成骨细胞在骨骼发育和矿化中扮演重要角色。然而，对肉仔鸡胫骨成骨细胞原代培养模型的建立和评价研究很少。因此，在目前研究中通试验1采用组织块法从1日龄AA肉公鸡胫骨中分离成骨细胞，通过细胞形态、碱性磷酸酶(ALP)染色和茜素红染色进行鉴定；试验2分别在成骨细胞持续培养第4、8、12、16、20、24、28和32天对原代培养的肉仔鸡胫骨成骨细胞的活力和矿化进行评价。

试验1结果表明，肉仔鸡胫骨原代成骨细胞呈梭形、三角形或多边形。ALP染色后95%以上细胞呈蓝黑色，连续培养4天后形成矿化结节；试验2结果表明，在整个培养过程中，虽然培养时间对乳酸脱氢酶(LDH)活性有影响(P=0.0012)，但LDH活性保持在相对稳定的水平。另外，培养时间显著影响(P≤0.0001)矿化结节的数量和面积比例，且随着培养时间的增加，其矿化结节数量呈线性和二次曲线增长(P<0.04)，并在24-32天内保持稳定。根据矿化结节数量和面积比例的最佳拟合断线模型或二次曲线模型(P<0.0001)评价最佳培养时间分别为17和26天。

结果表明，采用组织块法成功构建了肉仔鸡胫骨成骨细胞原代培养模型，其具有典型的成骨细胞形态、ALP活性和矿化特征，在持续培养4-32天内能保持相对稳定的活力，胫骨原代成骨细胞的最佳培养时间为17-26天。因此，该方法建立的肉鸡胫骨成骨细胞原代培养模型可用于进一步研究肉鸡骨骼发育和矿化的潜在机理。

本研究成功构建了稳定、可靠的肉鸡胫骨成骨细胞原代培养模型。

本研究旨在确定II b型钠磷协同转运载体（NaP-IIb）和无机磷转运载体2（PiT2）是否直接参与原代培养肉鸡鸡胚十二指肠上皮细胞磷吸收。针对NaP-IIb和PiT2基因设计小干扰RNA（siRNA）序列，合成并转染至原代培养肉鸡鸡胚十二指肠细胞，通过抑制效率分析筛选出对NaP-IIb和PiT2基因干扰有效的siRNAs，用于后续磷吸收试验。转染有效抑制NaP-IIb或PiT2的siRNA至原代培养肉鸡鸡胚十二指肠上皮细胞，待Transwell培养板上的细胞汇合成单层后，将磷转运载体基因（NaP-IIb或PiT2）沉默细胞或未转染细胞在含有0或0.25 mM磷（以KH₂PO₄形式引入）的吸收培养基中孵育，以检测十二指肠上皮细胞对磷的吸收。结果表明，si-1372和si-890分别为抑制NaP-IIb和PiT2基因表达的有效siRNA。与无磷组相比，添加磷可显著提高（P=0.065）原代培养肉鸡鸡胚十二指肠上皮细胞PiT2蛋白丰度，并增强（P<0.0001）其磷吸收。另外，NaP-IIb沉默显著降低（P=0.07）原代培养肉鸡鸡胚十二指肠上皮细胞磷吸收，但PiT2沉默对其并无影响（P=0.345）。综上所述，NaP-IIb可能直接参与肉鸡十二指肠上皮细胞磷吸收，而PiT2并未直接参与。

