Rapid Detection of Bovine Respiratory Syncytial Virus in Poland Using a Human Patient-Side Diagnostic Assay

Bovine respiratory syncytial virus (BRSV) plays a significant role in the etiopathogenesis of the respiratory syndrome in young cattle during their first year of life. Development of rapid and accurate BRSV diagnostic tools would aid in the appropriate control of this important pathogen. The objective of this study was to characterize infections induced by BRSV by means of rapid patient-side immunomigration assays used for diagnosis of human respiratory syncytial virus (hRSV) in humans. Nasal and tracheal swabs were obtained from healthy calves of various beef and dairy breeds - Holstein-Friesian, Simmental, Charolais, Belgian Blue and Limousin, between the ages of 5 and 12 months, from 26 farms. BRSV was identified using two rapid immunomigration assays, TruRSV® and Clearview® RSV, and compared with RT-PCR as a reference technique. BRSV was found in 73.1% of all the herds tested. High agreement with RT-PCR was obtained for TruRSV® (κ = 0.824), while in the case of the Clearview® RSV test, agreement with PCR was moderate (κ = 0.420). The results demonstrate that rapid patient-side immunomigration assays designed to detect hRSV can be used to accurately detect BRSV in field samples collected from cattle.

Bovine immunoglobulin G does not have an inhibitory effect on diagnostic polymerase chain reaction utilizing magnetic bead extraction methods as demonstrated on the detection of Bovine viral diarrhea virus in dairy calves

The objective of the current study was to investigate if the presence of colostral-derived immunoglobulin G (IgG) in blood is an inhibitor of diagnostic polymerase chain reaction (PCR) for detection of Bovine viral diarrhea virus (BVDV). Eleven precolostral and 11 postcolostral blood samples in ethylenediamine tetra-acetic acid (EDTA) anticoagulant as well as serum samples were collected from 11 Holstein bull calves. Calves were fed 3 liters of colostrum once, by oroesophageal tubing. Postcolostral, blood, and serum samples were collected at 48 hr of age. Serum IgG concentrations were determined in the precolostral and postcolostral serum samples using radial immunodiffusion. The blood samples (precolostral and postcolostral) were spiked with BVDV, and 2 diagnostic PCR extraction methods were applied to each sample. The extraction and amplification efficiencies of the 2 PCR methods on the precolostral and postcolostral EDTA blood samples were evaluated. Two of the 11 calves had inadequate passive transfer of colostral immunoglobulins at 48 hr of age based on the serum IgG concentrations. All blood samples from calves were negative for BVDV prior to the spiking with the virus. Evaluation of the 2 different methods among 3 different virus concentrations demonstrated that there was no difference in extraction or amplification efficiency in precolostral and postcolostral samples. The results of this study suggest that bovine IgG is not an inhibitor of PCR used for detection of BVDV in cattle. The methods used in the current study are acceptable for PCR detection of BVDV in cattle.

Effect of parenteral administration of glutamine on autophagy of liver cell and immune responses in weaned calves

The objectives of this study were to determine the effects of an increased jugular supply of L-Gln on post-weaning growth, immune responses, intestinal morphology and autophagy of weaned calves. At 35 days of age, 24 Holstein calves (initial 50 ± 1.5 kg; 35 ± 2 day of age) were randomly allocated to four treatments, and each treatment included five male and one female calves. Holstein calves were assigned to treatments of (i) i.v. infusion of 2 l of 0.85% NaCl, Control group [C]; (ii) i.v. infusion of 8 g/day of L-Gln mixed with 2 l of 0.85% NaCl solution [L]; (iii) i.v. infusion of 16 g/day of L-Gln mixed with 2 l of 0.85% NaCl solution [M]; and (iv) i.v. infusion of 32 g/day of L-Gln mixed with 2 l of 0.85% NaCl [H]; The infusion was 2 h/day for each of 14 consecutive days starting on day 1 after weaning. Feed and water were freely available to all calves. All calves were killed on the 14th day post-weaning for measurements of autophagy of liver cell and intestinal morphology. Gln has no effect on dry matter intake (DMI) and average daily gain (ADG). Gln infusion increased quadratically the abundance of CD4+, monocyte and the ratio of CD4+/CD8+. The urea N, Gln and Glucose in plasma increased linearly with increasing Gln loads. Gln infusion increased quadratically villus height and crypt depth of intestine. The autophagy level of liver cell was improved with the Gln infusion dose increased.

