Effect of decoquinate on the control of coccidiosis in young ruminating calves

Twenty-five 6-week-old Holstein male calves were each inoculated with 500,000 sporulated oocysts of Eimeria bovis. Two nontreated (control) and 3 treated calves (1.5 mg of decoquinate/kg of body weight in feed) were necropsied 7 days after inoculation. Similar groups of calves were necropsied at 12, 18, 22, and 28 days after inoculation. Treated calves were started on medicated feed 2 days before inoculation or at 7, 12, or 15 days after inoculation or were on continuous medication from the day of inoculation. Control calves were not given medication. Early schizonts were in the small intestines of control calves at 7 days after inoculation, but none was in the treated calves that were started on medicated feed 2 days before inoculation. Schizonts were present in the small intestine of both treated and control calves at 12 days after inoculation. At 18 days after inoculation, control calves had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestines, but treated calves only had schizonts in the small intestine. At 22 days, control calves had schizonts in the small intestine and gamonts and oocysts in the large intestine; treated calves had schizonts in the small intestine. At 28 days, controls still had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestine; the treated calves that had been on continuous medication did not have schizonts, gamonts, or oocysts in the tissues. Decoquinate apparently kills sporozoites or arrests development and release of merozoites from the schizonts when fed at 1.5 mg/kg of body weight in the feed.     

Evaluation of lasalocid and decoquinate against coccidiosis resulting from natural exposure in weaned dairy calves

Eighteen female Holstein calves, raised as natural herd additions under conditions typical of a well-managed midwestern United States dairy farm, were used in a natural-exposure study to determine the anticoccidial efficacies of lasalocid and decoquinate. Calves were allotted to 6 treatment blocks of 3 calves each as they were weaned. Within each block, calves were randomly assigned to be given either lasalocid or decoquinate or to remain as a nonmedicated control. Calves were given medication for 90 days and remained separated from other calves for 120 days. Adjusted weight gains were consistently greater in calves that were given medication; however, differences were not statistically significant. Fecal specimens were obtained from calves at weekly intervals during the study. Overall, oocyst shedding was low. During the medication period, quantitative mean fecal shedding of oocysts was reduced eightfold in calves given decoquinate and four-fold in calves given lasalocid, as compared with nonmedicated control calves. During the period following the medication period, calves that had been controls shed fewer oocysts than did calves that had previously been given medication. A pairwise comparison of the proportion of specimens that were oocyst-positive was made to assess qualitative oocyst shedding among treatment groups. During the medication period, qualitative oocyst shedding (all species, Eimeria bovis, E zuernii, species other than E bovis and E zuernii) was greater in controls than in either lasalocid-or decoquinate-treated groups. Like-wise, lasalocid-medicated calves shed oocysts more frequently than did the decoquinate-medicated group. After medication, qualitative findings were reversed. Little diarrhea was noticed in treatment or control calves during the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

癸氧喹酯预防人工感染肉仔鸡球虫病的药效试验

由于免疫预防还没有完全普及 ,迄今为止 ,控制肉仔鸡球虫病的主要手段仍然是化药防治 ,而耐药性产生又缩短了许多抗球虫药的使用寿命 ,因此引进新的抗球虫药就显得重要。本试验旨在证实癸氧喹酯预混剂的抗球虫药效 ,为引进该药在我国使用提供试验数据。1　材料1 .1　药物　癸氧     

The effect of intermittent treatment with sulphadimidine on coccidiosis in preruminant calves

Preruminant calves excreted coccidia oocysts in their faeces after 3 weeks of group housing. Two weeks of oral sulphadimidine (SDM) administration, 50 mg/kg on the first day of treatment followed by daily administration of 37.5 mg/kg, under the same housing conditions kept the faeces free of oocysts. Three weeks later, these calves excreted oocysts again. Repetition of the same treatment for 2 weeks controlled the infection again, but a second treatment for 5 days did not suffice. The repeated long treatment affected immunoglobulin levels adversely. SDM given repeatedly at a lower dose rate (30 mg/kg) for 1-week periods with medication-free intervals of 1 week controlled the infection and no adverse effects were noted. In comparison with controls, weight gains were greater in treated calves.     

