Vaccination of cattle against Rhipicephalus appendiculatus with detergent solubilized tick tissue proteins and purified 20 kDa protein

Three groups of 4 cattle have been vaccinated with either detergent solubilized tick tissue proteins (SMP) of male and female Rhipicephalus appendiculatus, a 20 kDa soluble integumental antigen, a mixture of both SMP and 20 kDa. Two weeks after one booster injection all cattle were challenged by infestation with adult ticks. Treatment had no influence on tick attachment but on cattle vaccinated by the 20 kDa 32.5% fed ticks died (p < 0.001). Moreover, the mean weight of ticks fed on 7 out of 12 vaccinated cattle was significantly lower (p < 0.05 to p < 0.001). Individual differences could be seen where the mean weight reduction was up to 30%. Moreover, ticks fed on 1 (group SMP) or 2 cattle (group 20 kDa) had some difficulties in converting their blood meal into eggs (p < 0.05 to p < 0.001).

Effect of monensin and supplemental hay on ruminal 3-methylindole formation in adult cows after abrupt change to lush pasture

The effect of feeding monensin, with or without dry hay plus wilted forage, on ruminal formation of 3-methylindole (3MI) was investigated in pastured cattle. Eighty-two cows were allotted to 3 groups. Cows of group-1 served as controls and were given a daily energy supplement (1 kg/head) without monensin for 1 day before and for 7 days after being allowed access to lush pasture. Cows of groups 2 and 3 were given the same daily energy supplement, which also contained monensin (200 mg/kg of supplement). Cows of group 3 also were fed dry hay for 5 days before the start of the study and continued to be given supplemental hay for 4 days after being allowed access to lush pasture containing a layer of wilted forage. Ruminal 3MI and indole concentrations increased on day 1 after all groups were allowed access to lush pasture. By day 7, 3MI concentration in all cows had decreased to pregrazing concentration. Indole concentration did not reach pregrazing concentration until day 10 for cows of groups 1 and 2. Group-3 cows had pregrazing indole concentration on day 7. Ruminal indole concentration did not differ (P greater than 0.05) between groups 1 and 2. Ruminal indole concentration was lower (P less than 0.01) in group-3 cows on all sample collection days, except day 10, compared with that in the other groups. Monensin reduced (P less than 0.01) 3MI formation on days 1 and 7 in group-2 cows, compared with group-1 cows. Group-3 cows had lower 3MI concentration than did group-1 cows (P less than 0.01) on days -1, 1, 4, and 7.(ABSTRACT TRUNCATED AT 250 WORDS)

An inactivated vaccine against ringworm

A new vaccine against ringworm, containing the inactivated Trichophyton verrucosum strain, was assessed on guinea pigs and calves under experimental conditions and on three herds of cattle under natural conditions. The vaccine elicited a distinct immune response of the cellular type. This type of immunity assessed by the migration inhibition test of leukocytes corresponded to the immunity evaluated by the challenge. In herds in which there were from 30 to 67% of naturally infected animals with T. verrucosum, two doses of the vaccine resulted in after 4 weeks a decrease of the number of animals with clinical changes from 40.5 to 100% depending on the group of animals under study.

Prevalence and control of Babesiosis in the Americas

This review presents up-to-date information on the distribution and control measures of babesiosis in Latin America. Bovine babesiosis caused by Babesia bovis and B. bigemia will be emphasized. The disease is endemic in most countries and poses a serious economic burden on livestock production in the region (U.S. $1365 million/year, FAO, 1989). Of the estimated 250 million cattle in Central and South America, approximately 175 million (70%) are in tick-infested regions. Humid, tropical and subtropical areas favor development of the main vector, the one-host tick Boophilus microplus. In many regions bovine babesiosis is enzootically stable as a consequence of a balanced host-parasite relationship. However, Latin America offers a wide range of epidemiologic conditions that are influenced by variations from tropical to cool climates and by susceptible purebred cattle that are regularly imported to upgrade local stocks. The control measures employed in most countries for babesiosis essentially rely on chemotherapy, use of acaricides for B. microplus, and to a lesser degree, on immunization methods. In general, these measures are expensive, time consuming, and in many cases, provide limited success. Finally, the zoonotic potential of babesiosis will be addressed, with special emphasis on the situation in the United States. Even though bovine babesiosis has long been eradicated from the U.S.A., human babesiosis is endemic in the northeastern region of the country.

