不同应激处理对猪血细胞参数和急性期蛋白浓度的影响

本试验模拟养猪生产中存在的不同应激条件,探讨应激类型与猪群血液急性期蛋白(acute phase proteins,APPs)浓度的关系,为评价猪群健康状态提供试验依据。利用猪多杀性巴氏杆菌病活疫苗(Pasteurella multocida vaccine,PMV)、猪乙型脑炎活疫苗(swine Japanese enceph-alitis vaccine,SJEV)及细菌脂多糖(lipopolysaccharide,LPS)分别模拟细菌性感染、病毒性感染及炎症状况的应激状态,研究不同应激状态下猪的行为学、血细胞参数及APPs浓度的变化。结果表明,LPS处理后仔猪出现呕吐、发烧和呼吸急促等现象。PMV处理后48 h中性粒细胞(neutro-phil,NEUT)和单核细胞(monocyte,MO)数量显著升高(P<0.05),LPS处理后24 h NEUT数量和处理后48 h MO数量显著升高(P<0.05);SJEV处理后48 h的血红蛋白(hemoglobin,HGB)含量和处理后24 h的血小板(platelet,PLT)数量显著降低(P<0.05);LPS处理后24和48 h红细胞(red blood cell,RBC)数量、HGB含量和PLT数量均显著降低(P<0.05)。触珠蛋白(hapto-globin,HPT)浓度在PMV处理后48 h和SJEV处理后72 h显著升高(P<0.05);主要急性期蛋白(major acute phase protein,MAP)浓度在PMV处理后72 h以及LPS处理后24、48和72 h显著降低(P<0.05),SJEV处理后24 h显著升高(P<0.05);载脂蛋白-A1(apolipoprotein-A1,Apo-A1)浓度在PMV处理后72 h、SJEV处理后48 h,LPS处理后24、48和72 h显著降低(P<0.05)。结果提示,正相急性期蛋白HPT浓度在细菌和病毒感染模型下显著升高,负相急性期蛋白Apo-A1浓度在本试验的3种感染模型下均显著降低,这初步证明了血液HPT和Apo-A1浓度可以作为评价猪只健康的指标。     

猪群免疫应激及运输应激检测指标的筛选

为筛选出猪应激时适宜的应激检测指标,选取35日龄左右的二元杂交仔猪模拟运输应激和免疫应激。采血、剖杀后取肝组织,通过荧光定量PCR法测定肝组织中3种细胞因子(IL-1β、IL-6、TNF-α)和6种急性期蛋白(CRP、HP、SAA、AGP、Apo-A1、pig-MAP) mRNA表达量;通过ELISA测定血清中IL-6、SAA、Apo-A1、AGP、MAP的含量。荧光定量PCR和ELISA结果显示：在2种应激中IL-6 mRNA表达虽然出现改变但规律不同,而Apo-A1和pig-MAP这2种急性期蛋白mRNA的表达都出现了相同变化(Apo-A1下调,pig-MAP上调)。因此,建议将Apo-A1和pig-MAP作为猪免疫应激和运输应激的检测组合指标。     

胸膜肺炎放线杆菌引起猪应激时急性期蛋白转录水平变化

为研究胸膜肺炎放线杆菌(APP)感染后猪肝组织急性期蛋白表达变化,选取6头健康三元杂交猪,随机分为应激组和对照组(每组3头,保证饲喂条件一致)。每头猪采血后,应激组滴鼻感染APP,对照组滴鼻等量的无菌生理盐水。感染4 h后对两组猪进行采血、剖杀,分别取肝组织冻存,肺组织进行细菌分离鉴定。采用ELISA试验测定血清中皮质醇质量浓度,荧光定量PCR法测定肝组织急性期蛋白CRP、HP、SAA、Apo-A1、ITIH-4的表达量。结果显示:应激组和对照组猪血清中皮质醇质量浓度在攻毒前无明显差异(P0.05);攻毒4 h后,应激组猪血清中皮质醇含量较对照组显著上调(P0.05);攻毒后,应激组猪肝组织SAA mRNA的表达量较对照组显著上调(P0.05),Apo-A1 mRNA的表达量显著下调(P0.01),CRP、HP和ITIH-4 mRNA表达量无显著变化。以上结果说明APP感染后,机体可通过调节SAA和Apo-A1表达量来参与应激调节。     

