半胱胺对仔猪免疫机能的调节作用

在日粮中添加不同剂量半胱胺，研究半胱胺对仔猪免疫机能的影响。选用90头新生“杜×长×大”三元杂交仔猪，随机分为3组，每组30头，分别饲喂基础日粮、基础日粮+120 mg/kg半胱胺、基础日粮+200 mg/kg半胱胺。试验期为45 d。每窝随机选取20头仔猪,分别在14、24、32、45日龄进行前腔静脉采血，测定部分免疫指标。结果表明，日粮中添加半胱胺能显著提高仔猪体重、平均日增重，降低料重比；显著提高断奶后仔猪血清IgA、IgG含量及白细胞吞噬率和T-淋巴细胞转化率。添加120 mg/kg半胱胺的日粮有较好的促生长作用，而添加200 mg/kg半胱胺的日粮更能增强仔猪的免疫机能。试验结果显示，日粮中添加适量半胱胺，可有效抑制仔猪断奶应激，提高仔猪免疫力。     

包被纳米氧化锌对断奶仔猪生长性能、抗氧化酶活性及血清生化和免疫指标的影响

本试验旨在研究饲粮中添加不同水平的包被纳米氧化锌对断奶仔猪生长性能、抗氧化酶活性及血清生化和免疫指标的影响。试验选取21日龄平均体重为(5.29±0.02)kg的长×大二元杂交断奶仔猪180头,随机分为5组,每组6个重复,每个重复6头仔猪。对照组饲喂基础日粮,普通氧化锌组饲喂基础日粮+2 500 mg/kg普通氧化锌,包被纳米氧化锌组分别在基础日粮中添加250、500、750 mg/kg包被纳米氧化锌,正试期14 d。结果表明:与对照组相比,日粮中添加500 mg/kg包被纳米氧化锌能提高断奶仔猪的平均日增重和日采食量(P<0.05),降低耗料增重比(P<0.05),且与普通氧化锌效果相当;与对照组相比,500 mg/kg包被纳米氧化锌组血清锌水平、铜锌超氧化物歧化酶活性和免疫球蛋白G含量升高(P<0.05),尿素氮和丙二醛含量降低(P<0.05),且均与普通氧化锌组差异不显著。结果表示,日粮中添加包被纳米氧化锌可显著促进仔猪生长,提高饲粮中蛋白质和锌的利用率,并能有效改善血清抗氧化酶活性,提高仔猪免疫力,且以日粮中添加500 mg/kg包被纳米氧化锌效果最佳,具有替代高剂量普通氧化锌的潜力。     

饲粮中添加卵黄抗体对断奶仔猪生长性能、血清生化指标、肠道形态及肠道微生物菌群的影响

本试验旨在研究饲粮中添加卵黄抗体对断奶仔猪生长性能、血清生化指标、肠道形态及肠道微生物菌群的影响。试验选取160头(25±1)日龄"杜×长×大"断奶仔猪,分为4个组,每个组4个重复,每个重复10头猪。各组分别饲喂以下4种饲粮:基础饲粮(对照组)、基础饲粮+0.4 kg/t硫酸黏杆菌素(抗生素组)、基础饲粮+1.0 kg/t卵黄抗体(卵黄抗体组)、基础饲粮+0.2 kg/t硫酸黏杆菌素+0.5 kg/t卵黄抗体(联用组)。试验期共计28 d。结果表明:1)与对照组相比,卵黄抗体组显著提高了断奶仔猪平均日增重(P0.05),显著降低了断奶仔猪料重比和腹泻率(P0.05),断奶仔猪平均日采食量无显著差异(P0.05)。与抗生素组相比,卵黄抗体组断奶仔猪生长性能无显著差异(P0.05),两者表现出相近的使用效果。2)与对照组相比,卵黄抗体组显著提高了断奶仔猪血清中总蛋白、白蛋白的含量(P0.05)。3)与对照组相比,卵黄抗体组显著增加了断奶仔猪回肠绒毛高度和绒隐比(P0.05),断奶仔猪十二指肠和空肠的绒毛高度、隐窝深度和绒隐比无显著差异(P0.05)。4)与对照组相比,卵黄抗体组显著降低了断奶仔猪回肠、盲肠中大肠杆菌数量(P0.05),显著增加了断奶仔猪回肠、盲肠中的乳酸杆菌数量(P0.05)。综上所述,饲粮中添加卵黄抗体能显著改善断奶仔猪生长性能,增强仔猪免疫力,提高肠道健康水平,促进有益菌生长,与抗生素有相近的使用效果,是很有发展潜力的抗生素替代品之一。     