Characterization of Shiga toxin-producing Escherichia coli (STEC) in feces of healthy and diarrheic calves in Urmia region, Iran

BACKGROUND AND OBJECTIVES

Shiga toxin-producing Escherichia coli (STEC) have emerged as human pathogens and contamination of foods of animal origin has been a major public health concern. The aim of the present study was to determine the dissemination of STEC in healthy and diarrheic calves in Urmia region which is located in West Azerbaijan province, Iran.

MATERIALS AND METHODS

In the current study, a total of 124 Escherichia coli isolates from clinically healthy (n = 73) and diarrheic calves (51) belonging to 6 different farms located in West Azerbaijan province, Iran, were screened by the polymerase chain reaction (PCR) assay for the presence of virulence genes characteristic for STEC, that is, Shiga-toxin producing gene(s) (stx1, stx2), intimin (eaeA) and enterohemolysin (hlyA).

RESULTS

STEC isolates were recovered from 21.92% (16/73) in healthy calves, and 19.6% (10/51) in diarrheic calves. Overall, PCR results showed that 6 (23.1%) isolates carried stx1 gene, 7 (26.92%) possessed stx2 gene while 13 isolates (50%) gave positive amplicon both for stx1 and stx2 genes. All stx positive isolates were assayed further to detect eaeA and hlyA sequences. Seven out of the 26 (26.92%) Shiga toxin gene positive isolates were positive for the eaeA gene, and 15 (57.69%) were positive for the hlyA gene. Both virulence genes (eaeA and hlyA) in the same isolate were observed in 5 (19.23%) of the stx(+) isolates. In total, diverse virulence gene profiles were detected, from which isolates with the genetic profile stx1 stx2 hlyA was the most prevalent. In addition, eaeA gene was more evident in isolates from diarrheic calves than in healthy calves.

CONCLUSION

There was no significant difference in detecting STEC isolates between healthy and diarrheic calves. It seems that calves to be the reservoir of STEC within the herds and calf management may represent specific control points for reducing STEC spread within dairy units.

Molecular screening and risk factors of enterotoxigenic Escherichia coli and Salmonella spp. in diarrheic neonatal calves in Egypt

The aim of the present study was to carry out molecular epidemiological investigation on enterotoxigenic Escherichia coli (ETEC) K99 and Salmonella spp. in diarrheic neonatal calves. Fecal samples were obtained from 220 diarrheic calves at 9 farms related to four governorates in central and northern Egypt. E. coli and Salmonella spp. isolates were examined for E. coli K99 and Salmonella spp. using PCR. ETEC K99 was recovered from 20 (10.36 %) out of 193 isolates, whereas Salmonella spp. was recovered from nine calves (4.09%). Multivariable logistic regression was used to evaluate the risk factors associated with both infections. ETEC K99 was significantly affected by age (P<0.01; OR: 1.812; CI 95%: 0.566-1.769), colostrum feeding practice (P<0.01; OR: 5.525; CI 95%: 2.025-15.076), rotavirus infection (P<0.001; OR: 2.220; CI 95%: 0.273-1.251), vaccination of pregnant dams with combined vaccine against rotavirus, coronavirus and E. coli (K99) (P<0.001; OR: 4.753; CI 95%: 2.124-10.641), and vitamin E and selenium administration to the pregnant dam (P<0.01; OR: 3.933; CI 95%: 0.703-1.248). Infection with Salmonella spp. was found to be significantly affected by the animal age (P<0.05; OR: 0.376; CI 95%: 0.511-1.369), Hygiene (P<0.05; OR: 0.628; CI 95%: 1.729-5.612), and region (P<0. 01; OR: 0.970; CI 95%: 0.841-1.624). The results of the present study indicate the importance of PCR as rapid, effective and reliable tool for screening of ETEC and Salmonella spp. when confronted with cases of undifferentiated calf diarrhea. Moreover, identification of the risk factors associated with the spreading of bacteria causing diarrhea may be helpful for construction of suitable methods for prevention and control.

