Some respiratory and enteric diseases of cattle: an update

Fibrinous pneumonia caused 40-45% of death losses in cattle shipped into Bruce County, Ontario. Feeding corn silage within the first 2 weeks of arrival increased mortality. Commingling cattle from different sources and keeping more than 110 cattle in a pen were detrimental. While use of antimicrobials in the starter ration was beneficial, prophylactic use of antimicrobials in the water was not. Mortality was directly proportional to morbidity and treatment costs. Vaccinating against any respiratory disease in the first 2 weeks after arrival was detrimental. Delaying vaccination for at least 2 weeks after arrival prevented the negative effects of vaccination in calves fed corn silage. Morbidity in cattle transported by train or truck did not differ. Bovine respiratory syncytial virus causes severe pulmonary edema-emphysema, with high morbidity and variable mortality, in confined calves in the fall and early winter. Death is usually from secondary bacterial pneumonia. Treatment involves use of pyrilamine maleate, dexamethasone and sulfamethazine. Salmonella muenster causes bloody diarrhea, abortion and death in cattle of any age. Treatment is with antibiotics selected by sensitivity tests. Cryptosporidium causes watery diarrhea in 1- to 2-week-old calves; infection is often fatal despite symptomatic treatment. Diagnosis is by identification of oocysts in fecal sugar flotation solution or May-Grünwald-Giemsa-stained fecal smears. Oral sulfamethazine has been used as a prophylactic.     

Factors associated with mortality and treatment costs in feedlot calves: the Bruce County Beef Project, years 1978, 1979, 1980.

Three years of data on factors associated with death losses and health costs in Ontario feedlot calves were analyzed. The results support the previously reported findings; however, significant differences in the third year (1980-81) of the study were noted. Calf groups that were "mixed" after arrival in the feedlot or had a larger than average number of calves (means = 142) had increased death losses and health costs. Calf groups whose ration was changed from dry hay to hay silage or corn silage as the major component of the ration during the first month after arrival had higher death losses and health costs. Feeding grain (barley/oats/corn) prior to, or concurrent with, the change to silage appeared to decrease the harmful effects. Cattle groups vaccinated against respiratory disease within two weeks of arrival experienced increased death losses and health costs. These effects were ameliorated by delaying vaccination in groups switched to silage; however, no benefits from delaying vaccination were noted in dry hay fed groups. Prophylactic antimicrobials in the water supply during the first week after arrival appeared particularly deleterious to the health of calf groups. The effects of prophylactic antimicrobials in the starter ration were unclear. During 1980-81, there was a marked decrease in the relative importance of fibrinous pneumonia as a cause of death and the feeding of silage was not significantly associated with mortality. Both these events may have arisen from the drastic decrease in the percentage of groups fed silage by two weeks postarrival (from 32% in previous years to 7% in 1980-81).     

A mail survey of the efficacy of prophylactic medication in feed and/or water of feedlot calves.

A mail survey of feedlot owners was conducted to evaluate the efficacy of prophylactic antimicrobials, given in the water, or in the ration at preventing illness and/or death. One hundred and twenty-seven farmers from southwestern Ontario collaborated in the study. The percentage of calves requiring individual antimicrobial treatment, for any reason within 28 days of arrival was 22.6% (median 17.8%) and 0.6% (median 0.2%) died in that period. The use of medicated starter rations was not associated with either treatment or mortality rates until the effects of a number of other variables were controlled, analytically. Thereafter, the use of medicated feed was associated with a decrease in mortality rate, but was unrelated to morbidity rate. Overall, the use of medicated water was not associated with treatment or mortality rates. The use of sulphonamides was associated with decreased morbidity, but increased mortality rates. After controlling, analytically using multiple regression, the effects of other variables, the use of medicated water was associated with a significant increase in mortality rates. The other major factors which influenced mortality rates were the number of calves per group, the number of subgroups of calves in each group and whether the group contained cattle from different sources; all were related to increased mortality rates. During a two year period, more feedlot owners appeared to be using medicated rations as opposed to medicated water, as a means of providing antimicrobials to their newly arrived calves.     

Factors associated with morbidity and mortality in feedlot calves: the Bruce County beef project, year two.