纳米氧化锌对断奶仔猪生长性能、血清免疫和生化指标的影响

本试验旨在研究饲粮添加不同剂量的纳米氧化锌对断奶仔猪生长性能、血清免疫和生化指标的影响。试验选用28日龄体重(9.37±0.48)kg"杜×长×大"三元杂交断奶仔猪150头,随机分为5组,每组3个重复,每个重复10头猪。对照组饲喂基础饲粮;试验1、2、3组在基础饲粮中分别添加150、300和450 mg/kg的纳米氧化锌;高锌组在基础饲粮中添加3 000 mg/kg的普通氧化锌。试验期为21 d。结果表明:1)与对照组相比,饲粮添加纳米氧化锌显著提高了仔猪的平均日采食量和平均日增重(P0.05),显著降低了料重比和腹泻率(P0.05),其中以300和450 mg/kg剂量组的作用效果较佳,且与普通氧化锌效果相当;2)与对照组相比,饲粮中添加纳米氧化锌和普通氧化锌能显著提高血清中免疫球蛋白A、白细胞介素-6和肿瘤坏死因子α含量(P0.05),显著降低血清尿素氮含量(P0.05)。由此可见,饲粮中添加300或450mg/kg的纳米氧化锌能提高断奶仔猪的免疫机能,改善生长性能,降低腹泻率,具有替代普通氧化锌的潜在应用价值。     

Effects of yeast culture on performance, gut integrity, and blood cell composition of weanling pigs

An experiment was conducted to determine the effects of yeast culture (YC) and modified yeast culture [YC + cell wall product (CWP) containing mannan oligosaccharides] in pig diets on the performance, gut integrity, and blood cell composition of weanling pigs and to determine whether these dietary supplements could replace antimicrobial growth promoters (AGP) in pig diets. A total of 480 weanling pigs (27 d old and 7.8 +/- 0.1 kg of BW) were assigned to 1 of 4 experimental treatments: 1) diets without AGP or YC (control diet); 2) control + AGP; 3) control + 0.125% YC; and 4) control + 0.125% YC + 0.2% CWP. Piglets were fed experimental diets for 5 wk after weaning. Blood samples were collected from 8 piglets at weaning and from 8 piglets per treatment on d 14 and 35 after weaning for blood cell composition. These piglets were slaughtered for measurement of villous length and crypt depth in the jejunal mucosa and microbial profiling on the intestinal digesta. Average daily gain (P = 0.06) and G:F (P = 0.02) were improved for piglets that were fed the supplemented diets compared with piglets that were fed the control diet. Average daily feed intake was unaffected by dietary treatment. Performance was similar in piglets fed diets supplemented with AGP, YC, and YC + CWP. Blood cell composition, villous length, crypt depth, and microbial composition in the gut were unaffected by dietary treatment, but they were affected by time after weaning. Red blood cells, hemoglobin, hematocrit value, mean cell volume, mean cell hemoglobin, percentage of lymphocytes in the leukocyte population, villous length, and crypt depth were greater (P < 0.05) at 5 wk after weaning than at 2 wk after weaning. Eosinophils (P = 0.06) in the leukocyte population tended to be greater at 5 wk after weaning. Concentration of neutrophils in the leukocyte population and percentages of CD4 and CD8 cells were lower (P < 0.02) at 5 wk after weaning. The CD4:CD8 ratio (P = 0.07) tended to be lower at 5 wk after weaning. Results suggest that yeast culture could be an alternative to AGP in the diets of weanling pigs and that addition of CWP to diets containing YC would not improve the performance or health of weanling pigs above that of YC alone. Thus, more insight into the mode of action of YC is needed.     

