Improving performance of finishing pigs with added valine,isoleucine, and tryptophan: validating a meta-analysis model

Based on results of a recent meta-analysis, we hypothesized that increased dietary Val, Ile, or Trp could correct possible amino acid interactions because of excess Leu in diets containing high levels of corn protein, namely dried distiller’s grains with solubles (DDGS). A total of 1,200 pigs (PIC TR4 × (Fast LW × PIC L02); initially 33.6 ± 0.6 kg) were used in a 103-d study. The 6 dietary treatments were corn–soybean meal (SBM)-DDGS-based as follows: (1) high SBM and low level of l-Lys HCl (HSBM), (2) high l-Lys HCl and moderate Ile, Val, Trp (AA above NRC 2012 estimates; NC), (3) moderate l-Lys HCl and high Ile, Val, and Trp (PC), and PC with either increased (4) L-Val (PC+Val), (5) L-Ile (PC+Ile), or (6) L-Trp (PC+Trp). Pigs fed the NC diet were predicted to have the poorest average daily gain (ADG), the PC diet to be intermediate, and pigs fed the HSBM, PC+Val, PC+Ile, and PC+Trp have the same and highest predicted ADG. In the grower period (34 to 90 kg), ADG was greater (Ρ < 0.05) for the pigs fed HSBM and PC+Val diets than the NC with pigs fed other diets intermediate. Pigs fed HSBM were more (Ρ < 0.05) efficient (G:F) than the NC and PC with pigs fed other diets intermediate. In the finisher period (90 to 136 kg), ADG was greater (Ρ < 0.05) for pigs fed PC+Ile than that of the NC with pigs fed other diets intermediate. Pigs fed PC+Val had greater (Ρ < 0.05) average daily feed intake (ADFI) than the NC with pigs fed other diets intermediate. However, PC+Ile pigs were more (Ρ < 0.05) efficient than PC+Val with pigs fed other diets intermediate. Overall, ADG was greater (Ρ < 0.05) for pigs fed HSBM, PC+Val, and PC+Ile diets than the NC with pigs fed other diets intermediate. Pigs fed the PC+Val diet had greater (Ρ < 0.05) ADFI than the NC with pigs fed other diets intermediate. No differences were detected between treatments for overall G:F or other carcass characteristics. In conclusion, increasing Val or Ile in high l-Lys-HCl-DDGS-based diets improved growth performance compared with pigs fed diets containing high levels of l-Lys HCl without added Val and Ile. These results present evidence that the recently developed meta-analysis can predict the relative differences in overall ADG for pigs fed the NC, PC, PC+Val, and PC+Ile diets; however, the predicted G:F was less accurate. The data demonstrate that the negative effects of high Leu concentrations in corn-DDGS-based diets can be reversed by increasing the ratios of Val and Ile relative to Lys.     

木质材料粉末涂饰技术的应用和前景

分析比较了常用木质材料表面装饰技术,重点介绍了国内外粉末涂料及粉末涂饰技术在木质材料应用的现状和 进展,就其技术特点、发展前景和在木质上开发应用的研究内容进行论述和探讨。     

离心式滚磨光整加工的机理分析及工艺选择

阐述了离心式滚磨光整加工的加工机理,对离心式滚磨加工中滚筒中质点的受力情况和加速度进行了分析.从实际生产应用出发,介绍了其加工质量的有关因素和对应的解决方法.     

RESEARCH ON SURFACE QUALITY OF BELT GRINDIIIG

Through a large number of tests of grinding the cycloidal flanks with abrasive belt, the surface roughness and residual stress exist in the complex curved parts resulting from large-curvature belt-grinding are discussed. The effect of the technical parameters on surface quality is analyzed and the empiric formula is given. This is enable to provide the grinding process with correct selecting of technical parameters.     

