Effects of Dietary Yeast Cell Wall Polysaccharides Supplementation to Late Gestation and Lactation Diets on Reproductive Performance and Blood Profiles of Sows and Their Offspring

This study was conducted to determine the effects of yeast cell wall polysaccharides（YCWP） on reproductive performance, serum profiles and milk composition during late gestation and lactation. A total of 96 sows（Landrace × Yorkshire） were blocked on a basis of breed, parity（2-3）and their respective d 85 of gestation, and then randomly allotted to the following three dietary treatments： CON（basal diet, treatment 1）, YCWP1（CON＋0.2% YCWP, treatment 2） and YCWP2（CON＋0.4% YCWP, treatment 3）. The experiment lasted from d 85 of gestation to weaning（d 21 of lactation）. Sows fed YCWP diets had lower backfat thickness reduction from postpartum to weaning（ P〈0.05）. The supplementation of YCWP tended to increase litter weight at weaning（P=0.08） compared with CON. The non-lipid and total milk solids in colostrum was improved by YCWP2（P〈0.05）.No differences were observed in milk composition among dietary treatments（ P〉0.05）. The supplementation of YCWP decreased（P〈0.05） the levels of alanine amino transferase（ALT）, aspartate amino transferase（AST）, while it did not affect（ P〉0.05） alkaline phosphatase（ALP）, total protein（TP）,albumin（ALB）, globulin（GLB）, glucose（GLU）, total cholesterol（TC）, triglyceride（TG） or immunoglobulin G（IgG） in the sow serum. The serum IgG of piglets was increased by the YCWP. The levels of serum ALT and AST were reduced（P〈0.05） for suckling piglets in YCWP treatments. Taken together, the results of current studies might indicate beneficial effects of YCWP supplementation to late gestation and lactation diets on the sow productivity by improving litter weight at weaning, reducing backfat loss, and increasing serum IgG concentrations of piglets.

Impacts of low level aflatoxin in feed and the use of modified yeast cell wall extract on growth and health of nursery pigs

This study was to investigate the effect of corn naturally contaminated with aflatoxins(AF)under the regulatory level on the growth performance and health of nursery pigs,and the efficiency of yeast cell wall based feed additive(YC)mainly composed ofβ-glucans and mannan oligosaccharide(MOS)(Integral A+,Alltech,Lexington,KY)in prevention of mycotoxicosis.Pigs(60 barrows and 60 gilts at 6.02 ± 0.83kg BW)were randomly allotted to 4 treatments in a randomized complete block design based on a 2×2 factorial arrangement with 10 pens(5 barrow and 5 gilt pens)per treatment and 3 pigs per pen.Pigs were fed experimental diets for 5 wk.First factor was AF(0 or 20 mg/kg in feed)and the second factor was YC(0 or 2 g/kg in feed).Feed intake and body weight were measured weekly,and blood samples were used to measure blood cell counts,immunoglobulin G(Ig G),tumor necrosis factor-a(TNF-a),oxidative damage status,and serological evaluation related to liver health.Aflatoxin decreased(P<0.05)the number of platelet count(247.4 to 193.5×10~3/μL),and it also tended to increase the level of albumin(P=0.055,3.46 to 3.63 g/d L),albumin:globulin ratio(P=0.050,2.09 to 2.37),and Ca(P=0.080,10.79 to 10.97 mg/d L).Yeast cell wall based feed additive increased(P < 0.05)ADG(493 to 524 g/d),and ADFI(796 to 846 g/d)of pigs whereas G:F was not affected,and it also tended to increase(P=0.055)albumin level(3.46 to 3.63 g/d L).Interactions(P < 0.05)on hemoglobin,hematocrit,and platelet count indicated that YC further increased their levels when pigs were eating AF contaminated feed.Interactions(P < 0.05)on urea nitrogen and blood urea N to creatinine ratio indicated that YC further decreased their levels when feed were contaminated with AF.In conclusion,low level of 20 mg AF/kg under the regulatory level had minor effects on hematology without affecting growth performance,however the supplementation of 2 g/kg YC as a source ofβ-glucans and MOS in feed can improve feed intake and therefore the growth of pigs.

