Effects of anticoccidial and antibiotic growth promoter programs on broiler performance and immune status

This study investigated the effects of various coccidiosis control programs in combination with antibiotic growth promoters (AGPs) on growth performance and host immune responses in broiler chickens. The coccidiosis programs that were investigated included in ovo coccidiosis vaccination (CVAC) with Inovocox or in-feed medication with diclazuril as Clinacox (CLIN) or salinomycin (SAL). The AGPs were virginiamycin or bacitracin methylene disalicylate plus roxarsone. As a negative control, chickens were non-vaccinated and fed with non-supplemented diets (NONE). All animals were exposed to used litter from a commercial broiler farm with confirmed contamination by Eimeria parasites to simulate in-field exposure to avian coccidiosis. Broiler body weights in the CVAC group were greater at 14 and 32 days of age, but not at day 42, compared with the NONE, CLIN, and SAL groups. At day 14, the SAL group showed decreased body weight and reduced ConA-stimulated spleen cell proliferation compared with the CLIN and SAL groups. In contrast, at days 34 and 43, splenocyte proliferation was greater in the CVAC and CLIN groups compared with the NONE and SAL groups. Lymphocyte subpopulations and cytokine mRNA expression levels in the intestine and spleen were also altered by the denoted treatments. Collectively, these results suggest that in ovo coccidiosis vaccination or coccidiostat drug medication programs in combination with AGPs influences chicken growth and immune status in an Eimeria-contaminated environment.     

Protective efficacy of a live attenuated Mycoplasma hyopneumoniae vaccine with an ISCOM-matrix adjuvant in pigs

An attenuated Mycoplasma hyopneumoniae vaccine that requires intrathoracic administration is commercially available for use against mycoplasmal pneumonia in China. Given the limitations of such a route of administration, this study was undertaken to assess the capacity of an ISCOM-matrix adjuvant to enhance immunogenicity following intramuscular use. Immune responses in pigs following vaccination and subsequent intra-tracheal bacterial inoculation were examined using lymphocyte proliferation, serology and mucosal IgA in both nasal and saliva swabs.Vaccination induced clear lymphocyte proliferation, but only slight serum antibody responses although these were significantly increased following experimental infection. Mucosal IgA was not detected in either nasal or salivary secretions. Following bacterial challenge, animals vaccinated with the adjuvant-containing live vaccine exhibited less severe pulmonary lesions (median score 3.67) than unvaccinated pigs (median score 13.58). The degree of ciliary loss on the respiratory tract surface was reduced in vaccinated pigs compared with experimentally infected controls. The findings indicated that the adjuvant vaccine administered IM provided protection against experimentally induced mycoplasmal pneumonia and could have commercial potential.     

Safety of an attenuated West Nile virus vaccine, live Flavivirus chimera in horses

REASON FOR PERFORMING STUDY: West Nile virus (WNV) infection is endemic and able to cause disease in naive hosts. It is necessary therefore to evaluate the safety of new vaccines. OBJECTIVES: To establish: 1) the safety of a modified live Flavivirus/West Nile virus (WN-FV) chimera by administration of an overdose and testing for shed of vaccine virus and spread to uninoculated sentinel horses; 2) that this vaccine did not become pathogenic once passaged in horses; and 3) vaccine safety under field conditions. METHODS: There were 3 protocols: 1) In the overdose/shed and spread study, horses were vaccinated with a 100x immunogenicity overdose of WN-FV chimera vaccine and housed with sentinel horses. 2) A reversion to virulence study, where horses were vaccinated with a 20x immunogenicity overdose of WN-FV chimera vaccine. Horses in both studies were evaluated for abnormal health conditions and samples obtained to detect virus, seroconversion and dissemination into tissues. 3) In a field safety test 919 healthy horses of various ages, breeds and sex were used. RESULTS: Vaccination did not result in site or systemic reactions in either experimental or field-injected horses. There was no shed of vaccine virus, no detection of vaccine virus into tissue and no reversion to virulence with passage. CONCLUSIONS: WN-FV chimera vaccine is safe to use in horses with no evidence of ill effects from very high doses of vaccine. There was no evidence of reversion to virulence. In addition, administration of this vaccine to several hundred horses that may have been previously exposed to WNV or WNV vaccine resulted in no untoward reactions. POTENTIAL RELEVANCE: These studies establish that this live attenuated Flavivirus chimera is safe to use for immunoprophylaxis against WNV disease in horses.     

