A reduction in the duration of infection with Tritrichomonas foetus following vaccination in heifers and the failure to demonstrate a curative effect in infected bulls

Seven batches of 25% water-phase, oil-in-water vaccine were prepared from whole cultures of Tritrichomonas foetus. Two inoculations were given, spaced 6 weeks apart, to virgin heifers and infected bulls. A significant reduction (P less than 0.01) in the duration of infection in vaccinated heifers was seen when they were challenged by being bred to a bull infected with the same isolate as that contained in the vaccine. Only 1/12 vaccinated heifers were pregnant 4.5 months after the end of the breeding season compared to 2/12 in the control group. The vaccine, therefore, has no practical advantage. Vaccine was supplied to 2,724 bulls on properties where the infection was present. From these bulls, 110 reliable results were obtained, where bulls had been infected, been inoculated and tested 1 month later. No curative effect was demonstrable with 69/110 (62.7%) bulls, remaining infected after the course of inoculations. There was also no difference between vaccine batches or between bulls of different ages. Further work on improving the vaccine is indicated. Three media suitable for the culture of T. foetus are described in detail.     

Effect of two commercial vaccines to Campylobacter fetus subspecies on heifers naturally challenged

Efficacy of two commercial vaccines containing Campylobacter fetus subspecies on heifers naturally challenged by service with an infected bull was tested. Sixteen heifers were vaccinated parentally two times with 3 weeks as interval, eight with commercial vaccine A and the other eight with commercial vaccine B. Eight other heifers were used as unvaccinated controls. Forty days after the first vaccine dose, the heifers were served by an infected bull during 60 days. Measure of systemic immune response and identification of the microorganism from genital secretions by culture and immunofluorescent antibody test (IFAT) were done. Vaccinated and control heifers had a poor reproductive performance (pregnancy rates were 2/8, 3/8 and 0/8 in groups A, B and C, respectively) and were infected by both methods during breeding time and after it. Moreover, one heifer in the groups B and C remained infected until 300 days post-breeding time. Neither vaccinated nor control heifers had an important increment of systemic antibody level. Only, they had a slight increment of antibody level after the breeding period and it may be because of natural stimulus by the infected bull during the copula. Culture and IFAT yielded high correlation on identification of C. fetus subspecies.     

Measurement of antibody in serum and genital fluids of bulls by ELISA after vaccination and challenge with Tritrichomonas foetus

An enzyme-linked immunosorbent assay (ELISA) was developed for detecting antibody to Tritrichomonas foetus using both whole cell antigen (WCA) and membrane protein antigen (MPA). The test was used to detect specific antibody in serum, preputial washings and seminal plasma samples from 7 adult bulls which were vaccinated subcutaneously on 3 occasions with a membrane protein vaccine against T. foetus var brisbane in an oil adjuvant, and from 4 unvaccinated control animals. One month after administration of the third dose of vaccine, vaccinated and control bulls were repeatedly challenged with the live vaccine strain of the T. foetus. A steady increase in serum antibody titre was detected after each inoculation of vaccine when both antigens were used in the ELISA. However, MPA was more sensitive. After challenge, vaccinated bulls developed an increased titre. No specific antibody was detected in control bulls, except in one bull after challenge in which seroconversion was detected. The serum antibody titres of both groups of animals were also measured with the microagglutination test which proved less sensitive than the ELISA. Antibody titres to both antigens, although lower than in serum, were detected in the seminal plasma of vaccinated animals. The control bulls remained non-responsive. No antibody was detected by ELISA in preputial washings from either control or vaccinated bulls prior to challenge. Post-challenge, some of the vaccinated bulls were responsive with both antigens whereas the control bulls remained negative.     