Effects of yeast cell wall on growth performance, immune responses and intestinal short chain fatty acid concentrations of broilers in an experimental necrotic enteritis model

Subclinical necrotic enteritis(NE) causes devastating economic losses in the broiler chicken industry,especially in birds raised free of in-feed antibiotics. Prebiotics are potential alternatives to in-feed antibiotics. Yeast cell wall extract(YCW) derived from Saccharomyces cerevisiae is a prebiotic with known immune modulating effects. This study examined the effects of YCW and antibiotics(AB) during subclinical NE on broiler growth performance, intestinal lesions, humoral immune response and gut microflora metabolites. The study employed a 2 × 3 factorial arrangement of treatments. Factors were:NE challenge(yes or no) and feed additive(control, AB, or YCW). Each treatment was replicated in 8 floor pens with 15 birds per pen. Challenged birds had higher feed conversion ratio(FCR) than unchallenged birds on d 35(P < 0.05). Dietary inclusion of AB decreased FCR regardless of challenge(P < 0.05) on d 24 and 35. Inclusion of YCW reduced serum interleukin-1(IL-1) concentration in NE challenged birds(P < 0.01) and increased immunoglobulin(Ig) G(P < 0.05) and Ig M(P < 0.05) levels compared to other dietary treatments regardless of challenge. Yeast cell wall extract increased formic acid concentration in cecal contents during challenge and increased butyric acid concentration in unchallenged birds on d 16.This study indicates YCW suppressed inflammatory response, promoted generation of immunoglobulin and increased short chain fatty acid production suggesting potential benefits to bird health.

Dietary supplementation of yeast cell wall improves the gastrointestinal development of weaned calves

The purpose of this study was to investigate the potential benefits of yeast cell wall(YCW)on the gastrointestinal development of weaned calves.Twenty healthy Holstein male calves(BW=92±8.29 kg and 60±5 d of age)were randomly allocated into 2 groups:CON with no YCW,and YCW(accounted for0.16%of the basal diet).The dietary concentrate-to-roughage ratio was 40:60.All the calves were fed regularly twice a day at 09:00 and 16:00 and had free access to water.The experiment lasted for 60 d.The results showed that calves fed YCW showed higher(P<0.05)length,width,and surface area of papillae in the ventral sac of the rumen as compared to CON.For the dorsal sac of the rumen,the muscularis thickness was thicker(P<0.05)in the YCW group when compared with CON group.The villus height of YCW calves was higher(P<0.05)than that of CON in the ileum.Calves supplemented with YCW also showed a higher(P<0.05)villus height-to-crypt depth ratio in the ileum.The YCW calves exhibited a greater(P<0.05)thickness of the wall in the duodenum and jejunum.Calves supplemented with YCW improved(P<0.05)the claudin 1 mRNA expression in the ileum and occludin mRNA expression in the jejunum and ileum.The YCW increased(P<0.05)the contents of secretory immunoglobulin A in the jejunum and ileum of calves.In conclusion,dietary supplementation with YCW could improve the gastrointestinal development of weaned calves.

Determination of <i>α</i>-1,3-Linked Mannose Residue in the Cell Wall Mannan of <i>Candida tropicalis</i>NBRC 1400 Strain

To investigate the chemical structure of cell wall mannan obtained from pathogenic yeast, Candida tropicalis NBRC 1400 (former antigenic standard strain, IFO 1400). As a result of two-dimensional NMR analysis, it was shown that the mannan of this strain is composed of α-1,6-, α-1,3-, α-1,2- and β-1,2-linked mannose residues. In this research, the mannan was subjected to three degradation procedures, acid-treatment, α-mannosidase, and acetolysis under two conditions in order to determine the chemical structure of the antigenic oligomannosyl side chains in this molecule. The 1H-nuclear magnetic resonance spectra of resultant oligosaccharides, pentaose and hexaose, demonstrated the existence of the oligomannosyl side chains corresponding to Manα1-3Manα1-2Manα1-2Manα1-2Man and Manα1-3Manα1-2Manα1-2Manα1-2Manα1-2Man, respectively, which have previously also been found in Candida albicans serotype A strain mannans. These findings indicate that C. tropicalis and C. albicans serotype A have no significant difference in the chemical structure of these cell wall mannans. Therefore, it can be interpreted that it is extremely difficult to distinguish both species by targeting the antigenic group in these mannans.