Prophylactic and therapeutic efficacy of nitazoxanide against Cryptosporidium parvum in experimentally challenged neonatal calves

Diarrhoea caused by Cryptosporidium parvum is a major problem in calves younger than 4 weeks of age. To date only a few compounds have been approved for prophylactic and none for therapeutic use. Nitazoxanide (NTZ) has proven its efficacy in vitro against C. parvum and is approved by FDA for the treatment of human cryptosporidiosis. In a first experimental study, 3 uninfected calves were treated with NTZ and pharmacokinetics was followed through blood samples. Serum samples of uninfected treated calves contained both NTZ metabolites (tizoxanide and tizoxanide glucuronide) and oral administration at 12 h intervals was considered as optimal. Three groups of three calves (1-3 days old) were then each inoculated with 1x10(7) oocysts of C. parvum (cattle genotype): the prophylactic group received 15 mg/kg body weight NTZ twice daily orally in milk from 1 day before to 8 days postinoculation (dpi). The therapeutic group received the same dosage of NTZ for 10 days from the appearance of diarrhoea (between 1 and 5 dpi). The control group was left untreated. All calves were monitored daily from day -1 to 28 dpi and faecal samples were collected for evaluation of consistency and for determination of oocyst numbers per gram (OPG) of faeces. Diarrhoea was observed in all calves within the first week. Neither prophylactic nor therapeutic use of NTZ improved the clinical appearance and calves of the therapeutic showed a longer diarrheic episode (p<0.05) with strong altered faecal consistency compared to the untreated control group. The number of days with oocyst excretion did not differ significantly between the groups. In 5 out of 6 infected and treated calves oocyst excretion stopped only after discontinuation of treatment. In the prophylactic and in the control group mean values of the sum of the daily OPG per calf (8.5x10(6) and 8.0x10(6), respectively) and of the mean daily number of OPG (0.3x10(6) and 0.3x10(6), respectively) were similar, while the therapeutic group showed significantly lower values (1.9x10(6) and 0.06x10(6), respectively, p<0.05). However oocyst determinations in this group may have been altered by the severe diarrhoea, diluting oocyst densities in the analysed faecal samples. In conclusion, these preliminary results about the first prophylactic and therapeutic use of NTZ in calves did not show the expected positive effect on the course of the Cryptosporidium-infection, neither on reducing the clinical severity, nor on oocyst excretion.

Treatment of calf diarrhea: intravenous fluid therapy

Severely dehydrated calves that are unable to suckle need intravenous fluids for effective resuscitation. Intravenous fluid therapy is also indicated for sick calves without obvious dehydration, such as calves with strong ion acidosis, ruminal acidosis (rumen drinkers), severe pneumonia, septicemia, or hypothermia. This article presents an updated overview of intravenous fluid therapy for calves, recent insights into the development of metabolic acidosis in young calves resulting from accumulation of D-lactate, a simplified algorithm for intravenous fluid therapy, and a procedure for ear vein catheterization under field conditions.

Growth, nutrient utilization, and body composition of dairy calves fed milk replacers containing different amounts of protein

