圆环病毒攻击下生物素添加水平对仔猪细胞免疫及生产性能的影响

将28d断奶、圆环病毒(PVC2)抗体阴性的(杜×长×大)三元杂交仔猪54头,平均分为6组,每组9头,单笼饲养。试验第1天全部猪口鼻接种圆环病毒,在玉米-豆粕型基础日粮中分别添加生物素0、0.10、0.20、0.30、0.40mg/kg和0.50mg/kg,以确定PCV2攻击下,仔猪饲粮生物素添加水平对细胞免疫及生产性能的影响。结果表明:饲粮中添加生物素0.30mg/kg,仔猪外周血E总花环形成率和T淋巴细胞转化率较高,并可促进外周淋巴器官维持正常形态、提高胸腺生长指数;添加0.50mg/kg提高生产性能的效果最佳。由本试验可得出,添加生物素可促进仔猪淋巴器官生长和细胞免疫反应并能提高生产性能,以添加0.30mg/kg的效果较好。     

圆环病毒攻击下日粮中生物素的添加水平及其对仔猪部分免疫指标及生产性能的影响

本试验旨在确定猪圆环病毒2型(PCV2)攻击下,玉米-豆粕型日粮中生物素的适宜添加水平及其对仔猪部分免疫指标及生产性能的影响.将28日龄断奶、PCV2抗体检测阴性的(杜×长×大)三元杂交仔猪54头,平均分成6个处理,每个处理9个重复,每个重复1头猪.试验第1天试验猪全部口鼻接种PCV2,分别饲喂添加了0、0.10、0.20、0.30、0.40和0.50 mg/kg生物素的日粮,试验期35 d.结果显示:(1)添加0.50 mg/kg生物素时,仔猪35 d的日增重、料重比显著高于0 mg/kg生物素添加组(P<0.05);(2)日粮中添加0.30～0.50 mg/kg生物素,试验第21天和第35天,仔猪血清IgG水平显著高于0～0.20 mg/kg添加组(P<0.05);(3)添加0.30 mg/kg生物素,可以提高试验后期仔猪血清IFN-γ水平;(4)35 d日增重、料重比,以及接种后21和35 d仔猪血清IgG水平与生物素添加量分别呈2次及3次曲线回归.由结果得出,PCV2攻击下,日粮中添加0.30～0.50 mg/kg的生物素,对提高仔猪生产性能,提高IgG及后期IFN-γ水平有良好效果.     

日粮中添加柠檬酸对断奶仔猪生产性能的影响

选用日龄相同、平均体质量相近的大白×长白断奶仔猪32头,采用完全随机区组设计分成4个处理.对照组饲喂基础日粮,试验1、2、3组,分别在基础日粮中添加1%、1.5%和2%柠檬酸.结果表明在18 d试验期内,试验组比对照组仔猪的平均日增体质量分别提高9%、13.8%和15.4%,其中添加2%柠檬酸的试验组与对照组平均日增重差异显著(P＜0.05);料肉比分别降低6.7%、9.1%和10%;每kg增重饲料成本分别下降1.6%、1.8%和1.3%,并且添加柠檬酸显著降低了仔猪腹泻.试验结果显示以添加2%柠檬酸的试验组生产成绩和经济效益最好.     

日粮中添加怀山药豆对断奶仔猪生产性能的影响

文章旨在研究怀山药豆对断奶仔猪生产性能的影响,试验将120头28日龄的健康、体重一致的断奶仔猪随机分成4组,每组3个重复,每个重复10头,分别为Ⅰ组：饲喂基础日粮（对照组）,ⅠⅠ组：基础日粮+1%怀山药豆,Ⅲ组：基础日粮+3%怀山药豆,Ⅳ组：基础日粮+5%怀山药豆,试验期28 d。结果表明,（1）生长性能：Ⅲ组、Ⅳ组相比Ⅰ组全程平均日采食量、平均日增重显著提高（P <0.05）;料肉比降低,但差异不显著（P> 0.05）;腹泻率显著降低（P <0.05）;(2)血清生化及免疫性能：Ⅲ组、Ⅳ组血清ⅠgA和ⅠgG水平均显著高于Ⅰ组（P <0.05）;(3)盲肠微生物数量：与试验Ⅰ组相比,Ⅲ、Ⅳ组肠道中大肠杆菌、沙门氏菌数量降低,乳酸杆菌、双歧杆菌数量提高,但差异不显著（P> 0.05）。结论 ：在断奶仔猪日粮中添加怀山药豆可提高断奶仔猪生长性能,降低肠道中大肠杆菌、沙门氏菌的数量,提升乳酸杆菌、双歧杆菌的数量,提高抗腹泻能力,还可以促进仔猪机体血清中ⅠgA、ⅠgG的生成,提升抵抗力,综合改善仔猪生产的成绩。     