Prevention and control of coccidiosis in goats with decoquinate

Decoquinate was evaluated as a coccidiostat in domestic goats. Fifty goats less than 4 months of age were assigned to 5 groups (pens) of 10 goats each and were treated for 87 days with 0 (control), 0.3, 0.5, 1.0, or 4.0 mg of decoquinate in feed/kg of body weight. Goats were inoculated orally weight. Goats were inoculated orally with 30,000 oocysts, mainly Eimeria christenseni (74%) and E ninakohlyakimovae (20%) on day 19. Nontreated goats developed profuse watery diarrhea and tenesmus and gained weight poorly; 2 died. Treated goats did not develop clinical coccidiosis and gained significantly more weight (P less than 0.05), regardless of the dose used. Treated goats also had significantly fewer (P less than 0.05) oocysts in feces than did nontreated controls. Oocyst numbers were inversely related to dose; a more rapid decrease in oocyst numbers occurred as the dose was increased. At the doses used, decoquinate was safe in goats and was an effective drug for the prevention of clinical coccidiosis.     

Control of bovine coccidiosis with monensin: in nonresistant newborn calves

Newborn Holstein male calves were purchased within 3 days after birth and were removed from the local farms to the Dixon Springs Agricultural Research Center. They were hand-fed for 7 weeks and then weaned to a prepared feed. Eight groups, each of 4 calves, were housed in separate pens. In each of 4 pens (pens 2 to 5), 1 calf was inoculated with sporulated oocysts of Eimeria bovis (and was not medicated); 1 calf was inoculated and given feed with added monensin at the dosage level of 10 g/906 kg of feed; and 2 calves were inoculated and given medicated feed with added monensin at the dosage level of 20 g/906 kg or 30 g/906 kg. In the 4 other pens (6 to 9), the calves were inoculated with E zuernii and otherwise were given feed without or with added monensin as in pens 2 through 5. Another group of 5 calves (all kept in 1 pen), served as noninoculated, nonmedicated controls. At 14 days after inoculations with E bovis, the single calves in each of the 4 pens that were given the nonmedicated feed began to show clinical signs of coccidiosis and discharged increasing numbers of oocysts. The other inoculated calves (given monensin) had fewer clinical signs and discharged fewer oocysts in the feces as the level of medication in the feed increased. The calves inoculated with E zuernii developed only moderately severe infections when compared with those inoculated with E bovis. Inoculated (with E bovis) nonmedicated calves had severe reductions in feed consumption and weight, and 3 of 4 died.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of vaccination infectious bovine rhinotracheitis and simultaneous administration of levamisole on primary humoral responses in calves.

In a study on the primary humoral response of calves vaccinated against infectious bovine rhinotracheitis (IBR) and simultaneously given levamisole, mild but consistent suppression of the group's geometric mean serum-neutralization titer to IBR virus occurred between 12 and 59 days later. The quantitative determination of circulating immunoglobulins (Ig) over the same period indicated a slight decrease in the IgG concentrations from an initial geometric mean concentration of 18.28 mg/ml before calves were vaccinated to 15.29 mg/ml after vaccination, and the control calves (vaccinated and given saline solution only) maintained their prevaccination IgG geometric mean concentration of 20.92 mg/ml. Difference was not observed in the circulating IgM values of the 2 groups. Levamisole had no apparent effect on the circulating Ig-bearing lymphocyte values when compared with control calves during the 24 hours of treatment. It was concluded that a single treatment of levamisole may mildly suppress the primary humoral response to IBR vaccination in calves, but it is unlikely that this would affect the animal's capability to recover from, or maintain resistance to, IBR infection.     

Alteration of neutrophil function associated with coccidiosis in cattle: influence of decoquinate and dexamethasone

Twenty Holstein steers subclinically infected with coccidia were allotted to 2 groups of 10 steers each. One group received a diet containing 0.5 mg of decoquinate/kg of body weight. After 25 days on the diet, there was no difference between the groups in lymphocyte blastogenic responsiveness to mitogens; however, there were differences in neutrophil function. Lymphocytes from steers of the decoquinate-fed group had decreased random migration under agarose, enhanced cytochrome C reduction, and enhanced iodination activity. Other measures of neutrophil function evaluated (chemotactic index, Staphylococcus aureus ingestion, and antibody-dependent and -independent cell-mediated cytotoxicity) were not affected. After 30 days of decoquinate feeding, half of the cattle in each group received 5 daily IM injections of dexamethasone (0.04 mg/kg of body weight). The dexamethasone-treated steers from the group that did not have decoquinate in the diet developed clinical coccidiosis, whereas the decoquinate-treated steers remained clinically normal. Lymphocyte and neutrophil function were again evaluated for a 3-day period beginning 4 days after dexamethasone treatment was halted. Neutrophils from the steers that developed clinical coccidiosis after dexamethasone administration had significantly (P less than 0.05) inhibited random migration under agarose, cytochrome C reduction, and iodination activity, but significantly (P less than 0.01) enhanced S aureus ingestion. The feeding of decoquinate prevented the inhibition of neutrophil cytochrome C reduction and lessened the inhibition of neutrophil iodination in the dexamethasone-treated group. Dexamethasone treatment was associated with an inhibition of lymphocyte blastogenic responsiveness to phytohemagglutinin in principals as well as controls.     