Field evaluation of an exoantigen-containing Babesia vaccine in Venezuela

Bovine babesiosis is endemic in Venezuela, causing significant losses in highly susceptible imported cattle. Current immunoprophylactic methods include the less desirable use of live parasites. Inactivated vaccines derived from exoantigen-containing supernatant fluids of in vitro Babesia bovis and B. bigemina cultures have been developed and constitute a major improvement in vaccine safety, stability and ease of handling. Vaccination trials conducted under field conditions provide the final evaluation of a culture-derived B. bovis-B. bigemina vaccine. During a 5-year period, approximately 8,000 cattle were vaccinated and 16 clinical trials carried out in 7 states of Venezuela. Clinical, serologic and parasitologic data were collected monthly from 10% of the animals over a 2-year period. Data were also collected from a similar number of nonvaccinated control cattle. Analysis of results from these trials demonstrated a reduction in the incidence of clinical disease among vaccinated animals and complete protection against mortality caused by babesiosis. Vaccine efficacy was measured calculating the incidence rates of disease and mortality among vaccinated and nonvaccinated cattle. Use of this inactivated vaccine offers the best combination of safety, potency and efficacy for the effective immunoprophylactic control of bovine babesiosis.

Impact of Babesia bovis and Babesia bigemina on the production of beef cattle in Uruguay

Uruguay is situated in a marginal area for the development of Boophilus microplus (30 degrees 35 degrees South Lat.) with important areas of enzootic instability for Babesia bovis and B. bigemina. The livestock products represent 70% of our exports, for which reason it is fundamental to evaluate the losses in the production that these haemoparasites cause as basic information to take future decisions. In the period 1988-1990, several works were carried out by our laboratory to know the incidence of babesiosis in the reduction of liveweight gains. The results are shown and discussed in the work. Experiment I: the weight increase of the control group (x = 0.248 kg/day), was 23% higher than that of the infected group with Babesia spp (from Uruguay), but significant statistical differences were not found (P < 0.05). These animals were kept in boxes and the food was controlled for 76 days. Experiment II: the incidence of Babesia spp (same strain) was studied for 140 days on Hereford heifers (n = 14) on natural pastures. The control group obtained x = 25.29 kg of liveweight gain and it was 45% higher than that of the infected group, significant statistical difference were found (P < 0.05). Experiments with attenuated strains III: four studies were carried out inoculating B. bovis and B. bigemina in bovines about one year old, in different growth systems, searching for the limit of application. Significant statistical differences between those groups were not found during the experiment (about 180 days) (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anaplasma marginale: failure of sera from immune cattle to confer protection in passive-transfer experiments

High levels of immunity to Anaplasma marginale were induced in cattle either by vaccination using sonically disrupted A. marginale-infected erythrocytes or by repeated infection with different strains of the rickettsia. In both instances, high levels of anti-A. marginale antibody were detected in the sera of the immune cattle by immunoblotting. Serum from one animal that had been made immune by repeated infection was transferred intravenously to A. marginale-susceptible calves (three non-splenectomised and two splenectomised) undergoing initial A. marginale infection at serum doses of 2-10 ml/kg. Neither the course nor the outcome of infection as indicated by the parasite levels attained or the level of anaemia induced was altered in the calves that received the immune serum relative to the course or outcome of infection in control calves (two non-splenectomised and two splenectomised) that received serum from an two splenectomised) that received serum from an A. marginale-naive donor animal. In a similar experiment, a pool of sera from four steers that had been vaccinated with sonically disrupted A. marginale initial bodies was transfused into two intact A. marginale-susceptible calves during the early stage of A. marginale infection at a dose of 10 ml/kg. No difference was observed in the course or outcome of infection in these calves relative to the course or outcome of infection in the two non-splenectomised calves that were transfused with non-immune serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined vaccination of cattle against FMD and rabies