基础日粮添加蜂胶对断奶仔猪生产性能的影响

试验选用50头"杜长大"三元杂交断奶仔猪为材料.随机分为对照组和试验组,研究蜂胶对断奶仔猪腹泻率、平均日增重和料重比等生产性能的影响.对照组只饲喂仔猪基础日粮,试验组则在基础日粮中添加蜂胶,试验为期30d.研究结果表明,与对照组相比较,试验组仔猪的平均日增重提高19.28%(P<0.05),而腹泻率下降21.74%(P<0.01),料重比降低了15.34%(P<0.05).因此,在断奶仔猪日粮中添加适量的蜂胶对仔猪生长性能和防病功能是有益的.     

日粮中添加浓缩大豆卵磷脂对断奶仔猪生产性能的影响

在断奶仔猪日粮中,为了获得快速生长满足机体对能量的需要,一般需添加１％－３％的植物油或动物脂肪。但是,在仔猪断奶阶段,由于胆汁分泌不足以及脂肪酶活性尚未发育完全,大量添加油脂效果往往不很理想。磷脂作为一类特殊的脂类物质,既是动物体的重要组成成分,也可参与脂肪代谢和体内脂质转运,同时还起着肠道油脂乳化剂的作用。因此从理论上讲,对脂肪的吸性具的一定的促进作用。为了验证上述结论,特进行了本次实验。１材料与方法１．１试验猪的选择与分组试验用断奶小猪均为杜ｘ长ｘ大杂交后代,生长状况良好,个体差异小,公母比…     

日粮中添加微生态制剂对断奶仔猪生产性能的影响

试验基于研究微生态制剂在断奶仔猪上的应用效果设计。试验选取3种市售微生态制剂进行效果求证和比较,结果显示,仔猪日粮中添加派富和其它两种市售微生态制剂均有助于提高断奶仔猪的生产性能,但结果有较显著差异。综合比较,添加派富优于对照组和其它两种市售微生态制剂。     

日粮中添加维生素C对夏季断奶仔猪生产性能的影响

为了探明添加维生素Ｃ对夏季断奶仔猪生产性能的影响。将４８头杜斯仔猪随机分为４组,Ⅰ、Ⅱ、Ⅲ、Ⅳ组,每ｋｇ日粮分别添加１００ｍｇ、２００ｍｇ、３００ｍｇ、０ｍｇ维生素Ｃ进行试验。结果表明：Ⅱ组与对照组仔猪增重差异显著（Ｐ〈０．０５）,Ⅱ组较对照组日增重增加１２５ｇ,饲料转化率提高１０．４９％;Ⅰ、Ⅲ组与对照组仔猪增重差异不显著（Ｐ〉０．０５）,但日增重分别比对照组提高８３ｇ和５６ｇ,饲料转化率提高１     

断奶日粮中添加不同酸制剂对仔猪生产性能的影响

早期断奶仔猪由于消化机能尚无发育完善,消化机能和胃酸分泌不足,因而将给仔猪带来如营养、环境和群体等结构方面应激变化,仔猪表现为食欲下降,消化不良,抗病能力下降等。酸化剂由于能降低断奶仔猪胃内容物的ｐＨ值,使胃内容物ｐＨ值维持相对稳定,对于改善消化道酶...     

日粮中添加酶制剂对断奶仔猪生产性能及消化率的影响

以60头35日龄长白断奶仔猪为试验动物，在玉米／豆粕基础日粮中添加0．05％，0．10％，0．15％的酶制剂。结果表明，0．10％酶制剂添加水平对断奶仔猪生产性能和日粮养分的消化率及添加剂的经济效益达到最大值。     

Effect of porcine circovirus type 2 (PCV2) vaccination on PCV2-viremic piglets after experimental PCV2 challenge

The objective of this study was to evaluate the effect of porcine circovirus type 2 (PCV2) vaccines on PCV2-viremic and -seropositive piglets born from naturally PCV2-infected sows against postnatal PCV2 challenge. The experimental design was aimed at mimicking commercial swine rearing conditions to evaluate the response of the PCV2 vaccine on PCV2-viremic and -seropositive piglets after experimental PCV2 challenge. PCV2a (or 2b)-viremic piglets received a PCV2 vaccine at 21 days of age followed by a PCV2b (or 2a) challenge at 49 days of age (28 days post vaccination). The PCV2 vaccines elicited a high level of humoral (as measured by immunoperoxidase monolayer assay and neutralizing antibody titers) and cellular (as measured by the frequency of PCV2-specific interferon-γ-secreting cells) immune response in the PCV2-viremic piglets after vaccination even in the presence of maternally derived antibodies (MDA). The initial infection of PCV2 in the pigs was not affected by PCV2 vaccination, however the challenging PCV2 was reduced by PCV2 vaccination on PCV2-viremic pigs. The results from this study demonstrate that the PCV2 vaccine used in this study is effective at reducing PCV2 viremia and lymphoid PCV2 DNA, even for PCV2-viremic pigs with passively acquired MDA at the time of vaccination.     