Effects of continuous or intermittent lipopolysaccharide administration for 48 hours on the systemic inflammatory response in horses

Objective-To determine whether the method of lipopolysaccharide (LPS) administration (intermittent vs continuous) affects the magnitude and duration of the systemic inflammatory response in horses and whether prolonged (48 hours) endotoxemia induces laminitis. Animals-12 healthy adult horses (10 mares and 2 geldings). Procedures-Horses were randomly assigned to receive LPS (total dose, 80 μg; n = 4) or saline (0.9% NaCl) solution (80 mL/h; 4) via constant rate infusion or 8 bolus IV injections of LPS (10 μg, q 6 h;4) during a 48-hour period. Physical examinations were performed every 4 hours, inflammatory cytokine gene expression was determined for blood samples obtained every 8 hours, and IV glucose tolerance tests were performed. Results-All LPS-treated horses had signs of depression and mild colic; those signs abated as the study progressed. Administration of LPS increased expression of interleukin-1β, interleukin-6, and interleukin-8, but results were not significantly different between LPS treatment groups. Cytokine expression was significantly higher on the first day versus the second day of LPS treatment. Interleukin-1β expression was positively correlated with rectal temperature and expression of other cytokines. Glucose and insulin dynamics for both LPS groups combined did not differ significantly from those of the saline solution group. Signs of laminitis were not detected in any of the horses. Conclusions and Clinical Relevance-Horses developed LPS tolerance within approximately 24 hours after administration was started, and the method of LPS administration did not affect the magnitude or duration of systemic inflammation. Laminitis was not induced in horses.     

Effects of inoculations with Eimeria zuernii on young calves treated with decoquinate or narasin with or without dexamethasone

Sixteen 7-week-old Holstein male calves were inoculated with sporulated oocysts of Eimeria zuernii. Four calves (controls) were euthanatized and necropsied at 14 and 20 days after inoculation (DAI). Two calves were treated with 20 mg of dexamethasone (IM) on 13, 14, and 15 DAI and euthanatized and necropsied 17 DAI and 2 calves were given similar treatments and necropsied 20 DAI. The 8 other calves were euthanatized and necropsied 20 DAI. Two were started on the anticoccidial drug decoquinate in feed 13 DAI; 2 others were given decoquinate on the same schedule plus dexamethasone on 13,14, and 15 DAI. Two calves were given the antibiotic narasin in feed beginning 13 DAI and 2 calves were given parasin on the same schedule plus dexamethasone on 13,14, and 15 DAI. All calves, except 2 controls necropsied 14 DAI and 4 calves given decoquinate, discharged moderate-to-large numbers of oocysts in feces and had moderate-to-serve changes in fecal consistency. Histologic examinations revealed large numbers of endogenous stages in tissues of calves treated or not treated with dexamethasone. Few endogenous stages were observed in tissues from calves that were given decoquinate or decoquinate plus dexamethasone. Calves given narasin or narasin plus dexamethasone had moderate-to-large numbers of endogenous stages in the tissues.     

癸氧喹酯干混悬剂对不同地区分离球虫株的敏感性试验

分别进行癸氧喹酯对历史分离球虫株和现行临床分离球虫株的敏感性试验,结果显示,癸氧喹酯干混悬剂对历史分离球虫株和现行临床分离球虫株的敏感性较好,抗球虫指数大于180,表现出高效的抗球虫活性,能有效提高鸡只生长性能,提高饲料转化率。     

Evaluation of decoquinate, lasalocid, and monensin against experimentally induced sarcocystosis in calves

Effects of decoquinate, lasalocid, and monensin against experimentally induced sarcocystosis (Sarcocystis bovicanis) were evaluated in 12 calves, 3 of which were inoculated, nontreated controls. Three additional calves were noninoculated, nontreated controls. Drugs were administered in the feed (33 mg/kg of feed) of the treated calves (3 calves/group) for 87 days. Eight of the 12 inoculated calves died from acute sarcocystosis during the experiment (the 3 inoculated, nontreated controls, the 3 calves given decoquinate, and 2 of the 3 calves given lasalocid). Large numbers of sarcocysts were found in tissues from inoculated calves that survived in the experiment (1 of the 3 calves given lasalocid and the 3 calves given monensin). Although large numbers of sarcocysts developed in the muscles of monensin-treated calves, monensin may have an ameliorating effect on acute sarcocystosis.     

