海藻多糖可溶性粉增强猪免疫功能的临床应用研究

为进一步探讨海藻多糖可溶性粉作为饲料添加剂在猪的规模化生产中大面积应用的临床效果及安全性,选取35～50日龄临床自然感染猪圆环病毒2型(PCV2)仔猪150头,随机分为3组,每组50头,分别设供试药物组(在饲料中添加海藻多糖可溶性粉200 mg/kg,连用7 d)、药物对照组(在饲料中添加黄芪多糖粉200 mg/kg,连用7 d)和阳性对照组(不处理)。于用药前1 d、用药后第7天和第14天每组随机选择10头试验猪测定血清中猪白细胞介素-2(IL-2)、白细胞介素-6(IL-6)、干扰素-γ(INF-γ)、肿瘤坏死因子-α(TNF-α)等细胞因子和免疫球蛋白G(IgG)水平。结果表明,在临床自然感染猪圆环病毒2型(PCV2)的仔猪日粮里添加200 mg/kg海藻多糖可溶性粉能升高猪血清中IL-2、 IL-6、TNF-α、IFN-γ和IgG水平;试验期间,在仔猪日粮中添加200 mg/kg海藻多糖可溶性粉连用7 d无不良反应出现。由该试验结果可以得出,海藻多糖可溶性粉能够提高猪的免疫功能,临床使用是安全的。     

Effects of forage source and particle size on chewing activity,ruminal pH,and saliva secretion in lactating Holstein cows

The present study investigated the effects of dietary forage source (quality) and particle size on chewing activity, saliva secretion, and ruminal pH. Twelve multiparous lactating Holstein cows, four of which were ruminally cannulated, were used in a replicated 4 × 4 Latin square experimental design with a 2 × 2 factorial arrangement of treatments. Cows fed wild‐rye hay diets had longer daily eating times than cows fed oaten hay diets. Treatments had no effect on ruminating time; therefore, resting time varied inversely to eating time. Neither the rate nor the amount of saliva secretion while eating, ruminating, or resting was affected by diet, resulting in similar total daily saliva secretions across treatments (231 L/day). Total volatile fatty acids (VFAs) in the ruminal fluid from animals fed oaten hay diets were higher than those from animals fed wild‐rye hay diets; further, VFAs increased with decreasing forage particle size (FPS). Consistent with elevated VFA concentrations, reducing FPS and including oaten hay in the diet decreased mean ruminal pH and increased the daily time of ruminal pH under 5.8. Results of this study suggest that forage source and particle size affect ruminal pH might be via variations in VFA production rather than increased salivary recycling of buffering substrates.     

Effects of colostrum whey on immune function in the digestive tract of goats

The objective of the present study is to examine whether colostrum whey can have an effect on immune function in goats digestive tract. Two milliliters of colostrum whey (colostrum group) or water (control group) were administrated orally to goats every day for 3 weeks. Blood was collected twice a week for 3 weeks to measure immunoglobulin A (IgA), interleukin 8 (IL‐8), and IL‐10. At the end of the experimental period, the parotid glands, oral mucosa, lingua, esophagus, jejunum, and ileum were collected for immunohistochemical detection of IgA, cathelicidin‐7, and S100A8. The ratio of the length of IgA‐positive mucosal surface in the esophagus to the total esophageal length was significantly greater in the colostrum group than in the control group. The number of IgA‐positive cells in the labial gland and ileum in the colostrum group was significantly higher than that in the control group. There were no significant differences between the colostrum and control groups in the number of cathelicidin‐7‐positive cells in the jejunum and ileum and in the number of S100A8‐positive cells in the lingua, jejunum, and ileum. These results suggest that colostrum stimulates the recruitment of plasma cells into the labial gland, which then secrete more IgA into the saliva.     