Effect of porcine circovirus type 2 (PCV2) vaccination on porcine reproductive and respiratory syndrome virus (PRRSV) and PCV2 coinfection

The objectives were to determine if PCV2 vaccination is effective in reducing disease and lesions associated with PRRSV and PCV2 coinfection and if there is a difference between intradermal (ID) and intramuscular (IM) route of PCV2 vaccination. Seventy-four, 21-day-old pigs were randomly allocated into one of six groups. On day 0, pigs were vaccinated with 2ml Suvaxyn((R)) PCV2 One Dose (Fort Dodge Animal Health, Inc.) by intramuscular (VAC-M-COINF) or intradermal (VAC-D-COINF) routes. On day 28, pigs were either singularly (PRRSV-only, PCV2-only) or coinfected (COINF) with PRRSV and PCV2. All pigs in all groups were necropsied on day 42. All vaccinated pigs seroconverted (IgM, IgG, and neutralizing antibodies) to PCV2 between 14 and 28 days post-vaccination. After challenge, all groups inoculated with PRRSV had reduced average daily gain compared to CONTROLS and PCV2-only (P<0.001). COINF pigs had significantly (P<0.05) reduced anti-PCV2-IgG antibody levels and neutralizing antibody levels compared to both vaccinated groups. COINF pigs had more severe lung lesions compared to VAC-M-COINF (P<0.05). COINF pigs had higher amounts of PCV2 DNA in serum samples and feces (P<0.05) and increased amounts of PCV2 in lymphoid tissues (P<0.05) compared to both vaccinated groups. In summary, PCV2 vaccination was effective at inducing a neutralizing antibody response and significantly reducing PCV2-associated lesions and PCV2 viremia in pigs coinfected with PCV2 and PRRSV. Differences between intradermal and intramuscular routes of vaccine administration were not observed.     

A meta-analysis on experimental infections with porcine circovirus type 2 (PCV2)

A meta-analysis was performed with the aim to identify factors with a relevant influence on the expression of clinical postweaning multisystemic wasting syndrome (PMWS) under experimental conditions. Data from 44 studies were included in the analysis. Several variables were studied: number of pigs in the experiment, intake of colostrum, serological status against porcine circovirus type 2 (PCV2), strain of PCV2 used for inoculation, the route and dose of inoculation, and use of potential triggering factors (such as co-infections, vaccinations, or immunomodulator products). Multiple correspondence analysis and log-linear regression methods were used to establish the relationships between the studied variables and the number of PCV2 infected pigs that developed PMWS. Based on the results of the meta-analysis, the most successful animal experiment aimed to develop PMWS should include: (1) colostrum-deprived pigs, (2) age of inoculation below 3 weeks, (3) high doses of PCV2 inoculum, (4) PCV2 strain from genotype 1, and (5) co-infection with another swine pathogen as a triggering factor.     

Epidemiology and horizontal transmission of porcine circovirus type 2 (PCV2)

Porcine circovirus type 2 (PCV2) is a small, non-enveloped, circular, single-stranded DNA virus of economic importance in the swine industry worldwide. Based on the sequence analyses of PCV2 strains, isolates can be divided into five subtypes (PCV2a-e). PCV2 is an ubiquitous virus based on serological and viremia data from countries worldwide. In addition, PCV2 DNA was discovered in archived samples prior to the first recognition of clinical disease. Recently, a worldwide shift in PCV2 subtype from PCV2a to PCV2b occurred. PCV2 DNA can be detected in fecal, nasal, oral and tonsillar swabs as well as in urine and feces from both naturally and experimentally infected pigs. PCV2 DNA can be detected early in the infectious process and persists for extended periods of time. The effectiveness of disinfectants for reducing PCV2 in vitro is variable and PCV2 is very stable in the pig environment. Limited data exist on the horizontal transmission of PCV2. Direct transmission of PCV2 between experimentally or naturally infected animals and na?ve animals has been documented and the incorporation of clinical or subclinically infected animals into a population represents a risk to the herd. Indirect transmission through the oral, aerosol or vaccine routes is likely a lesser risk for the transmission of PCV2 in most swine populations but may be worth evaluating in high heath herds. The objective of this review was to discuss data on the epidemiology and horizontal transmission of PCV2.     

