鸡CSRP3基因编码区SNPs及其与肌纤维性状的相关分析

CSRP3基因是肌细胞分化所必需的正向调节因子,在肌肉生长发育过程中发挥重要作用。研究以220只63日龄(上市日龄)"花山麻鸡"为研究素材,应用PCR扩增与测序首次扫描了鸡CSRP3基因编码区SNPs,并将其与腓肠肌外侧头肌纤维平均面积、直径和密度等肌纤维性状进行关联分析。结果显示:在鸡CSRP3基因编码区共发现G180A、C240T、G246A、C252T、C546T、A633G 6个SNPs,均为同义突变;相关分析表明,A633G位点的多态性与花山麻鸡腓肠肌外侧头肌纤维平均面积存在极显著的基因型效应(P<0.01),与肌纤维平均直径、肌纤维平均密度存在显著的基因型效应(P<0.05)。结果表明,CSRP3基因可作为影响鸡骨骼肌生长发育的候选基因,可选择CSRP3基因编码区的633位点作为鸡骨骼肌肌纤维性状的分子标记辅助选择的候选标记。     

Effects of muscle type on beef taste‐traits assessed by an electric sensing system

To assess the role of muscle fiber type in beef taste‐traits, we analyzed cooked meats from bovine masseter, diaphragm, psoas major, longissimus thoracis, and semitendinosus muscles with an electric taste sensing system (INSENT SA402B). The system is composed of five taste sensors of polymer membranes fixing different lipids. The sensors, CT0, CA0, AAE, C00 and AE1 are designed to respond to the individual tastes of salty, sour, umami, bitter and astringent, respectively. The system found significant differences in the converted outputs of CA0 (cvCA0), C00 (cvC00) and AE1 (cvAE1) among the bovine muscles. The slow‐type muscles (masseter and diaphragm) showed lower cvCA0, higher cvC00, and higher cvAE1 than did the fast‐type muscles (psoas major, longissimus thoracis, and semitendinosus). Lactic acid content was different among muscle types and was highly related to the cvCA0 output and pH. carbonyl compounds and free fatty acids were higher in the slow‐type muscles. Free fatty acids were major components causing the difference in the C00 output among the muscle types. Iron content was also different among the muscle types and related to the cvC00 and cvAE1 outputs. These results suggested that the muscle fiber type affects the beef taste characteristics.     

纤维和蛋白质对肠道健康和环境的影响

由于膳食纤维和蛋白质对肠道健康和环境都有潜在的有益或有害影响,因此,膳食纤维和蛋白质在猪肠道中的发酵是一个值得关注的问题.本文综述了近年来有关膳食纤维和蛋白质发酵对猪肠道环境的影响及其对猪粪和猪舍含氮气体和异味排放的影响,同时探讨了蛋白质发酵和相关代谢化合物的生产,与膳食纤维发酵、对肠道健康、细菌蛋白质合成和氮排泄的影...     

奶牛非饲草来源纤维营养研究进展

本文在总结分析国内外最新研究成果的基础上,对非饲草来源纤维(NFFS)对奶牛的营养作用和生理影响及其机理进行了综述,主要从NFFS部分替代饲草对奶牛生产性能、瘤胃草垫层和瘤胃发酵的影响,以及NFFS部分替代精料对饲料效率、生产性能和亚急性瘤胃酸中毒(SARA)奶牛生理的影响等方面进行论述,旨在为NFFS饲料在奶牛饲粮中的科学合理利用提供理论参考和依据。     

政策认知、执行力度与资源化利用满意度——基于河北省380家生猪养殖主体调研数据(上)

参与主体对于政策的评价是衡量政策实施效果的重要指标，探明政策参与主体满意度影响因素有助于了解主体自身需求，从而提高政策实施水平。文章基于对河北省380家生猪养殖主体调研数据，运用多元有序Logistic回归方法，分析生猪养殖主体自身政策认知以及相关政策执行力度对畜禽养殖主体废弃物资源化利用满意度的影响。结果表明：养殖主体资源化利用政策了解程度能够显著提升其资源化利用政策满意度；仅考虑养殖主体政策参与力度，随着参与力度增加，满意度亦会显著提升。但综合考虑其他因素，参与力度对于满意度提升效果则不再显著；养殖主体感知政策执行力度增加不利于政策满意度提升。此外，生猪养殖主体废弃物资源化利用政策了解程度增加，可以显著提升其报告资源化利用政策“满意”可能性。而单纯提高资源化利用政策执行力度并不能显著提高养殖主体资源化利用政策满意度。因此，要提高养殖主体政策满意度，应多渠道提升宣传力度，鼓励养殖主体积极参与，提高其参与意识，不断改善现有政策执行方式。     

