BACKGROUND: Cryptosporidium parvum is a protozoan parasite which belongs to apicomplexa phylum. The parasite infects both wild and domesticated animals and human beings as well. OBJECTIVES: The purpose of the present study was to detect oocyst shedding and diarrhea pattern in experimental cryptosporidiosis and their correlation with weight loss in neonatal calves. METHODS: Twelve Holstein calves of both sexes were obtained at birth from dairy farm and randomly divided into two groups of 6 calves. Six calves were orally infected with 107 C.Parvum oocysts at the 12h post parturition. The control group was not infected. Clinical signs were examined and fecal samples were collected by the rectal examination twice a day. All calves were weighed from day 0 to day 30 with 3 days intervals to determine effects of cryptosporidiosis on weight gain. RESULTS: All infected calves were noticeably depressed and had a decreased appetite from 3 days post inoculation (DPI) while they received colostrum. Subsequently, watery diarrhea with clumps of mucus and yellow or pale changes of feces color were observed. The infected calves have had diarrhea for 5-8 days that remarkably had got dehydrated. The most severity of diarrhea was 4-6 DPI. Oocyst excretion started 4 DPI, peaked at 6 DPI (60.48×106±9.03oocysts/g feces) and continued until 11 DPI. Control calves had no diarrhea and other clinical signs during the whole period of the trial. The mean weight gain of control group was significantly higher than inoculated group during experiment (p<0.001). The Weight of the infected calves was retarded until 9 days old and then risen subsequently. CONCLUSIONS: Present study showed the role of C.Parvum as the primary cause of diarrhea and weight loss among neonatal calves.

BACKGROUND: Diagnosis of Cryptosporidium species based on morphological characteristics is very limited and has no taxonomic value alone, and therefore the use of molecular methods removes these limitations to some extent. OBJECTIVES: The aim of this study was to determine the predominant Cryptosporidium genotypes in calves with diarrhea. METHODS: Study were conducted in calves aged less than 3 months for a period of 2 years. During the study period, 160 dung samples were collected from neonatal calves and examined first microscopically and then by molecular techniques. Stools were analyzed for the presence of Cryptosporidium oocysts by Sheather's Sugar Flotation Solution followed by Ziel-Neelsen staining method. DNA of parasite was extracted and multiplex nested-PCR protocol basis on the 18srRNA were done to identify three cattle-adapted species (C. andersoni, C. bovis and C. ryanae) plus the zoonotic species C. parvum. RESULTS: 110 fecal samples were collected from livestock in Alborz province and 50 fecal samples were collected from livestock in Shahroud city. Of the 160 animals examined, 90 were female and 70 were male. In total, out of 160 animals examined, 85 cases (53.12%) had diarrhea, of which 55 cases (34.37%) were positive using Ziel-Neelsen staining. Since all positive cases were related to diarrhea samples and related to calves under one month old, a significant relationship was observed between diarrhea status and the presence of this parasite (p < /em><0.05). In terms of seasonal distribution, no difference was observed in the rate of diarrhea and positive parasitic cases. The presence of 305 bp band in all Ziel-Neelsen positive samples confirmed the presence of C. parvum in all samples. CONCLUSIONS: Neonatal calves are more likely to be infected with Cryptosporidium parvum, as confirmed by the present study.