Male Holstein calves < 1 wk of age were allowed a 2-wk adaptation period after purchase, and then were blocked by BW and assigned randomly within block to either a baseline slaughter group or one of four experimental groups (n = 8 to 9 per group). Treatments were isocaloric milk replacers (12.5% solids) fed at 12% of BW that contained 16.1, 18.5, 22.9, or 25.8% CP (DM basis) from whey protein sources. After a 6-wk feeding period, all calves were slaughtered and the weights and chemical composition of the viscera-free carcasses (VFC; including head, hide, feet, and tail) were determined. Gain of BW (0.38, 0.45, 0.56, and 0.62 kg/d) and gain:feed ratio (0.51, 0.59, 0.71, and 0.78) increased linearly (P < 0.001) as dietary CP increased; rate of change in body length, wither height, and heart girth also increased linearly (P < or = 0.05). Balance measurements conducted during wk 3 and 4 of the experimental period showed that both absorbed N (16.9, 20.0, 25.8, and 30.6 g/d) and retained N (7.6, 9.0, 13.2, and 15.6 g/d) increased linearly (P < 0.001) as dietary CP increased. Retained N as a percentage of absorbed N increased linearly (P < 0.01) as dietary CP increased (44.3, 44.7, 50.7, and 50.9%), whereas biological value was unaffected (71.1, 68.7, 69.5, and 67.3%; P = 0.26). Digestible energy and ME represented 94.5 and 89.7% of intake energy, respectively, and were not affected by dietary CP content. Plasma urea N concentration increased linearly (2.9, 3.3, 4.6, and 6.0 mg/dL) as dietary CP increased. Contents of water (68.2, 69.1, 70.2, and 70.5%; P < 0.001) and protein (19.6, 20.0, 20.0, and 20.2%; P < 0.10) in VFC increased linearly, whereas contents of fat (7.2, 6.2, 5.5, and 5.2%; P < 0.001) and ash (5.1, 5.2, 4.8, and 4.7%; P < 0.02) decreased linearly as dietary CP increased. Trends in visceral tissue composition were similar to those for VFC. The content of water in VFC tissue gain increased, whereas contents of fat and energy decreased, as dietary CP increased. Final VFC energy and gain of energy in VFC were not affected by dietary CP. At similar initial ME intakes, increasing dietary CP (i.e., increasing protein: energy) linearly increased ADG, gain:feed, N retention, and deposition of lean tissue in VFC, demonstrating that diet composition can markedly affect components of body growth in preruminant dairy calves.

Supplemental lactoferrin improves health and growth of Holstein calves during the preweaning phase

Lactoferrin is a milk protein that exhibits broad-spectrum antimicrobial properties. Previous studies indicated that supplemental lactoferrin may alter the microbial populations in the gut of nonruminants and increase preweaning weight gains in calves. In the present study, 40 Holstein calves were used to examine the effects of supplemental lactoferrin (0, 1, 2, or 3 g/d) on health, growth, and feed intake from 3 d of age to 2 wk postweaning. Lactoferrin was mixed and fed with a nonmedicated milk replacer. Calves were housed in individual pens and offered a textured, nonmedicated starter and water for ad libitum consumption. Body weight and heart girth were measuredweekly. Intakes of milk replacer and starter were determined daily. Fecal consistency was monitored three times per week. Calves were weaned when they met certain criteria based on body weight gain and starter intake. Preweaning fecal score responded quadratically, with the group fed 1 g/d of lactoferrin having the lowest score. Overall and preweaning number of days medicated responded in the same manner as fecal score. Preweaning average daily gain and gain-to-feed ratio increased linearly with lactoferrin supplementation, whereas postweaning gain-to-feed ratio decreased linearly with lactoferrin. Overall average daily heart girth gain increased linearly with lactoferrin. Body weight, weaning age, and dry matter intake were not different among treatments. Based on the observed improved gain-to-feed ratios, increased average daily gains, improved fecal scores, and reduced morbidity in preweaned calves, it appears that lactoferrin may be a beneficial supplement in the diets of neonatal calves prior to weaning.

An experimental infection model for reproduction of calf pneumonia with bovine respiratory syncytial virus (BRSV) based on one combined exposure of calves

Bovine respiratory syncytial virus (BRSV) has been recognised as an important pathogen in calf pneumonia for 30 years, but surprisingly few effective infection models for studies of the immune response and the pathogenesis in the natural host have been established. We present a reproducible experimental infection model for BRSV in 2-5-month-old, conventionally reared Jersey calves. Thirty-four colostrum-fed calves were inoculated once by aerosol and intratracheal injection with BRSV. Respiratory disease was recorded in 91% of the BRSV-inoculated calves, 72% had an accompanying rise in rectal temperature and 83% exhibited >5% consolidation of the lung tissue. The disease closely resembled natural outbreaks of BRSV-related pneumonia, and detection of BRSV in nasal secretions and lung tissues confirmed the primary role of BRSV. Nine mock-inoculated control calves failed to develop respiratory disease. This model is a valuable tool for the study of the pathogenesis of BRSV and for vaccine efficacy studies.