The results of the second year of the project confirmed most of the major findings from the initial year. Feeding cornsilage, particularly as the major roughage in the first month after arrival was associated with excess mortality. Mixing of cattle from different sources and vaccinating against respiratory disease appeared to be the most important additional factors that increased mortality rates. Delaying vaccination at least two days postarrival may have prevented the negative effects of vaccination but only in calves fed cornsilage. Morbidity rates were highly variable among farms but were positively correlated with mortality rates and treatment costs. The occurrence of infectious thromboembolic meningoencephalitis appeared to share some of the same risk factors as mortality; whereas, urolithiasis did not. Water deprivation may be a risk factor in the occurrence of urolithiasis. Fibrinous pneumonia was again the most frequent cause of death. Relative to year one, infectious thromboembolic meningoencephalitis increased in frequency and only one death was attributed to bovine virus diarrhea.     

The effect of route and dosage of immunization on the serological response to a Pasteurella haemolytica and Haemophilus somnus vaccine in feedlot calves

The effect of route and dosage of administration on the serological response to a vaccine containing genetically attenuated leukotoxin of Pasteurella haemolytica combined with bacterial extracts of P. haemolytica and Haemophilus somnus (Somnu-Star Ph, Biostar Inc., Saskatoon, Saskatchewan) was evaluated in a controlled field trial in 301 feedlot calves. Vaccination of calves on arrival at the feedlot with Somnu-Star Ph significantly (p < 0.05) increased P. haemolytica and H. somnus serum antibody titers and reduced bovine respiratory disease (BRD) morbidity. A single subcutaneous vaccination with Somnu-Star Ph was as effective in stimulating a humoral antibody response and in reducing BRD morbidity as double vaccination by the intramuscular or the subcutaneous route. Furthermore, there were no swellings or adverse reactions observed with either subcutaneous or intramuscular administration of Somnu-Star Ph.

These results suggest that feedlot calves can be immunized subcutaneously once on arrival with Somnu-Star Ph. Double vaccination was of no added value in this trial, because the majority of BRD morbidity occurred prior to revaccination fourteen days postarrival. Additional larger-sized field trials are needed to monitor the duration of immunity following vaccination and to test the effect of route and dosage of vaccination on mortality.

     

The protective effect of vaccination against experimental pneumonia in cattle with Haemophilus somnus outer membrane antigens and interference by lipopolysaccharide.

A semi-purified outer membrane anionic antigen (AA) fraction was isolated from Haemophilus somnus by a modified procedure of anion exchange chromatography to yield a protein fraction free of lipopolysaccharides (LPS). The AA fraction (1 mg) was administered with or without the homologous lipopolysaccharide (10 micrograms/kg body weight) as vaccines to groups of cattle twice, three weeks apart. A control group which did not receive any antigen was included in the trial. Six weeks after the first vaccination, the animals were challenged intratracheally with a virulent pneumonic strain of H. somnus (70986) and observed for clinical signs of respiratory disease. The cattle were euthanized six days later and the lungs were evaluated for the severity of lesions macroscopically as well as histopathologically. Vaccination with AA alone provided the best protection against pneumonia as indicated by significantly lower clinical scores, less extensive gross lung lesions and mild histopathological lesions with immune cell infiltration. However, when AA was combined with LPS in the vaccination, this protective effect was negated and the animals showed more detrimental histopathological lesions than the controls.     

The association between serological titers in infectious bovine rhinotracheitis virus, bovine virus diarrhea virus, parainfluenza-3 virus, respiratory syncytial virus and treatment for respiratory disease in Ontario feedlot calves.

A seroepidemiological study of the association between antibody titers to infectious bovine rhinotracheitis, parainfluenza-3, bovine virus diarrhea and bovine respiratory syncytial viruses, and treatment for bovine respiratory disease was conducted. A total of 322 calves from five different groups were bled on arrival, then one month later all cases (cattle treated for bovine respiratory disease) were rebled together with an equal number of controls (cattle not treated for any disease). Titers to these viruses varied significantly from group to group. Based on seroconversion, infectious bovine rhinotracheitis virus was active in 4.4%, bovine virus diarrhea virus in 24%, parainfluenza-3 virus in 69.5% and bovine respiratory syncytial virus in 71.3% of the cattle. Cattle with low titers to infectious bovine rhinotracheitis and/or bovine respiratory syncytial viruses on arrival, were at increased risk of subsequent treatment for bovine respiratory disease. Treated cattle also had significantly greater increases to parainfluenza-3 and/or bovine virus diarrhea viruses than control calves. Treatment rates varied considerably from group to group and were not strongly correlated with weight gain in the postarrival period.     