Three groups of crossbred calves were vaccinated with FMD vaccine only, combined FMD + rabies vaccine and rabies vaccine alone. Efficacy of the vaccines was determined by serum antibody assay at different intervals postvaccination. The results of the study indicated that the immune response of animals to a single inoculation of FMD vaccine only as well as combined FMD + rabies vaccine was unsatisfactory due to maternally derived antibodies to FMD virus antigen. However two inoculations elicited a satisfactory antibody response to FMD virus antigens in both group of animals. Rabies antigen alone as well as combined FMD + rabies antigen induced satisfactory serum antibody titres to rabies antigen. There was no significantly different serological responses in animal administered FMD vaccine only, rabies vaccine only or combined FMD + rabies vaccine.

Condensed tannins in some forage legumes: their role in the prevention of ruminant pasture bloat

For the past 20 years, the focus in our laboratory has been on finding the causes of ruminant pasture bloat and eventually breeding a bloat-safe alfalfa (Medicago sativa L.); i.e., with bloat potential reduced to the economic threshold. In the mid-seventies, the mechanisms of bloat were explored and found to be more physical than chemical. Characteristic of all bloating legumes after ingestion was a very rapid initial rate of ingestion by rumen microbes. Through the study of bloating and non-bloating legumes, factors were elucidated in the plant that would slow this process. One of these factors was the presence of condensed tannins in the herbage. Some of the non-bloating legumes contained these secondary metabolites, but no condensed tannins were found in any of the bloating legumes. Therefore, species containing an appreciable amount of condensed tannins in their leaves and stems are considered to be non-bloating. Conventional breeding methods have not been successful in producing an alfalfa with condensed tannins in its herbage. New approaches using tissue culture techniques are being attempted, but genetic engineering has the greatest potential for success.

Babesia divergens vaccine

A vaccine strategy against Babesia divergens bovine babesiosis was successfully developed after perfecting of an efficient in vitro culture. Crude supernatants and purified fractions were able to induce a vaccine protection in gerbils against B. divergens infection. More, supernatants induced an effective vaccine protection in cattle. The role of B. divergens exoantigens of 17, 37, 46, 70 and 90 kDa in the development of the immune response was clearly demonstrated in gerbils, cattle, and man.

Successful vaccination against Boophilus microplus and Babesia bovis using recombinat antigens

Current methods for the control of the cattle tick Boophilus microplus and the agent of bovine babesiosis, Babesia bovis are unsatisfactory. Effective immunological control of both parasites would have great advantages. However, naturally acquired immunity to the tick is generally unable to prevent serious production losses. A vaccine against the tick, based on a novel form of immunization, is being developed. A protective antigen has been isolated from the tick, characterized and produced as an effective, recombinant protein. A vaccine incorporating this antigen is currently undergoing field trials. In the Australian situation, improved tick control will probably increase endemic instability with respect to B. bovis. Fortunately, a trivalent, recombinant B. bovis vaccine has also been developed. This too is now undergoing pre-registration field trials.

Enhancement of the immune response by intradermal vaccination in cattle with enterotoxigenic Escherichia coli (ETEC) vaccine without adjuvant

A comparison was made of the efficiency of intradermal and subcutaneous routes of vaccination in immunizing cattle with a killed vaccine of Escherichia coli K99+. In this study 135 heifers aged 8-18 months were included. The effect of the number of intradermal injection sites was examined, as well as the optimal time interval between the initial and booster intradermal vaccination. The intradermal route was found to be significantly superior to the subcutaneous route. The optimal time for intradermal booster was approximately 2 weeks. Increasing the number of intradermal injection sites up to 50 (using the same amount of antigen) did not result in an enhancement of the antibody level.