Formulation of colostrum supplements, colostrum replacers and acquisition of passive immunity in neonatal calves

Provision of an adequate mass of IgG from maternal colostrum is essential to health and survival of neonatal calves. Colostrum supplements (CS) have been developed to provide supplemental immunoglobulin when maternal colostrum is of poor quality. However, colostrum replacers (CR) that provide > or = 100 g of IgG have not been formulated. Our objective was to determine the absorption of IgG in newborn calves fed CS derived from bovine serum or CR derived from bovine immunoglobulin concentrate. The CS were prepared by collecting, processing, and spray drying bovine serum and blending with other ingredients to provide 45 to 50 g of IgG per dose. The CR were prepared by further processing bovine serum to increase IgG concentration to > 50% IgG and blending with other ingredients to provide 100 to 122 g of IgG per dose. Holstein calves (n = 160) were fed 90 to 244 g of IgG from CS or CR in 1 or 2 feedings in two experiments. Blood was collected from each calf by jugular venipuncture at 0 and 24 h of age and plasma IgG was determined by turbidimetric immunoassay. Apparent efficiency of IgG absorption was calculated. Plasma IgG concentrations at 24 h of age were indicative of IgG intake and averaged 5.5 to 14.1 g/L in calves fed CS and CR. Mean apparent efficiency of IgG absorption in calves fed CS was 25 and 28% in experiments 1 and 2, respectively. Mean apparent efficiency of IgG absorption in calves fed CR ranged from 19 to 32% and were affected by method of processing and number of times fed. Treatment of plasma with polyethylene glycol reduced the efficiency of IgG absorption in experiment 1. The addition of animal fat to CR had no effect on IgG absorption. A second feeding of CR increased plasma IgG, but efficiency of absorption was reduced. Mean body weights at 60 d of age were not affected by treatment and ranged from 64.3 to 78.2 kg. Plasma IgG concentration in calves fed > or = 122 g of IgG from Ig concentrate approached (9.9 g/L) or exceeded 10 g/L, indicating successful transfer of passive immunity. Provision of IgG to prevent failure of passive transfer is possible with CR containing >20% IgG when fed at 454 g per dose.

Both L- and D-lactate contribute to metabolic acidosis in diarrheic calves

Diarrhea in neonates is often complicated by metabolic acidosis. We used blood gas analysis and HPLC to determine whether bacterial fermentation might contribute to acidosis in diarrheic calves. Diarrheic calves (n = 21) had significantly lower pH, PCO(2), HCO(3)(-) and a higher anion gap than healthy calves (n = 21). Serum concentrations (mean +/- SD, mmol/L) of DL-, L- and D-lactate were also significantly higher in diarrheic (8.9 +/- 5.1, 4.1 +/- 3.4 and 5.2 +/- 5.7) than in healthy calves (1.7 +/- 1.2, 2.0 +/- 1.1 and too low to quantify). D- and L-lactate accounted for 64% anion gap increase in diarrheic calves. Fecal D- and L-lactate concentrations were also significantly higher in diarrheic calves (9.4 +/- 3.0 and 11.9 +/- 2.7 mmol/L) than healthy calves (1.1 +/- 0.1 and 1.6 +/- 0.1 mmol/L). The elevated concentrations of serum and fecal D-lactate suggest gut bacterial fermentation contributes to the development of acidosis in diarrhea.

Addition of casein or whey protein to colostrum or a colostrum supplement product on absorption of IgG in neonatal calves