谷物膳食纤维对高胆固醇饮食小鼠脂质代谢及肠道菌群的影响

本研究旨在探讨谷物膳食纤维(DF)对高胆固醇饮食小鼠的脂质代谢和肠道菌群的影响。选取C57BL/6J小鼠30只,并根据体重随机分为4组,分别饲喂基础饲粮(对照,CO组,n=8)、基础饲粮+5 g/kg DF(CO+DF组,n=8)、高脂高胆固醇饲粮(HF组,n=7)及高脂高胆固醇饲粮+5 g/kg DF(HF+DF组,n=7)。试验期8周,测定各组小鼠生长性能、血清和肝脏生化指标、粪便总胆固醇(TC)、短链脂肪酸(SCFA)、相关肝脏胆固醇和胆汁酸(BA)蛋白表达及肠道菌群。结果表明:1)CO+DF组的最终体重显著低于CO组(P<0.05),与HF组相比,CO组和HF+DF组的4周和最终体重均显著降低(P<0.05),肝脏和脂肪的重量显著减少(P<0.05)。且与HF组相比,DF+HF组摄食效率显著降低(P<0.05)。2)CO+DF组血清TC、甘油三酯(TG)含量及天冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性以及肝脏TC和TG含量显著低于CO组(P<0.05),CO组和HF+DF组显著低于HF组(P<0.05),粪便TC含量仅在HF+DF组显著低于HF组(P<0.05)。3)DF对肝脏胆固醇调节元件结合蛋白-2(SREBP-2)、3-羟基-3-甲基戊二酰辅酶A还原酶(HMGR)、肝脏X受体α(LXRα)、微管相关蛋白1轻链3-Ⅰ(LC3-Ⅰ)和微管相关蛋白1轻链3-Ⅱ(LC3-Ⅱ)蛋白表达没有显著影响(P>0.05)。CO+DF组肝脏胆固醇7-羟化酶(Cyp7a1)的蛋白表达水平显着低于CO组(P<0.05),但HF组和HF+DF组之间没有显著差异(P>0.05)。4)HF+DF组的粪便总SCFA和丙酸盐含量显著高于HF组(P<0.05)。与相应的对照组相比,CO+DF组和HF+DF组的粪便丁酸盐含量显著增加(P<0.05)。5)在门水平上,DF组厚壁菌门(Firmicutes)相对丰度减少,HF+DF组的拟杆菌门(Bacteroidetes)相对丰度高于HF组。梭状芽孢杆菌属ⅪⅤa(ClostridiumⅪⅤ)相对丰度在CO+DF组和HF+DF组显著增加(P<0.05)。此外,与其他组相比,仅HF+DF组中阿克曼菌属(Akkermansia)相对丰度显著增加(P<0.05)。由此可见,每千克饲粮添加5 g DF可降低饲喂含脂45%饲粮小鼠的体重和肝脏脂肪含量,降低血清TC、TG含量及AST和ALT活性以及肝脏TC和TG含量,降低胆固醇合成相关蛋白Cyp7a1的表达水平,提高总SCFA含量及肠道有益菌群和优势菌群相对丰度。     

The efficacy of a single chain recombinant equine luteinizing hormone (reLH) in mares: induction of ovulation, hormone profiles, and inter-ovulatory intervals

The objectives of this study were to determine the efficacy of recombinant equine luteinizing hormone (reLH) in shortening the time to ovulation in cycling mares and to determine the effects of treatment on endogenous hormones and inter-ovulatory intervals. In study 1, mares of light horse breeds (3–20 years) were treated with either a vehicle, various doses of reLH, or human chorionic gonadotropin (hCG). Cycling mares were examined by palpation and ultrasound per rectum daily or every 12 h from the time of treatment to ovulation. In studies 2 and 3, jugular blood samples were collected daily or every 12 h from the time of treatment to ovulation for analysis of LH, follicle stimulating hormone (FSH), estradiol-17β (E₂), and progesterone (P₄) by radioimmunoassays (RIA). Increasing doses of reLH (0.3, 0.6, 0.75, and 0.9 mg) showed increasing effectiveness at inducing ovulation within 48 h of treatment. Treatments with the 0.75 and 0.9 mg doses of reLH resulted in 90% and 80% ovulation rates, which were similar to hCG treatment (85.7%). Except for the early rise in LH after treatment with 0.5, 0.65, and 1.0 mg of reLH, hormone profiles appeared to be similar between control and treated cycles. Inter-ovulatory intervals were similar between control and treatment cycles. In conclusion, reLH is a reliable and effective ovulatory agent that does not significantly alter endogenous hormone profiles or affect inter-ovulatory intervals.     