Effect of vaccination with the R mutant Escherichia coli (J5) antigen on morbidity and mortality of dairy calves

A prospective cohort study was undertaken to determine the efficacy of Escherichia coli 0111:B4 (J5) vaccination in dairy calves. Calves on 2 units were vaccinated when they were 2 to 3 days old and 2 weeks later with the J5 antigen or they were left unvaccinated, and were observed during the first 60 days of age for morbidity and mortality. Events recorded were death, the first case of illness, the first sign of a respiratory tract condition, the first sign of diarrhea, and the first treatment. The time to death or to a morbid event was examined as a function of vaccination status, using the Cox model of survival analysis, where serum IgG concentration at 2 to 3 days of age and gender of the calf were included to control confounding. Signs of morbidity in 517 calves were followed, 189 from unit 1 and 328 from unit 2. Vaccination was associated with a 2.15-fold reduction in risk of death on unit 2 (P = 0.042), but with a 2.43-fold increase in risk of death on unit 1 (P = 0.0035). The only association found between vaccination and morbidity was a 1.34-fold reduction in risk of respiratory tract signs for vaccinated calves on unit 2 (P = 0.055). Necropsy results and clinical investigations indicated that calves on unit 1 were poorly nourished and emaciated. Antibodies to J5 2 weeks after vaccination were significantly (P = 0.0002) lower in calves on unit 1 than in calves on unit 2. The findings offered a possible explanation for the adverse vaccination effect in calves on unit 1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Antimicrobial drug use and related management practices among Ontario swine producers

A mail survey of swine producers in Ontario was undertaken during 1991 to describe the types, frequency, and motives for antimicrobial use. Two hundred operations that marketed fewer than 350 hogs per year, and 800 that marketed more than 350 per year were sent questionnaires, 63% of which were completed and returned. Most operations (86%) added antimicrobials to starter (weanling pig) rations, while fewer (29%) added these drugs to finisher pig rations. The most commonly used antimicrobials were tylosin, carbadox, and furazolidone in weanling pigs, and tylosin, lincomycin, and tetracycline in finishers. Water medication of grower-finisher pigs was practised on 25% of farms; 80% of farms had injected at least some grower-finisher pigs with antimicrobials in the 12 mo preceding the survey. Approximately 20% of operations that added antimicrobials to finisher rations did so for growth promotion purposes only, while others used them for disease treatment, prevention, control, or a combination of reasons. Among those not using antimicrobials in finisher rations, 83% did not believe they were necessary and 37% were concerned about the potential for residues in marketed hogs.     

Epidemiological aspects and financial impact of lumpy skin disease in Ethiopia

The financial cost of clinical Lumpy Skin Disease (LSD) and the financial benefit of its control through vaccination were studied based on questionnaire survey in Oromia region of Ethiopia from the perspective of livestock farmers. Production loss impacts for local zebu cattle were compared with those of Holstein Friesian (HF)/crossbred cattle in the study area. Annual cumulative incidence of LSD infection in HF/crossbred and local zebu cattle were 33.93% (95% CI: 30.92-36.94) and 13.41% (95% CI: 12.6-14.25) respectively and significantly different (p<0.05). Annual mortality was also significantly higher in HF/crossbred 7.43% (95% CI: 5.76-9.10) than in local zebu cattle 1.25% (95% CI: 0.98-1.52). The annual financial cost was calculated as the sum of the average production losses due to morbidity and mortality arising from milk loss, beef loss, traction power loss, and treatment and vaccination costs at the herd level. The financial cost in infected herds was estimated to be USD 6.43 (5.12-8) per head for local zebu and USD 58 (42-73) per head for HF/crossbred cattle. A partial budget analysis was used to estimate the financial benefit of an annual vaccination program in both the local zebu and HF/crossbred cattle farming systems. The marginal rate of return (MRR) gained from this control intervention was estimated to be 34 (3400%) and the net benefit per head was USD 1 for local zebu and USD 19 for HF/crossbred cattle. Vaccination thus enabled financial costs due to LSD to be reduced by 17% per head in local zebu herds and 31% per head in HF/crossbred herds. These results could provide guidance to producers and the government in their endeavors to control the disease.     