骨形态蛋白（bone morphogenetic protein，BMP）和促分裂原活化蛋白激酶（mitogen-activated protein kinase，MAPK）信号通路在调控骨骼形成和发育中扮演着重要角色。然而，目前关于肉鸡饲粮不同非植酸磷水平（non-phytate phosphorus，NPP）对这些信号通路及其与骨磷沉积和骨骼发育相关性的影响尚不清楚。因此，本试验旨在研究饲粮添加磷对肉鸡BMP和MAPK信号通路及其与骨磷沉积和骨骼发育相关性的影响。将800只1日龄AA肉公鸡按体重随机分成5个处理组，每个处理组8个重复。5个处理组饲粮的NPP水平分别为：1-21日龄：0.15、0.25、0.35、0.45和0.55%，22-42日龄：0.15、0.22、0.29、0.36和0.43%。试验结果表明，随着饲粮NPP水平的增加，14和28日龄肉鸡胫骨细胞外信号调节激酶1（Extracellular Signal-Regulated Kinase 1，ERK1）的mRNA表达、14日龄肉鸡胫骨磷酸化ERK1及28和42日龄肉鸡胫骨BMP2的蛋白表达线性降低（P<0.04），而42日龄肉鸡胫骨c-Jun氨基末端激酶1（c-Jun N-terminal kinase 1，JNK1）的mRNA表达线性增加（P<0.02）。在14日龄，肉鸡胫骨灰分总磷沉积量、骨矿物质含量、骨密度、骨强度及胫骨灰分与ERK1和JNK1 mRNA表达及磷酸化ERK1呈显著负相关（r=-0.726~-0.359，P<0.05），而胫骨碱性磷酸酶活性和骨钙素含量与ERK1 mRNA表达及磷酸化ERK1呈显著正相关（r=0.405~0.665，P<0.01）。在28日龄，肉鸡的胫骨灰分总磷沉积量、骨矿物质含量、骨密度、骨强度及胫骨灰分与ERK1 mRNA表达和BMP2蛋白表达呈显著负相关（r=-0.518~-0.370，P<0.05），而与胫骨碱性磷酸酶呈显著正相关（r=0.382~0.648，P<0.05）。结果表明，ERK1和JNK1 mRNA表达、BMP2蛋白表达及磷酸化ERK1与胫骨灰分总磷沉积量、骨矿物质含量、骨密度、骨强度及胫骨灰分呈显著负相关，但是与胫骨碱性磷酸酶活性和骨钙素呈显著正相关，表明肉鸡骨磷沉积和骨骼发育受BMP和MAPK信号通路的调节。本研究揭示了肉鸡骨磷沉积和骨骼发育受BMP和MAPK信号通路调节的机制。

本试验研究了不同硒源和硒水平对肉鸡生长性能、胴体性能、抗氧化性能及肉品质的影响。试验采用2×2+1两因子完全随机试验设计，将320只1日龄AA商品肉仔鸡按体重随机分为5个处理组，添加的2种硒源分别为亚硒酸钠和酵母硒，2个硒添加水平分别为0.20和0.40 mg/kg，4个处理组共用一个不加硒的对照组。试验期为42天。研究结果表明，与对照组相比，添加硒可显著降低肉仔鸡前后期耗料/增重比、后期死亡率和42日龄肉仔鸡腿肌中丙二醛含量，显著提高肉仔鸡后期平均日增重和日采食量、42日龄肉仔鸡全净膛率和腹脂率、胸肌和腿肌中硒含量和谷胱甘肽过氧化物酶（GSH-Px）活性。酵母硒形态有机硒在提高腿肌pH值及降低剪切力方面的效果显著优于亚硒酸钠形态无机硒。此外，添加0.4 mg/kg硒对降低腿肌剪切力及提高胸肌和腿肌GSH-Px活性的效果明显优于添加0.2 mg/kg硒。当硒添加水平由0.2提高到0.4 mg/kg时，亚硒酸钠形态无机硒不能增加胸肌和腿肌中硒含量，而酵母硒形态有机硒则显著提高了胸肌和腿肌中硒含量。综上所述，在肉仔鸡饲粮中添加硒可以提高肉鸡生产性能，抗氧化能力和肌肉硒含量；相比于亚硒酸钠形态无机硒，酵母硒形态有机硒在提高肉鸡肉品质方面效果更佳。