Active immunization of beef heifers against luteinizing hormone: III. Evaluation of dose and longevity

Objectives were to evaluate the dose (Exp. 1) and purity of LH preparations (Exp. 2) on the anti-LH antibody response in heifers. Experiment 3 evaluated the longevity of LH immunization on sterility in heifers. In Exp. 1, 115 crossbred heifers were injected every 3 wk for 6 wk with .1, .33, 1.0, 3.0 or 9.0 mg of LH-ovalbumin. Concentrations of anti-LH antibodies generated were quantified by determining the percentage of binding of [125I]LH in serum. Mena LH binding over wk 0 to 12 was greater in heifers immunized with 1.0 mg conjugate than in heifers immunized with other doses (P less than .05). In Exp. 2, LH-ovalbumin conjugates were made from either LH-1, LH-2 or LH-3, which had relative immunological potencies of 2.1, 1.5 and 1.2 x NIH-LH-S1 units/mg, respectively. Forty-eight crossbred beef heifers were immunized against one of these three LH-ovalbumin conjugates, against LH conjugated without ovalbumin (LH-LH), or against ovalbumin alone (Oval). Estrous cycle activity was monitored by measuring serum progesterone concentration. Potency of the LH preparation used in the LH-ovalbumin conjugate was correlated (r = .94) with its ability to produce LH antibodies. In Exp.3, heifers were injected with 1 mg antigen every 2 wk for 10 wk. Five LH-1 heifers and five control heifers were slaughtered for examination of ovaries 10 wk after the last booster injection. The remaining five LH-I and five control animals were placed with a bull 8 wk after the last booster. All five control heifers conceived by 4 +/- 1 wk after placement with the bull whereas the LH-immunized heifers remained acyclic for 42 to 96 wk.     

Immune response to Neospora caninum in naturally infected heifers and heifers vaccinated with inactivated antigen during the second trimester of gestation

The objective of this study was to compare the immune response to Neospora caninum in naturally infected heifers and heifers inoculated with a killed whole N. caninum tachyzoite preparation during the second trimester of gestation. Nine Holstein heifers were used in this study; three naturally infected heifers were born from seropositive dams, and six seronegative heifers were born from seronegative dams. Four seronegative heifers were subcutaneously vaccinated with a killed whole N. caninum tachyzoite preparation at weeks 13, 15 and 17 of gestation. A killed whole N. caninum tachyzoite preparation containing 45 mg of protein/5 ml dose was formulated with 70% of mineral oil adjuvant (13% consisting of Arlacel C, 85% Marcol 52 and 2% Tween-80). Similarly, two seronegative heifers (negative controls) were inoculated with mock-infected bovine monocytes in oil adjuvant. Humoral immune responses were tested by using an indirect fluorescent antibody test (IFAT) and an indirect enzyme-linked immunosorbent assay (ELISA) for detecting isotype specific antibodies. Cellular immune responses were assessed by lymphocyte proliferation test (LPT) and IFN-gamma production. N. caninum-specific antibody responses increased in immunized cattle by week 15 of gestation (mean reciprocal antibody titers 450+/-252), peaked at week 23 (mean 16,000+/-6400). Maximum antibody response in naturally infected heifers was observed at week 19 of gestation (mean: 3467+/-2810). Mean serum IFAT titers were significantly higher in immunized heifers compared with those in naturally infected heifers from weeks 17 to 25 (P < 0.05). Analysis of isotype specific antibodies in naturally infected heifers revealed a predominant IgG1 response in one heifer and a predominant IgG2 response in the other two. Similar titers of IgG1 and IgG2 occurred in immunized heifers. Control heifers remained seronegative throughout the study by IFAT and ELISA. Significant antigen-specific proliferation responses were only detected in naturally infected heifers in week 19 of gestation. Peripheral mononuclear blood cells (PMBC) from immunized animals produced IFN-gamma in similar concentrations to those of infected animals (P > 0.05). No abortion was seen in any experimental group; however, one calf from a vaccinated heifer died due to dystocia. All calves from vaccinated and control heifers were seronegative by IFAT at 6 months of age; in contrast, calves born from naturally infected heifers remained seropositive with titers > or = 200. Killed vaccine induced similar immune responses to those found in chronically, naturally infected cattle which did not abort; however, different immune pathways may be followed in vaccinated and natural infected heifers with differences in degree of protective immunity.     