固态发酵醋糟饲料对育肥猪生长性能、养分表观消化率、血清指标及粪便中挥发性脂肪酸含量的影响

本试验旨在研究固态发酵醋糟饲料(SFVD)对育肥猪生长性能、养分表观消化率、血清指标及粪便中挥发性脂肪酸(VFA)含量的影响。选择体况相近[(59.04±0.33)kg]的健康“杜×长×大”三元杂交生长育肥猪60头,随机分为2个组,每组3个重复,每个重复10头猪。对照组饲喂基础饲粮+150 mg/kg土霉素钙,试验组饲喂基础饲粮+5%的SFVD。预试期6 d,正试期35 d。结果表明:与对照组相比,基础饲粮中添加5%的SFVD对育肥猪平均日采食量(ADFI)具有一定的促进趋势(P=0.056);显著降低了育肥猪饲粮中干物质(DM)、粗蛋白质(CP)、有机物(OM)和总能(GE)的表观消化率(P<0.05),对粗脂肪(EE)表观消化率有一定的促进趋势(P=0.052);显著提高了育肥猪血清谷草转氨酶(AST)和谷胱甘肽过氧化物酶(GSH-Px)活性(P<0.05),血清高密度脂蛋白(HDL)和免疫球蛋白A(IgA)含量也呈现出一定的升高趋势(P=0.055和P=0.077);显著提高了育肥猪粪便中丙酸含量(P<0.05),粪便中甲酸和总挥发性脂肪酸(TVFA)含量也呈现出一定的升高趋势(P=0.071和P=0.054)。由此可见,基础饲粮中添加5%的SFVD对育肥猪生长性能、肠道健康及免疫性能的提高具有潜在的促进作用。     

邻菲咯啉浓度对瘤胃微生物体外发酵的影响

邻菲咯啉是一种二肽酶抑制剂。本试验用体外法测定了不同浓度邻菲咯啉对瘤胃微生物发酵产气量、氨氮浓度、真蛋白含量及饲料干物质降解率的影响。结果表明 ,邻菲咯啉浓度与产气量呈直线负相关(Y=-16.75X +29.52 ,r=0.7976,P<0.05);与发酵液氨氮浓度呈直线负相关(Y= -0.5757X +3.3036,r=0.8384,P<0.05) ;与发酵管内容物真蛋白含量呈直线正相关(Y=1.35X +11.45,r=0.8423,P<0.05) ;与内容物饲料干物质降解率呈直线负相关(Y= -10.14X +55.08,r=0.9275,P<0.01)。     

紫花苜蓿对杂交猪育肥性能和相关基因表达量的影响

为了研究紫花苜蓿对猪生长及肉质性能的作用,选用16头长×大外二元育肥猪,在基础饲料中添加4%苜蓿,应用免疫组织化学、酶联免疫吸附试验、实时荧光定量PCR研究脂肪代谢相关因子在mRNA水平和蛋白质水平表达的差异。结果显示:饲料中添加苜蓿后,杂交猪骨骼肌细胞中瘦素(leptin)基因(P<0.05)和蛋白(P>0.05)的表达量下降,与日增重呈轻度负相关(r=-0.314);转录因子C/EBPβ(CCAAT/en-hancer binding proteins,CEBPβ)基因和蛋白的表达量变化不明显;过氧化氢酶体激活增殖受体(peroxisome proliterator actiated receptors,PPARr)基因和蛋白水平高于对照组(P>0.05),与日增重(r=-0.837)、瘦肉率(r=-1.000)、pH1(r=-1.000)呈高度负相关,与脂率(r=1.000)、熟肉率(r=1.000)高度正相关;脂联素(adiponectin)基因(P>0.05)和蛋白(P<0.05)表达量高于对照组,与脂率(r=-1.000)、熟肉率(r=-1.000)、胴体重(r=-0.500)、屠宰率(r=-0.500)、肉色评分(r=-0.500)、pH24(r=-0.500),肌内脂肪含量(r=-0.500)负相关,与日增重(r=0.837)、瘦肉率(r=1.000)、pH1(r=1.000)、眼肌面积(r=0.500)、失水率(r=0.500)正相关;脂肪分化相关蛋白(adiposedifferentiation-related protein,ADFP)基因(P>0.05)和蛋白(P<0.05)表达量上调,但与肉质、体增重等指标相关性不大;脂蛋白脂酶(lipo-protein lipase,LPL)基因和蛋白变化不明显,与各项屠宰指标不相关。这些结果表明一定量的紫花苜蓿下调Leptin、通过CEBPβ上调PPARr、ADFP和Adiponectin 3个基因和蛋白的表达,增加猪的日增重、肌内脂肪,影响肉质性状,对LPL的作用较小。这些研究为紫花苜蓿在养猪业中的开发利用奠定了理论基础。     