An experiment was conducted to investigate the effect of dietary supplementation with flavonoid from Scutellaria baicalensis Georgi (SBGFN) as SBGFN-zinc (SBGFN-Zn) on growth performance, meat quality, immune responses and antioxidation of broilers.  A total of 450 one-d-old Arbor Acres male broilers were randomly allocated to 5 treatments with 6 replicates of 15 birds per replicate for each treatment in a completely randomized design.  Birds were fed a SBGFN-unsupplemented corn-soybean meal basal diet (control) or the basal diet supplemented with 60, 120, 180 or 240 mg SBGFN kg^–1 from SBGFN-Zn for 42 d.  Dietary SBGFN supplementation affected (P<0.03) drip loss in thigh muscle, total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) activity in liver of broilers at 42 d of age.  Chicks fed the diets supplemented with 120, 180 and 240 mg SBGFN kg^–1 had lower (P<0.03) drip loss of thigh muscle than those fed the control diet.  Chicks fed the diet supplemented with 180 mg SBGFN kg^–1 had higher (P<0.03) liver T-SOD and GSH-Px activity than those fed the diets supplemented with 0, 60 and 120 mg SBGFN kg^–1.  The results from the present study indicate that dietary supplementation with 180 mg SBGFN kg^–1 as SBGFN-Zn improved both meat quality and antioxidative ability of broilers.   

Two experiments were conducted to investigate the effect of in ovo zinc (Zn) injection on the embryonic development, tissue Zn contents, antioxidation and related gene expressions of fertilized eggs of Arbor Acres broiler breeders.  Experiment 1 was conducted to determine an optimal embryonic age for early in ovo injection.  A total of 720 fertilized eggs with similar weights were randomly allotted to 4 treatments with 6 replicates per treatment and 30 eggs per replicate in a completely randomized design.  The eggs were injected with 0.1 mL sterilized water at 3, 6 and 9 embryonic days of incubation (E3, E6 and E9) or non-injection (the control), respectively.  The results from experiment 1 showed that E3 and E6 injections increased (P<0.05) the embryonic mortalities, and decreased (P<0.05) hatchabilities compared to the non-injected control, but no differences (P>0.05) between E9 injection and the non-injected control were observed in either embryonic mortality or hatchability.  The findings suggest that the E9 is the optimal embryonic age for early in ovo injection.  In experiment 2, a total of 672 fertilized eggs with similar weights were randomly allocated to 7 treatments with 6 replicates per treatment and 16 eggs per replicate in a completely randomized design.  The eggs were injected with 0 (the negative control), 50, 100, 150, 200, or 250 μg Zn/egg as reagent grade ZnSO₄·7H₂O in a 0.1-mL solution, or non-injection (the positive control), respectively at E9–10.  The results from the experiment 2 demonstrated that no differences (P>0.05) among 50 and 100 μg Zn/egg groups and the negative control were observed in the embryonic mortality and hatchability, however, the injection of 200 μg Zn/egg increased (P<0.05) the embryonic mortality, and injections of 150 and 200 μg Zn/egg decreased (P<0.05) hatchabilities compared with the controls.  The embryonic tibia Zn contents at E20 were increased (P<0.05) by injections of 150, 200 and 250 μg Zn/egg.  Zinc injection did not affect (P>0.05) malonaldehyde (MDA) contents, copper- and Zn-containing superoxide dismutase (CuZnSOD) activities and mRNA expression levels in the liver and heart of chick embryos at E15 and E20.  Compared with the negative control, injections of 50, 150 and 200 μg Zn/egg up-regulated (P<0.05) the metallothionein (MT) mRNA expression levels in the embryonic liver at E20.  These results indicated that in ovo Zn injections increased Zn contents in the embryonic tibia and MT mRNA expression levels in the embryonic liver at E20, however, injections of 150–200 µg Zn/egg were harmful to the embryonic development.