Effects of fermented soybean meal on growth performance,diarrheal incidence and immune‐response of neonatal calves

The effects of partial substitution of fermented soybean meal (FSBM) for soybean meal (SBM) on immune‐physiological parameters, growth performance and diarrheal incidence in neonatal calves after microbial infection were investigated. Holstein calves (n = 12) were randomly assigned to two dietary treatments: the SBM and the FSBM group. The latter group received a calf starter containing 5% FSBM instead of SBM. In order to evaluate the immunocompetence against microbial infection, all calves were challenged with porcine live vaccine by intramuscular injection at 21 days of age. The incidence and severity of diarrhea were significantly less (P < 0.05) in the FSBM group compared to those in the SBM group at 21 and 42 days of age. Feeding FSBM starter resulted in a higher (P < 0.05) relative amount of bacterial‐specific IgA than those on SBM at days 5 and 14 post‐microbial infection (DPMI). Viral‐specific IgA also increased (P < 0.05) at 5 DPMI in the FSBM group when compared to the SBM group. The average concentration of haptoglobin of calves fed FSBM was generally higher at 3 DPMI. Our results indicate that FSBM plays a role in the alleviation of diarrhea and in the production of immune‐related effector cells such as IgA and haptoglobin in calves.     

Specific IgA antibody response to coproantigens of Cryptosporidium parvum in serum and saliva of calves after experimental infection

The antibody response to coproantigens of Cryptosporidium parvum was examined in saliva and sera of calves experimentally infected with C. parvum. Coproantigens of C. parvum with approximate molecular masses of 17, 15 and less than 14kDa were found in the feces of infected calves on day 3 or later, and 60 and 23kDa coproantigens observed between days 4 and 9 post-infection, respectively. The antibody reactivity to the coproantigens was mainly attributable to IgA class antibodies in saliva and was detectable during the convalescent phase of infection. A 15kDa protein isolated from the feces of infected calves by immunoaffinity adsorption using a monoclonal anti C. parvum antibody was recognized by IgA antibodies present in the saliva during the convalescent phase of infection. These results suggest that this coproantigen may be released from C. parvum sporozoites and may induce IgA antibody production in the mucosal immune system of infected calves.     

Validation of three commercially available immunoassays for quantification of IgA, IgG, and IgM in porcine saliva samples

The objectives of this study were to perform the optimization and validation of three commercially available immunoassays for the measurement of IgA, IgG, and IgM (Igs) in porcine saliva samples and to determinate if their concentrations may be used to distinguish healthy from diseased animals. Intra and inter assay coefficients of variation were lower than 15% in all cases. All methods showed good linearity and recovery; and detection limits were low enough to detect Igs levels in healthy and diseased animals. The clinical validation showed an increase statistically significant (P<0.05) in the group of diseased animals versus healthy pigs. Therefore, these assays may be used in porcine saliva samples, in addition, the measurement of Igs in saliva could be a practical tool, simple and minimally invasive, to evaluate the humoral immune status of pigs.     

Effects of dietary phytoncides extracted from Korean pine (Pinus koraiensis) cone on performance,egg quality,gut microflora,and immune response in laying hens

This study was conducted to evaluate the effects of dietary phytoncides extracted from discarded Korean pine cones (Pinus koraiensis) on the performance, egg quality, immune response and gut microflora in laying hens. A total of 400 Hy‐Line brown laying hens (50‐week old) were allotted into four dietary treatments including a control diet or a diet supplemented with phytoncides at 0.002%, 0.004% and 0.008%. During the 6 weeks of experimental feeding, 0.008% of dietary phytoncides improved egg production, feed conversion ratio (p < 0.05), but not feed intake, egg weight or feed efficiency. Although dietary phytoncides had no effect on egg quality, decreases in Haugh units depending on storage periods were improved by 0.008% of dietary phytoncides (p < 0.05). To investigate the roles of dietary phytoncides on the alteration of the immune response during inflammation, lipopolysaccharide (LPS) or saline was intraperitoneally injected into 10 hens per diet group on the end date of the experimental feeding period. Serum immunoglobulins and splenic cytokine expression at mRNA levels were then measured at 4 hr postinjection. Although the levels of IgA were decreased by LPS injection in all dietary groups, dietary phytoncides at 0.008% showed a higher level of IgA by LPS (p < 0.05). Interestingly, although LPS injection resulted in an enhanced expression of proinflammatory cytokines such as IL‐1β and IL‐6, dietary phytoncides at 0.008% showed less increased levels of them (p < 0.05). Gut microflora was examined from 10 hens per diet group at the end of the experimental period. While the number of Lactobacillus spp. was increased (p < 0.05), Escherichia coli counts in the cecal contents were decreased by 0.008% of dietary phytoncides. Taken together, these results demonstrate that dietary supplementation of 0.008% phytoncides improved the egg production, immune responses during inflammation and gut microflora in laying hens.     

