Responses of growth performance,antioxidant function,small intestinal morphology and mRNA expression of jejunal tight junction protein to dietary iron in yellow-feathered broilers

This study aimed to investigate the dose-effect of iron on growth performance,antioxidant function.intestinal morphology,and mRNA expression of jejunal tight junction protein in 1-to21-d-old yellow-feathered broilers.A total of 7201-d-old yellow-feathered maleb roilers were allocated to 9 treatments with 8 replicate cages of 10 birds per cage.The dietary treatments were consisted of a basal diet(contained 79.6 mg Fe kg^(-1))supplemented with 0,20,40,60,80,160,320,640,and 1,280 mg Fe kg^(-1)in the form of FeSO_(4)·7H_(2)O.Compared with the birds in the control group,birds supplemented with 20mg Fe kg^(-1)had higher average daily gain(ADG)(P<0.0001).Adding 640 and 1,280 mg Fe kg^(-1)significantly decreased ADG(P<0.0001)and average daily feed intake(ADFI)(P<0.0001)compared with supplementation of 20mg Fe kg^(-1).Malondialdehyde(MDA)concentration in plasma and duodenum increased linearly(P<0.0001),but MDA concentration in liver and jejunum increased linearly(P<0.05)or quadratically(P<0.05)with increased dietary Fe concentration.The villus height(VH)in duodenum and jejunum,and the ratio of villus height to crypt depth(V/C)in duodenum decreased linearly(P?0.05)as dietary Feincreased.As dietary Fe increased,the jejunal relative mRNA abundance of claudin-1 decreased linearly(P=0.001),but the jejunal relative mRNA abundance of zona occludens-1(ZO-1)and occludin decreased linearly(P?0.05)or quadratically(P?0.05).Compared with the supplementation of 20 mg Fe kg^(-1),the supplementation of640 mg Fe kg^(-1)or higher increased(P?0.05)MDA concentrations in plasma,duodenum,and jejunum,decreased VH in the duodenum and jejunum,and the addition of 1,280 mg Fe kg^(-1)reduced(P?0.05)the jejunal tight junction protein(claudin-1,ZO-1,occludin)mRNA abundance.In summary,640 mg of supplemental Fe kg^(-1)or greater was associated with decreased growth performance,increased oxidative stress,disrupted intestinal morphology,and reduced mRNA expression of jejunal tight junction protein.

Molecular cloning and ontogenesis expression of fatty acid transport protein-1 in yellow-feathered broilers

Fatty acid transport protein-1 （FATP-1） is one of the important transporter proteins involved in fatty acid transmembrane transport and fat deposition. To study the relationship between FATP-1 mRNA expression and fat deposition, chicken （Gallus gallus） FATP-1 sequence was first cloned by rapid amplification of cDNA ends （RACE）. Tissue samples of chest muscle, leg muscle, subcutaneous fat, and abdominal fat were collected from six male and six female broilers each, at 22 days, 29 days, and 42 days, respectively. The tissue specificity and ontogenesis expression pattern of the FATP-1 mRNA of yellow-feathered broilers was studied by real-time reverse transcription polymerase chain reaction （RT-PCR）, and the fat deposition laws in different tissues were also compared. A 2,488 bp cDNA sequence of chicken FATP-1 was cloned by RACE （GenBank accession no. DQ352834）, including 547 bp 3＇ end untranslated region （URT） and 1,941 bp open reading frame （ORF）. Chicken FATP-1 encoded 646 amino acid residues, which shared 83.9% and 83.0% identity with those of human and rat, respectively. The results of quantitative PCR demonstrated a constant FATP-1 mRNA expression level in the chest muscle and subcutaneous fat of both male and female broilers at three stages, whereas the expression level of the FATP-1 mRNA in the leg muscle at 42 days was significantly higher than that at 22 days or 29 days. In the abdominal fat of male broilers, the gene expression significantly increased with age, whereas the female broilers showed a dramatic downregulation of FATP-1 expression in abdominal fat at 42 days. This suggested a typical tissue-and gender-specific expression pattern of chicken FATP-1, mediating the specific process of fatty acid transport or utilization in muscle and adipose tissues.