退化高寒草甸斑块根—土复合体特征研究

高寒草甸斑块的根-土复合体对局部水土流失过程具有调控作用,为研究其特征及抗侵蚀效应,本研究选取三江源区达日县境内典型中度退化草甸的植被斑块为研究对象,调查草甸斑块中心与边缘植物群落特征,测定斑块边缘0～10 cm土层和斑块中心0～20 cm土层的容重、含水率、毛管孔隙度等土壤物理性质,并开展单根拉伸和根-土复合体直剪试验。结果表明：受优势种矮嵩草的分布影响,地上生物量主要分布在斑块中心,根系主要分布在0～10 cm土层;斑块中心区域土壤抗剪强度、内摩擦角和粘聚力均随土层深度的增加而减小;斑块边缘区域土壤粘聚力,抗剪强度明显高于斑块中心区域,草甸斑块植物根系是土壤抗剪强度的主要影响因素。草甸斑块根-土复合体能明显增加退化草甸土壤的抗侵蚀能力,研究结果可为深入研究高寒草甸根系固土功能及水土流失调控提供科学依据。     

Zinc supplementation strategies in feedlot heifers receiving an extended-release implant or an aggressive re-implant program

Two hundred eight Angus-crossbred heifers (291 ± 23 kg) from four sources were used in a randomized complete block design. The objective of the study was to determine the effects of implant strategy and Zn supplementation on performance, carcass characteristics, muscle fiber diameter, and mineral status of heifers. Heifers were assigned to a 2 × 2 factorial study for 168 d, and factors included Zn and implant (IMP). Heifers were supplemented Zn (mg/kg dry matter [DM]; ZnSO₄) at national (30; NRC) or industry (100; IND) recommendations. Implant strategies (Merck Animal Health, Madison, NJ) included extended-release Revalor-XH on day 0 (REV-XH; 20 mg estradiol + 200 mg trenbolone acetate) containing four uncoated pellets and six coated pellets or the uncoated implant Revalor-200 on day 0 and again on day 91 (REV-200; 20 mg estradiol + 200 mg trenbolone acetate). Heifers were blocked by weight within source to pens of five or six heifers per pen (nine pens per treatment). A corn silage-based diet was fed during the growing period (days 0–55) followed by transition to a corn-based finishing diet. Weights were taken consecutively on days −1/0, 55/56, and 167/168. Liver and muscle from the longissimus thoracis were collected from one heifer per pen on days −5, 14, 105, and 164. Data were analyzed via Mixed Procedure of SAS. Average daily gain (ADG) and liver mineral used Period as the repeated effect. Corresponding to periods of high hormone payout from each implant, days 0–28 and 91–120 ADG were greatest for REV-200, whereas REV-XH numerically peaked during days 56–91 (IMP × Period; P = 0.02). Day 91 IND body weight tended to be heavier (P = 0.06) and day 120 body weight was heavier (P = 0.05) than NRC heifers. No effect of Zn or IMP on final body weight was observed (P ≥ 0.21). Muscle fiber cross-sectional diameter on day 164 was greater (P = 0.05) in IND than NRC. Liver Mn concentrations decreased by day 14 regardless of implant, though days 105 and 164 concentrations were lesser for REV-200 than REV-XH (IMP × Period; P = 0.02). No effects of Zn, IMP, or the interaction were observed for carcass-adjusted gain to feed, days 0–168 DM intake, hot carcass weight, or ribeye area (P ≥ 0.11). The nominal differences in performance between implant strategies suggest that extended-release implants may be an effective implant strategy to replace re-implant programs in heifers, whereas the improved performance of heifers fed IND vs. NRC during times of peak hormone payout suggests a role for Zn in periods of rapid growth.     

脱氢表雄酮对AA肉种鸡生产性能和肌纤维发育的影响

为探讨母源性添加DHEA对子生理机能影响的母体效应机制,本试验选用100羽16周龄AA种母鸡随机分成对照组、低剂量试验组、中剂量试验组和高剂量试验组,每组25只。于34周龄开始在饲料中添加DHEA,剂量分别为0、25、50和100 mg.kg-1,连续饲喂7周,期间记录每天的产蛋数并称重。在试验的第49天禁饲12 h,宰杀各组鸡。采集血液、腹脂、左侧胸肌和腿肌,计算产蛋率、平均蛋重、腹脂率、相对胸肌重和相对腿肌重。测定血清中尿酸(UA)和肌酐(Cr)含量。取腿肌和胸肌制作冰冻组织切片,测定肌纤维直径和密度。结果表明,与对照组相比,低剂量组母鸡产蛋率极显著升高(P0.01),中剂量组和高剂量组则极显著降低(P0.01);试验组平均蛋重差异不显著(P0.05);高剂量组母鸡的相对腿肌重显著升高(P0.05),而低剂量组和中剂量组差异不显著(P0.05);试验组腹脂率和相对胸肌重量差异不显著(P0.05);低剂量组血清UA含量极显著升高(P0.01),中剂量组有升高趋势,高剂量组显著升高(P0.05);中剂量组和高剂量组血清Cr含量没有显著变化(P0.05),低剂量组极显著升高(P0.01);3个剂量组AA肉种鸡胸肌肌纤维直径和密度均没有显著变化(P0.05);低剂量组腿肌肌纤维直径没有显著变化(P0.05),中剂量组显著减小(P0.05),高剂量组极显著减小(P0.01);低剂量组腿肌肌纤维密度没有显著变化(P0.05),中剂量组显著增大(P0.05),高剂量组极显著增大(P0.01)。