Residue depletion of decoquinate in chicken tissues after oral administration

Wang, Z.‐Y., Cai, C.‐Y., Chang, X.‐H., Fei, C.‐Z., Qiu, M.‐Q., Jiang, S.‐X., Xue, F.‐Q., Zhang, L.‐F. Residue depletion of decoquinate in chicken tissues after oral administration. J. vet. Pharmacol. Therap.  36 , 116–121. A rapid, sensitive, and reliable high‐performance liquid chromatography tandem mass spectrometry (LC‐MS/MS) method was developed and validated for the analysis of decoquinate in chicken tissues. The compounds were extracted using acetonitrile by liquid–liquid extraction (LLE) and purified with an Oasis^? HLB solid‐phase extraction (SPE) cartridge. Chromatographic separation was performed on an XTerra C₁₈ reversed‐phase column with a mobile phase of water containing 0.1% formic acid and acetonitrile. The analyte was detected by tandem quadrupole mass spectrometry after positive electrospray ionization by multiple reaction monitoring. The detection and quantitation limits were 1 and 2.5 μg/kg, respectively. The recoveries of edible tissues ranged from 85.3% to 104.9%, with relative standard deviations (RSD) lower than 10.4%. The depletion profile of decoquinate was studied in healthy chickens after oral administration of feed containing 27.2 mg/kg decoquinate for 10 consecutive days. The residue concentrations of decoquinate in chicken muscle and liver were detected using the developed method. The highest residue concentrations were attained 0.25 day post‐treatment, and decoquinate residues were still detected 5 days postmedication in the tissues examined. The developed method has been successfully applied to the depletion study of decoquinate in chicken tissues. The recommended withdrawal period with oral administration based on our research is 3 days.     

Protection against bovine rotaviruses in newborn calves by continuous feeding of immune colostrum

Three pregnant cows were inoculated intramuscularly with inactivated vaccine to bovine rotavirus (BRV) serotype 1 (BRV-1) and serotype 2 (BRV-2). Serum neutralizing antibody (NA) titers against both serotypes increased significantly after immunization. NA titers of colostrum obtained from immunized cows against BRV-1 and BRV-2 were 29286 and 38109, respectively, which were significantly higher than those from non-immunized control cows. Nine and 6 colostrum deprived calves were orally challenged with BRV-1 and BRV-2, respectively, and monitored for clinical manifestation and viral shedding. Five calves of them, 3 with BRV-1 and 2 with BRV-2, received 2 l of milk replacer supplemented with 10% immune colostrum 2 hr before challenge and twice daily for the first 5 days after challenge. Other 10 calves, 6 with BRV-1 and 4 with BRV-2, were fed only milk replacer as controls. All control calves developed severe diarrhea and shed a large amount of BRV in feces, beginning from 24 to 48 hr after challenge inoculation. On the contrary, all calves but one fed colostrum supplement remained clinically healthy after challenge, and BRV was not detected in their feces during feeding immune colostrum. The possibility that continuous feeding of immune colostrum is capable of preventing newborn calves from diarrhea associated with BRV and viral shedding was suggested.     

Effects of bovine respiratory syncytial virus on airway function in neonatal calves

Respiratory syncytial virus (RSV) infection causes severe lower respiratory tract disease in infants and calves. Neonatal respiratory tract infection in children often produces persistent changes in lung function. The specific objective of this study was to determine whether neonatal calves have transient or persistent alterations in pulmonary function and airway reactivity following RSV infection. Six 2- to 3-day-old Holstein bull calves were inoculated with 10 ml of bovine respiratory syncytial virus (BRSV) inoculum (10(2.7) to 10(3.8) cell culture infective doses/ml) intranasally and 10 ml of BRSV inoculum (10(4.8) to 10(5.9) cell culture infective doses/ml) intratracheally for 4 consecutive days, and 5 other calves were sham-inoculated. Prior to inoculation (day 0) and on days 4, 14, and 30 after the last inoculation, body weight (kg), dynamic compliance (Cdyn), pulmonary resistance (RL), and 2 indices of airway reactivity (effective dose [ED] 65Cdyn and ED200RL) were measured. Control calves gained weight progressively throughout the study, whereas RSV-inoculated calves failed to gain weight for 14 days, but equaled control calf weight by 30 days after inoculation. The Cdyn of control calves increased significantly by 30 days, but did not in the RSV-infected calves. Pulmonary resistance was increased significantly at 4, 14, and 30 days, but was unaffected by sham inoculation. The ED65Cdyn and ED200RL indicated an age-dependent increase in reactivity to histamine and an increase in responsiveness in the infected group beginning at 14 days and persisting until the end of the study.(ABSTRACT TRUNCATED AT 250 WORDS)