  In the present study, the effect of manganese (Mn) on antioxidant status and the expression of the manganese superoxide dismutase (MnSOD) gene in cultured primary myocardial cells collected from the chick embryos was investigated.  The hypothesis that Mn supplementation would enhance the expression of MnSOD in cultured primary myocardial cells of chick embryos was tested.  Eggs collected from Mn-depleted Arbor Acres laying breeder hens were incubated for 10 days and then myocardial cells were isolated and cultivated for 8 days.  The embryonic myocardial cells on day 6 were treated with Mn in the cell culture medium at different time points when the proportion of cells showing spontaneous contraction was over 95% after the 3-day primary culture.  A completely randomized design involving a 3 Mn levels (0, 0.5 and 1.0 mmol L^–1)×3 incubation time points (12, 24 and 48 h) factorial arrangement of treatments (n=6) was used in the current experiment.  The results showed that MnSOD activity and mRNA expression level were induced by Mn and increased with incubation time, which supported the hypothesis that Mn would enhance the expression of the MnSOD gene, and thus might protect myocardial cells from oxidative stress during the chick embryonic development.

An experiment was conducted to investigate the effect of dietary supplementation of xylo-oligosaccharides (XOS) on growth performance, meat quality, immune functions, duodenal morphology and intestinal microbial populations of broilers fed a conventional corn-soybean meal basal diet. A total of 450 1-day-old commercial Arbor Acres male broiler chicks were randomly allocated by bodyweight to 1 of 5 treatments with 6 replicate cages (15 broilers per cage) for each of 5 treatments in a completely randomized design. Chicks were fed the basal corn-soybean meal diets supplemented with 0, 25, 50, 75, or 100 mg of XOS kg–1 of diet, respectively, for an experimental duration of 42 days. The results showed that supplementation of XOS affected feed conversion rate (feed/gain, F/G) during days 22–42 and 1–42 (P<0.03), drip loss in thigh muscle (P=0.02), and duodenal crypt depth (P=0.005) on day 42, but had no effect (P>0.05) on all other measured indices. The chicks fed the diet supplemented with 100 mg of XOS kg–1 had the lowest (P<0.05) F/G and drip loss in thigh muscle. The drip loss in thigh muscle decreased linearly (P=0.003) as the supplemented XOS increased. Duodenal crypt depth decreased (P<0.05) at the supplemental level of 75 mg of XOS kg–1. The results indicate that dietary supplementations of 75 and 100 mg of XOS kg–1 are beneficial to broilers fed a conventional corn-soybean meal diet.

An experiment was carried out to investigate the relative bioavailability of tribasic zinc (Zn) sulfate relative to Zn sulfate for broilers fed a conventional corn-soybean meal diet. A total of 504 1-d-old Arbor Acres commercial male chicks were randomly assigned by body weight of birds to one of seven treatments involving a 2×3 factorial arrangement with three levels of added Zn (30, 60, or 90 mg of Zn kg–1) and two Zn sources (tribasic Zn sulfate and Zn sulfate) plus a control with no added Zn for an experimental phase of 14 d. Plasma Zn, tibia ash Zn, pancreas Zn, and pancreas metallothionein (MT) messenger RNA (mRNA) were analyzed at 6 or 14 d of age post-hatching. The results showed that plasma Zn, tibia ash Zn, pancreas Zn, and pancreas MT mRNA increased linearly (P<0.002) as dietary Zn concentration increased at 6 or 14 d of age. The R2 for a linear model was greater on d 6 than on d 14 for the above 4 responsive criteria, and among these indices, the fitting of the tibia ash Zn concentration was the best (R2=0.99). Therefore, based on slope ratios from the multiple linear regressions of the above 4 indices of the birds at 6 d of age on daily intake of dietary Zn, the bioavailabilities of tribasic Zn sulfate relative to Zn sulfate (100%) were 95.6% (P=0.18), 83.5% (P=0.01), 87.9% (P=0.53), and 75.9% (P=0.38) for the tibia ash Zn, pancreas Zn, plasma Zn, and pancreas MT mRNA, respectively. The results indicated that generally, Zn from tribasic Zn sulfate was as available as Zn from Zn sulfate for broilers.