The effects of the addition of nonimmunoglobulin protein on absorption of immunoglobulin G (IgG) from colostrum or colostrum supplement products were determined in two experiments. In experiment 1, 48 Holstein calves were fed 4 L of pooled maternal colostrum or 4 L of reconstituted colostrum supplement with 0, 200, or 400 g of added whey protein concentrate or casein. In experiment 2, 38 Jersey calves were fed 2 L of pooled maternal colostrum with 100 or 200 g of whey protein concentrate or casein added immediately before feeding. Blood was collected at 24 h of age and plasma IgG concentration, total protein, hematocrit (experiment 1 only), and plasma urea N were determined. In experiment 1, blood samples were also collected at 4, 8, 12, 16, and 20 h to evaluate absorption of IgG and protein and urea N concentrations. The addition of 400 g of casein to colostrum supplement in experiment 1 reduced plasma IgG from 5.66 g/L (0 g of casein addition) to 3.88 g/L, increased plasma urea N at 24 h, and reduced the change in plasma total protein from 0 to 24 h. Hourly plasma IgG concentrations increased with the consumption of colostrum or supplements but increased more rapidly in calves fed whey protein concentrate and more slowly in calves fed casein. The addition of 200 g of casein or whey protein concentrate to colostrum supplements had no effect on plasma IgG concentration at 24 h of age. The addition of 100 or 200 g of casein or whey protein concentrate to maternal colostrum had no effect on plasma urea N, total protein, or plasma IgG in experiment 2. The addition of nonimmunoglobulin protein to colostrum supplements or maternal colostrum did not affect IgG absorption from the intestine of newborn calves unless the amount of total protein exceeded 500 g of protein.

Bovine respiratory syncytial virus (BRSV): a review

Bovine respiratory syncytial virus (BRSV) infection is the major cause of respiratory disease in calves during the first year of life. The study of the virus has been difficult because of its lability and very poor growth in cell culture. However, during the last decade, the introduction of new immunological and biotechnological techniques has facilitated a more extensive study of BRSV as illustrated by the increasing number of papers published. Despite this growing focus, many aspects of the pathogenesis, epidemiology, immunology etc. remain obscure. The course and outcome of the infection is very complex and unpredictable which makes the diagnosis and subsequent therapy very difficult. BRSV is closely related to human respiratory syncytial virus (HRSV) which is an important cause of respiratory disease in young children. In contrast to BRSV, the recent knowledge of HRSV is regularly extensively reviewed in several books and journals. The present paper contains an updated review on BRSV covering most aspects of the structure, molecular biology, pathogenesis, pathology, clinical features, epidemiology, diagnosis and immunology based on approximately 140 references from international research journals.

Yeasts in the gastrointestinal tract of preweaned calves and possible involvement of Candida glabrata in neonatal calf diarrhea

To examine the possibility of a mycotic involvement in neonatal calf diarrhea (NCD) the presence of fungi was assessed in (a) the intestinal contents of dead calves and fecal samples submitted for routine laboratory examination, (b) fecal specimens, sampled once in winter and once in summer, of calves raised on 2 farms with different management systems, and (c) mucosal scrapings of various segments of the digestive tract of a diarrheic calf, massively shedding Candida glabrata. C. glabrata was the most prevalent fungal species isolated from the routine samples. It was the only fungus which was shed by the calves on the 2 farms, for continuous, more or less prolonged periods, but exclusively in the winter months. Diarrhea and C. glabrata shedding seemed to be associated. C. glabrata colonized the abomasum (the functional equivalent of the monogastric stomach) but not the other segments of the digestive tract of the euthanized calf. Based on the findings of this study it seems that while some yeast species may be considered as commensals of the digestive tract of calves, and consequently their isolation from intestinal contents or fecal samples has no clinical significance, others, such as C. glabrata may be involved in enteric pathogenic processes. Moreover, characteristics of the culture, previous chemotherapeutic treatments, the animal's age and possibly climatic conditions should be taken into account before deciding on the fungal isolate's clinical relevance. Determination of mycotic involvement in NCD by routine mycological examination of intestinal contents and fecal samples of diarrheic calves may be useful to avoid unnecessary and potentially harmful antibacterial therapy.

Identification of gamma delta T lymphocyte subsets that populate calf ileal mucosa after birth

Ileal intraepithelial and lamina propria lymphocytes from newborn, 1.5-week-old, and 3-week-old calves were compared to determine to what extent the mucosa becomes populated after birth. Single and dual fluorescence flow cytometry were used with monoclonal antibodies to bovine (Bo) CD molecules to identify lymphocyte subpopulations. Few ileal mucosal lymphocytes were present in calves at birth. However, by 1.5 weeks of age, the villi were populated with large numbers of lymphocytes, and by 3 weeks of age, the numbers had increased further. These included a prominent subpopulation of gamma delta T cells. Several subsets of gamma delta T cells populated ileal mucosa after birth. The predominant subset coexpressed BoCD2, and a smaller subset coexpressed BoCD8. WC1+ gamma delta T cells comprised the smallest subset. All gamma delta T cell subsets coexpressed ACT2, a molecule expressed on activated WC1+ and WC1- gamma delta T cells from cattle.