Clinical evaluation of the efficacy of inoculating cattle with a vaccine containing Tritrichomonas foetus.

To test the efficacy of a polyvalent Tritrichomonas foetus vaccine, 130 nulliparous heifers were randomly assigned to either receive the test T foetus vaccine or to serve as nonvaccinated controls. The polyvalent test vaccine consisted of a Campylobacter fetus/Leptospira canicola-grippotyphosa-hardjo-icterohaemorrhagiae-pamona bacterine containing 5 x 10(7) killed T foetus/dose. The polyvalent control vaccine consisted of the aforementioned formulation without T foetus. Heifers were administered 2 doses of control or experimental vaccine at 3-week intervals. Heifers were bred to T foetus-infected bulls and their conception and pregnancy rates were determined throughout gestation. In addition, serum samples were analyzed to determine induced concentrations of antitrichomonal antibodies and vaginal secretions were sampled to determine T foetus infection rates in control and vaccinated animals. One week after each of the 15-day breeding periods, 60% (6 of 10) of tested vaccinates and 80% (8 of 10) of tested control animals were T foetus culture-positive. The mean duration of infection of vaccinates was 3.8 weeks (+/- 7.5 days), compared with 5.4 weeks (+/- 7.5 days) of infection for control heifers. All vaccinates developed increased immunofluorescence and serum neutralizing antibody titers following the first immunization, and had additional increases of at least fourfold in response to the second injection. In contrast, no consistent increase in immunofluorescence or serum neutralizing antibodies was observed in control animals. Conception rates were 89.2% for vaccinates and 85.9% for control animals 30 days after breeding and 80 to 90% of these remained pregnant 60 days after breeding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transmission of bovine virus diarrhoea virus (BVDV) by artificial insemination (AI) with semen from a persistently-infected bull

Twelve heifers that did not have antibodies to bovine virus diarrhoea virus (BVDV) were inseminated with semen from a bull that was persistently infected with the virus and contained 10(4.0)-10(6.5) TCID50 0.1 ml-1. All 12 became infected, as indicated by seroconversion within 2 weeks of insemination. Four control heifers were inseminated with virus-free semen. The virus was not transmitted to these animals in spite of close contact with the heifers inseminated with the infected semen. All the heifers became pregnant and gave birth to clinically normal calves at term. However, one calf was born persistently infected with BVDV. After the birth of this persistently-infected calf the control heifers and their calves seroconverted. The study demonstrates that BVDV may be transmitted in cattle by artificial insemination (AI). Therefore entry of persistently-infected animals into AI centres should be prevented.     

The live attenuated bovine viral diarrhea virus components of a multi-valent vaccine confer protection against fetal infection

Fetal infection with bovine virus diarrhea virus (BVDV) causes severe economic loss and virus spread in cattle. This study investigated the ability of modified live BVDV I and II components of a commercially available modified live virus (MLV) vaccine (Breed-Back FP 10, Boehringer Ingelheim Vetmedica Inc.) to prevent fetal infection and abortion, and therefore the birth of persistently infected animals. Heifers immunized with vaccine 4-8 weeks before insemination showed no adverse effects. All vaccinated animals had seroconverted to BVDV 4 weeks after immunization. Pregnant heifers were divided into two vaccination and two control groups and challenged with type I or II BVDV on days 60-90 of gestation. Seroconversion, clinical signs, immunosuppression, viremia, mortality, abortion rate, and fetal infection were studied. Post-challenge, 6/11 (type I challenged) and 8/11 (type II challenged) vaccinated heifers were free from clinical signs of BVD. Post-challenge clinical signs noted in the vaccinated groups were mild to moderate, while all unvaccinated controls had clinical signs ranging from moderate to severe. Viremia was not detected post-challenge in any of the vaccinated heifers. However, 100% of the controls were BVDV viremic on at least 1 day post-challenge. One of 22 vaccinated heifers had transient leukopenia, whereas 2/8 and 6/7 unvaccinated heifers in control groups I and II, respectively, had transient leukopenia. Type II BVDV infection led to abortion or death in 86% of unvaccinated heifers. The corresponding vaccinated group showed no deaths or abortions. All control group fetuses were infected with BVDV. The test vaccine gave 91% (type I BVDV challenged) and 100% (type II BVDV challenged) protection from fetal infection. This vaccine is safe and effective against fetal infection, abortion (type II BVDV) and the birth of persistently infected animals.     