日粮铜水平对断奶至2月龄生长肉兔生产性能及血清指标的影响

本文旨在探讨日粮铜水平对断奶至2月龄生长肉兔生产性能、血清指标的影响.选用新西兰断奶肉兔100只,随机分为5组,每组20个重复,每个重复1只兔.对照组饲喂基础日粮,试验组分别饲喂在基础日粮中以五水硫酸铜形式添加20、40、80和160 mg/kg铜的日粮,预试期7 d,正试期21 d.结果表明:日粮铜水平对生长肉兔平均日增重影响极显著(P=0.002 4),对料重比和平均日采食量无显著性影响(P>0.05);日粮铜水平对铜锌超氧化物歧化酶和血清铜蓝蛋白活性影响不显著(P>0.05),对血清总蛋白、球蛋白含量有显著影响(P=0.0403,P=0.0436),对白蛋白、白球比、尿素氮、总胆同醇含量无显著影响(P>0.05);日粮铜水平极显著影响血清胰岛素的含量(P=0.005 9),显著影响血清生长激素水平(P=0.024 8),对类胰岛素样生长因子-Ⅰ无显著影响(P>0.05).综合本试验结果,断奶至2月龄生长肉兔铜适宜添加水平为40～80 mg/kg(日粮实际含量为50～90 mg/kg).     

酿酒酵母发酵液对断奶仔猪生长性能、小肠发育及小肠黏膜免疫功能的影响

本试验旨在探究酿酒酵母(S.cerevisiae)发酵液对断奶仔猪生长性能、小肠发育及小肠黏膜免疫功能的影响。选取平均体重为(6.57±0.13)kg的26日龄"长白×杜洛克"断奶仔猪60头(公母各占1/2),按体重和性别随机分为3个组,每组4个重复,每个重复5头仔猪。3个组分别为:对照组(基础饲粮+300 m L/kg空白培养液)、酿酒酵母发酵液组(基础饲粮+300 m L/kg酿酒酵母发酵液)和抗生素组(基础饲粮+20 mg/kg硫酸黏杆菌素+40 mg/kg杆菌肽锌)。试验期21 d。结果表明:1)与对照组相比,酿酒酵母发酵液组和抗生素组的平均日增重(ADG)和平均日采食量(ADFI)显著或极显著升高(P0.05或P0.01),料重比极显著降低(P0.01);但酿酒酵母发酵液组与抗生素组的以上生长性能指标均无显著差异(P0.05)。2)与对照组相比,酿酒酵母发酵液组和抗生素组的十二指肠、空肠和回肠黏膜总蛋白、DNA和RNA含量显著或极显著升高(P0.05或P0.01);但酿酒酵母发酵液组与抗生素组的以上指标均无显著差异(P0.05)。3)与对照组相比,酿酒酵母发酵液组和抗生素组的十二指肠和回肠绒毛高度显著升高(P0.05),十二指肠、空肠和回肠绒毛高度/隐窝深度(V/C)显著或极显著升高(P0.05或P0.01);但酿酒酵母发酵液组与抗生素组的以上指标均无显著差异(P0.05)。4)与对照组相比,酿酒酵母发酵液组和抗生素组的十二指肠、空肠和回肠黏膜免疫球蛋白A、免疫球蛋白G和免疫球蛋白M含量均显著或极显著升高(除空肠黏膜免疫球蛋白G外)(P0.05或P0.01);但酿酒酵母发酵液组和抗生素组的以上指标均无显著差异(P0.05)。结果显示,饲粮中添加酿酒酵母发酵液能够提高断奶仔猪的生长性能,促进小肠发育,提高小肠黏膜免疫功能,达到与抗生素相当的效果。提示酿酒酵母发酵液可有效缓解断奶应激,减少或者替代抗生素在断奶仔猪饲粮中的使用,这为研发无抗饲粮提供了有力的理论依据和数据支持。     