Effects of zinc methionine and zinc oxide on performance, blood characteristics, and antibody titer response to viral vaccination in stressed feeder calves

Ninety steers with an average weight of 214 kg were purchased at 2 feeder calf sales and transported 70 to 100 km. On arrival at the feedlot, steers were weighed and identified, blood was withdrawn, and the steers were vaccinated against bovine herpesvirus-1 (BHV-1) and parainfluenza3 (PI3), using a modified live vaccine, and randomly assigned to treatment groups. Treatments were: control (no supplemental zinc; zinc methionine; and zinc oxide. The control diet contained 26 mg of zinc/kg diet, and zinc was added in treatments 2 and 3 to provide 25 mg of supplemental zinc/kg diet. Neutralizing antibody titers were determined on serum samples taken on days 0 and 14 as a measure of the immune response to BHV-1 and PI3 vaccination. Weight gains for the 28-day study were similar across treatments. Dry matter intake tended to be higher in steers fed supplemental zinc from either source, because steers fed zinc methionine and zinc oxide consumed 5.2 and 4.4% more feed, respectively, than controls. Antibody titers against BHV-1 tended to be higher in steers supplemented with zinc methionine on day 14. Differences between treatments were not found for PI3 titers. Mortalities did not occur and morbidity rate was low.

Genetic, phenotypic, and environmental parameter estimates of calving difficulty, weight, and measures of pelvic size in beef heifers

The heritabilities for and the genetic, phenotypic, and environmental correlations among calving difficulty scores (CDS) and measures of size of the pelvic inlet were estimated using 547 records of 2-yr-old heifers from three synthetic breed groups. Calving difficulty score was treated first as a trait of the dam and then as a trait of the calf and was analyzed on three scales: raw scores from 0 to 3 (0 = normal birth, 3 = most difficult delivery requiring a hard pull, veterinary assistance, or surgical intervention), Snell-transformed scores, and a binary (0, 1) scale. Estimates of heritability for CDS as a trait of the dam were similar to those when it was considered a trait of the calf. Heritability estimates for CDS on the raw and transformed scales were similar and moderate in magnitude (.36 +/- .15 to .47 +/- .18) but were higher than most reported estimates. However, on the binary scale the estimates were lower (.26 +/- .17, .28 +/- .14). Estimates of heritability for the horizontal and vertical pelvic diameters and the pelvic area were high, implying that pelvic size in heifers might be readily modified by selection. The genetic and phenotypic correlations between CDS as a dam trait and pelvic dimensions were low, whereas the correlations between CDS and dam weight at calving were moderate. As a calf trait, CDS was highly correlated genetically with calf birth weight, but the phenotypic correlations were moderate.

Protective vaccination against bovine leukaemia virus infection by means of cell-derived vaccine

Tests were performed to determine whether live mammalian cells producing env gene glycoproteins and main structural protein p24 of bovine leukaemia virus (BLV), heterologous to bovine species, could serve as an immunogen in cattle to prevent induction of bovine leukaemia. Ovine virus-non-producing clonal cells NP-2 were used as the immunogen. The NP-2 cells synthesized only the env gene products--glycoprotein gp51 and gp30 and main structural protein p24 of BLV. The NP-2 cells, inoculated into rats, induced an antibody response directed against envelope glycoproteins of BLV. The antibodies neutralized the infectivity of BLV as determined by the VSV/BLV pseudotype neutralization test. Similar results were obtained by vaccination of cattle with these cells. A dose of less than or equal to 2 x 10(6) live cells inoculated subcutaneously induced an antibody response in cattle, while a high dose of killed cells was ineffective. The antibodies in cattle were directed against env products of BLV. A group of 92 cows was vaccinated and followed up for 4 years. The antibody levels fluctuated slightly during the 4-year observation period, generally decreasing with time, but revaccination always increased the antibody titre. No transfer of seropositivity was observed to seronegative animals which were kept in contact with vaccinated ones. In a separate experiment a group of young heifers, after repeated vaccination, were challenged with a high dose of infectious virus and/or virus-producing cells. The response to BLV infection was followed by syncytial induction assay after co-cultivation of white blood cells with indicator cells CC81.(ABSTRACT TRUNCATED AT 250 WORDS)