水合硅铝酸钠钙对生长肥育猪生长性能、养分表观消化率及抗氧化能力的影响

本试验旨在研究水合硅铝酸钠钙(HSCAS)对生长育肥猪生长性能、养分表观消化率及抗氧化能力的影响。选择(48.0±10.0)kg的健康"杜×长×大"生长猪45头,随机分为3个处理,每个处理5个重复,每个重复3头猪。对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮中添加0.25%和2.50%HSCAS的饲粮。试验期为70d,分为48～80kg(前期)和81～110kg(后期)2阶段进行。结果表明:1)与对照组相比,添加0.25%HSCAS对猪生长性能、血清尿素氮(UN)含量和抗氧化能力均无显著影响(P>0.05),但显著降低了后期粗蛋白质(CP)和能量的表观消化率(P<0.05);2)与对照组相比,添加2.50%HSCAS显著提高了后期和全期的料重比(P<0.05),显著提高了血清UN含量(P<0.05),显著降低了后期生长育肥猪CP、粗灰分和能量的表观消化率、血清超氧化物歧化酶活性及总抗氧化能力(P<0.05)。由此可知,饲粮中添加0.25%HSCAS对生长育肥猪的生长和健康无明显影响,但添加量达到2.50%可显著降低其生长性能、养分表观消化率和抗氧化能力。     

急性期蛋白应用于动物健康检测的研究进展

急性期蛋白(APPs)是一类在一般情况下浓度较低,急性期反应(APR)时浓度急剧升高或下降的主要由肝脏合成的蛋白。不同的APPs在不同动物体内的浓度升高倍数不同,导致不同动物的主要APPs不同。常见的主要APPs包括C-反应蛋白(CRP)、触珠蛋白(Hp)、血清淀粉样A蛋白(SAA)、α1-酸性糖蛋白(AGP)、微管结合蛋白(MAP)等。文章对采用APPs作为一种新的检测方法用于实际生产中某些疾病的防控与诊断,以及动物体日常健康情况监察的研究进行了综述。     

不同蛋白质原料对断奶仔猪生长性能、养分表观消化率、血清免疫和抗氧化指标及肠道形态的影响

本试验旨在研究不同蛋白质原料(大豆浓缩蛋白、昆虫蛋白KT100、血浆蛋白粉)对断奶仔猪生长性能、养分表观消化率、血清免疫和抗氧化指标及肠道形态的影响。选取108头体重[(7.71±1.23) kg]相近的健康28日龄“杜×长×大”断奶仔猪,随机分为3个组,每组6个重复,每个重复6头猪。试验分为前期(第1～14天)和后期(第15～28天)。Ⅰ组(对照组)前期饲喂含8%大豆浓缩蛋白的试验饲粮,后期饲喂含6%大豆浓缩蛋白的试验饲粮;Ⅱ组前期饲喂含8%昆虫蛋白KT100的试验饲粮,后期饲喂含6%昆虫蛋白KT100的试验饲粮;Ⅲ组前期饲喂含6%血浆蛋白粉的试验饲粮,后期饲喂含4%血浆蛋白粉的试验饲粮。试验期28 d。结果表明：1)试验前期、后期和全期,各组之间断奶仔猪的平均日增重(ADG)、平均日采食量(ADFI)和饲料转化率(FCR)均无显著差异(P>0.05)。2)第14天,与Ⅰ组相比,Ⅱ组的粗蛋白质(CP)表观消化率有降低的趋势(P=0.07)。第28天,与Ⅰ组相比,Ⅱ和Ⅲ组的干物质(DM)和有机物(OM)表观消化率显著提高(P<0.05),Ⅲ组的CP消化率显著提高(P<...     