Combination of competitive exclusion and immunization with an attenuated live Salmonella vaccine strain in chickens

To use the advantages of both the competitive exclusion (CE) technique and immunization with a live Salmonella vaccine, the combination of these methods was studied. Specific-pathogen-free chickens were pretreated by combined or single administration of a CE culture and a commercial live Salmonella typhimurium vaccine on days 1 and 2 of life and challenged with Salmonella typhimurium on day 3 to study the exclusion effect by both the CE preparation and the Salmonella vaccine. The exclusion effect by the CE culture combined with the immunologic effect by the live vaccine was studied after challenge of the birds on day 43 of age. The number of challenge organisms in ceca was used to evaluate the efficacy of the pretreatment. The protective exclusion effect of the CE culture was substantial in very young chicks and still detectable in 6-wk-old birds. The attenuated Salmonella typhimurium vaccine produced only an initially occurring exclusion effect. Because the exclusion effect of the CE culture was considerably stronger than the exclusion effect of the attenuated Salmonella typhimurium vaccine, the combination of both did not result in an additive protective effect. In order to exploit the exclusion potential between Salmonella strains and to attain an additive exclusion effect by a CE culture and a vaccine strain, live Salmonella vaccines are needed that are sufficiently attenuated without affecting genes essential for colonization exclusion of other Salmonella organisms. In 6-wk-old birds, the exclusion effect by the CE culture combined with the immunologic effect by the live Salmonella vaccine resulted in a degree of protection considerably beyond that generated by the exclusive use of the two methods. The administration of the live Salmonella vaccine strain prior to or simultaneously with the CE culture revealed the best protective effect because such combinations ensure an adequate persistence of the vaccine strain as prerequisite for the expression of an exclusion effect in very young chicks and the development of a strong immune response affording protection in older birds.     

Effect of avoparcin interaction with anticoccidial compounds on the growth and carcase composition of broilers

The anticoccidial drugs narasin, lasalocid, monensin and salinomycin, with and without avoparcin, were fed to 1280 broiler chickens from 1 to 49 d old. At day 49 significant interactions were detected between avoparcin and the anticoccidial compounds for body weight and food consumption. This indicated that the increases in body weight and food consumption obtained with avoparcin were greater with some anticoccidial compounds (lasalocid and salinomycin for body weights and lasalocid for food consumption) than with others (monensin and narasin for body weights and monensin, narasin and salinomycin for food consumption). Overall there was evidence that avoparcin increased body weight (5.8%), food consumption (2.5%) and efficiency of food utilisation (2.9%). In addition avoparcin produced significant increases in plucked weight and the proportion of visceral fat together with and decreases in the proportions of edible giblets and waste offal.     

Investigations towards an efficacious and safe strangles vaccine: submucosal vaccination with a live attenuated Streptococcus equi

As part of a search for a safe and efficacious strangles vaccine, several different vaccines and different vaccination routes were tested in foals. The degree of protection was evaluated after an intranasal challenge with virulent Streptococcus equi by clinical, postmortem and bacteriological examinations. Inactivated vaccines containing either native purified M-protein (500 microg per dose) or whole S equi cells (10(10) cells per dose) administered at least twice intramuscularly at intervals of four weeks, did not protect against challenge. Different live attenuated S equi mutants administered at least twice at intervals of four weeks by the intranasal route were either safe but not protective or caused strangles. In contrast, a live attenuated deletion mutant administered intramuscularly, induced complete protection but also induced unacceptable local reactions at the site of vaccination. Submucosal vaccination in the inner side of the upper lip with the live attenuated mutant at > or =10(8) colony-forming units per dose, appeared to be safe and efficacious in foals as young as four months of age. The submucosal vaccinations caused small transient swellings that resolved completely within two weeks, and postmortem no vaccine remnants or other abnormalities were found at the site of vaccination.     