Problem of fascioliasis in animal husbandry in Thailand

One of the most important parasitic diseases in adult cattle and buffalo in Thailand is fascioliasis, caused mainly by Fasciola gigantica. The economic loss from fascioliasis in cattle and buffalo throughout Thailand has been assessed at not less than 100 million Baht. Recent investigations have been shown that the average prevalence of F. gigantica in cattle and buffalo in Thailand was 11.8%. However, the prevalence varies considerably between villages, ranging from 0 to 85%. The prevalence is high in areas surrounding dams or large ponds in which Lymnaea auricularia rubiginosa, the intermediate host of F. gigantica is found. An epidemiological study revealed that the disease has a seasonal pattern from which the following conclusion for control of the disease can be drawn. Strategic liver fluke treatment of all cattle and buffalo which are older than 8 months should be carried out once a year in September. In addition, animals in poor condition should be treated in April to prevent severe losses, especially in high prevalence areas or where strategic treatment was missed. Problems of liver fluke control include the lack of knowledge about the parasite on the part of the farmers and the lack of availability of drug supplies at the village level, both of which are important to allow strategic treatment of animals. To approach these problems, the government had developed "Farmer Self-Help Worm Control Program" in seven provinces in Northeast Thailand which is operated by village farmers trained as program "keymen". This program is very effective and will be extended throughout Thailand in the next Seventh Social and Economic Development Plan.

Application of interferons in the control of infectious diseases of cattle

Recovery from infection involves a number of complex interactions between specific cells of the immune system. Many of these interactions are mediated by cytokines, which can activate these cells to kill or reduce the replication rate of the pathogen. Availability of large quantities of recombinant cytokines has provided the opportunity to investigate the mechanism or mechanisms of action of each cytokine in vitro and in vivo. In the present review, we describe the application of interferons to reduce morbidity and mortality of cattle suffering from bovine respiratory disease and mastitis. The potential application of interferons in disease modulation as well as the impediments to their use are discussed.

Suppressing immature house and stable flies in outdoor calf hutches with sand, gravel, and sawdust bedding

Sand, gravel, sawdust, and pine shavings were used as bedding in outdoor calf hutches and compared with straw relative to the density of immature (maggot) house flies, Musca domestica, and stable flies, Stomoxys calcitrans. In 6-wk field trials, average densities of house and stable fly maggots in concrete mix sand ranged from only .3 to 1.6 and 0 to .1 maggots/L, respectively; pea size gravel bedding also strongly suppressed densities from less than .1 to .3 and less than .1 to .1 maggots/L, respectively. These densities represent reductions of 76 to greater than 99% relative to straw bedding, but both sand and gravel compacted and became soiled with calf feces, which resulted in unacceptable bedding sanitation and foul odors. Densities of house and stable fly maggots in pine shavings did not differ from those in straw bedding. Nevertheless, in sawdust bedding, maggot density was limited to averages of 1.4 to 8.3 house and 9.8 to 11.8 stable fly maggots/L; this represented reductions of 45 to 91% relative to straw. In a follow-up trial, house and stable fly maggot densities in sawdust averaged 11.3 and 43.9 maggots/L, respectively, reductions of 77 and 46%. These findings suggest that bedding calf hutches with sawdust during warm weather can be useful as an ecologically sound approach to controlling muscoid fly populations on dairy farms.

Vaccination with 'concealed' antigens: myth or reality?

Cattle infested with the tick Boophilus microplus produce antibodies to intrinsic membrane glycoproteins of the tick, as well as to Bm86, a well characterized antigen from the tick gut. Several factors explain how cattle could produce antibody to such antigens, which one would expect to be 'concealed' from the host's immune system, during natural infestation. It has been shown that the carbohydrate determinants on many tick glycoproteins are cross-reactive immunologically and that the reaction of bovine antibodies with intrinsic membrane glycoprotein is at least partially blocked by low molecular weight carbohydrate. Further, antisera from cattle exposed to ticks react with a glycosylated, native Bm86 but not with a non-glycosylated, recombinant Bm86. Thus the reaction of concealed antigens with antibodies produced as a result of tick infestation appears to be due to a relatively non-specific reaction with carbohydrate determinants on tick glycoprotein. Evidence is also presented that antibodies directed against carbohydrate determinants of Bm86 are not protective. Care must therefore be exercised in interpreting the results of antibody reaction with glycoproteins in such complex organisms.