低温等离子体技术对猪舍环境和生猪健康的影响

试验旨在探究低温等离子体技术的使用对猪舍内环境和猪群健康的影响。选取4栋猪舍、60头初始重约为60 kg的育肥猪和36头妊娠日龄为15 d的母猪作为试验样本，试验期60 d。试验组母猪和育肥猪猪舍内安装使用低温等离子体设备，对照组猪舍内未安装设备。采取现场采样、实验室分析的方法，对比试验组和对照组各猪舍内氨气(NH₃)、硫化氢(H₂S)、臭气浓度以及细菌菌群结构的差异，同时分析各处理组的饲料养分表观消化率和血清指标。结果表明：试验组育肥舍和母猪舍内空气中NH₃、H₂S和臭气浓度均低于对照组(P<0.05)；试验组育肥舍内气溶胶中细菌多样性和丰度均低于对照组(P>0.05)；试验组育肥猪和母猪的饲料养分表观消化率和血清生化指标与对照组均无显著差异，育肥猪试验组的IgM和IgG含量高于对照组(P<0.05)。低温等离子技术的使用能有效改善猪舍环境质量，且对育肥猪和母猪的健康无负面影响。     

Serum haptoglobin concentration in growing swine after intranasal challenge with Bordetella bronchiseptica and toxigenic Pasteurella multocida type D.

The acute phase reaction, in association with progressive atrophic rhinitis (AR), was monitored for 3 wk using serum haptoglobin (HPT) quantification in thirty-six, 15 kg swine after intranasal challenge with varying doses of Pasteurella multocida type D (toxigenic strain) and Bordetella bronchiseptica. The challenge doses were administered alone or in combination with pigs divided into 9 isolated treatment groups. Increasing doses of B. bronchiseptica were associated with lower serum HPT (P < 0.05), whereas increasing doses of P. multocida tended to increase serum HPT (0.05 < P < 0.10). Significant and positive correlation of mean HPT and AR score was found in these pigs; increased AR scores were associated with elevated mean HPT concentration (r = 0.41, P < 0.01). A significant interaction between P. multocida and B. bronchiseptica dose indicated that increasing the dose of B. bronchiseptica, for a fixed P. multocida dose, was associated with less AR (P < 0.05). The AR scores were greater in pigs given P. multocida, than B. bronchiseptica alone. These results indicate that a complex interaction between Pasteurella multocida and Bordetella bronchiseptica causes progressive atrophic rhinitis and alters serum HPT concentration in swine.     

Pig-major acute phase protein and haptoglobin serum concentrations correlate with PCV2 viremia and the clinical course of postweaning multisystemic wasting syndrome