玉米脱水酒精糟及其可溶物和维生素 Ｅ水平对肥育猪生长性能、胴体和肉品质的影响

本试验旨在研究饲粮中玉米脱水酒精糟及其可溶物（ＤＤＧＳ）和维生素 Ｅ（ＶＥ）水平对肥育猪生长性能、胴体和肉品质的影响。采用 ３×２两因子完全随机试验设计,设 ３个玉米ＤＤＧＳ水平（０、１５％、３０％）和 ２个维生素 Ｅ水平（１０、２１０ｍｇ／ｋｇ）。选取平均体重为（６０±２）ｋｇ的“杜 ×长 ×大”三元杂交肥育猪 ４８头（公母各占 １／２）,按性别、体重随机分为 ６个组,每个组 ８个重复,每个重复 １头猪。试验期为 ４２ｄ。结果表明：１）玉米 ＤＤＧＳ水平对肥育猪平均日增重和料重比无显著影响（Ｐ＞０．０５）,对平均日采食量影响极显著（Ｐ＝０．００６）,维生素 Ｅ水平及玉米 ＤＤＧＳ和维生素 Ｅ的互作对生长性能无显著影响（Ｐ＞０．０５）;２）玉米 ＤＤＧＳ和维生素Ｅ水平及其互作对胴体重、屠宰率、胴体斜长、背膘厚度、板油率和眼肌面积等胴体品质评定指标影响均不显著（Ｐ＞０．０５）,胴体脂肪碘值随饲粮中玉米 ＤＤＧＳ水平的提高而极显著升高（Ｐ＝０．００１）;３）玉米 ＤＤＧＳ水平对肌肉 ｐＨ、肉色、剪切力、滴水损失和大理石评分影响均不显著（Ｐ＞０．０５）,饲粮中添加 ２１０ｍｇ／ｋｇ维生素 Ｅ可显著降低肌肉剪切力和滴水损失（Ｐ＜０．０５）。可见,在肥育猪基础饲粮中添加 １５％ ～３０％玉米 ＤＤＧＳ和 ２１０ｍｇ／ｋｇ维生素 Ｅ对其生长性能、胴体和肉品质无显著负影响。     

饲粮纤维源对育肥猪生长性能、胴体组成和肉品质的影响

本文旨在探讨不同纤维源对育肥猪生长性能、胴体组成和肉品质的影响.试验选用125头初始体重为(48.88±0.81) kg健康“杜×长×大”三元杂交生长肥育猪,随机分为5组,每组5个重复,每个重复5头猪,分别饲喂基础饲粮(对照组)以及添加玉米纤维、大豆纤维、小麦麸纤维和豌豆纤维的4种试验饲粮,饲粮纤维的添加量为30％.试验猪体重约为100kg时结束试验.结果表明:1)与对照组相比,大豆纤维组猪的末重和平均日增重显著降低(P＜0.05),大豆纤维组、小麦麸纤维组和豌豆纤维组猪的平均日采食量极显著降低(P＜0.01),小麦麸纤维组和豌豆纤维组猪的料重比显著降低(P＜0.05).2)饲粮中添加4种纤维有降低猪屠宰率的趋势(P=0.06),但对猪的胴体斜长和眼肌面积无显著影响(P＞0.05);而大豆纤维组、小麦麸纤维组和豌豆纤维组猪的平均背膘厚显著低于对照组(P＜0.05).3)饲粮中添加4种纤维有增加猪背最长肌中粗蛋白质含量的趋势(P=0.07),但对背最长肌PH45min亮度值、大理石纹评分和剪切力均无显著影响(P＞0.05);与对照组相比,豌豆纤维组猪的背最长肌pH24h显著提高(P＜0.05),背最长肌滴水损失显著降低(P＜0.05);而大豆纤维组和小麦麸纤维组猪背最长肌肌内脂肪含量显著降低(P＜0.05).本研究提示,饲粮中不同的纤维来源会对育肥猪的生长性能、胴体组成和肉品质产生不同程度的影响,其中,豌豆纤维对保障育肥猪的生长性能、改善肉品质的效果较好.     

烟酸对高精料饲粮肥育肉牛生长性能及血清生化指标的影响

本文旨在研究高精料饲粮中添加烟酸对肥育肉牛生长性能、养分表观消化率和血清生化指标的影响。选择体况良好、体重(402.2±25.4)kg的杂交公牛[西门塔尔()×中国黄牛(♀)]24头,随机分成4组,每组6头牛。Ⅰ组、Ⅱ组、Ⅲ组和Ⅳ组在精料中分别添加200、400、600和800 mg/kg的烟酸(以干物质计),饲粮精粗比85∶15,试验期56 d。结果表明:补饲烟酸对干物质采食量没有显著影响(P>0.05),Ⅳ组的生长性能优于其余3组。Ⅳ组饲粮粗蛋白质、粗脂肪的表观消化率显著地高于其余3组(P<0.05),酸性洗涤纤维表观消化率显著地高于Ⅲ组(P<0.05),中性洗涤纤维表观消化率显著地高于Ⅱ组和Ⅲ组(P<0.05)。烟酸水平对血清葡萄糖、甘油三酯和β-羟基丁酸的浓度无显著影响(P>0.05),Ⅳ组血清非酯化脂肪酸浓度极显著地高于其余3组(P<0.01)。结果提示,高精料饲粮中补饲烟酸可提高肥育肉牛生长性能和养分表观消化率,本试验条件下以精料中添加800 mg/kg的烟酸效果较好。     