高锌日粮长期暴露对断奶仔猪生长性能和血清生化指标的影响

试验选用60头日龄相近(23±1)临床检查健康的“杜×长×大”三元杂交断奶仔猪,按体重和性别随机分成3组,每组20头,分别饲喂基础日粮、基础日粮+3000 mg/kg 氧化锌、基础日粮+500 mg/kg 蛋氨酸锌。在断奶后0、21、42、70 d,每组随机选取10头仔猪,前腔静脉采血,测定部分血清生化指标。结果表明,在断奶后0~42 d,添加高锌日粮组仔猪的体重和日增重显著（P<0.05)或极显著（P<0.01)高于对照组仔猪,而在断奶后42~70 d,对照组仔猪日增重显著高于添加高锌日粮组仔猪（P<0.05）;在断奶后42~70 d,添加高锌日粮组仔猪血清AST和ALT水平显著(P<0.05)或极显著(P<0.01)高于对照组仔猪,而血清TP、ALB水平显著（P<0.05)或极显著（P<0.01)低于对照组仔猪;在断奶后21~70 d,添加高锌日粮组仔猪血清ALP水平极显著高于对照组仔猪（P<0.01）。因此,断奶仔猪早期饲喂高锌日粮能显著缓解仔猪断奶应激,而长期饲喂高锌日粮对断奶仔猪有毒副作用。     

复合植物精油在断奶仔猪饲料中的应用研究

旨在验证复合植物精油（百里香酚7.3%,牛至油10.0%）改善断奶仔猪生长性能的功效。选用160头体重相近、体况良好、28日龄断奶的杜×长×大三元杂交仔猪,随机分成4组,分别为对照组和试验1、2、3组,每组4个重复,每个重复10头猪。对照组饲喂玉米—豆粕型基础日粮,试验1、2、3组在基础日粮中分别添加80、120、150 mg/kg复合植物精油。试验期间观察并记录仔猪生长及健康状况,试验结束时,采用统计学方法比较各组仔猪的生长性能指标（末体重、平均日增重、平均日采食量、料重比）、健康指标（腹泻率、死淘率）以及肠道黏膜通透性指标（D-乳酸含量、二胺氧化酶活性）。结果表明,与对照组相比,试验2、3组仔猪的末体重、平均日增重、平均日采食量均显著提高（P〈0.05）,料重比则显著降低（P〈0.05）;3个试验组仔猪的腹泻率及死淘率均显著低于对照组（P〈0.05）;与对照组相比,3个试验组仔猪血浆中的D-乳酸含量和二胺氧化酶活性分别极显著（P〈0.01）和显著降低（P〈0.05）。综合考虑促生长效果及饲养成本,仔猪基础日粮中复合植物精油的推荐添加量为120 mg/kg。     

香甜鲜复合诱食剂对断奶仔猪生长性能、血清生化指标、养分表观消化率和粪便微生物菌群的影响

本试验旨在研究饲粮中添加不同水平香甜鲜复合诱食剂对断奶仔猪生长性能、血清生化指标、养分表观消化率和粪便微生物菌群的影响。选取(43±4)日龄体重相近的健康大白仔猪72头,随机分为3个组,每组3个重复,每个重复8头猪。对照组饲喂基础饲粮,试验组分别在基础饲粮中添加1和2 kg/t的香甜鲜复合诱食剂。试验期28 d。结果表明:与对照组相比,饲粮中添加2 kg/t香甜鲜复合诱食剂能够显著提高断奶仔猪平均日采食量和平均日增重(P0.05);饲粮中添加香甜鲜复合诱食剂对养分表观消化率、血清生化指标和粪便微生物菌群的影响不显著(P0.05)。由此可见,饲粮中添加2 kg/t香甜鲜复合诱食剂能提高断奶仔猪平均日采食量和平均日增重,提高生长性能。本试验条件下推荐断奶仔猪饲粮中添加2 kg/t香甜鲜复合诱食剂为宜。     

高铜对断奶仔猪生长性能及血清激素水平的影响

选用60头28日龄±2日龄“长大定”三元杂交断奶仔猪,按体重和性别随机分成3组,每组20头。Ⅰ组(对照组)仔猪饲喂基础日粮;Ⅱ组仔猪在断奶后14d内饲喂基础日粮 250mg/kg铜(CuSO4.5H2O),然后再饲喂基础日粮;Ⅲ组仔猪饲喂基础日粮 250mg/kg铜(CuSO4.5H2O)。试验期为28d。所有实验猪均于断奶后0,7,14d和28d称重,计算采食量,观察断奶后腹泻情况。同时每组固定10头仔猪,于断奶后0,7,14d和28d,经前腔静脉采血,测定部分血清激素水平。结果表明,高铜日粮能显著提高断奶仔猪体重(AW)、平均日增重(ADG)和日采食量(ADFI),降低料重比(F/G)和断奶后腹泻率,显著提高断奶仔猪血清GHI、NS、T3和T4的水平。     