IgA and secretory component (SC) in the third eyelid of domestic animals: a comparative study

Objective The third eyelid of domestic animals is important for the production and distribution of tears, in removing ocular debris and in protection of the globe, and has significant immunologic functions. Although it is known that tears contain antibodies of the immunoglobulin A (IgA) isotype which are produced mainly by plasma cells of the lacrimal gland, very little is known about the antibody repertoires in the third eyelid of domestic animals. To assess whether IgA is derived from local synthesis, we analyzed the location of IgA‐producing cells and the cellular distribution of secretory component (SC) in the third eyelid of domestic animals in a comparative study. Animal studied A total of 83 third eyelids of dogs, cats, pigs, cows, sheep, goats and horses were investigated in the course of this study. Procedures Third eyelids were obtained immediately after death, cut length‐wise, fixed overnight and processed for immunohistochemical detection of IgA and SC by the ABC technique. Results The results show that IgA‐producing plasma cells are densely populated in subepithelial spaces of the surface epithelium as well as in the nictitating gland in a species‐specific manner. In contrast, the SC could be demonstrated exclusively in glandular acinar and ductal epithelial cells and in different cell types of the surface epithelium, preferentially located on the bulbar side of the nictitating membrane. Conclusion It is suggested that most of the SC is locally produced by resident plasma cells and subsequently transferred through the surface epithelium and glandular duct cells by transcytosis. This indicates that the third eyelid is an important member of the secretory immune system in domestic animals.     

Interference of the humoral immune response against resident and nonresident intestinal commensal strains in weaning pigs

Not nocuous bacteria are important for the maturation and the modulating activity of the gut immune system. However, the humoral immune response against commensal and probiotic bacteria is less documented, particularly in farmhouse animals. Blood serum and saliva were collected in two trials where probiotics, Lactobacillus rhamnosus GG (LbR), well-defined human isolate (Trial A), and a novel and abundant porcine commensal, Lactobacillus sobrius strain 001^T (LbS) (Trial B), were supplemented to weaning pigs. Anti-LbR IgA were present in serum of pigs before treatment with LbR, but also after 1 or 2 weeks in control pigs, notwithstanding the absence of DNA from LbR in colon. Pigs fed or not LbS for 1 or 2 weeks had LbS-specific IgA, in saliva and in serum. Colon contents of control subjects were positive for DNA from LbS. We hypothesized that part of this IgA strain-specific activity is partially related to immune cross-reactivity between different Lactobacillus-species. With the procedure of Shu et al. [Shu, Q., Bird, S.H., Gill, H.S., Rowe, J.B., 1999. Immunological cross-reactivity between the vaccine and other isolates of Streptococcus bovis and Lactobacillus. FEMS Immunol. Med. Microbiol. 26, 153–158], after ELISA test on blood serum or saliva pre-incubated with LbR or LbS, each strain blocked a relevant part of IgA specific for the other. So bacteria with different affinity for the pig present reciprocal crossed immune activity. When probiotics are supplied to weaning pigs, the possible action of already present multi-effective IgA should be considered. The mechanism of IgA induction by certain probiotics needs to be addressed in further studies.     

Effect of dietary boron on immune function in growing beef steers*

Thirty‐six Angus and Angus × Simmental cross steers (initial BW 269.5 ± 22.3 kg) were used to determine the effects of dietary boron (B) on performance and immune function. Steers were fed on one of the three dietary treatments: (i) control (no supplemental B; 7.2 mg B/kg DM), (ii) 5 mg supplemental B/kg DM and (iii) 50 mg supplemental B/kg DM, from sodium borate for 78 days. Supplementation of dietary B had no effect on body weight (BW) gain, feed intake or gain:feed during the study. Jugular blood samples were collected prior to feeding on days 28, 63 and 77 for plasma‐B analysis. Supplementation of dietary B increased (p < 0.001) plasma B‐concentration in a dose‐responsive manner. Furthermore, plasma B‐concentration was correlated (p < 0.001; R² = 0. 95) to daily B‐intake (mg B/day). Jugular blood was also collected, from an equal number of steers from each treatment, on day 42 or 44 for determination of in vitro production of interferon‐γ and tumour necrosis factor‐α from isolated monocytes and assessment of lymphocyte proliferation. Dietary B did not affect T‐ or B‐lymphocyte proliferation or in vitro cytokine production from monocytes. On day 49 of the study, the humoral immune response was assessed by i.m. injection of a 25% pig red blood cell (PRBC) solution for determination of anti‐PRBC IgG and IgM titre responses. Boron‐supplemented steers had greater (p = 0.035) anti‐PRBC IgG titres than controls on day 7 but not on day 14 or 21 post‐injection. Anti‐PRBC IgM titres did not differ throughout the sampling period. Results from this study indicate that supplemental B had minimal effects on immune function and did not affect performance of growing steers.     