Optimization of Fermentation Condition of Yeast Culture

Culture condition of every phase for fermentation of yeast culture was studied, and its solid and liquid conditions of elaboration were optimized to improve the total counts of living cells. Results showed that microzyme grew best at 30℃ when solid fermented, and the count of the living cells reached the tiptop with pH 5.5. The count of Candida tropicalis could reach 137.96× 10^9 cfu·g^-1, the count of Saccharomyces cerevisia could reach 134.62× 10^9 cfu·g^-1 the best liquid fermentation condition for cell-wall broken was 50℃ for 28 h, the rate of cell-wall broken could reach 80% at least; the rate of vitamin loss in yeast could be the minimun, the loss rate of vitamin B6 in Candida tropicalis and Saccharomyces cerevisiae was 8.71% and 19.54% respectively, the loss rate of vitamin B2 was 19.39% and 13.18%, respectively, and the loss rate of vitamin B6 was 6.3% and 3.04%, respectively.

酵母复合微生态制剂对鲤鱼生长性能、免疫指标及抗氧化能力的影响

本试验旨在研究饲料中添加酵母复合微生态制剂对鲤鱼生长性能、免疫指标及抗氧化能力的影响,并确定其适宜的添加量。选用初始体重为(35±0.5)g的鲤鱼540尾,随机分为6组,每组3个重复,每个重复30尾鱼,预饲14 d。以基础日粮为CK组,试验组分别饲喂含0.1‰、0.5‰、1‰、2‰、3‰酵母复合微生态制剂饲料,饲养56 d后采样分析。结果表明:(1)与CK组相比,饲料中添加酵母复合微生态制剂可显著提高鲤鱼的生长性能,2‰、3‰组增重率(WGR)增加了23.01%、24.15%(P<0.05),特定生长率(SGR)增加了13.79%、14.37%(P<0.05),饲料系数(FCR)降低了18.09%、18.59%(P<0.05)。(2)与CK组相比,饲料中添加酵母复合微生态制剂可显著提高鲤鱼的免疫指标,2‰、3‰组溶菌酶(LSZ)提高了47.9%、48.74%(P<0.05),免疫球蛋白M(IgM)提高了48.31%、49.44%(P<0.05),补体C3(C3)提高了39.61%、39.61%(P<0.05),碱性磷酸酶(AKP)提高了17.05%、17.44%(P<0.05),总蛋白(TP)提高了31.03%、30.38%(P<0.05)。(3)与CK组相比,饲料中添加酵母复合微生态制剂可显著提高鲤鱼的抗氧化能力,2‰、3‰组总抗氧化能力(T-AOC)提高了41.69%、41.36%(P<0.05),超氧化物歧化酶(SOD)提高了37.63%、45.71%(P<0.05),过氧化氢酶(CAT)提高了41.69%、41.36%(P<0.05),丙二醛(MDA)降低了22.71%、20.92%(P<0.05)。由此得出,饲料中添加2‰、3‰酵母复合微生态制剂能够显著提高鲤鱼的生长性能、血清免疫指标及肝脏抗氧化能力。基于2‰、3‰添加量组各指标差异不显著,建议酵母复合微生态制剂的最佳添加剂量为2‰。

酵母细胞壁来源、作用机理及在动物养殖中的应用

酵母细胞壁具有吸附病原微生物、调整有益菌落和调节免疫功能等作用,其作为酵母类生物饲料原料的重要组成部分,已经被广泛应用于畜禽养殖的各个环节。本文就酵母细胞壁来源、组成、作用机理及在动物养殖中的应用进行综述,以期为酵母细胞壁在实际生产中的合理应用提供理论参考。