Changes in diarrhea,nutrients apparent digestibility,digestive enzyme activities of weaned piglets in response to chitosan‐zinc chelate

A total of 120 weanling barrows weighing 6.11 ± 0.20 kg were randomly allotted to four treatments with three replications (i.e. pen) of ten piglets per replicate. Pigs were received corn‐soybean basal diet (control) or the same basal diet supplemented with the following sources of zinc: (i) 100 mg/kg of Zn as ZnSO₄; (ii) 100 mg/kg of Zn as chitosan‐Zn chelate (CS‐Zn); and (iii) 100 mg/kg of Zn as ZnSO₄ mixed with chitosan (CS + ZnSO₄). The results showed that CS‐Zn could highly improve average daily gain and average daily feed intake than those of ZnSO₄ or CS+ ZnSO₄ (P < 0.05). The pigs fed dietary CS‐Zn had lower diarrhea incidence and higher apparent digestibility of crude protein than those of the pigs fed dietary ZnSO₄ (P < 0.05). The protease activities in duodenal content of the pigs receiving CS‐Zn diets was higher than that of the pigs fed dietary ZnSO₄ or CS + ZnSO₄ (P < 0.05). The amylase activity in duodenal content of the pigs fed dietary CS‐Zn was higher than that of the pigs receiving ZnSO₄ diets or basal diets (P < 0.05). These results indicated that dietary CS‐Zn showed different bioactivities from ZnSO₄ or CS + ZnSO₄ in reducing the incidence of diarrhea, improving activities of digestive enzymes and growth performance of weaned pigs.     

饲粮添加不同水平三丁酸甘油酯对断奶仔猪生长性能、血清生化指标、肠组织形态和养分消化率的影响

本试验旨在研究饲粮添加不同水平三丁酸甘油酯对断奶仔猪生长性能、血清生化指标、肠组织形态和养分消化率的影响。选取平均体重为7.66 kg的21日龄“杜×长×大”断奶仔猪200头,随机分为5组,每组5个重复,每个重复8头猪。对照组饲喂添加40 mg/kg杆菌肽锌的基础饲粮,试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组在基础饲粮中分别添加1000、1500、2000、2500 mg/kg三丁酸甘油酯,试验期为42 d。结果表明:与对照组相比,饲粮中添加2000和2500 mg/kg三丁酸甘油酯显著提高了仔猪平均日增重(P<0.05),显著降低了料重比(P<0.05),显著增加了血清中免疫球蛋白M含量(P<0.05);饲粮中添加1500、2000、2500 mg/kg三丁酸甘油酯显著提高了仔猪血清葡萄糖和总蛋白含量(P<0.05),显著提高了空肠、回肠的绒毛高度和绒毛高度/隐窝深度(P<0.05),显著提高了仔猪对饲粮中粗蛋白质、粗脂肪、钙和磷的表观消化率(P<0.05),显著降低了血清中球蛋白含量和二胺氧化酶活性(P<0.05);饲粮中添加1000 mg/kg三丁酸甘油酯显著提高了血清中总蛋白含量(P<0.05),显著降低了血清中二胺氧化酶活性(P<0.05),显著提高了仔猪对饲粮中粗蛋白质和粗脂肪的表观消化率(P<0.05)。由此可见,仔猪饲粮中添加1000~1500 mg/kg三丁酸甘油酯可替代抗生素药物添加剂;饲粮中添加2000~2500 mg/kg三丁酸甘油酯不仅可替代抗生素药物添加剂,而且可显著提高仔猪生长性能,改善肠组织形态,增强免疫力,提高养分消化率。     

