg of Mycofix Plus. The feeding of OTA-T-2 toxin diets reduced (P<0.05) the level of anti-Newcastle disease virus antibody titers by 10.4%. When broilers were administered lipopolysaccharide, the results of real-time PCR showed that broilers fed OTA-T-2 toxin reduced the cytokine mRNA expression levels of interleukin-2 and interferon-gamma to some extent but not significantly (P>0.05). The concentrations of interleukin-2 and interferon-gamma in serum were significantly decreased (P<0.05) by OTA-T-2 toxin combination. Histopathological studies demonstrated that OTA-T-2 toxin combination caused abnormalities in the thymus, bursa of Fabricius, spleen, and liver. Ochratoxin A-T-2 toxicity could be counteracted by Mycofix Plus partially but not significantly (P>0.05). The concentrations of OTA and T-2 toxin used in this study are under the maximum tolerated levels recommended by Canadian Food Inspection Agency. Our study clearly put the standard and detoxification method for these toxins into question. We suggest that it may be time to reduce the maximum allowable limits of OTA and T-2 mycotoxins in feeds to improve animal health and the safety of the food chain.

Complete genome sequence analysis of a recent chicken anemia virus isolate and comparison with a chicken anemia virus isolate from human fecal samples in China.

ABSTRACT A new isolate of chicken anemia virus (CAV) was designated GD-1-12. GD-1-12 was isolated from a 12-day-old commercial broiler in Guangdong province, China, in 2012. The GD-1-12 CAV caused high mortality, severe anemia, thymic atrophy, and subcutaneous hemorrhage in commercial broilers. Here, we report the complete genome sequence of GD-1-12 CAV and comparison with the complete genome sequence of another CAV that was isolated from human fecal samples in China (GenBank accession no. JQ690762). The genomes of the two CAV isolates shared high homology, although a deletion was identified by comparison. The findings from this study provide additional insights into the molecular characteristics of the CAV genomes and should advance knowledge for continuous monitoring and, perhaps, preventing the spread of the virus in chickens as well as in humans.

Identification of a Chicken Anemia Virus Variant-Related Gyrovirus in Stray Cats in China, 2012

The chicken anemia virus (CAV), is a known member of the genus Gyrovirus and was first isolated from chickens in Japan in 1979. Some reports have also demonstrated that CAV can be identified in human stool specimens. In this study, a variant of CAV was detected using PCR with CAV-based primers in fecal samples of stray cats. The genome of CAV variant was sequenced and the results suggest that it could be a recombinant viral strain from parental CAV strains JQ690762 and AF311900. Recombination is an important evolutionary mechanism that contributes to genetic diversification. These findings indicate that CAV variant might have originated from CAV-infected chickens. The epidemiology and pathogenesis of this novel virus remains to be elucidated. This study underscores the importance of CAV surveillance and it presents the first evidence suggesting the possibility of CAV homologous recombination in cat.

Phylogenetic and molecular characterization of chicken anemia virus in southern China from 2011 to 2012

Chicken anemia virus (CAV) is an important pathogen that causes severe immunosuppression in young chickens. We have characterized 13 CAVs isolated from different commercial farms in southern China between 2011 and 2012. We discovered 92 variable residues compared to 37 other CAV complete genome sequences from other parts of the world listed in GenBank; these residues have not been previously observed. All of the Chinese CAV genomes that were characterized in this study had a glutamine at position 394, a hallmark of highly pathogenic CAVs. We also discovered that intra-group genetic recombination plays a role in generating genetic diversity in natural populations of CAV. The GD-J-12 isolate was a possible recombinant between GD-C-12 and GD-M-12 in the genomic region that encompassed both the coding and non-coding regions.

Isolation, identification and evolution analysis of a novel subgroup of avian leukosis virus isolated from a local Chinese yellow broiler in South China.