Comparison of antibody values in sera of pigs vaccinated with a subunit or an attenuated vaccine against classical swine fever

Ten pigs, aged 85 days, were vaccinated with a subunit vaccine containing 32 g of classical swine fever virus glycoprotein E2 (gp E2) (group 1), and a further 10 pigs were vaccinated with a C strain vaccine (10^4±0.15 TCID₅₀/ml), produced by amplification in minipig kidney (MPK) cell culture (group 2). Nine non-vaccinated pigs served as a control group (group 3). Serum samples were collected before (day 0) and at 4, 10, 21 and 28 days after vaccination and were analysed by two commercially available enzyme immunoassays and by a neutralizing peroxidase-linked assay (NPLA). At the same times, peripheral blood was taken for determining the total leukocyte count and the body temperature was taken daily. Antibodies were not detected in serum samples collected before vaccination (day 0), and no side-effects that could be connected with vaccination were observed during the trial. Ten days after vaccination 6/10 pigs vaccinated with the subunit vaccine were seropositive. On days 21 and 28, the ratios of serologically positive to vaccinated pigs were 9/10 and 10/10, respectively. Four of the ten pigs that were vaccinated with the C strain vaccine were positive on day 21 and 9/10 on day 28. However, the results of the NPLA showed that only 4/10 pigs had an antibody titre >1:32 at the end of the trial in both the vaccinated groups, even though the subunit vaccine initiated an earlier and higher level of neutralizing antibodies than the vaccine produced from the C strain. Challenge was performed 28 days after vaccination on four randomly selected pigs from both vaccinated groups. The pigs survived the challenge without showing any clinical signs of classical swine fever (CSF), while two nonvaccinated control pigs died on the 10th and 12th days after infection.     

The efficacy and economic benefits of Supercox, a live anticoccidial vaccine in a commercial trial in broiler chickens in China

The efficacy and economic benefits of Supercox, a live anticoccidial vaccine were examined and compared with an anticoccidial drug in a trial in broiler chickens under modern commercial conditions in China. In total, 40,660 chickens were used in the present study, half of which were vaccinated with the Supercox vaccine comprising a precocious line of Eimeria tenella and non-attenuated lines of Eimeria maxima and Eimeria acervulina, and the other half were medicated with Diclazuril delivered as feed additive at the dosage of 1mg/kg of feed. The vaccine was administered orally to 7-day-old chickens. No clinical diseases were diagnosed in any of the vaccinated birds. However, clinical coccidiosis occurred in a large proportion of medicated control birds and these chickens had to be treated with anticoccidial drugs (Diclazuril and Toltrazuril). Comparison of production performance between vaccinated birds and medicated control birds revealed that the vaccine Supercox performed better than anticoccidial drugs in terms of mortalities, costs and overall economic benefits (profits). These findings demonstrated that the use of the Supercox vaccine could control clinical coccidiosis in broilers and achieve production performance superior to that using anticoccidial drugs, particularly where drug resistance might result in failure to control clinical diseases.     

Safety of multiple,submucosal inoculations of a live attenuated strangles vaccine in pregnant mares

A live attenuated vaccine against Streptococcus equi was administered submucosally in the upper lip to 224 pregnant and healthy mares to evaluate its safety. After a primary immunisation the mares were inoculated every 3 months until foaling. As control group, 206 mares of the same breeding farm were administered the solvent of the vaccine submucosally. None of the 430 mares presented any clinical evidence of strangles and neither local nor systemic reactions to vaccination were noticed. There was no association between abortion and vaccination. Furthermore no case of S. equi infection was revealed at post mortem examinations of aborted foals.     