Immunomodulation in weanling swine with dietary selenium

The capability of dietary selenium (Se) to augment the immune response was evaluated in 96 crossbred weanling swine. Six groups of 16 pigs were fed diets with Se supplemented as sodium selenite at 0, 0.3, 0.6, 0.9, 1.2, and 1.5 mg/kg. The basal diet contained 0.068 mg of Se/kg. Weight gain, feed consumption, and feed efficiency were similar for all diets. Whole blood concentrations of Se linearly increased as the dietary concentrations of Se increased. The humoral response was monitored by immunoglobulin G titers to lysozyme and ribonuclease, using an enzyme-linked immunosorbent assay. Although no significant difference in immunoglobulin G titers to either antigen was detected among diets, a similar trend in antibody response was noted. The diet with 0.9 mg of added Se/kg produced the highest antibody response to both antigens, whereas the diet with 0.3 mg of added Se/kg produced the lowest titers for both antigens. Cell-mediated immunity was evaluated in the pigs by the dermal response to phytohemagglutinin. Significant difference was not detected in pigs fed the various diets in terms of the mean diameters of their dermal reactions to phytohemagglutinin injections. Although blood concentrations of Se were increased, rate and efficiency of weight gain and humoral and cell-mediated immunity were not significantly improved by adding 0.3 to 1.5 mg of Se/kg to diets.     

The Effect of Dietary Sulphate Copper Supplementation on Growth Performance, Intestinal Digestive Enzymes and Absorptive Transporters in Weanling Pigs

The experiment was conducted to assess the effects of dietary supplementation of Cu on the growth performance,digestive enzymes,tissue minerals and absorptive transporters in small intestinal mucosa of weanling pigs.One hundred crossbred pigs weaned at 28±2 d of age were assigned randomly to one of the following diets with 5 replicates:corn-soybean basal diet with 10,100,175,250 mg/kg of Cu as CuSO4·5H2O.The results showed that 250 mg/kg Cu had a positive effect (P0.05) on average daily gain,daily feed intake and ratio of gain/feed.Compared to 10 mg/kg Cu,higher Cu had significant effect on the apparent digestibility of protein and fat (P0.05).The supplementing of Cu improved amylase and lipase activity in jejunum content and lipase in pancreas (P0.05) and had no effect on intestinal morphology.The liver Cu elevated approximately 4-fold in pigs fed diet with 250 mg/kg Cu compared with pigs fed diet with 10 mg/kg Cu,no increases were observed in pigs receiving the lower level of Cu (100 and 175 mg/kg).Both Fe and Zn contents in kidney and liver were not affected by Cu supplementation.There was no positive effect (P0.05) of Cu supplementation on PepT1 (peptide transporter 1) and SGLT1 (sodium/glucose cotransporter) mRNA abundance in intestinal mucosa.However,higher supplementing level (250 mg/kg) significantly elevated the DMT1 (divalent metal transporter) mRNA abundance in duodenum mucosa.These results suggested that dietary supplementation with 250 mg/kg Cu could improve growth performance,nutrient digestibility and intestinal enzyme activities of weanling pigs.     

植物乳杆菌和非淀粉多糖复合酶对断奶仔猪生长性能、粪便微生物菌群及血清指标的影响

本试验旨在研究饲粮中添加植物乳杆菌(Lactobacillus plantarum)和非淀粉多糖(NSP)复合酶对断奶仔猪生长性能、粪便微生物菌群及血清指标的影响,从而达到代替抗生素的目的。试验采用单因素完全随机设计,选择28日龄健康断奶仔猪192头,平均体重为(7.15±0.36)kg,随机分为4个组,每组6个重复,每个重复8头猪。对照组(CT组)饲喂在基础饲粮中添加40 mg/kg杆菌肽锌的饲粮;试验组分别饲喂在基础饲粮中添加1 g/kg植物乳杆菌(PT组)、1 g/kg NSP复合酶(ZT组)、1 g/kg植物乳杆菌+1 g/kg NSP复合酶(PZT组)的饲粮。试验期35 d。结果表明:1)各组间断奶仔猪的试验末重、平均日增重、平均日采食量及料重比均无显著差异(P0.05)。2)各组间断奶仔猪粪便中乳酸菌数量、大肠杆菌数量及乳酸菌/大肠杆菌均无显著差异(P0.05)。但与对照组相比,PZT组断奶仔猪粪便中乳酸菌数量和乳酸菌/大肠杆菌有增加趋势(0.05≤P0.10),大肠杆菌数量有降低趋势(0.05≤P0.10)。3)各组间断奶仔猪的血清生化指标、免疫指标均无显著差异(P0.05)。由此可知,饲粮中复合添加植物乳杆菌和NSP复合酶可促进肠道菌群平衡,有益于仔猪健康生长,从而达到替代抗生素的目的。     

