Effects of supplemental palygorskite instead of zinc oxide on growth performance,apparent nutrient digestibility and fecal zinc excretion in weaned piglets

The aim of this study was to determine the effects of dietary supplementation of palygorskite instead of zinc oxide (ZnO) on growth performance, apparent nutrient digestibility and zinc contents in serum and feces in weaned piglets. One hundred and sixty‐five piglets (28 days of age, 7.10 ± 0.86 kg) were allotted to five treatments on the basis of weight and sex. Each treatment included three replicates of 11 piglets. The piglets were fed the same basal diet supplemented with 0 mg/kg (control group), 1800 mg/kg, 2400 mg/kg, or 3000 mg/kg palygorskite or 2500 mg/kg ZnO for 28 days. There was no significant difference for incidence of diarrhea among the four treatments during the 0–14‐day feeding period. Compared with the control group, piglets offered diets supplemented with 1800 mg/kg palygorskite had higher (P < 0.05) average daily gain (ADG) and crude protein digestibility. Fecal digestibility of energy in 1800 mg/kg palygorskite and ZnO groups were higher (P < 0.05) than that in the control group. Both the zinc concentrations in serum and fecal zinc excretion in palygorskite groups and control group were all lower (P < 0.05) than that in the ZnO group. In conclusion, dietary supplementation with 1800 mg/kg palygorskite can improve growth performance and nutrient digestibility and can also decrease zinc excretion in feces in weaned piglets.     

不同蛋白和锌水平对早期断奶仔猪结肠蛋白质腐败产物和腹泻的影响

采用2×2因子设计(蛋白水平23%或17%,ZnO100mg/kg或3000mg/kg),选用21日龄断奶的杜长大三元杂交猪32头,体质量(6.3±0.4)kg,随机分为4组,每组设4个重复,每个重复2头猪,试验期4周。试验结束后,从每个重复中随机挑选1头试猪进行屠宰,收集结肠内容物。结果表明,玉米-豆粕型基础日粮中添加3000mg/kg饲料级ZnO,对高蛋白诱发的高腹泻发生率有极显著的抑制作用(P0.01),这可能是由于高锌可明显降低结肠内容物挥发性盐基氮和氨氮含量(P0.01),显著提高高蛋白日粮的胰蛋白酶(P0.05)、胃蛋白酶活性(P0.05)和CP表观消化率(P0.05)所致。     

不同形式氧化锌对断奶仔猪生长性能和肠道健康的影响

本试验旨在研究不同形式氧化锌对断奶仔猪生长性能、营养物质表观消化率、血清抗氧化能力及肠道形态的影响。采用完全随机区组试验设计,将144头健康三元(杜×长×大)杂交断奶仔猪[(6.42±0.51) kg]分为3个组,每组6个重复,每个重复8头猪。试验期28 d,分为前期(第1～14天)和后期(第15～28天)2个阶段。各组分别为：普通氧化锌组(在前期基础饲粮中添加1 600 mg/kg普通氧化锌,后期添加110 mg/kg,以锌元素计);钝化氧化锌组(在前期基础饲粮中添加1 600 mg/kg钝化氧化锌,后期添加110 mg/kg,以锌元素计);纳米氧化锌组(在前期基础饲粮中添加1 600 mg/kg纳米氧化锌,后期添加110 mg/kg,以锌元素计)。基础饲粮为玉米-豆粕型。结果表明：1)试验前期,与普通氧化锌组相比,钝化氧化锌组断奶仔猪第14天体重和平均日增重显著提高(P<0.05),料重比显著降低(P<0.05);钝化氧化锌组和纳米氧化锌组腹泻率显著降低(P<0.05)。试验全期(第1～28天),与普通氧化锌组相比,钝化氧化锌组和纳米氧化锌组断奶仔猪腹泻率显著降低...     