The aim of the present longitudinal study was to assess the evolution of two acute phase proteins (APPs), pig-major acute phase protein (pig-MAP) and haptoglobin (HPT), in serum from pigs that developed postweaning multisystemic wasting syndrome (PMWS) in comparison to healthy and wasted non-PMWS affected pigs. In addition, evidence of infection with other pathogens and its relation with variations in APPs concentrations was also assessed. Fourteen independent batches of 100–154 pigs were monitored from birth to PMWS outbreak occurrence in 11 PMWS affected farms. Pigs displaying PMWS-like signs and age-matched healthy controls were euthanized during the clinical outbreak. PMWS was diagnosed according to internationally accepted criteria and pigs were classified as: (i) PMWS cases, (ii) wasted non-PMWS cases and (iii) healthy pigs. At the moment of PMWS occurrence, pig-MAP and HPT concentration in PMWS affected pigs were higher than in healthy ones (p < 0.0001). No differences in APPs serum concentrations between subclinically PCV2-infected pigs and healthy non-PCV2-infected pigs (based on quantitative PCR on serum results) were detected. Results showed a significant correlation between PCV2 loads and both pig-MAP (R = 0.487–0.602, p < 0.0001) and HPT (R = 0.326–0.550, p < 0.05–0.0001) concentrations in serum of PMWS affected pigs, indicating that the acute phase response in PMWS affected pigs occurred concomitantly to PCV2 viremia. No other pathogen, apart from PCV2, was consistently related with variations in APPs concentrations. A ROC analysis, made to determine the capacity of discrimination of both APPs between PMWS affected and non-affected pigs, showed higher sensitivity and specificity values using pig-MAP compared to HPT. These results suggest that pig-MAP might be a better indicator of PMWS status than HPT. Moreover, the fact that APR occurred some weeks before the start of clinical signs suggests that APPs could provide valuable prognostic information for PMWS development.     

Haptoglobin and pig-major acute protein are increased in pigs with postweaning multisystemic wasting syndrome (PMWS)

The objective of this study was to determine the serum concentration levels of selected acute phase proteins (APP), haptoglobin (HPT) and pig-major acute phase protein (pig-MAP), in postweaning multisystemic wasting syndrome (PMWS) affected pigs and PCV2-subclinically infected pigs. In a first study, a group of 15 eight-week-old conventional pigs from a PMWS affected farm were bled and a complete necropsy, histopathology and in situ hybridisation to detect PCV2 were performed. Based on the results, pigs were classified as suffering from PMWS (n = 10) or healthy animals (n = 5). In a second study, a group of 45 pigs from another PMWS affected farm were selected and bled at 3, 7, 12 and 28 weeks of age. The assessment of PCV2 infection status in these pigs was retrospectively done by PCV2 PCR in serum samples. Selected APP were measured in the serum of all studied pigs by means of radial immunodiffusion. Mean HPT and pig-MAP levels were significantly increased (p = 0.004 and p = 0.0006 respectively) in PMWS-affected pigs when compared to levels found in healthy pigs (2.52 +/- 0.88 mg/mL vs. 1.06 +/- 0.73 mg/mL for HPT and 3.81 +/- 1.53 mg/mL vs. 0.76 +/- 0.34 mg/mL for pig-MAP). In the second study, no significant difference in mean HPT and pig-MAP values were observed between PCV2 PCR positive and negative pigs of any age. However, both APP increased significantly with age in PCV2 PCR negative pigs. Altogether, the present results suggest that APP levels are significantly increased in pigs that develop PMWS, but not in animals with a PCV2 subclinical infection.     

Development and validation of a novel competitive ELISA for the detection of serum amyloid A in pigs

The objective of this study was to develop a novel competitive ELISA to measure the acute phase protein serum amyloid A (SAA) in pigs using species-specific reagents. Polyclonal antibodies were produced in rabbits immunised with recombinant porcine SAA (rSAA) expressed in Escherichia coli. Both the rSAA and polyclonal antibodies were used to develop a novel competitive assay that was analytically and clinically validated. This assay had within- and between-run coefficients of variation of 8.6% and 25%, respectively, and demonstrated a high level of accuracy as determined by linearity-under-dilution (correlation coefficient, r=0.965). The analytical and functional limits of detection were 3.3 and 105.02mg/L, and the upper and lower quantification limits were 66.9 and 2.8mg/L, respectively. Statistically significant differences (P<0.0001) were found between the concentrations of SAA in healthy and diseased pigs. This novel assay precisely and sensitively measures SAA levels in pigs and will facilitate the more accurate assessment and study of the acute phase response in this species.     