Duration of immunity induced in chickens by an attenuated live Salmonella enteritidis vaccine and an inactivated Salmonella enteritidis/typhimurium vaccine

The aim of this study was to examine the duration of immunity of different vaccination schemes using the S. enteritidis live vaccine Gallivac Se and the S. enteritidis-S. typhimurium inactivated vaccine Gallimune Se+St. Three groups of Lohman Brown chickens were used. Group one was vaccinated three times orally with Gallivac Se at weeks one, seven and 13 of age. Group two was vaccinated twice orally with Gallivac Se in weeks one and seven and once i.m. with Gallimune Se+St in week 14 of age. A third group was not vaccinated and served as the control group. Eight randomly selected chickens from each of the three groups were challenged with a nalidixic acid resistant S. enteritidis PT4 strain in weeks 24, 51 and 71 of age and the same number of animals were challenged with a S. typhimurium DT 104 strain in weeks 26, 54 and 73 (75) of age.The chickens were euthanised seven days post challenge and the number of challenge strain organisms (log10 cfu) in the liver and on caecal mucosa was determined.The quantitative investigation of the challenge strain in the liver and caecal mucosa revealed a statistically significant (p < 0.05) lower challenge strain burden in the vaccinated groups compared with the non-vaccinated control group up to week 71 (73) of age. The protective effects were demonstrated for both challenge strains.     

鸡传染性支气管炎弱毒疫苗株安全性和免疫效力初步评价

通过对QX基因型IBV分离株SDZB0808进行鸡胚连续100次传代致弱后获得子代病毒P100。为了明确P100的的致弱效果和免疫原性,对其进行了安全性和免疫效力评价。安全性试验结果显示,P100以105.5 EID50/只的剂量对3日龄的SPF鸡进行免疫后试验,与正常对照组相比没有明显临床症状和病理变化,气管和肾脏组织也没有病理组织损伤。免疫效力试验结果发现,P100以104.5 EID50/只的剂量免疫3日龄SPF鸡,14d后对同源强毒SDZB0808和异源强毒SDIB821/2012的攻击都具有100%的临床保护,病理组织学检查发现P100免疫攻毒组试验鸡气管和肾脏与正常对照没有差异,排毒检测结果显示P100免疫攻毒组试验鸡内脏组织病毒检出率大大低于攻毒对照组。本研究结果表明P100对SPF鸡具有良好的安全性和免疫效力,可以作为IBV弱毒疫苗候选株。     

Effects of temperature and stabilizer on the viability of a live attenuated avian metapneumovirus vaccine

A commercial live attenuated, freeze-dried avian metapneumovirus vaccine, Pneumomune, was assessed for its viability at three different temperatures (5.6 C, 21 C, and 37 C). No significant reduction in virus titer was observed when the vaccine was stored at 5.6 C for a period of 24 hr. However, reductions in virus titer of 1 log10 and 2 log10 were observed after 24 hr at 21 C and 37 C, respectively. Batch-to-batch variation in virus reduction was also observed. The addition of a dye or a vaccine stabilizer to the vaccine preparation did not have any deleterious effect on the survival of vaccine virus.     

Influence of dietary electrolyte balance, source of added potassium and anticoccidial agents on the performance of male broilers

1. The performance of 1680 male broiler chickens was measured from one to 42 d of age. They were given diets with three (125, 165 and 205 mEq/kg) electrolyte balances (sodium + potassium - chloride), two sources of added potassium (carbonate or sulphate) and two anticoccidial agents (90 mg/kg of either monensin or lasalocid). 2. The dietary treatments had no significant effects on the growth performance of broiler chickens in the starter phase. 3. In the finisher phase, the chickens given the diets containing lasalocid utilised food less efficiently that those given the diets containing monensin. 4. There were significant interactions between dietary electrolyte balance and source of added potassium on body weight gains and food:gain ratios in the finisher phase. In diets with an electrolyte balance of 205 mEq/kg, the inclusion of potassium sulphate instead of potassium carbonate increased body weight gains by 3.4% and reduced food:gain ratios by 4.6%. 5. The body weight gains of chickens given the finisher diets containing lasalocid and added potassium carbonate were reduced by 2.6% compared to those of chickens given the diets containing monensin or added potassium sulphate. 6. The litter moisture content was higher in pens with chickens on the diets with an electrolyte balance of 205 mEq/kg than on the diets with either 125 or 165 mEq/kg. Both lasalocid and potassium sulphate tended to increase the litter moisture content. 7. It may be concluded that the inclusion of 90 mg/kg of either monensin or lasalocid in broiler diets does not alter the balance of electrolytes required for optimum growth performance of broiler chickens.     