BACKGROUND: Heat treatment of colostrum has been suggested as a control measure to eliminate or reduce the transfer of colostrum-borne pathogens to dairy calves.Objectives: The aims of this study were to determine the effects of on-farm heat treatment of bovine colostrum on colostral bacterial counts and IgG concentration and evaluation of passive transfer of immunity in neonatal dairy calves. Methods: Ninety-six L of first milking colostrum was collected from Holstein cows and pooled to create a uniform batch. Twenty-four calves were enrolled in 4 treatment groups before suckling occurred and fed raw colostrum (n=6), heat-treated colostrum at 60 ºC for 30 min (n=6), heat-treated colostrum at 60 ºC for 60 min (n=6) and heat-treated colostrum at 60 ºC for 90 min (n=6). Colostrum samples were collected before and after heat treatment and cultured for total bacterial count and analyzed for total IgG concentration. For the first and second feeding 2 L of colostrum was bottle fed by 2 and 12 h of age respectively. Serum samples were collected from calves at 0 h (precolostrum) and 6, 24, 48, 72 h (postcolostrum) and analyzed for serum total protein and IgG concentrations. Results: Heat treatment of colostrum at 60 ºC for 30 and 60 min reduced total bacterial count, yet maintained colostrul IgG concentration compared to the control. There was no difference between treatment groups when examining serum total protein and IgG concentrations, but apparent efficiency of IgG absorption was significantly greater at 6 h in calves that were fed heat-treated colostrum compared to calves fed raw colostrum. ConclusionS: There was no effect of on-farm batch heat treatment of colostrum at 60 ºC till 90 min on serum concentration of IgG.

BACKGROUND: Annexins (including annexin A1 and annexin A2) are important proteins which have some roles in organisms such as intracellular signal conduction, membrane cellular skeletal connection, cellular proliferation and differentiation, especially inhibitory function in inflammation processing. Pasteurella multocida is the most common bacterial pathogen and has high prevalence in pneumonia. Objectives: This study was aimed to determine experimentally annexin A1 and annexin A2 in the serum of calves affected by Pasteurella multocida pneumonia. Methods: In this research, 10 male calves (2 - 4 months) were allocated to two equal groups, one group as the case: 300 ml in dilution 2×109 CFU Pasteurella multocida bacteria and the other as control group: 300 ml normal saline inoculated by special lavage catheter through oral to trachea. Clinical scores were recorded based on available tables. In treatment group, about 18 to 24 hours after inoculation and synchronous with observation clinical signs changes, bronchoalveolar lavage for cytology and bacteriology examination were done of fluids results from washing. Blood sampling was taken from calves jugular vein in both groups then blood serums were examined by using ELISA kits. Results: The rates of annexin A1 and annexin A2  in blood serum of treatment group showed significant increase (using independent t test) compared to control group (p<0.05). Conclusions: It seems these annexins (annexin A1 and annexin A2) can be used as important biomarkers in blood serum to diagnose inflammation processes such as pneumonia.

Effects of IV and aerosol administration of 5-hydroxytryptamine (5-HT) on ventilation, pulmonary mechanics values, pulmonary arterial pressure, and heart rate were investigated in healthy unsedated Friesian calves. Minute volume increased significantly, mainly because of an increase in respiratory rate. Except for total pulmonary resistance after bolus injection, continuous administration of 5-HT given by either route caused significant alterations of lung dynamic compliance and total pulmonary resistance, the former decreasing to one-fifth of its baseline value and the latter increasing twofold. Pulmonary arterial pressure increased significantly, whatever the speed or route of administration. Administration of a bolus did not affect heart rate, whereas continuous iv administration of 5-HT as well by perfusion or by aerosol resulted in sustained tachycardia. It was concluded that 5-HT induces reversible bronchoconstriction and pulmonary vasoconstriction in healthy unsedated calves, 5-HT-induced functional alterations depend on the speed of administration, and excess of 5-HT production or depression in uptake by the lungs during bovine respiratory tract diseases could contribute to pulmonary dysfunction.

A model of bovine pneumonic pasteurellosis, using an indwelling bronchial catheter for inoculation and subsequent lavage of a single main stem bronchus of the lung, was evaluated in a preliminary efficacy trial of an experimental therapeutic compound, Inoculation of 10(7) Pasteurella haemolytica organisms into the bronchus consistently induced a focal pneumonic lesion with typical morphology of pneumonic pasteurellosis in the left or right caudal lung lobe. The experimental treatment caused significant (P < 0.05) reduction in lung lesion volume, compared with that of a saline-treated control. It also caused significant (P < 0.05) reduction in lavage fluid bacterial counts at 48 hours after inoculation, compared with counts in the controls. The inflammatory cell count and the percentage of neutrophils increased markedly in lavage fluids 8 hours after inoculation, but differences were not detected between treatments. Significant differences between treatments were not found in clinical signs, rectal temperature, or histologic changes. This model appears to be a sensitive indicator of treatment efficacy and has the advantage over previous models of pneumonic pasteurellosis of allowing sequential monitoring of the primary lesion site.