Urine levels of luteinizing hormone as predictor of the period of ovulation for advantage of timed‐artificial insemination in murrah buffalo (Bubalus bubalis)

Assessment of urine levels of luteinizing hormone (LH) for predicting the reproductive status of animals is in practice. The aim of this study was to predict the period of ovulation based on the urine levels of LH for timed‐artificial insemination to increase the conception rate in buffaloes, which are naturally silent‐oestrous animals. Level of LH in urine was assessed using ELISA, and a cut‐off LH concentration for prediction of ovulation period was obtained using receiver operating characteristic analysis. Artificial insemination was performed before‐ and after ‐positive prediction of ovulation period adopting this method, and the rates of conception were assessed. Urine LH level of 105 mIU/ml (n = 14) was derived as a cut‐off concentration which predicts the ovulation period. The buffaloes in the positively predicted group (day 1 or 2) inseminated via intracervical route had an increase in the conception rate (83.33%); however, the insemination in the before‐positive‐prediction group resulted in poor conception rates (day 0; 16.66%) compared to that of the naturally inseminated group (day 0; 75.0%). In conclusion, the urinary LH would possibly be a fairly reliable predictor of the ovulation period. The day when cut‐off LH concentration is obtained may be taken as the most favourable time for artificial insemination, so as to attain a much better rate of conception in the buffalo.     

Evaluation of Aloe vera and synbiotic as antibiotic growth promoter substitutions on performance,gut morphology,immune responses and blood constitutes of broiler chickens

This study was performed to investigate the effect of dietary supplementation with Aloe vera (AV) powder and synbiotic as growth promoter agents on performance, gut morphology, immune responses, hematology and serum biochemistry in broilers. A total of 240‐day‐old male broiler chicks (Ross 308) were randomly assigned to six treatments with four replicates. Birds were offered either a corn‐soybean meal basal diet (control) or the basal diet supplemented with 200 mg/kg virginiamycin (VM), 1 g/kg synbiotic (Syn), 2.5 g/kg AV (AV1), 5.0 g/kg AV (AV2) or 7.5 g/kg AV (AV3). Chickens fed any of the diets, except diet AV1, exhibited better feed conversion ratios at the 14–28 day period and higher average daily gain and duodenal villus height/crypt depth ratio at 42 days than those fed the control diet. Synbiotic supplementation caused a marked increase in the serum antibody titer against infectious bursal disease and infectious bronchitis vaccines. Feeding diet AV3 significantly increased red blood cell count and hemoglobin concentration, and decreased serum triglyceride level compared to the control group. The results suggested that dietary inclusion of 5 and 7.5 g/kg AV, similar with synbiotic supplementation, can be applied as effective alternatives to in‐feed antibiotics for broiler diets.     

Salivary IgA: a suitable measure of immunity to gastrointestinal nematodes in sheep

Infection with gastrointestinal nematodes (GIN) is a major constraint on the productivity of grazing livestock. The development of selection methods to quickly and accurately identify animals capable of developing an effective natural immunity to infection would contribute to the development of sustainable worm control programs. A carbohydrate larval surface antigen (CarLA), present on the infective-stage larvae (L3) of all trichostrongylid nematodes, is a target antigen for host antibody (Ab). The levels of various Ab isotypes in serum and/or saliva of field-grazed lambs were assessed by ELISA, and Ab titres compared with parasite faecal egg counts (FECs) and a range of animal productivity parameters. Levels of anti-CarLA IgA in saliva proved to be the most heritable (h(2)=0.3), and had the closest genetic correlation with FEC (r=-0.5). Those animals identified as having 'high levels' of anti-CarLA IgA typically have 20-30% lower FEC than animals with low or undetectable titres. Furthermore, animals with 'high levels' of anti-CarLA IgA tend to have improved growth rates post-weaning, and have no tendency for increased breech-soiling. The assay performed well regardless of parasite genera present on pasture. The saliva assay has a number of key practical advantages over the use of FEC for selection purposes: animals can be identified without a requirement to withhold anthelmintic treatment; sampling is rapid and easy and there is a significantly reduced barrier to adoption within the farming community. Measurement of anti-CarLA IgA in saliva by ELISA offers a practical, rapid and easy method of selecting for natural immunity to GIN in sheep.     