Short-term effect of dietary yeast nucleotide supplementation on small intestinal enzyme activities, bacterial populations and metabolites and ileal nutrient digestibilities in newly weaned pigs

In previous studies, dietary nucleotides have been shown to improve performance in single-stomached animals by promoting the renewal of small intestine epithelial cells and by influencing the activity and composition of the microbial community in the digestive tract. The present experiment was carried out with 12 barrows weaned at the age of 18 days and fitted with a simple T-cannula at the distal ileum. To determine short-term effects of dietary yeast nucleotides, the piglets received a grain-soybean meal-based basal diet with or without supplementation of 1 g/kg of a dried yeast product containing free nucleotides. Dietary supplementation with yeast did not affect bacterial numbers in the ileum as well as ileal concentrations of individual short-chain fatty acids (SCFA), total SCFA and total lactic acid (p > 0.05). Moreover, there was no effect of supplemental yeast nucleotides on ileal α-amylase, leucine amino peptidase, maltase and lactase activities (p > 0.05), as well as on ileal dry matter, crude protein and crude fibre digestibilities (p > 0.05). In conclusion, short-term supplementation with dietary yeast nucleotides did not affect microbial metabolite concentrations, bacterial numbers and enzyme activities in the ileal digesta as well as ileal nutrient digestibilities of newly weaned pigs.     

Effect of graded levels of dietary betaine on ileal and total tract nutrient digestibilities and intestinal bacterial metabolites in piglets*

The study was conducted to investigate the effects of graded dietary inclusion levels of betaine on ileal and total tract nutrient digestibilities and intestinal bacterial metabolites in piglets. A total of eight barrows with an average initial body weight of 7.9 kg were randomly allocated to one of the four assay diets with two pigs per treatment in four repeated measurement periods. The assay diets included a basal diet based on wheat, barley and soybean meal alone, or supplemented with a liquid betaine product at dietary levels of 1.5, 3.0, or 6.0 g betaine per kilogram diet (as‐fed). Ileal digestibilities of dry matter and neutral detergent fibre increased both quadratically and linearly, and ileal digestibility of glycine increased linearly as dietary betaine level increased (p < 0.05). Furthermore, total tract digestibility of crude protein increased quadratically (p < 0.05) and total tract digestibilities of most amino acids tended to increase quadratically (p = 0.06 to p = 0.11) with increasing dietary betaine level. Moreover, there were linear increases in the concentrations of most bacterial metabolites which were significant p < 0.05 for ileal d ‐lactic acid and for faecal diaminopimelic acid. The results demonstrate that dietary betaine supplementation stimulates bacterial fermentation of fibre in the small intestine and bacterial degradation of crude protein in the large intestine.     

Effects of zinc oxide and Enterococcus faecium SF68 dietary supplementation on the performance, intestinal microbiota and immune status of weaned piglets

The objective of this study was to determine the effects of zinc oxide (ZnO) and the probiotic Enterococcus faecium SF68 (Cylactin) dietary supplementation on the performance, intestinal microbiota and immune parameters of the weaned piglet reared under commercial conditions. The diets were devoid of antibiotic growth promoters (AGP). Two hundred and eight crossbred piglets were allocated to a 2 x 2 factorial experiment involving two levels of zinc oxide supplementation (0 or 3100 mg ZnO/kg feed), and two levels of E. faecium SF68 supplementation (0 or 1.4 x 10(9)CFU/kg feed (Cylactin ME10)). The diets were offered ad libitum for 20 days post-weaning. Piglet performance was assessed by calculating average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) on a pen basis. In addition, components of the distal ileal digesta, tissue-associated and mesenteric lymph node (MLN) bacterial populations were enumerated and serum immunoglobulin G (IgG) and intestinal immunoglobulin A (IgA) concentrations were determined on days 6 and 20 post-weaning. Regression analysis was used to determine the relationship between the bacterial populations at the different sites. Supplementation of the post-weaning diet with either ZnO or E. faecium SF68 did not affect piglet performance. E. faecium SF68 did not affect gastrointestinal bacterial populations but did tend to reduce serum IgG (P<0.1) on day 20. Zinc oxide reduced anaerobic (P<0.05) and tended to decrease lactic acid (P<0.1) bacterial translocation to the MLN, and tended to increase intestinal IgA concentration (P<0.1) on day 20. Generally, luminal bacterial populations were found to be poor predictors of tissue-associated or MLN populations. ZnO and E. faecium SF68 dietary supplementation were ineffective under these trial conditions. Further investigations into the possible immunomodulator role of dietary ZnO are warranted.     