饲粮中添加桑叶对育肥猪生长性能、脂肪代谢和肉品质的影响

本试验旨在研究饲粮中添加桑叶对育肥猪生长性能、脂肪代谢和肉品质的影响。试验选用初始体重[(55.85±1.37)kg]基本一致的健康"杜×大×长"三元杂交肥育猪63头,随机分为3组,每组3个重复,每个重复7头,分别饲喂基础饲粮、含10%桑叶饲粮、含20%桑叶饲粮,试验期65 d。结果表明:1)和基础饲粮相比,饲粮中添加10%桑叶对育肥猪生长速度影响不显著(P>0.05),板油率和背膘厚度显著降低(P<0.05),平均日增重、眼肌面积、料重比和胴体率差异不显著(P<0.05);2)和基础饲粮相比,饲粮中添加10%桑叶可减缓肌肉pH下降速度,显著提高肌肉肌苷酸和脂肪含量(P<0.05);3)和基础饲粮相比,饲粮中添加20%桑叶显著抑制血清脂肪酶、小肠蔗糖酶活性和降低育肥猪血脂含量(P<0.05),显著提高胰腺、板油脂肪酶活性(P<0.05);饲粮添加10%桑叶显著激活育肥猪肝脏己糖激酶、丙酮酸激酶活性(P<0.05),显著降低肝脏丙酮酸含量(P<0.05)。由此得出,饲粮中添加10%桑叶,不影响育肥猪生长速度,可降低猪板油率和背膘厚度,提高肌肉肌苷酸、脂肪含量,作用机理是通过调控育肥猪蔗糖酶、脂肪酶及肝脏糖代谢酶活性达到对脂肪代谢和沉积的调控。     

IWO缓冲层对MOCVD-ZnO:B薄膜性能的影响研究

金属有机化学气相沉积(MOCVD)技术生长的绒面ZnO透明导电(ZnO-TCO)薄膜应用于Si基薄膜太阳电池上能够形成"陷光结构",以提高薄膜太阳电池效率和稳定性。本文将电子束反应蒸发技术生长的掺W的In2O3(In2O3:W,(IWO)薄膜作为缓冲层,应用于MOCVD-ZnO:B薄膜与玻璃之间,可促进ZnO:B薄膜的生长,并且有效提升薄膜的光散射特性。当IWO缓冲层厚度为20nm时,获得的IWO/ZnO:B薄膜的电阻率为2.07×10-3Ω.cm,迁移率为20.9cm2.V-1.s-1,载流子浓度为1.44×1020 cm-3;同时,薄膜具有的透过率大于85%,且在550nm处绒度较ZnO:B薄膜提高了约9.5%,在800nm处绒度较ZnO:B薄膜提高了约4.5%。     

饲粮蛋白水平对肥育猪不同部位肌纤维发育增生的影响

试验比较研究了接近等氨基酸模式下,饲粮蛋白水平对肥育猪不同部位肌肉肌纤维发育增生的影响。饲粮蛋白水平分别为10%、18%、26%,试验选用平均体重约53kg的长×大二元杂交去势公猪54头。试验采用单因子完全随机区组设计,随机分为3个处理,每个处理3个重复(圈),每个重复6头猪,在接近等氨基酸模式TD-Lys:TD-Met:TD-Thr:TD-Trp=100:34.6:71.7:19.2,且在等能(14.2MJ/kg)条件下进行试验。采用石蜡切片方法,测定了肥育猪肌纤维横截面积、直径与密度,探讨在接近等氨基酸模式下饲粮蛋白水平对肥育猪肌纤维发育增生的影响。结果表明,通过提高饲粮蛋白质水平,进而提高动物体蛋白质的沉积效率,机体蛋白质含量的增加导致不同部位肌纤维横截面积和直径增大,即肌纤维体积增大,随着肌纤维的增粗,导致单位面积内肌纤维密度下降。