Initiation of Steroidogenesis Precedes Expression of Cholesterologenic Enzymes in the Fetal Mouse Testes

Sexual differentiation is a carefully regulated process that ultimately results in a development of the male or female phenotype. Proper development of the male phenotype is dependent upon the action of testosterone and anti‐mullerian hormone. Leydig cells start to produce testosterone around day 12.5 in the fetal mouse testis, and continue to produce high levels of this hormone throughout gestation. In the present study, we examined whether expression of lanosterol 14α‐demethylase (cyp51) and cytochrome P450 NADPH reductase, both involved in the cholesterol production, occurs simultaneously with proteins required for the production of steroid hormones. Immunocytochemical staining with the antibodies against cyp51, cytochrome P450 NADPH reductase, steroidogenic acute regulatory protein (StAR) and 3beta‐hydroxysteroid dehydrogenase I (3β‐HSD I) was used to determine the ontogeny of expression of these four proteins. As expected, 3β‐HSD I and StAR proteins were detected on day 12.5 p.c., while expression of cyp51 and NADPH cytochrome P450 reductase appeared 1 day later, on day 13.5. Thereafter, the expression of all four proteins remained strong throughout gestation. Results of this study suggest that initial steps of steroid hormone production in murine Leydig cells are mostly dependent on exogenously derived cholesterol, while from day 13.5 onwards, mouse Leydig cells are able to synthesize cholesterol and are therefore not dependent on exogenous cholesterol resources.     

不同形式补铁补硒对仔猪生长性能、血液生化指标、免疫性能的影响

[目的] 比较母猪和仔猪不同形式的补铁补硒对仔猪生产性能、血液生化指标、免疫性能的影响。[方法] 将32头母猪随机分为8组,每组4头,1~4组基础日粮中添加硫酸亚铁和亚硒酸钠,5~8组基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸。2组和6组母猪所产仔猪于3日龄肌注铁硒合剂;3组和7组仔猪基础日粮中添加硫酸亚铁和亚硒酸钠;4组和8组仔猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸;1组和5组仔猪饲喂基础日粮,不接受任何形式的补铁补硒。母猪预产期前30 d开始饲喂试验日粮,仔猪7日龄时开始饲喂试验日粮,试验至仔猪21日龄断奶结束。测定并比较不同组别仔猪生长性能指标、血液生化指标以及免疫性能指标,以及不同组别母猪初乳和常乳中的铁硒含量。[结果] 在仔猪补铁补硒形式相同的条件下,母猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸（5~8组）与基础日粮中补充硫酸亚铁和亚硒酸钠（1~4组）相比,能够显著（P<0.05）或极显著（P<0.01）提高仔猪的初生重、断奶重、断奶存活率、断奶合格率,2日龄和21日龄血浆铁含量、血浆硒含量、血红蛋白含量、血浆转铁蛋白含量、IgA含量、IgG含量、IgM含量,以及母猪初乳和常乳中的铁硒含量;在2种形式的母猪补铁补硒条件下,与不补铁补硒相比,仔猪不同补铁补硒形式（2~4组和6~8组）对其断奶重、断奶存活率、断奶合格率,以及21日龄血浆铁含量、血浆硒含量、血红蛋白含量、血浆转铁蛋白含量、谷胱甘肽过氧化物酶活性、IgA含量、IgG含量、IgM含量均有极显著（P<0.01）的提高作用,并且仔猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸的效果优于肌注铁硒合剂和基础日粮中补充硫酸亚铁和亚硒酸钠。[结论] 母猪和仔猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸,能有效提升仔猪的生长性能、血液生化指标和免疫性能。     

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。     

A cell preparation of Enterococcus faecalis strain EC-12 stimulates the luminal immunoglobulin A secretion in juvenile calves

The immune system in juvenile calves is immature, so calves are susceptible to several diarrheal and respiratory diseases. Oral administration of lactic acid bacteria (LAB) is known to improve the growth performance and prevent diarrheal and respiratory diseases by stimulating the immune system in juvenile calves. Most of the immunostimulation by LAB is achieved by their cell wall components, and therefore we evaluated the immunostimulation of the cell preparation of Enterococcus faecalis strain EC-12 (EC-12) in juvenile calves in a clinical field. Twenty-nine 1-week old calves were used. Fourteen calves were administered 0.2% (w/w) of an EC-12 preparation that supplemented a milk replacer, and other calves were not supplemented. Feces and serum was collected at day 0, 7 and 49 after the administration to measure the IgA and IgG concentration. The fecal IgA concentration was increased by EC-12 administration at day 49, and the serum IgA concentration was also increased at day 7. These results suggested that oral administration of EC-12 in juvenile calves might have an immunostimulatory effect and provide earlier recovery of IgA levels in mucosal immunity.     