口服免疫多糖(酵母细胞壁)对南美白对虾抗哈维弧菌感染的作用

在南美白对虾(Penaeusvannamei)饲料中分别加100 0、200 0、300 0、400 0和500 0mg·kg-1Bm的免疫多糖(酵母细胞壁),连续投喂28d后,通过检测供试虾血清、肝胰腺和肌肉中酸性磷酸酶(ACP)、碱性磷酸酶(ALP)和过氧化物酶(POD)的活性及经过哈维弧菌的活菌攻毒,探讨口服不同剂量的免疫多糖(酵母细胞壁)对南美白对虾体内免疫相关酶活性的影响和对人工感染哈维弧菌抗病力的作用。结果表明,在南美白对虾饲料中添加100 0mg·kg-1Bm的免疫多糖(酵母细胞壁),能显著提高供试南美白对虾血清和肌肉中ACP和ALP活性(t测验,P<0 05),极显著地提高肝胰腺中ACP、ALP和POD的活性(t测验,P<0 01),增强抗哈维弧菌感染的能力。免疫多糖(酵母细胞壁)不同添加剂量的试验组之间则未出现显著差别(t测验,P>0 05)。试验结果表明免疫多糖(酵母细胞壁)在南美白对虾饲料中的添加量以100 0mg·kg-1Bm为宜。

免疫多糖(酵母细胞壁)对中华鳖非特异性免疫功能的影响

报道了口服免疫多糖（酵母细胞壁）对中华鳖（Pelodiscus sinensis）非特异性免疫功能影响的研究结果。试验中共设6个组，在各组饵料中免疫多糖的添加量依次为每千克鳖重0mg（对照组）、500．0mg（试验Ⅰ组）、1000．0mg（试验Ⅱ组）、1500．0mg（试验Ⅲ组）、2000．0mg（试验Ⅳ组）和2500．0mg（试验Ⅴ组）。投喂28d后，取其血液，测定了中华鳖血液中自细胞的吞噬活性、血清溶菌活力和补体活性。研究结果表明，试验Ⅰ～Ⅲ组中华鳖白细胞吞噬活性和溶菌酶的活性均显著高于对照组（t测验，P％0．05），而试验Ⅳ组和Ⅴ组与对照组中华鳖血液中自细胞的吞噬活性和溶菌酶活性没有显著差异（t测验，P〉0．05），补体C3和C4活性最高的是投喂量为每千克鳖重1000．0mg和1500．0mg的第Ⅱ组与第Ⅲ组，2个组与对照组间存在显著差异（t测验，P〈0．05），而第1组、第Ⅳ组和第Ⅴ组与对照组之间无显著性差异（t测验，P〉0．05）。研究结果证明在中华鳖饵料中添加免疫多糖（酵母细胞壁）的量以每千克鳖重1000．0nag左右为宜，超过1500．0mg对中华鳖的免疫刺激作用会逐渐降低。

不同破壁方法提取酵母菌总RNA的比较

选择液氮碾磨、反复冻融、超声波、加玻璃珠漩涡振荡和蜗牛酶酶解5种方法破碎酵母菌细胞壁,再使用Trizol法提取酵母菌总RNA,通过对总RNA进行质量浓度和纯度分析,比较不同破壁方法对酵母菌总RNA提取的影响。结果表明:在使用Trizol法提取酵母菌总RNA的实验中,反复冻融和液氮碾磨是较为有效且简便的酵母菌细胞壁破碎方法。