Rinderpest vaccination responses among calves and adult cattle in Uganda monitored using ELISA assay

Responses to the Plowright Rinderpest vaccine by 43 calves and 70 adult cattle in Uganda in 1990, through the production of IgG antibodies, were monitored for 4 weeks using the ELISA assay. 80% of the calves were seronegative before vaccination of which 32% remained seronegative and 68% subsequently seroconverted at 2 weeks postvaccination. 20% of the calves were seropositive before vaccination but registered a decline during the 2nd and 4th weeks postvaccination. 50% of adult Ankole cattle seroconverted after 3 weeks postvaccination, while the other 50% of them, which were seropositive before vaccination, showed a decline in seronegative levels during the first 2 weeks postvaccination, but increased again at the 4th week. 90% of Friesian adult cattle were seronegative before vaccination; however, they all seroconverted within the 2nd week of postvaccination. The other 10% remained seropositive, with a slight decline of antibody levels during the 4 weeks after vaccination.     

Associations among antimicrobial drug treatments and antimicrobial resistance of fecal Escherichia coli of swine on 34 farrow-to-finish farms in Ontario, Canada

Logistic regression was used to model associations between antimicrobial treatment and resistance among fecal Escherichia coli of finisher pigs at the farm level. Four sets of potential risk factors representing different levels of refinement of antimicrobial use on farms were modelled on resistance to antimicrobials. Final models for each antimicrobial were constructed from treatment and management variables significant on initial screening, and corrections for overdispersion were made. In general, in-feed antimicrobial treatment of pigs was more consistently associated with an increased risk of resistance than individual-animal treatment. Antimicrobial treatment in starter rations was significant in final models of resistance to ampicillin, carbadox, nitrofurantoin, sulfisoxizole, and tetracycline. Treatment in grower–finisher rations was significantly associated with resistance to ampicillin, spectinomycin, sulfisoxizole, and tetracycline. There was little evidence that in-feed antimicrobials increased the risk of resistance to gentamicin, which is a drug used only for individual-pig treatment in this study population. These results suggest that antimicrobial medication of rations of post-weaning pigs selects for and maintains antimicrobial resistance among E. coli of finisher pigs. Although resistance was common on farms that did not medicate rations of post-weaning pigs, the results indicate that antimicrobial use does increase the risk of resistance to the antimicrobials studied.     

The effect of foot-and-mouth disease (FMD) vaccination on virus transmission and the significance for the field

Vaccination against foot-and-mouth disease (FMD) might be one of the control measures used during an FMD epidemic depending on the local epidemiological situation, the status of the country, and the opinion of policy makers. A sound decision on vaccination can be made only if there is sufficient scientific knowledge on the effectiveness of vaccination in eliminating the virus from the population. An important question is whether a single vaccination applied as an emergency vaccine can contribute to the control of an epidemic. This paper presents the results of transmission experiments on vaccine efficacy in groups of cattle, pigs, and sheep and concludes that vaccination seemed to be effective in cattle and sheep, but was less effective in pigs. The possible implications for application to field conditions are discussed.     

An evaluation of the anamnestic test for brucellosis in cattle of the northern pastoral area