Avian leukosis virus (ALV) causes high mortality associated with tumor formation and decreased fertility, and results in major economic losses in the poultry industry worldwide. Recently, a putative novel ALV subgroup virus named ALV-K was observed in Chinese local chickens. In this study, a novel ALV strain named GD14LZ was isolated from a Chinese local yellow broiler in 2014. The proviral genome was sequenced and phylogenetically analyzed. The replication ability and pathogenicity of this virus were also evaluated. The complete proviral genome sequence of GD14LZ was 7482 nt in length, with a genetic organization typical of replication-competent type C retroviruses lacking viral oncogenes. Sequence analysis showed that the gag, pol and gp37 genes of GD14LZ have high sequence similarity to those of other ALV strains (A–E subgroups), especially to those of ALV-E. The gp85 gene of the GD14LZ isolate showed a low sequence similarity to those other ALV strains (A–E subgroups) but showed high similarity to strains previously described as ALV-K. Phylogenetic analysis of gp85 also suggested that the GD14LZ isolate was related to ALV-K strains. Further study showed that this isolate replicated more slowly and was less pathogenic than other ALV strains. These results indicate that the GD14LZ isolate belongs to the novel subgroup ALV-K and probably arose by recombination of ALV-K with endogenous viruses with low replication and pathogenicity. This virus might have existed in local Chinese chickens for a long time.

Circular RNA alterations are involved in resistance to avian leukosis virus subgroup-J-induced tumor formation in chickens

Avian leukosis virus subgroup (ALV-J) is an oncogenic neoplasm-inducing retrovirus that causes significant economic losses in the poultry industry. Recent studies have demonstrated circular RNAs (circRNAs) are implicated in pathogenic processes; however, no research has indicated circRNAs are involved in resistance to disease. In this study, over 1800 circRNAs were detected by circRNA sequencing of liver tissues from ALV-J-resistant (n = 3) and ALV-J-susceptible chickens (n = 3). 32 differentially expressed circRNAs were selected for analyzing including 12 upregulated in ALV-J-resistant chickens and 20 upregulated in ALV-J-susceptible chickens, besides, the top five microRNAs (miRNAs) for 12 upregulated circRNAs in ALV-J-resistant chickens were analyzed. Gene ontology and KEGG pathway analyses were performed for miRNA target genes, the predicted genes were mainly involved in immune pathways. This study provides the first evidence that circRNA alterations are involved in resistance to ALV-J-induced tumor formation. We propose circRNAs may help to mediate tumor induction and development in chickens.

Effects of lycopene supplementation in both maternal and offspring diets on growth performance, antioxidant capacity and biochemical parameters in chicks

This study investigated the effects of different supplementation ways of lycopene during pre-hatch (from the diet of hens) and post-hatch (from the diet of progeny) on production performance, antioxidant capacity and biochemical parameters in chicks. In total, 360 hens were fed diets supplemented with 0 (control group) or 40 mg lycopene/kg diet. From 28 to 34 days after the start of supplementation (30 weeks old), 650 qualified eggs were collected to artificial incubation. In this trial, 2 × 2 factorial designs were used. Male chicks hatched from hens fed with 0 or 40 mg lycopene/kg diet were fed a diet containing either 0 or 40 mg lycopene/kg diet. The results showed that, relative to control, in ovo-deposited lycopene significantly increased chick birth body weight, improved liver total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) and glutathione to oxidized glutathione ratio (GSH: GSSG), and significantly declined liver malondialdehyde (MDA) level and increased liver lycopene content during 0-14 days after hatching. On days 14 after hatching, dietary lycopene in diet began to take over gradually. Both supplementation ways of lycopene increased immune organ index, serum high-density lipoprotein (HDL) cholesterol, villus length and villus/crypt in duodenum, jejunum and ileum. Data in this study suggested lycopene supplementation could improve antioxidant capacity and immune function, and regulate lipid metabolism in chicks.

Molecular characterization, phylogeny analysis and pathogenicity of a Muscovy duck adenovirus strain isolated in China in 2014.

This study aimed to characterize a novel adenovirus (AdV) isolated from diseased Muscovy ducks in China. After the AdV was successfully propagated in duck embryo fibroblasts, the morphological and physicochemical properties of the virions were studied by electron microscopy and different tests. The results of the analyses were in conformity with AdV properties. The full genome sequence was determined and analyzed. The new isolate (named CH-GD-12-2014) shared over 91% sequence identity with duck AdV-2 representing the species Duck aviadenovirus B. The most important distinguishing feature between the two DAdV strains was the presence of a second fiber gene in the Chinese isolate. Phylogeny reconstruction confirmed the affiliation of the virus with goose and duck AdVs in the genus Aviadenovirus. Experimental infection resulted in embryo death, and intramuscular inoculation provoked morbidity and mortality among ducks and chickens.