Pulmonary lavage samples were collected from 90- to 130-day-old calves before and 6 days after aerosol inoculation with bovine herpesvirus-1 (BHV-1) or parainfluenza-3 (PI3) virus. Alveolar lining material was separated from lavage fluids by high-speed centrifugation and phospholipids were extracted from alveolar lining material and analyzed by high-performance liquid chromatography. Phosphatidylcholine and phosphatidylethanolamine were 74.2 +/- 6.5% and 13.3 +/- 2.8%, respectively, of the total phospholipid content in the surfactant obtained from calves before virus inoculation. Other phospholipids were represented by substantially lower percentages. Infection with either of the 2 viruses caused a significant (P < 0.05) decrease in the percentage of phosphatidylcholine to 66.0 +/- 8.0% and 65.1 +/- 10.8% in the calves inoculated with BHV-1 and PI3 virus, respectively. A significant (P < 0.05) increase in the percentage of phosphatidylethanolamine to 18.1 +/- 2.2% and 17.8 +/- 4.5% developed in calves inoculated with BHV-1 and PI3 virus, respectively. Infection with BHV-1 also induced an increase (not significant) in the percentage of phosphatidylinositol from 5.5 +/- 2.8% to 7.8 +/- 2.2%. A similar, but not significant, increase in the percentage of phosphatidylinositol was also seen in the calves inoculated with PI3 virus. Less substantial changes in the percentage of other phospholipids were detected after virus infection.

The in vivo effects of a single prophylactic dose of recombinant bovine interferon (rBoIFN)-alphaI1 in calves with salmonellosis were investigated, using a Salmonella typhimurium infection model. Treatment with rBoIFN-alphaI1 reduced the degree of septicemia compared with that in control groups, and, in one experiment, using disease of reduced severity, body temperature was lower in treated calves than in controls.

Tissue specimens from muscle, liver, kidney, and injection sites were collected, and serum was obtained from 3 calves euthanatized on each of posttreatment days 5 and 22. Calves were treated with 6.7, 13.4, or 20 mg of oxytetracycline (OTC)/kg of body weight, IM, once daily for 3 days; these dosages are 1, 2, and 3 times the label dose, respectively. One control calf was euthanatized on each of posttreatment days 5 and 22. In treated male calves killed 2 days after the last injection, OTC residues were detected in all tissues and serum, using high-performance liquid chromatography. Tissues from all injection sites also were considered positive for antimicrobial residues, using swab test on premises (STOP), microbial inhibition test (MIT), and thin-layer chromatography-biautography (TLCB) test. Kidney tissues from a calf given 13.4 mg of OTC/kg and kidney and liver tissues from a calf given 20 mg of OTC/kg also were considered positive, using the MIT and TLCB. Results of the STOP only were considered positive for the liver and kidney of a calf given 20 mg of OTC/kg, but substitution of Saskatoon antibiotic medium-3 for the original medium (antibiotic medium-5) allowed the STOP to detect residues in these tissues from all treated calves. In female calves killed 19 days after the last injection, the STOP, MIT, and TLCB procedures revealed positive results for tissues from some injection sites, but revealed negative results for other tissues. High-performance liquid chromatographic analyses detected OTC in tissues from injection sites from all treated calves, in muscle and liver from a calf given 20 mg of OTC/kg, and in kidneys from calves given 13.4 or 20 mg of OTC/kg. The STOP, MIT, and TLCB procedures lacked the sensitivity of high-performance liquid chromatography for detection of OTC residues.