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。     

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 dietary supplementation of lipid‐encapsulated zinc oxide on colibacillosis,growth and intestinal morphology in weaned piglets challenged with enterotoxigenic Escherichia coli

This study was aimed to evaluate the effect of dietary supplementation of lipid‐encapsulated (coated) zinc oxide ZnO on post‐weaning diarrhea (colibacillosis) in weaned piglets challenged with enterotoxigenic Escherichia coli (ETEC). Thirty‐two 35‐day‐old weaned piglets were orally challenged with 3 × 10¹⁰ colony forming units of ETEC K88 while eight piglets received no challenge (control). Each eight challenged piglets received a diet containing 100 ppm ZnO (low ZnO), 2500 ppm ZnO (high ZnO) or 100 ppm of lipid (10%)‐coated ZnO (coated ZnO) for 7 days; control pigs received the low ZnO diet. Daily gain, goblet cell density in the villi of the duodenum, jejunum and ileum, and villus height in the jejunum and ileum, which decreased due to the challenge, were equally greater in the coated ZnO and high ZnO groups versus low ZnO group. Fecal consistency score, serum interleukin‐8 concentration, subjective score of fecal E. coli shedding, and digesta pH in the stomach, jejunum and ileum, which increased due to the challenge, were equally low in the coated ZnO and high ZnO groups versus low ZnO. Results suggest that a low level of coated ZnO might well substitute for a pharmacological level of native ZnO in dietary supplementation to alleviate colibacillosis of weaned piglets.     

The effect of dietary phosphorus and calcium level, phytase supplementation, and ileal infusion of pectin on the chemical composition and carbohydrase activity of fecal bacteria and the level of microbial metabolites in the gastrointestinal tract of pigs

Two experiments with growing pigs were conducted to determine the effects of dietary P and Ca level, phytase supplementation, and ileal pectin infusion on ileal and fecal P and Ca balance, chemical composition of fecal mixed bacterial mass (MBM), and bacterial metabolic activity. Pigs (initial BW = 30 kg) were fitted with simple T-cannulas at the distal ileum. They were fed a low-P corn-soybean meal control diet (3 g of P/kg) or the control diet supplemented with monocalcium phosphate (MCP; 7 g of P/kg; Exp. 1) or 1,000 FTU phytase/kg (Exp. 2). The daily infusion treatments consisted of 60 g of pectin dissolved in 1.8 L of demineralized water or 1.8 L of demineralized water as the control infusion, infused via the ileal cannula. In each experiment, 8 barrows were assigned to 4 dietary treatments according to a double, incomplete 4 x 2 Latin square. The dietary treatments in Exp. 1 were the control (Con-) diet with water infusion; the control (Con+) diet with pectin infusion; the MCP diet with water infusion; and the MCP diet with pectin infusion. In Exp. 2, the pigs received the same Con- and Con+ treatments as in Exp. 1 and, in addition, the phytase-supplemented diet in combination with water or pectin infusion. After a 15-d adaptation period, feces were collected for 5 d followed by ileal digesta collection for 24 h. In Exp. 1, supplemental MCP increased (P 相似文献   

Assessment of dietary zinc requirement of weaned piglets fed diets with or without microbial phytase

Fifty-four pigs, weaned at 26 days of age at an average body weight of 7.74 kg were used in a 26-day experiment to assess the zinc requirement of piglets, using diets based on maize and soybean meal, with or without microbial phytase. The nine experimental diets were the basal diet containing 33 mg of zinc/kg supplemented with 10, 25, 40, 60 or 80 mg of zinc as sulphate (ZnSO(4), 7H(2)O)/kg and the basal diet supplemented with 0, 10, 25 or 40 mg of zinc as sulphate/kg and 700 units (U) of microbial phytase (Natuphos)/kg. Pigs were fed the basal diet for a 7-day adjustment period prior to the 19-day experimental period. Microbial phytase enhanced plasma alkaline phosphatase (AP) activity, plasma zinc and bone zinc concentrations. These parameters increased linearly with zinc intake, with a similar slope with and without phytase. The response of bone zinc-to-zinc added did not plateau. Without microbial phytase, plasma AP activity and zinc concentration were maximized when dietary zinc reached 86 and 92 mg/kg respectively. With microbial phytase they were maximized when dietary zinc concentration reached 54 and 49 mg/kg respectively. Accounting for a safety margin, the recommended supply of zinc for weaned piglets up to 16 kg fed maize-soybean meal diets supplemented with zinc as sulphate is thus of 100-110 mg/kg diet. This supply may be reduced by around 35 mg if the diet is supplemented with 700 U of microbial phytase.     