Dietary L-theanine alleviated lipopolysaccharide-induced immunological stress in yellow-feathered broilers

L-theanine, a natural nonprotein amino acid with a high biological activity, is reported to exert anti-stress properties. An experiment with a 3 ? 2 factorial arrangement was conducted to investigate the effects of dietary L-theanine on growth performance and immune function in lipopolysaccharide(LPS)-challenged broilers. A total of 432 one-day-old male yellow-feathered broilers were randomly assigned to 3 dietary treatments(control, antibiotic and L-theanine diets) with 2 subgroups of each(6 replicate cages;12 birds/cage). Birds from each subgroup of the 3 dietary treatments were intra-abdominally injected with the same amount of LPS or saline at 24, 25, 26 d of age. Both dietary L-theanine and antibiotic improved(P < 0.05) the growth performance of birds before LPS injection(d 1 to 21). The effect of dietary L-theanine was better(P < 0.05) than that of antibiotic. Lipopolysaccharide decreased feed intake(FI) and body weight gain(BWG) from d 22 to 28(P < 0.05), BWG and feed to gain ratio(F:G) from d 29 to 56(P < 0.05), increased mortality in different growth periods(P < 0.05), elevated the levels of serum cortisol, a1-acid glycoprotein(a1-AGP), interleukin-6(IL-6) on d 24 and 25(P < 0.05), reduced immune organ indexes and contents of jejunal mucosal secretory immunoglobulin A(s Ig A) on d 28(P < 0.05). The decreased FI and BWG, as well as increased F:G and mortality in LPS-challenged birds, were alleviated by dietary L-theanine or antibiotic from d 29 to 56 and from d 1 to 56. Dietary L-theanine mitigated the elevated serum a1-AGP level on d 25, serum IL-6 concentration on d 24 and 26, and the decreased jejunal mucosal s Ig A content on d 28 of the LPS-challenged birds. The results indicated that L-theanine had potential to alleviate LPS-induced immune stress in broilers.

Dietary supplementation with pioglitazone hydrochloride and L-carnosine improves the growth performance,muscle fatty acid profiles and shelf life of yellow-feathered broiler chickens

The present study aimed to investigate the effects of dietary pioglitazone hydrochloride(PGZ)and L-carnosine(LC)supplementation on the growth performance,meat quality,antioxidant status,and meat shelf life of yellow-feathered broiler chickens.Five hundred broiler chickens were randomly assigned into 4 experimental diets using a 2×2 factorial arrangement with 2 PGZ supplemental levels(0 and 15 mg/kg)and 2 LC supplemental levels(0 and 400 mg/kg)in basal diets for 28 d.The feed-to-gain ratio decreased whereas the average daily gain increased with PGZ supplementation.Greater dressing per-centages,contents of intramuscular fat(IMF)in breast and thigh muscles,C18:3n-6,C18:1n-9 and monounsaturated fatty acid(MUFA)percentages of thigh muscle were observed with PGZ addition.Additionally,significant synergistic effects between PGZ and LC on the C18:1n-9 and MUFA contents were found.Supplementation with LC decreased drip loss,cooking loss and total volatile basic nitrogen,and increased the redness(a*)value,the superoxide dismutase and glutathione peroxidase activities in thigh muscles.Moreover,the malondialdehyde content decreased when diets were supplemented with LC,and there was a synergistic effect between PGZ and LC.Additionally,the mRNA abundance of lipogenesis-related genes,such as peroxisome proliferator-activated receptor y(PPARγ),PPARγco-activator 1αand fatty acid-binding protein 3,increased with PGZ supplementation,and relevant anti-oxidation genes,such as nuclear factor erythroid-2-related factor 2 and superoxide dismutase 1,were enhanced with LC supplementation.In conclusion,the results indicated that the supplementation of PGZ and LC could improve the growth performance,antioxidant ability,IMF content,and meat shelf life of yellow-feathered broiler chickens.