SUMMARY An investigation of the anamnestic test for brucellosis using Brucella abortus 45/20 vaccine was carried out in 3 groups of weaner cattle on 2 farms in western Queensland. Each group originally consisted of about 500 cattle. They were bled before and at 6 or 10 weeks after vaccination and again in the following year. The serums were tested by the complement fixation (CFT), Rose Bengal (RBT) and indirect haemolysis tests (IHLT). Most of the cattle reacting to one or more of the tests were killed and selected tissues were subjected to bacteriological examination for B. abortus. B. abortus was isolated from 19 of 30 (63%) pre-vaccinal reactors, 23 (24%) of 96 cattle reacting at 6 or 10 weeks after vaccination (the anamnestic test) and 1 (2%) of 50 cattle reacting one year after vaccination. The reactor found to be infected the year after vaccination had high serological titres in each of the 3 serological tests: RBT of 3, CFT of 128 and IHLT of 256. A subsequent test showed the group to be brucellosis-free. The CFT was the most efficient test. In the pre-vaccination tests 17 of 19 infected animals were positive in the CFT compared with 11 positive in the IHLT and 17 in the RBT. In post vaccination tests 22 of 23 infected animals were positive in the CFT compared with 18 in the IHLT and 19 in the RBT. At the pre-vaccinal and anamnestic tests (6 or 10 weeks after vaccination) 19 of 57 (33%) cattle with CF titre of 4 or 8 yielded B. abortus on culture compared with none of 26 cattle with similar titres in the year after vaccination. The interpretation of CF titres in cattle following 45/20 vaccination needs to be re-examined.     

A mail survey of factors associated with morbidity and mortality in feedlot calves in southwestern Ontario.

The design and results of a mail survey of a simple random sample of southwestern Ontario feedlot owners are presented. The survey provided general data about management of feedlot calves and the association between a number of factors and disease and/or death rates. The number of calves purchased was related positively, in a linear manner, to mortality and morbidity rates. Increased levels of morbidity and mortality were noted when the ration was changed to corn silage from dry-hay within the first month after arrival. However, it was not clear whether the ration changes preceded or followed increased rates of morbidity and mortality. Prophylactic levels of antimicrobials in the water supply were associated with increased death losses. Shipping cattle by truck, rather than train, was associated with decreased rates of disease. Processing factors, including using vaccines against respiratory disease, were not associated significantly with mortality or morbidity. It was concluded that reducing the number of calves, to approximately 100 per group, not changing the ration to silage within the first month and not using antibiotics in the water supply on arrival could significantly reduce disease and death losses.     

The epidemiology of bovine respiratory disease: What is the evidence for preventive measures?

Bovine respiratory disease (BRD) is the most common and costly disease of beef cattle in North America. Despite extensive research, industry practices are often more informed by dogma than by fact. Frequently advocated interventions, including vaccination, various processing procedures, and nutritional manipulation, have limited impact on morbidity and mortality. Evidence for use of oral antimicrobials, either in feed or water, appears to be equivocal. In contrast, preconditioning and metaphylaxis have significant scientific evidence of efficacy, with weaning prior to sale potentially being the most important component of preconditioning. The inability to reach more definitive conclusions in preventing BRD may be attributable to difficulties in investigating the disease. Study challenges include potential for extensive confounding, tremendous variability, the multi-factorial nature of the disease, and inadequate methods for diagnosis.     

Evaluation of tickGARD(PLUS), a novel vaccine against Boophilus microplus, in lactating Holstein-Friesian cows

The effects of vaccination with the Bm 86 vaccine TickGARD(PLUS) against infestation with cattle tick (Boophilus microplus) and of holding cattle on a feedpad until 09:00 hours after the morning milking was tested on 40 mid lactation Holstein cattle using a factorial design. Vaccination resulted in a 56% reduction in tick numbers in the field over one generation, and a 72% reduction in laboratory measures of the reproductive efficiency of ticks. The liveweight gain of vaccinated cattle over 27 weeks was 18.6 kg higher than that of controls, and vaccinated cattle tended to have lower somatic cell count in milk (SCC). There were no other significant differences in measures of production. Cattle kept on the feedpad after the morning milking carried 26% more ticks than those returned immediately to their paddocks.     