Metabolic response of the gastrointestinal tract and serum parameters of rabbits to diets containing chicory flour rich in inulin

A 36-day experiment carried out on 54-day-old rabbits addressed the analysis of physiological properties of diets supplemented with chicory roots flour. Twenty-four rabbits were allocated in individual cages to three treatments, in which they were fed each diet with the chicory flour at 0, 25 and 50 g/kg (control, ChF(2.5) and ChF(5) groups respectively). The chicory preparation administered at a higher dose, lowered ileal pH and viscosity, and evoked increased hydration of ileal and caecal digesta, compared to the control treatment (p 相似文献   

Increased dietary zinc oxide changes the bacterial core and enterobacterial composition in the ileum of piglets

This study was conducted to investigate the effects of increased dietary ZnO on the bacterial core and enterobacterial composition in the small intestine of piglets that were fed diets containing a total of 124 or 3,042 mg of Zn per kilogram of diet, respectively. Zinc was supplemented to the basal diet as ZnO. Bacterial 16S rRNA genes of ileal DNA extracts were PCR-amplified with 2 bar-coded primer sets and sequenced by 454 pyrosequencing. The bacterial core species were calculated from the relative abundances of reads present in 5 of 6 samples per group and at a minimum of 5 sequences per sample. The reference database SILVA was used to assign sequence reads at an alignment minimum of 200 bases and 100% identity. Lactic acid bacteria dominated the bacterial core, but showed diverse responses to dietary ZnO. Of the dominant Lactobacillus spp., Lactobacillus reuteri was reduced due to increased dietary ZnO (44.7 vs. 17.9%; P=0.042), but L. amylovorus was not influenced. However, the changes of relative abundances of other lactic acid bacteria were more noteworthy; Weissella cibaria (10.7 vs. 23.0%; P=0.006), W. confusa (10.0 vs. 22.4%; P=0.037), Leuconostoc citreum (6.5 vs. 14.8%; P=0.009), Streptococcus equinus (0.14 vs. 1.0%; P=0.044), and S. lutetiensis (0.01 vs. 0.11%; P=0.016) increased in relative abundance. Nonlactic acid bacteria that were influenced by increased dietary ZnO included the strict anaerobic species, Sarcina ventriculi, which showed a strong numerical decrease in relative abundance (14.6 vs. 5.1%). Species of the Enterobacteriaceae increased their relative abundance, as well as species diversity, in the high dietary ZnO experimental group. Bacterial diversity indices were increased due to increased dietary ZnO (P < 0.05), which was traced back to the increase of sequences from subdominant species. Increased dietary ZnO led to an increase of less prominent species and, thus, had a major impact on the bacterial composition and diversity in piglets. This effect may help to stabilize the intestinal microbiota in the sensitive postweaning period.     

Nanosize of zinc oxide and the effects on zinc digestibility,growth performances,immune response and serum parameters of weanling piglets

The aim of this study was to investigate the effect of dietary supplementation of nanosize zinc on zinc digestibility, growth performances, immune response and serum parameters of weanling piglets. Ninety‐six LYD weanling piglets were assigned to control, zinc oxide (ZnO), organic‐Zn (Zn‐methionine) and nanosize ZnO (nano‐Zn) groups with four replicates. The zinc was at the 120 mg/kg level in the treatment group's diet, while the control group's was 80 mg/kg Zn. The experiment results indicated that the nano‐Zn and organic‐Zn groups had significantly higher Zn digestibility compared to the ZnO and control groups. For the immune response traits, the IgG level and goat red blood cells (GRBC) antibody titer were nano‐Zn and organic‐Zn>ZnO>control; in the phytohemagglutinin (PHA) challenge test result, nano‐Zn>organic‐Zn>ZnO>control; in regard to the γ‐globulin level, nano‐Zn and organic‐Zn>ZnO and control, with significant difference between groups. In the serum parameters aspect, serum Zn concentration in nano‐Zn and organic‐Zn groups were higher than in the ZnO and control groups, serum growth hormone concentration was increased in the nano‐Zn group than in the other groups. In conclusion, nanosize zinc oxide for dietary supplementation can increase zinc digestibility, serum growth hormone levels and carbonic anhydrase activity and enhance the immune response of weanling piglets.     