酵母壁多糖对断奶仔猪生长性能和小肠黏膜形态结构的影响

本研究旨在探讨饲粮中添加酵母壁多糖对断奶仔猪生长性能和小肠黏膜形态结构的影响。试验采用单因素试验设计方法,选取180头遗传背景一致、健康状况良好、胎次和体重接近的21日龄断奶仔猪,随机分为4个组,每组5个重复,每个重复9头猪。4个组分别饲喂对照饲粮、0.15%酵母壁多糖饲粮、0.30%酵母壁多糖饲粮和0.45%酵母壁多糖饲粮。试验期21 d。结果表明:1)与对照组相比,饲粮中添加酵母壁多糖能够显著提高断奶仔猪平均日增重和平均日采食量(P<0.05);酵母壁多糖有降低断奶仔猪腹泻率和料重比的趋势,但差异不显著(P>0.05)。2)与对照组相比,饲粮中添加酵母壁多糖能够显著提高断奶仔猪空肠绒毛高度/隐窝深度值(P<0.05),添加0.45%酵母壁多糖能够显著提高断奶仔猪空肠绒毛高度和十二指肠绒毛高度/隐窝深度值(P<0.05)。由此可知,酵母壁多糖可提高断奶仔猪的生长性能,并改善小肠黏膜形态结构;综合生长性能、小肠黏膜形态及经济成本等指标,其在仔猪饲粮中的适宜添加量为0.30%。

酵母细胞壁多糖的研究进展

随着科学技术的发展,多糖的活性功能已经被人们所认识。而酵母细胞壁多糖作为多糖中的一种,其研究也在不断深入。酵母细胞壁多糖具有许多活性功能,如能吸附病原菌,增强细胞免疫力,提高巨噬细胞活性,抗辐射,抗病毒,提高抗癌功能等。目前,酵母细胞壁多糖的提取方法主要是碱法、高压均质破壁法,酶法。在食品工业中,酵母细胞壁多糖能充当乳化剂、增稠剂、低热食品原料等角色。但由于提取技术的限制,其主要还是作为添加剂常见于饲料中。为了更好的利用酵母细胞壁多糖的功能价值,更充分的为人类健康服务,本文对酵母菌细胞壁多糖物质的活性功能,提取方法及其在食品中的应用进行了综述。

酵母细胞壁对犊牛生长性能、营养物质表观消化率和血清免疫指标的影响

本试验旨在研究饲粮添加酵母细胞壁(YCW)对犊牛生长性能、营养物质表观消化率和血清免疫指标的影响。选取体重[(112.57±8.29) kg]和日龄(60±5)相近、健康的30头荷斯坦断奶公犊牛,随机分为5个组,每组6个重复,每个重复1头牛。各组酵母细胞壁添加量分别占精料补充料的0(对照组)、0.20%、0.40%、0.80%和1.60%,饲粮精粗比为40∶60。试验期为60 d。结果表明:1)饲粮添加酵母细胞壁可提高犊牛平均日增重(ADG),0.20%和0.40%组ADG分别较对照组提高了10.64%和11.70%(P> 0.05); 0.40%组料重比较对照组降低了11.30%(P>0.05)。试验第60天,0.40%和0.80%组胸围指数和体躯指数显著高于对照组(P<0.05)。0.40%组犊牛粪便评分显著低于对照组(P<0.05)。2) 0.40%组中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和钙表观消化率显著高于对照组(P<0.05),0.40%和0.80%组粗脂肪(EE)表观消化率显著低于对照组(P<0.05)。3)试验第30天,0.40%组血清免疫球蛋白G(IgG)含量显著高于对照组(P<0.05)。试验第60天,0.40%组血清免疫球蛋白A(IgA)含量显著高于对照组(P<0.05),1.60%组血清IgG含量显著高于对照组(P<0.05),0.80%组血清白细胞介素-4(IL-4)含量显著高于对照组(P<0.05),对照组血清肿瘤坏死因子-α(TNF-α)含量显著高于其他各组(P<0.05)。综上所述,饲粮添加酵母细胞壁可增强犊牛机体免疫力,降低犊牛腹泻,提高营养物质表观消化率,提高生长性能,其中添加0.40%酵母细胞壁的效果最好。