Effect of graded concentrations of gossypol on calf performance: toxicological and pathological considerations

The effects of feeding diets containing 0, 100, 200, 400, or 800 ppm of free gossypol were examined in 60 Holstein bull calves from 1 to 120 d of age. The concentrations of free gossypol were varied by varying amounts of cottonseed meals from three different sources. Cottonseed meal totaled 31% of each treatment ration. Feed consumption, BW, and blood parameters were collected on all calves at 30-d intervals throughout the trial. There were no significant differences between the groups for feed consumption, BW, or average daily gain. Changes in the group means for hematology and chemistry variables examined were modest and insufficient to distinguish diagnostically between safe and unsafe free gossypol concentrations for the different groups. Clinical evidence of disease was limited to the calves fed 400 or 800 ppm of free gossypol after 90 d of age. One calf in the group fed 400 ppm and 4 in the group fed 800 ppm died as a result of circulatory failure associated with gossypol consumption. We conclude from this study that a ration containing up to 200 ppm of free gossypol is safe, 400 ppm of free gossypol is toxic, and 800 ppm of free gossypol results in death losses. These results are compatible with previously reported naturally occurring toxicological outbreaks.

Rotavirus infection in calves in Bangladesh

Faecal samples from 434 calves under 1 year of age (307 diarrhoeal and 127 normal) were collected from three dairy farms and one village in selected areas of Bangladesh. The samples were tested by an enzyme-linked immunosorbent assay (ELISA) to detect the presence of rotavirus antigen. Of 402 dairy calves tested, 28 (7.0%) were positive, of which 21 (7.2%) were from diarrhoeic calves and 7 (6.3%) from non-diarrhoeic calves. Rotavirus infection varied from farm to farm (2.7-9.2%) and there was no positive response from any of the 32 village calves. Rotavirus was most commonly found in calves of 1 week of age or less (up to 22.2% in one group) but was not found in any calves later than 6 months of age. More than 80% of rotavirus-positive samples from diarrhoeic calves exhibited a titre of 128 or more (geometric mean 345 +/- 4.5), whereas non-diarrhoeal calves had titres less than or equal to 128 (geometric mean = 29 +/- 1.9), suggesting that rotavirus infection in calves in Bangladesh was mostly associated with diarrhoea.

Pneumocystis carinii in large domestic animals in Denmark. A preliminary report

By microscopic examination of toluidine blue O stained autopsy lung imprints Pneumocystis carinii was shown in 6 calves out of 160 (3.8%), in 1 sheep out of 28 (3.6%) and in 8 pigs out of 119 (6.7%). This is the first report of Pneumocystis carinii in calves, sheep and pigs in Denmark.

Neonatal calf diarrhea induced by rotavirus

This presentation summarizes the results of a comprehensive study on rotaviruses isolated in Italy from calves and rabbits affected by neonatal diarrhea. The results clearly indicated that rotavirus infection is widespread and supported the evidence for an etiologic role of these viruses in neonatal diarrhea. The evidence of differences in virulence among bovine rotaviruses appeared also to be confirmed. Conventionally reared calves were fully susceptible to the experimental infection induced by three rotaviruses originating from heterologous hosts, i.e. monkeys, pigs and rabbits, respectively. When rotavirus strains of bovine, simian, porcine and rabbit origin were compared by cross neutralization tests, it was found the simian and porcine strains were indistinguishable and both appeared to relate antigenically to the bovine strain. On the other hand, a reciprocal antigenic correlation was found between bovine and rabbit isolates. Finally, it was proven that feeding newborn calves with colostrum of their dams, previously vaccinated with an inactivated rotavirus vaccine, could prevent the neonatal diarrhea from occurring.