Correlation between a proteolytic method and a radioimmunoassay for porcine serum pepsinogen concentrations

The measurement of serum pepsinogen concentrations by enzymatic method and immunoassay provides diagnostic values and should be helpful in the detection of gastric diseases related to a rise of blood pepsinogen. In the present study, the correlation between a conventional enzymatic method and a recently developed radioimmunoassay (RIA) for serum pepsinogen A was investigated. A total of 123 sera samples of porcine foetuses (n = 28), adult healthy pigs (n = 56), pigs with parakeratosis (n = 25) and pigs with ulceration of the pars oesophagea (n = 14) were tested. Overall, there was a slight correlation between the two methods (r = 0.60). In relation to individual animal groups, the correlations (r) were 0.39 (P>0.05), 0.74 (P<0.001), 0.19 (P>0.05) and 0.34 (P>0.05) in foetuses, healthy pigs, pigs with parakeratosis and pigs with ulcers, respectively. In both methods, pepsinogen concentrations (means+/-SE) were significantly higher (P<0.05) in pigs with parakeratosis (1778 +/- 86.00 mUTyr/L; 690 +/- 53.00 ng/mL) and in pigs with ulcers (2026 +/- 153.00 mUTyr/L; 1747 +/- 94.00 ng/mL) when compared to healthy pigs (935 +/- 58.00 mUTyr/L; 275 +/- 35.00 ng/mL). The proteolytic method gave a significant increased activity (P<0.05) in foetuses (1150 +/- 82.00 mUTyr/L) vs. (935 +/- 58.00 mUTyr/L) in healthy adult pigs, indicating an additional proteolytic activity in the sera of foetuses or neonates.     

Acute-phase protein response in pigs experimentally infected with Haemophilus parasuis

The acute-phase protein (APP) response to an infection caused by Haemophilus parasuis, the etiological agent of Glässer's disease in pigs, was characterized measuring serum concentrations of pig major acute-phase protein (pig MAP), haptoglobin (HPT), C-reactive protein (CRP) and apolipoprotein A-I (ApoA-I) in colostrum-deprived pigs. They were divided into six experimental groups: non-immunized control group (I); immunized with a non-commercial bacterin (II); with an OMP-vaccine (III); with a sublethal dose (IV); and with two commercial bacterins (V and VI). All groups were challenged intratracheally with 5 × 10⁹ CFU of H. parasuis 37 days after immunisation. The highest levels of the positive APPs (pig MAP, HPT and CRP) and the lowest levels of the negative APPs (ApoA-I) were observed in the animals that died as a consequence of the infection, both those in the non-inmunized and in the immunized groups. However, the surviving animals (all of them in groups II, V and VI, two pigs in group III, and three in group IV) showed a minor variation in APP response, mainly on day 1 post-challenge (p.c.), and then tended to recover the initial values. APP response was still less pronounced in the groups of pigs previously immunized with bacterins. In conclusion, APP response can reflect Glässer-disease ongoing, showing a correlation between the severity and duration of the clinical signs and lesions and the magnitude of changes in the APP levels.     

The association between plasma levels of acute phase proteins, haptoglobin, alpha-1 acid glycoprotein (AGP), pig-MAP, transthyretin and serum amyloid A (SAA) in Large White and Meishan pigs

During infection, the acute phase response triggers the release of acute phase proteins (APP), alpha-(1) acid glycoprotein (AGP), serum amyloid A (SAA) and Pig-MAP into the circulation, accompanied by a decrease in plasma levels of transthyretin. We quantified the association between these APP in 26 apparently healthy pigs from two breeds, 13 Large White and 13 Meishan (16 male; 10 female). There was a significant correlation between plasma levels of haptoglobin and Pig-MAP (r=0.57; p<0.05), but no significant associations between any of the other APP tested. We also measured the relationship between PigMAP, transthyretin and SAA, and the proportions of peripheral blood mononuclear sub-sets, CD8(+) cells, CD4(+) cells, CD11R1(+) cells, MHC DQ(+) cells, and monocytes. There were correlations between both plasma levels of Pig-MAP and the proportion of monocytes (r=0.55; p<0.05) and plasma levels of transthyretin and the proportion of MHC DQ(+) cells (r=0.40; p<0.01). Breed and sex influenced plasma levels of Pig-MAP but not plasma levels of transthyretin. Overall, these results suggest closer links between the mechanisms that regulate the release haptoglobin, Pig-MAP and monocytes compared to those that regulate the release of AGP, SAA and transthyretin.     