Effects of Antibacterial Peptide Cecropin on Prouduction Performance，Immune Function and Serum Biological Parameters of Weaner Piglets

This experiment was conducted to study the effects of antimicrobial peptide cecropin on production performance,immune function and serum biological parameters of weaner piglets.A total of 240 weaner hybrid piglets （Landrace×Large White×Duroc） with average body weight （8.35±0.12）kg were randomly divided into 4 treatments with 6 replicates of 10 each.The four treatments were control group （fed a basal diet）,antibiotics group （fed basal diet＋140 mg/kg 50% kitasamycin＋100 mg/kg olaquindox ＋600 mg/kg 10% colistin sulfate）,antimicrobial peptide group （fed basal diet＋350 mg/kg antimicrobial peptide cecropin）,compatibility group （antibiotics + antibacterial peptide group）（fed basal diet＋250 mg/kg antimicrobial peptide cecropin＋50 mg/kg olaquindox ＋200 mg/kg 10% colistin sulfate）,each group was half male and half female.The pre-test period lasted for 7 days,the trial period lasted for 34 days.The results showed that compared with control group,the average daily gain in compatibility group was significantly increased （P＜0.05）,the average daily feed intake in antibiotic group and antimicrobial peptide group was significantly decreased （P＜0.05）,the feed conversion ratio and diarrhea rate in all three experimental groups were significantly decreased （P＜0.05）.The antibody blocking rate and serum IgG,IgA contents in antimicrobial peptide group and compatibility group were significantly increased （P＜0.05）,the serum urea nitrogen and blood sugar contents in antimicrobial peptide group and compatibility group were significantly decreased （P＜0.05）,but the serum total protein and albumin contents were significantly increased （P＜0.05）.In conclusion,dietary supplementation appropriate level of antimicrobial peptide cecropin could replace part of the antibiotics,and adding high dose of antimicrobial peptide cecropin could replace antibiotics used in feed completely.     

Metaphylactic effect of minerals on the immune response,biochemical variables and antioxidant status of newborn calves

The aim of this study was to evaluate whether injectable zinc and copper affect host immune responses and antioxidant status of newborn calves. For this study, 19 newborn calves were divided into two groups. The control group consisted of 10 animals; and the treated group consisted of nine animals that received copper edetate (Cu‐ed) and zinc edetate (Zn‐ed) subcutaneously at the first day of life at doses of 0.3 mg/kg and 1.0 mg/kg respectively. Blood and faecal samples were collected for laboratory analyses (seric biochemistry, proteinogram, antioxidant enzymes and parasitological examination) on days 10, 20 and 30 after birth. On day 10, treated animals showed increased levels of total proteins, as well as increased globulin levels compared to the control group, a finding probably related to the increase in ceruloplasmin and IgG heavy chain. Thirty days after mineral metaphylactic administration, IgG light chain and acid glycoprotein levels significantly increased in treated animals (p < .05). There were no significant differences between groups regarding the biochemical analyses (triglycerides, cholesterol, glucose and urea). On the other hand, the superoxide dismutase and catalase activities increased on day 10 after treatment. In the control group, eight animals showed severe diarrhoea and one died 8 days after birth. Two animals from this group showed mild diarrhoea. Only three treated animals had severe diarrhoea, and six showed signs of mild diarrhoea. All animals that showed severe diarrhoea (control = 8; treated = 3) had hyperthermia (over 39.5°C), and therefore, antibiotic therapy was administered (sulfadiazine and trimethoprim) for five consecutive days. In summary, Zn‐ed and Cu‐ed decreased the frequency and intensity of diarrhoea, modulated superoxide dismutase (SOD) and catalase (CAT) enzymes and also heightened the immune responsiveness of newborn calves, suggesting a new approach to improve cattle performance and minimize the occurrence of diarrhoea.