Distribution of antibodies against porcine circovirus type-2 (PCV2) in single site and multi-site farrow-to-finish farms in Brazil

A comparative serologic study was performed in seven single site (SS) farrow-to-finish farms and four multi-site (MS) farrow-to-finish farms, with or without post-weaning multisystemic wasting syndrome (PMWS). In each farm, 30 blood samples were collected for each category of the production cycle: sows, farrowing crate, nursery, grower pigs, and finishing pigs. Sera were evaluated for the presence of antibodies to porcine circovirus type-2 (PCV2) via immunoperoxidase monolayer assay. Serologic profiles for PCV2 were different between SS and MS farms. Seroconversion following the decline in maternal antibodies occurred at a later stage on SS farms (grower pigs) than MS farms (nursery pigs). MS farms tended to have lower antibody titers than SS farms in the categories of sow, piglet, and nursery, while higher antibody titers were found in grower pigs. Characterization of serologic profiles for different farms may provide important information for the adoption of vaccination programs.     

Distribution of antibodies against porcine circovirus type-2 (PCV2) in single site and multi-site farrow-to-finish farms in Brazil

A comparative serologic study was performed in seven single site (SS) farrow-to-finish farms and four multi-site (MS) farrow-to-finish farms, with or without post-weaning multisystemic wasting syndrome (PMWS). In each farm, 30 blood samples were collected for each category of the production cycle: sows, farrowing crate, nursery, grower pigs, and finishing pigs. Sera were evaluated for the presence of antibodies to porcine circovirus type-2 (PCV2) via immunoperoxidase monolayer assay. Serologic profiles for PCV2 were different between SS and MS farms. Seroconversion following the decline in maternal antibodies occurred at a later stage on SS farms (grower pigs) than MS farms (nursery pigs). MS farms tended to have lower antibody titers than SS farms in the categories of sow, piglet, and nursery, while higher antibody titers were found in grower pigs. Characterization of serologic profiles for different farms may provide important information for the adoption of vaccination programs.     

Reproduction in porcine circovirus type 2 (PCV2) seropositive gilts inseminated with PCV2b spiked semen

Background

Since 1999, field evidence of transplacental infection by porcine circovirus type 2 (PCV2) and reproductive failure has been reported in pigs. The objective of this study was to evaluate the clinical and pathological consequences of PCV2 infection in conventional PCV2-seropositive gilts by insemination with PCV2b-spiked semen.

Results

Six PCV2 seropositive gilts were inseminated with PCV2b-supplemented semen (infected) and three animals with semen and cell culture medium (controls). Only three out of the six infected animals were pregnant by ultrasonography on day 29 after insemination, while two out of the three controls were pregnant. One control gilt aborted on day 23 after insemination but not due to PVC2. Viraemia was demonstrated in four out of six infected and in one control gilt that became infected with PCV2a. Anti-PCV2 antibody titres showed dynamic variations in the infected group throughout the study. Among infected gilts, the animal with the lowest anti-PCV2 titre (1/100) at the beginning of the experiment and another that reached a similar low value during the experiment showed evident seroconversion over time and had also PCV2 positive foetuses. One placenta displayed mild focal necrosis of the chorionic epithelium positively stained by immunohistochemistry for PCV2 antigen.

Conclusions

PCV2-seropositive gilts can be infected with PCV2 after intrauterine exposure and low maternal antibody titre may increase the probability of a foetal infection.     

猪圆环病毒及其相关猪病的研究进展

猪圆环病毒自发现以来一直困扰着养猪业,造成了全球巨大的经济损失。该病毒可引发多种表症的疾病,如PMWS,PDNS,PBDC等。近年来越来越受到研究人员重视,对猪圆环病毒相关病的临床症状、特征性病变等方面作了大量研究,并且对其致病机理做了初步研究,取得了一些可喜进展。这些将为该病的预防诊断,以至彻底根除提供巨大帮助。     

Effect of dietary biotin supplementation on sow reproductive performance and soundness and pig growth and mortality

A 3-yr study was conducted to evaluate the effect of dietary biotin supplementation on the reproductive performance of 90 sows and gilts, and on the pre-weaning growth and mortality of 223 litters. Corn-soybean meal-based diets supplemented with either 0 or 440 micrograms/kg d-biotin were fed to sows throughout their reproductive cycle. Biotin supplementation had no beneficial effect (P greater than .10) on 107-d sow weight, sow weight at weaning, weaning to estrus interval, foot lesion score, hair loss score, structural soundness score, number of pigs born, number and percentage of pigs born alive or number and percentage of pigs alive at 21 d of age. Biotin supplementation had no effect (P greater than .10) on pig growth or mortality to 21 d of age. These data do not support the concept that biotin supplementation of sow diets is needed.