Adiponectin and IGF-1 are negative acute phase proteins in a dog model of acute endotoxaemia

The objective of this study was to evaluate the influence of an experimentally induced acute inflammation on serum adiponectin and insulin-like growth factor 1 (IGF-1) levels in the dog, and to compare their evolution with other well-established acute phase proteins (APPs) such as C-reactive protein (CRP), and haptoglobin (Hp). Therefore levels of adiponectin, IGF-1 and a profile of APPs were measured in healthy dogs after intravenous administration of E. coli LPS (0.02 mg/kg) and compared with dogs injected with saline solution (0.2 mL/kg). Adiponectin and IGF-1 were both decreased in response to endotoxins in the dog. Significant positive correlations were found between adiponectin and IGF-1 (r=0.31; p<0.05). Adiponectin had also a significant negative correlation with CRP (r=-0.39; p<0.05) and Hp (r=-0.27; p<0.05), whereas IGF-1 had significant negative correlation with CRP (r=-0.52; p<0.001). The results obtained in the present study indicate that adiponectin and IGF-1 behave as negative acute phase proteins after acute inflammatory stimulus in dogs.     

Growth performance,immune status,gastrointestinal tract ecology,and function in nursery pigs fed enzymatically treated yeast without or with pharmacological levels of zinc

Growth performance and physiological responses of nursery piglets when fed enzymatically treated yeast (HY40) and pharmacological ZnO alone or in combination were investigated. A total of 144 pigs (21 d old, BW 7.32 ± 0.55 kg) were placed in 36 pens (4 pigs/pen). Pigs were randomly assigned to one of four dietary treatments (n = 9): 1) control corn-wheat-soybean meal diet (control), 2) control + HY40 (HY40), 3) control + (ZnO) and 4) control + HY40 + ZnO (HY40+ZnO). Inclusion of HY40 and ZnO was 0.5% and 3,000 ppm in phase I (days 0 to 14), respectively, and halved in phase II (days 15 to 42). All diets contained 0.2% TiO₂ for determination of apparent total tract digestibility (ATTD) of components. Body weight and feed disappearance were recorded weekly. One pig per pen was killed for organ weights, blood, and tissue samples on day 14. Except for phase II, when HY40 + ZnO pigs had greater average daily feed intake (P = 0.004) than all other treatments, there were no (P > 0.05) interactions between HY40 and ZnO on growth performance. Pigs fed HY40 or ZnO containing diets were heavier (P < 0.05) than pigs fed without by the end of the study. On day 14, pigs fed additives exhibited higher (P ≤ 0.009) ATTD of dry matter (DM) and gross energy (GE) than control pigs. On day 28, pigs fed control, HY40, and HY40 + ZnO had greater (P ≤ 0.022) ATTD of DM, crude protein, and GE than piglets fed ZnO only. Pigs fed HY40 + ZnO had lower ileal digesta Escherichia coli concentration (P < 0.05) than HY40 and control pigs. Ileal digesta of pigs fed ZnO diets had higher lactobacillus to E. coli ratio (1.44 vs. 1.20; P = 0.001), exhibited higher concentrations of acetic (P = 0.01) and butyric acid (P = 0.01) but lower lactic (P = 0.02) and total short chain fatty acids (P = 0.033) than pigs fed non-ZnO diets. Greater (P < 0.05) mRNA expression of nutrient transporters, tight junction proteins, and fecal excretion of zinc (Zn) was observed in ZnO pigs relative to non-ZnO pigs. Pigs fed HY40 diets had greater (P = 0.002) villus height to crypt depth ratio (VH:CD) than non-HY40 pigs. The concentration of plasma IgA was higher (P = 0.04) in HY40 + ZnO pigs relative to other pigs, whereas HY40 pigs showed higher (P < 0.001) jejunal IgA than non-HY40 pigs. Although the mode of action of HY40 and ZnO differed, the present study indicated that HY40 improved growth performance and jejunal function and immunity, making HY40 an effective alternative to pharmacological ZnO in nursery pigs feeding programs.