纳米氧化锌对断奶仔猪生长性能和肠黏膜屏障的影响

本文旨在研究纳米氧化锌对断奶仔猪生长性能和肠黏膜屏障的影响及其机理。选用96头平均体重为(5.7±0.2)kg的21日龄"杜×长×大"断奶仔猪,随机分成3组:1)对照组,饲喂基础饲粮;2)氧化锌组,饲喂在基础饲粮中添加3 000 mg/kg锌(氧化锌)的试验饲粮;3)纳米氧化锌组,饲喂在基础饲粮中添加300 mg/kg锌(纳米氧化锌)的试验饲粮。每组4个重复,每个重复8头仔猪,试验期14 d。结果表明:1)与对照组相比,纳米氧化锌组断奶仔猪平均日增重提高了7.26%(P<0.05),腹泻率降低了70.82%(P<0.05),但与氧化锌组差异不显著(P>0.05)。2)与对照组相比,纳米氧化锌组仔猪28和35日龄绒毛高度分别提高了12.64%和10.80%(P<0.05);28日龄隐窝深度降低了15.42%(P<0.05);28和35日龄绒毛高度/隐窝深度分别提高了33.61%和17.11%(P<0.05);28和35日龄血浆D-乳酸含量分别降低了28.97%和20.23%(P<0.05),二胺氧化酶活性分别降低了28.61%和24.92%(P<0.05)。氧化锌组和纳米氧化锌组之间各指标差异不显著(P>0.05)。结果提示,断奶仔猪饲粮中添加300 mg/kg锌(纳米氧化锌)可提高平均日增重,降低腹泻率,改善肠黏膜形态,降低肠黏膜通透性,其效果与添加3 000 mg/kg锌(氧化锌)相当。     

锌源和水平对异育银鲫生长性能、组织锌沉积和抗氧化功能的影响

本试验旨在研究实用饲料中添加不同水平的硫酸锌及羟基蛋氨酸螯合锌( MHA-Zn)对异育银鲫生长性能、组织锌沉积和抗氧化功能的影响.试验选用初重为(2.73±0.01)g的异育银鲫1 120尾,随机分为7个处理,每处理4个重复,每重复40尾.以白鱼粉和豌豆蛋白粉为蛋白质源设计基础饲料,对照组饲喂基础饲料,试验组在基础饲料中分别添加不同水平硫酸锌至饲料锌含量分别为50(ZN50组)、65 mg/kg(ZN65组)和MHA-Zn至饲料锌含量分别为37.5(MZN37.5组)、50(MZN50组)、65(MZN65组)和200 mg/kg(MZN200组).试验期8周.结果表明:1)与对照组相比,各试验组存活率较高(P＞0.05);低剂量MHA-Zn组(MZN37.5组、MZN50组和MZN65组)鲫鱼的增重率和蛋白质效率显著降低(P＜0.05),但MZN200组和硫酸锌组(ZN50组和ZN65组)的增重率及蛋白质效率与对照组间差异不显著(P＞0.05).2)硫酸锌组的鲫鱼椎骨锌沉积量随饲料锌含量的增加呈上升趋势,ZN65组显著高于对照组(P＜0.05);MHA-Zn组的鲫鱼椎骨沉积量随饲料锌含量的增加呈先上升后下降的抛物趋势,MZN65组显著高于ZN65组(P＜0.05);且经一元二次回归分析,当添加MHA-Zn饲料中锌含量为131.3 mg/kg时,椎骨锌沉积量达最大值.3)肝胰脏抗氧化指标不受饲料锌的影响(P＞0.05);MHA-Zn组的碱性磷酸酶活性呈下降趋势.由此得出:当实用饲料中锌满足异育银鲫生长需要时,进一步补充硫酸锌对其生产性能没有显著影响,补充MHA-Zn至饲料锌含量为131.3 mg/kg时,鲫鱼椎骨锌沉积量达最大值.     