A retrospective study of 51 cases of abdominal problems in the calf: etiology, diagnosis and prognosis

A retrospective study of 51 calves less than two months of age showing signs of abdominal pain or presented because of abdominal distension was carried out to evaluate the relationship between etiological, diagnostic, and prognostic characteristics. We found that the age of the calf differed with the type of lesion present. Calves under eight days of age had a 73% incidence of lesions which required surgical therapy. Atresia of part of the intestinal tract was the most frequently diagnosed problem, In eight-day to two-month-old calves, medical causes of colic were more common; only 26% of cases had lesions that required surgical correction. Gaseous distension of the abomasum and intestine was the most frequent cause of colic in older calves. Other abdominal problems observed in this study included abomasal ulceration and abomasal torsion.Mortality was more common in calves with surgical problems. Of the 21 calves with surgical problems, 76% died compared with a 20% mortality rate in the 30 calves with medical problems. Because of the high incidence of surgical problems in young calves, mortality was 69% in calves under eight days of age and only 33% in older calves. The chance of recovery decreased with the severity of hypothermia and dehydration. Most calves (75%) which were recumbent at presentation died, whereas only 29% of calves which were alert and able to stand at presentation died. Hematological findings indicative of severe inflammation were poor prognostic signs. Heart rate and the apparent severity of abdominal pain were not useful prognostic indicators.

Severity and nature of acidosis in diarrheic calves over and under one week of age

A prospective study of the severity of dehydration and acidosis was carried out in 42 calves under 35 days of age presented for treatment of neonatal diarrhea. Clinically the mean level of dehydration was 8 to 10%. The plasma volume was 65% of that in the hydrated calf but the calves only gained 6.5% in weight during therapy.Calves under eight days of age often had a lactic acidosis. Blood pH was 7.118+/-0.026 (mean +/- 1 standard error), bicarbonate concentration 18.8+/-1.3 mmol/L, base deficit 11.4+/-1.7 mmol/L and lactate of 3.6+/- 0.06 mmol/L. Calves over eight days usually had a nonlactic acidosis. Blood pH was 7.042+/-0.021, bicarbonate 10.8+/-1.0 mmol/L, base deficit 19.5+/-1.2 mmol/L and lactate 1.2+/-0.3 mmol/L. These values were all significantly different from those in younger calves.Over all calves there was a poor correlation between the severity of acidosis and dehydration(r=0.05). The severity of lactic acidosis was related to the severity of dehydration. Mean bicarbonate requirements to correct acidosis were calculated to be 200 mmol(17 g of sodium bicarbonate)and 450 mmol(37 g of sodium bicarbonate)in calves under and over eight days of age respectively. Both groups of calves required a mean volume of 4L of fluid to correct dehydration.

Necrosis of the brain in calves following dehorning

This is a report of an acute hemorhagic necrotizing encephalitis following dehorning in calves on pasture. Calves were found either dead or down in extremis. Multiple necrotic inflammatory lesions were found in the cerebral cortices of affected calves at postmortem. Necrosis and hemorhage were observed microscopically to be more prominent than inflammation, indicating the peracute overwhelming nature of the process. The etiology was not determined but clostridial infection was suspected.

Metabolic acidosis without clinical signs of dehydration in young calves

Metabolic acidosis without clinical signs of dehydration was diagnosed in four calves between nine and 21 days of age. In each calf either coma or depression with weakness and ataxia was observed. Two calves had slow deep respirations. Treatment with intravenous administration of solutions of sodium bicarbonate was accompanied by a rise in blood pH and a return to normal demeanor, ambulation and appetites, allowing these calves to return to their respective herds.

A yeast related ethanol intoxication syndrome in experimental calves: prevention with nystatin

In a calf nutrition-metabolism study in which a high glucose (60% glucose and 3% lard) versus a high fat (23% glucose and 30% lard) milk replacer were compared, a syndrome characterized by anorexia, an unstable gait, depression, a distended abdomen and an odor of alcohol on the breath was observed in some calves. These signs were associated with intoxicating levels of plasma ethanol and the predominance of the yeast species Torulopsis glabrata in gastrointestinal contents of afflicted calves. Nystatin, a yeast inhibitor, was extremely useful in preventing the problem.