Effect of benzoic acid on growth performance, nutrient digestibility, nitrogen balance, gastrointestinal microflora and parameters of microbial metabolism in piglets

In order to investigate the effects of benzoic acid on growth performance, nutrient digestibility, nitrogen balance and gastrointestinal microflora of piglets, we conducted a performance experiment and a separate balance study. The performance experiment involved four different dietary treatments: (1) basal diet (negative control); (2) basal diet supplemented with benzoic acid at 5 g/kg; (3) basal diet supplemented with benzoic acid at 10 g/kg; (4) basal diet supplemented with potassium diformate at 12 g/kg. Each dietary treatment was assigned to nine replicate groups, each consisting of two piglets. Live weight, daily weight gain, feed intake and feed conversion ratio were monitored as performance parameters over a 35-day period. Supplementation of the diet with benzoic acid resulted in a dose-dependent increase in feed intake and body weight gain and an improved feed conversion ratio. Piglets fed the diet supplemented with benzoic acid at 10 g/kg outperformed the control piglets in mean feed intake, body weight gain and feed conversion ratio by 9%, 15% and 6% respectively. Growth performance of the piglets fed the diet with benzoic acid at 10 g/kg was similar to that of piglets fed the diet supplemented with potassium diformate. In the balance experiment three groups of six piglets each were fed either a control diet or diets supplemented with benzoic acid at 5 or 10 g/kg respectively. Benzoic acid did not significantly affect nutrient digestibility but increased nitrogen retention. Piglets fed the diets supplemented with benzoic acid at 5 or 10 g/kg retained 5% and 6% more nitrogen, respectively, than control piglets. Supplementation of benzoic acid did not influence the pH value or the concentration of ammonia in the gastrointestinal tract but reduced the number of bacteria in the digesta. In the stomach the number of total aerobic, total anaerobic, lactic acid forming and gram-negative bacteria was reduced; in the duodenum the presence of benzoic acid reduced the number of gram-negative bacteria and in the ileum the number of total aerobic bacteria in a dose-dependent manner. Benzoic acid also considerably reduced the concentration of acetic acid in the duodenum. In conclusion, the data of this study suggest that benzoic acid exerts strong antimicrobial effects in the gastrointestinal tract of piglets and therefore enhances growth performance and nitrogen retention.     

Effect of chito-oligosaccharide on growth performance, intestinal barrier function, intestinal morphology and cecal microflora in weaned pigs

A total of 180 weanling pigs (21 ± 3 d of age; 5.98 ± 0.04 kg) were used to investigate the effect of chito-oligosaccharide (COS) on growth performance, intestinal barrier function, intestinal morphology, and cecal microflora. Based on initial BW, gender and litter, the pigs were given 5 treatments during a 14-d feeding experiment, including a basal diet (control), 3 diets with COS supplementation (200, 400, or 600 mg/kg), and a diet with colistin sulfate (CSE) supplementation (20 mg/kg). Six randomly selected pigs from each treatment were used to collect serum, duodenal, jejunal, ileal, and cecal samples on d 7 and 14 postweaning. From d 1 to 7 postweaning, pigs fed COS or CSE had greater ADG and ADFI compared with the control pigs. From d 1 to 14, diets with either 400 or 600 mg/kg COS, or 20 mg/kg CSE increased (P < 0.05) ADG and G:F compared with the control diet. No significant differences were observed in ADG, ADFI, and G:F between the pigs fed COS and CSE. Pigs fed either 400 or 600 mg/kg COS, or 20 mg/kg CSE had less (P < 0.05) diamine oxidase (DAO) in the serum, but greater concentration of (P < 0.05) DAO in jejunal mucosa, than the control pigs on d 7 postweaning. Treatments did not affect villous height and crypt depth of the duodenum, jejunum, or ileum. Pigs fed COS at 400 mg/kg had greater (P < 0.05) concentration of Bifidobacteria and Lactobacilli in the cecum than pigs fed the control diet and CSE diet on d 7 postweaning. Supplementation of COS or CSE decreased (P < 0.05) the population of cecal Staphylococcus aureus compared with the control diet on d 7 postweaning. The number of cecal Bifidobacteria in pigs fed 600 mg/kg COS was greater (P < 0.05) than that of pigs fed the control diet or CSE diet on d 14 postweaning. No significant differences were observed in Escherichia coli counts in the cecum among treatments. The present results indicate that dietary supplementation of COS at 400 or 600 mg/kg promotes growth performance and improves gut barrier function, increases the population of Bifidobacteria and Lactobacilli, and decreases S. aureus in the cecum of weanling pigs.     