Vaccination against the avian infectious bronchitis virus affects sperm concentration, sperm quality and blood testosterone concentrations in cockerels

1. It was previously found that cockerels vaccinated with live attenuated avian infectious bronchitis virus (AIBV) have decreased serum testosterone concentrations, epididymal stones and reduced fertility. The objectives of this study were twofold: to determine if reduced fertility following vaccination with live attenuated virus was the result of reduced sperm concentration or reduced sperm quality and to determine if vaccination with a killed strain of virus caused a similar reduction in sperm function in vivo. 2. Specific-pathogen-free Single Comb White Leghorn cockerels were divided into three treatment groups: no vaccination (NONVAC), vaccination with killed AIBV virus (KVAC) or vaccination with live attenuated AIBV virus (LVAC). Semen was collected daily from 17 to 27 weeks of age, and semen quality was assessed frequently by analysing sperm concentration, viability, motility, and ability to reach and interact with the ovum in vivo. Blood plasma was assayed for testosterone concentration. 3. Differences in sperm analysis among treatment groups were limited. Sperm viability was increased in NONVAC during week 20 which then decreased in week 22 when compared to vaccinated cockerels. Acrosome damage was increased in vaccinated cockerels in week 22, and decreased in weeks 25 and 27 when compared to controls, which correlate to the period of epididymal stone development. Plasma testosterone concentrations and sperm concentrations among treatment groups were different only at 16 and 19 weeks of age, respectively. There were no differences across treatment groups in sperm mobility through Accudenz or in numbers of sperm holes in perivitelline membranes of eggs following insemination with semen from 27-week-old cockerels. No differences were observed in viability or acrosome integrity between cockerels with and without epididymal stones within treatment groups. 4. In conclusion, pre-pubertal vaccination against AIBV and subsequent epididymal stone formation had a limited effect on sperm concentration, sperm quality and plasma testosterone concentrations. Vaccination with killed AIBV vaccine did not diminish effects on sperm function in vivo.     

Vaccination: Is it Effective in Preventing Respiratory Disease or Influencing Weight Gains in Feedlot Calves?

Respiratory disease, both undifferentiated and etiologically defined, remains a major problem in feedlot cattle. Vaccination has been used in an attempt to reduce the frequency and/or severity of respiratory disease in the first few weeks after the cattle arrive at the feedlot.

The efficacy of vaccination has been studied both in controlled laboratory experiments and field trials as well as observational studies. (In this review, efficacy refers to the ability to reduce overall treatment rate and/or increase weight gains.) This review summarizes the data resulting from studies of vaccine efficacy.

In general, there is little published data to support the use of vaccines against respiratory disease under feedlot conditions. Treatment rates and weight gains usually did not differ between vaccinated and nonvaccinated groups. The use of live bovine virus diarrhea virus vaccines was associated with a significant subsequent increase in treatment rates. Criteria to be considered in future field trials are described.

     

Comparison of vaccination and treatment in controlling naturally occurring infectious bovine keratoconjunctivitis.

A vaccination study for infectious bovine keratoconjunctivitis was conducted on 108 newborn Hereford calves in the US Department of Agriculture Meat Animal Research Center cattle herd at Clay Center, Nebraska. Groups were allocated so that age of calf, sex of calf, and age of dam were equally distributed between the 54 vaccinated (group I) and the 54 nonvaccinated (group 2) control calves. The dams of both groups of calves were monitored as group 3 controls. An autogenous Moraxella bovis bacterin (formalin-killed, whole cells) was given IM at birth and at approximate intervals of 2 weeks for a total of 3 doses. Bacterial isolation rates for the cattle in groups 1, 2, and 3 during the summer were 92.6%, 92.6%, and 54.1%, respectively, and disease rates were 100%, 96.3%, and 70.6%. The rates were significantly (P less than 0.05) different between calves and cows. Vaccination of calves at birth permitted serum antibodies to develop before the calves were extensively exposed to infection; however, immunity to the disease did not develop. In a treatment study of other animals in the same herd, but in another pasture, the same criteria were used for allocation of 107 cow-calf pairs. Eye spray was applied to treated principals (group 4, 52 calves; and group 6, 53 cows) each week after examination and sample collection. Controls consisted of 54 calves (group 5) and 54 cows (group 7) that were examined and cultured bacteriologically in the same manner. The bacterial isolation and disease rates were less (P less than 0.05) in the treated calves (group 4) than in the nontreated controls (group 5). The differences in bacterial isolation rates between groups 6 and 7 were not significant, but group 6 had less (P less than 0.05) grade III lesions than did group 7. Weekly treatment appeared to be more effective in reducing the incidence of disease than did vaccination.