Immune responses of cattle to biochemically modified antigens from the midgut of the cattle tick, Boophilus microplus

Treatment of membrane antigens of the midgut (GM) of the cattle tick, Boophilus microplus with sodium metaperiodate (periodate), pronase and lipase significantly inhibited the reactivity of the GM with antibodies in the sera of 57 cattle vaccinated with GM. Treatment of GM with periodate only removed the correlation between antibody reactivity of sera and protection against infestation with ticks. A monoclonal antibody (MoAb QU13), which recognises protective antigens solubilized from GM (Lee + Opdebeeck 1991), did not react with GM treated with periodate. Cattle vaccinated with GM extracts were significantly protected against infestation with cattle ticks (P less than 0.05), whereas cattle vaccinated with either GM extracts treated with periodate or with antigens precipitated from GM extracts with MoAb QU13 and also treated with periodate, were not protected against infestation. These studies provide preliminary evidence that protective antigens in the tick midgut membrane either are carbohydrate or are dependent on carbohydrate for their specificity.

Problems and practice in mass medication of beef cattle

Mass medication is a health management tool that, when used appropriately, results in cost savings and sound economic return to the food animal producer. Careful planning and consideration should precede the implementation of a mass treatment program, clearly defining the goal to be achieved and a detailed plan of execution. For economic as well as professional reasons, indiscriminate administration of antimicrobials to large groups of food animals should be avoided.

Addition of chloride to a prepartal diet high in cations increases 1,25-dihydroxyvitamin D response to hypocalcemia preventing milk fever

In this study, we present evidence that cows fed highly cationic diets are less responsive to parathyroid hormone than those fed a highly anionic diet. Forty-seven Jersey cows (55 mo of age) were fed an alfalfa haylage-based diet supplemented with either anions (Cl-) or cations (Na+). Cows fed the high cationic diet suffered significantly more cases of milk fever (6 out of 23) than those fed the high anionic diet (1 out of 24). Concentrations of Ca at parturition and the first 2 d of lactation were significantly higher in cows fed the anionic diet. Secretion of parathyroid hormone in response to developing hypocalcemia was similar in cows fed either diet. Plasma hydroxyproline concentration (an index of bone Ca resorption activity) was greater in cows fed the anionic diet, suggesting better utilization of bone Ca. Plasma 1,25-dihydroxyvitamin D concentration was correlated inversely with plasma Ca and related directly to plasma parathyroid hormone in both groups of cows. However, the magnitude of the response (the amount of 1,25-dihydroxyvitamin D produced per unit increase in parathyroid hormone) was reduced greatly in cows fed the high cation diet. Because parathyroid hormone regulates both bone Ca resorption and renal 1,25-dihydroxyvitamin D production, these data suggest that prepartal diets high in cations decrease the ability of bone and renal tissues to respond to parathyroid hormone. Addition of anions to prepartal diets can reduce the excess cation balance of diets, increasing tissue response to parathyroid hormone and enabling the cow to better adapt to the Ca demands of lactation.

Crossprotective immunity between the Florida and a Zimbabwe stock of Anaplasma marginale

Cattle immunised by infection with the Florida stock of Anaplasma marginale were protected against subsequent homologous challenge, as demonstrated by complete prevention of microscopically detectable parasitaemia. Identically immunised cattle were partially protected against challenge with the Norton, Zimbabwe stock of A. marginale as determined by the significant prolongation of the prepatent period, a significantly lower peak parasitaemia, and a significantly lower percentage drop in haemoglobin concentration when compared to non-immunised calves challenged identically. The partial protection induced by live Florida stock immunisation demonstrates that while protection-inducing epitopes are shared between the two stocks, induction of complete immunity against a Zimbabwe stock may require alternative presentation of Florida stock epitopes or inclusion of additional Zimbabwe stock epitopes in the immunogen.