日粮中添加不同剂量有机酸型酸化剂替代抗生素对断奶仔猪生长性能的影响

旨在研究不同剂量有机酸型酸化剂替代抗生素对断奶仔猪生长性能的影响。试验选择健康、日龄相近、初始体重为（8.70±0.20）kg的杜×长×大杂交断奶仔猪144头,随机分为4组（分别为对照组,处理1、2、3组）,每组4个重复,每个重复9头仔猪。对照组饲喂基础日粮,处理1组在基础日粮上添加25 mg/kg金霉素和50 mg/kg喹烯酮,处理2组和处理3组在基础日粮上分别添加0.4%和0.7%有机酸型酸化剂（甲酸、乳酸、柠檬酸和富马酸）,试验共进行14 d。试验结果表明,处理1、2、3组相比于对照组断奶仔猪的日增重显著提高（P<0.05）,分别提高20.60%、7.90%和15.30%;与对照组相比,处理1、2和3组料重比显著降低（P<0.05）,分别降低13.20%、7.60%和13.35%;与对照组相比,处理1、2和3组腹泻率显著降低（P<0.05）,分别降低16.11、11.11和15.91个百分点;与对照组相比,处理1、2和3组日均采食量没有显著差异（P>0.05）;处理1组和处理3组对断奶仔猪日增重和料重比的改善程度接近。结果表明,通过添加有机酸型酸化剂能改善断奶仔猪的生长性能,添加高剂量的有机酸型酸化剂能达到金霉素和喹烯酮组合使用的效果。     

复合微生态制剂对断奶仔猪生长性能、腹泻率、免疫性能和肠道菌群的影响

本试验旨在研究复合微生态制剂对断奶仔猪生长性能、腹泻率、免疫性能和肠道菌群的影响。选取(30±2)日龄平均体重为(8.15±0.05)kg的莱芜黑猪断奶仔猪96头,随机分为4组,每组6个重复(公母各占1/2),每个重复4头猪。Ⅰ组为对照组,饲喂不添加任何益生菌和抗生素的基础饲粮;Ⅱ组为复合微生态制剂组,在基础饲粮中添加1.0‰肽菌素;Ⅲ组为抗生素组,在基础饲粮中添加500 mg/kg硫酸黏杆菌素;Ⅳ组为肽菌素和抗生素混用组,在基础饲粮中添加1.0‰肽菌素的同时添加200 mg/kg的喹乙醇和110 mg/kg的吉他霉素。预试期3 d,正试期28 d。结果表明,1)Ⅱ组平均日增重较Ⅰ、Ⅲ和Ⅳ组分别显著提高了13.16%、15.77%和10.66%(P0.05),F/G分别显著降低了8.54%、12.10%和6.50%(P0.05)。与Ⅰ组相比,Ⅱ、Ⅲ和Ⅳ组均显著降低了仔猪腹泻率(P0.05)。2)与Ⅰ和Ⅲ组相比,Ⅱ组肝脏指数和脾脏指数分别提高了12.13%、24.76%和14.60%、12.45%,血清免疫球蛋白G和免疫球蛋白A含量分别提高了49.73%、37.50%和61.05%、46.67%,且差异均显著(P0.05)。3)与Ⅰ和Ⅲ组相比,Ⅱ组显著降低了胃和十二指肠内容物的p H(P0.05),且显著提高了盲肠和结肠中乳酸杆菌数量(P0.05)。由此可知,本试验条件下,饲粮添加1.0‰复合微生态制剂肽菌素可改善断奶仔猪生长性能,降低腹泻率,促进免疫器官的发育,提高血清中免疫球蛋白含量,增强仔猪免疫力,降低胃和十二指肠内容物p H,改善肠道菌群平衡。