Performance responses and indicators of gastrointestinal health in early-weaned pigs fed low-protein amino acid-supplemented diets

The effects of low-protein AA-supplemented diets on piglet performance, visceral organ mass, incidence of diarrhea, intestinal microbial population, and fermentation were studied in a 3-wk trial. After a 7-d adaptation period, 96 piglets (approximately 6.2 kg of initial BW) were assigned to 4 corn-wheat, soybean meal-based dietary treatments in a completely randomized design to give 6 replicate pens per treatment (n = 4 piglets per pen). The treatments were a control wheat-corn-soybean meal-based phase I diet containing 23% CP, or the same diet with CP reduced to 21%, 19%, or 17% and supplemented with crystalline AA to achieve equal standardized ileal digestible contents of Lys, Met plus Cys, Thr, and Trp in all diets. Diets were formulated to similar nutrient levels and provided ad libitum. Blood from all pigs was taken on d 0, 7, 14, and 21 for determining plasma urea N. Weekly feed intake, BW changes, and G:F were determined. On d 21, 2 pigs per pen were randomly selected and killed to determine small intestinal morphology, digesta pH and ammonia levels, and luminal microbial counts. Average daily feed intake, ADG, and G:F were not affected (P > 0.10) by reducing CP to 21%, but a reduction to 19% or 17% decreased ADFI (P < 0.001) and ADG (linear, P < 0.001; quadratic, P < 0.05) over the 3-wk study period. Reducing CP to 19% had no effect (P > 0.10) on G:F; however, this response criterion was decreased linearly (P < 0.001) over the 3-wk study period as dietary CP declined. Water usage was only numerically decreased (P > 0.10) with dietary CP reduction. Plasma urea N was decreased linearly (P < 0.01) with CP reduction. Reducing CP from 23 to 17% had a linear (P < 0.05) and cubic effect on stomach and liver weights, respectively. Although histological data showed some differences among diets, no distinct trend was evident. Ammonia N in ileal digesta was reduced linearly (P < 0.01) as dietary CP was decreased. With the exception of valeric acid, VFA levels in ileal digesta of piglets fed low-protein diets were generally lower (P < 0.05) compared with the control diet. Diet had no effect on intestinal microbial counts (P > 0.10). The results show that piglet performance may suffer when dietary CP is reduced by 4 or more percentage units from 23% and support the hypothesis that low-CP diets help maintain enteric health in pigs by lowering toxic microbial metabolites such as ammonia.     

Apparent precaecal digestibility of nutrients and level of endogenous nitrogen in digesta of the small intestine of growing pigs as affected by various digesta viscosities.

Sixteen male growing pigs of about 24 kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine + cystine, threonine and tryptophan. Additionally, [15N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of 15N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276 mg per 12 h per kg0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150 mg per 12 h per kg0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.     

日粮锌对断奶仔猪血清溶菌酶活性的影响

选用40头28日龄断奶约滇陆杂交仔猪,分为1个对照组和4个试验组(试验组锌添加量分别为240、1000、3000和5000mg/kg),并分别于42、56日龄和70日龄测定仔猪血清中溶菌酶活性。结果表明:补锌均能提高溶菌酶活性,但适量高锌3000mg/kg对溶菌酶活性的提高程度更显著(P<0.05)。     

N-乙酰半胱氨酸对脂多糖刺激仔猪小肠黏膜免疫应激的影响

研究N-乙酰半胱氨酸(NAC)对脂多糖(LPS)刺激仔猪免疫应激的影响。选取18头健康仔猪,随机分成3个处理(对照组、LPS组和NAC组),每个处理6个重复。对照组和LPS组饲喂基础日粮,NAC组饲喂基础日粮+500 mg/kgNAC。试验期为20 d。LPS组和NAC组于试验第10、13、20天腹膜注射100μg/kg BW的LPS,对照组注射相应剂量的灭菌生理盐水。第10、20天注射LPS后3 h采血,第21天屠宰,取小肠黏膜。结果表明:NAC缓解了LPS刺激导致的血浆和小肠黏膜中TNF-α、IL-6、PGE2含量的升高(P<0.05),缓解了小肠黏膜HSP70相对表达量的升高(P<0.05)。由此可见,日粮中添加500 mg/kg NAC可有效抑制LPS刺激导致的血浆及小肠黏膜中炎性因子的升高,缓解免疫应激。