Effects of a protected inclusion of organic acids and essential oils as antibiotic growth promoter alternative on growth performance,intestinal morphology and gut microflora in broilers

This experiment was conducted to investigate the effects of protected essential oils and organic acids mixture on poultry feeding. A total of 450 1‐day‐old Cobb 500 chicks were randomly allotted into three treatments with six replicates. Birds were offered a basal diet (C), basal diet with 0.15 g/kg enramycin premix (A) and basal diet with 0.30 g/kg protected essential oils and organic acids mixture product (P). The results showed that protected essential oils and organic acids mixture supplementation reduced average daily feed intake and ratio of feed to gain (F/G) at 22–42 days of age, and F/G during 1–42 days of age also declined (P < 0.05). Product supplementation improved spleen index, villus height and crypt depth of the jejunum at 42 days when compared with the control (P < 0.05). In addition, secretory immunoglobulin A level of ileal mucosa and trypsin and chymotrypsin activities of intestinal tract were higher in the P treatment. Bacterial sequence analysis of the intestinal tract revealed that protected essential oils and organic acids mixture supplementation changed gut microflora mainly in Lactobacillus. These data suggested that dietary mixture of organic acids and essential oils addition could be used in the poultry industry as an antibiotic growth promoter alternative.     

Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 1. Feedlot performance, carcass quality, and production costs

Forty Angus-cross steers were used to evaluate 5 beef cattle management regimens for their effect on growth performance, carcass characteristics, and cost of production. A 98-d growing phase was incorporated using grass silage with or without growth promotants (trenbolone acetate + estradiol implants, and monensin in the feed) or soybean meal. Dietary treatments in the finishing phase were developed, with or without addition of the same growth promotants, based on exclusive feeding of forages with minimal supplementation or the feeding of barley-based diets. Overall, ADG for animals treated with growth promotants or fed supplemented diets (soybean meal and barley) was increased (P < 0.01) by 25 and 21%, respectively, compared with steers reared on grass silage alone and not treated with growth promotants. Except for HCW (P < 0.01), the use of growth promotants did not affect carcass measurements. Increasing the proportion of barley in the diet of steers finished on forage produced a heavier HCW (P < 0.01) and a greater (P < 0.01) quality grade. Because of their lower HCW and quality grade, cattle targeted to a forage-fed, nonimplanted beef market would need to garner a 16% premium to be economically competitive with cattle finished conventionally.     

鸡球虫病四价活疫苗对毒害艾美耳球虫和柔嫩艾美耳球虫的免疫效果观察

为评价一种商品化鸡球虫病四价活疫苗[柔嫩艾美耳球虫(E.tenella)、毒害艾美耳球虫(E.necatrix)、巨型艾美耳球虫和堆型艾美耳球虫]对E.necatrix和E.tenella的免疫保护效果,本研究基于试验鸡血便记分、存活率、相对增重率、病变值、卵囊值及抗球虫指数(ACI)等指标对其免疫效果进行检测.结果表明,免疫攻虫组抗E.necatrix和E.tenella的ACI分别为157.3和135.6,均低于160,表明该球虫疫苗抗两种球虫的效果均为低效.然而,免疫攻虫组鸡血便数量、血便记分、增重、卵囊产量和病变记分等指标均优于阳性对照组.综合指标显示,该疫苗对E.necatrix和E.tenella具有一定的免疫保护力,但单纯采用疫苗并不能够达到防控鸡球虫病的目的.