免疫多糖对南美白对虾免疫相关酶的激活作用

将免疫多糖 (酵母细胞壁 )作为免疫激活剂注射到南美白对虾 (Penaeusvannawei)体内后 ,通过定时测定供试虾血清、肌肉和肝胰腺提取液中的酸性磷酸酶 (ACP)、碱性磷酸酶 (ALP)和过氧化物酶 (POD)的活性 ,探讨了免疫多糖 (酵母细胞壁 )对南美白对虾免疫系统的免疫刺激效果。结果表明 ,南美白对虾经注射免疫多糖(酵母细胞壁 )刺激后 ,肝胰腺中的ACP和ALP活性明显增加 ,在注射后 72h ,ACP活性由对照组的 31.3U/L提高到 93.4U/L ,ALP活性由 38.3U/L提高到 12 8.0U/L ,而在血清和肌肉中ACP和ALP的活性没有明显变化。与对照组虾相比 ,试验组虾的血清、肌肉和肝胰腺提取液中POD活性均没有明显变化。

酵母壁多糖对断奶仔猪肠道挥发性脂肪酸和微生物菌群的影响

本研究旨在探讨饲粮中添加酵母壁多糖对断奶仔猪肠道挥发性脂肪酸和微生物菌群的影响。试验采用单因素试验设计方法,选取180头遗传背景一致、健康状况良好、胎次和体重接近的21日龄断奶仔猪,随机分为4个组,每组5个重复,每个重复9头猪。4个组试验猪分别饲喂对照饲粮(未添加酵母壁多糖)、0.15%酵母壁多糖饲粮、0.30%酵母壁多糖饲粮和0.45%酵母壁多糖饲粮。试验期21 d。结果表明:1)与对照组相比,饲粮中添加0.15%、0.30%和0.45%酵母壁多糖显著提高了仔猪结肠乙酸的含量(P<0.05);其中,0.30%和0.45%酵母壁多糖还显著提高了结肠丙酸、丁酸以及总挥发性脂肪酸的含量(P<0.05),且二者之间差异不显著(P>0.05)。2)与对照组相比,饲粮中添加0.15%、0.30%和0.45%酵母壁多糖显著降低了盲肠沙门氏菌和大肠杆菌数量(P<0.05),且0.30%和0.45%酵母壁多糖组之间差异不显著(P>0.05)。由此可知,酵母壁多糖可提高仔猪肠道挥发性脂肪酸含量,并改善肠道微生物菌群结构,根据回归方程预测,酵母壁多糖在仔猪饲粮中的适宜添加水平为0.31%~0.40%。

茯苓多糖对中华鳖非特异性免疫功能的免疫调节作用

研究了口服茯苓多糖对中华鳖(Trionyxsinensis)非特异性免疫功能的影响。试验共分3个组,在基础饲料中添加20·0mg/kg茯苓多糖作为试验组,添加500·0mg/kg酵母细胞壁作为免疫刺激剂对照组,以投喂基础饲料作为空白对照组。连续投喂28d后,测定中华鳖血液中白细胞的吞噬活性、血清溶菌活力和补体活性。结果表明:在中华鳖饲料中添加茯苓多糖和酵母细胞壁能显著提高中华鳖白细胞的吞噬活性(t检验,P<0·05),而2个试验组之间中华鳖血液中白细胞的吞噬活性没有显著差异(t检验,P>0·05);2个试验组中华鳖血清中补体C3和C4的活性与对照组之间呈显著差异(t检验,P<0·05),而试验组之间无显著性差异(t检验,P>0·05)。本研究结果说明在中华鳖饵料中添加茯苓多糖和酵母细胞壁对中华鳖的非特异性免疫功能有增强作用。

免疫多糖对受免黄鳝免疫保护力的增强作用

在饲料中添加不同剂量的免疫多糖(酵母细胞壁),连续投喂经注射接种嗜水气单胞菌(Aeromonashydrophila)脂多糖(lipopolysaccharide,LPS)的黄鳝(Monopterus albus)28 d后,通过测定供试黄鳝的增重量、血清中凝集抗体效价、溶菌酶活性、谷丙转氨酶(SGPT)活性、血清总蛋白含量、白细胞吞噬活性以及活菌攻毒后的免疫保护率(RPS),探讨了将LPS作为免疫原、免疫多糖(酵母细胞壁)作为免疫刺激剂结合使用对受免黄鳝免疫保护力的增强作用。结果表明,用添加100.0 mg/kg免疫多糖(酵母细胞壁)的饲料投喂受免黄鳝,不仅可以提高受免黄鳝对A.hydrophila LPS的免疫应答水平,也可以增强黄鳝的非特异性免疫力和抵抗A.hydrophi-la人工感染的能力,同时也证明了在饲料中添加免疫多糖(酵母细胞壁)对黄鳝的生长速度和肝脏功能均无不良影响。

免疫多糖(酵母细胞壁)对中华绒螯蟹抗病力的增强效果

在中华绒螯蟹(Eriocheri sinensis)的饲料中分别添加每千克蟹体重0 mg、400.0 mg、600.0 mg、800.0 mg、1000.0 mg和1 200.0 mg的免疫多糖(酵母细胞壁),连续投喂中华绒螯蟹28 d后,通过测定供试中华绒螯蟹的体重、及经投喂或注射患病中华绒螯蟹组织(浆)等攻毒方法后的死亡率,探讨了口服免疫多糖(酵母细胞壁)对中华绒螯蟹生长速度和抗病力的影响.结果表明,在中华绒螯蟹的饲料中添加每千克蟹体重400.0 mg至1 200.0 mg的免疫多糖(酵母细胞壁),对中华绒螯蟹的生长速度和身体颜色等没有显著影响;能有效地增强供试中华绒螯蟹的抗病力,与对照组相比,经口服攻毒后投喂不同剂量免疫多糖(酵母细胞壁)试验组的中华绒螯蟹有效率为52.4%～66.77%,而经注射攻毒后各试验组中华绒螯蟹的有效率为39.2%～49.9%,口服攻毒后的有效率稍高可能与病原体的感染方式有关.

酵母细胞壁和益生素对蛋鸡生产性能及免疫功能的影响

本研究旨在探讨酵母细胞壁和益生素的不同添加剂量组合对蛋鸡生产性能与免疫功能的影响。试验选择19周龄体重相近、健康的海兰褐蛋鸡512只,随机分成4组,分别饲喂基础饲粮(对照组,A组)、基础饲粮+0.4 mg/kg酵母细胞壁+50 mL/t益生素(B组)、基础饲粮+0.8 mg/kg酵母细胞壁+100 mL/t益生素(C组)、基础饲粮+1.2 mg/kg酵母细胞壁+150 mL/t益生素(D组),预试期1周,正试期8周。结果表明:1)整个试验期各组间蛋鸡日采食量、平均蛋重没有显著差异(P>0.05)。B、C和D组蛋鸡日产蛋量与产蛋率比A组均有不同程度的提高,其分别提高了2.76%(P>0.05)、6.22%(P<0.05)、2.26%(P>0.05)和2.83%(P>0.05)、6.19%(P<0.05)、2.27%(P>0.05);料蛋比降低,分别下降了3.83%(P<0.05)、6.70%(P<0.05)、2.87%(P>0.05)。C组蛋鸡日产蛋量、产蛋率与B、D组相比均有显著提高(P<0.05);料蛋比下降,分别下降了2.99%(P>0.05)和3.94%(P<0.05)。2)试验第14天和第28天,B、C和D组蛋鸡血清新城疫抗体效价均比A组有显著或极显著提高(P<0.05或P<0.01);C组蛋鸡血清新城疫抗体效价比B、D组均有提高,但差异不显著(P>0.05)。3)试验第14天和第28天,B、C和D组蛋鸡血液淋巴细胞转化率均比A组有显著或极显著提高(P<0.05或P<0.01);C组蛋鸡血液淋巴细胞转化率比B、D组均有提高,但差异不显著(P>0.05)。结果提示,饲粮中酵母细胞壁和益生素的不同添加剂量组合均可改善蛋鸡生产性能与免疫功能,以添加0.8 mg/kg酵母细胞壁+100 mL/t益生素效果最佳。