Prevention of persistent infection in calves by vaccination of dams with noncytopathic type-1 modified-live bovine viral diarrhea virus prior to breeding

OBJECTIVE: To determine the ability of a modified-live virus (MLV) bovine viral diarrhea virus (BVDV) type 1 (BVDV1) vaccine administered to heifers prior to breeding to stimulate protective immunity that would block transmission of virulent heterologous BVDV during gestation, thus preventing persistent infection of a fetus. ANIMAL: 40 crossbred Angus heifers that were 15 to 18 months old and seronegative for BVDV and 36 calves born to those heifers. PROCEDURE: Heifers were randomly assigned to control (n = 13) or vaccinated (27) groups. The control group was administered a multivalent vaccine where-in the BVDV component had been omitted. The vaccinated heifers were administered a single dose of vaccine (IM or SC) containing MLV BVDV1 (WRL strain). All vaccinated and control heifers were maintained in pastures and exposed to BVDV-negative bulls 21 days later. Thirty-five heifers were confirmed pregnant and were challenge exposed at 55 to 100 days of gestation by IV administration of virulent BVDV1 (7443 strain). RESULTS: All control heifers were viremic following challenge exposure, and calves born to control heifers were persistently infected with BVDV. Viremia was not detected in the vaccinated heifers, and 92% of calves born to vaccinated heifers were not persistently infected with BVDV. CONCLUSIONS AND CLINICAL RELEVANCE: These results document that vaccination with BVDV1 strain WRL protects fetuses from infection with heterologous virulent BVDV1.     

Experimental infection with Tritrichomonas suis in heifers.

Nine heifers were intravaginally challenged with 9.3x10(6) Tritrichomonas suis reference strains. Vaginal mucus and serum samples were collected weekly 4 weeks post-inoculation. Vaginal mucus was cultured for T. suis and sera was tested by ELISA against whole cell antigens for T. suis and Tritrichomonas foetus. All vaginal mucus cultures were T. suis-negative during the experiment. ELISA values for both antigens were similar and differences were not significant (P>0.05). Positive control serum samples from one heifer vaccinated against T. foetus showed anti-T. suis ELISA values. We concluded that T. suis intravaginal inoculation induced a low level of serum immune response in heifers measured by ELISA and both protozoa probably share a common antigen. However, under the experimental conditions of this trial, colonization of the heifers' genital tract was not possible in any of the nine animals.     

The long term efficacy of a Hardjo-pomona vaccine in preventing leptospiruria in cattle exposed to natural challenge with Leptospira interrogans serovar hardjo

The long term efficacy of a commercially prepared bivalent vaccine against Leptospira interrogans serovar hardjo and L. interrogans serovar pomona was evaluated in a group of 82 dairy heifers exposed to natural challenge with L. interrogans serovar hardjo for up to 55 weeks after calfhood vaccination. Nineteen heifers were vaccinated twice with a one-month interval, at calfhood (9 to 10 months). A further 18 heifers received a similar calfhood vaccination regimen plus a third injection at adulthood (22 to 23 months), while 19 heifers were vaccinated twice at adulthood only and finally 22 heifers were used as unvaccinated controls. At 55 weeks after calfhood vaccination and prior to adulthood vaccination, only 2.7% of the vaccinated heifers were found to have leptospiruria compared with 58.5% of the unvaccinated heifers (p less than 0.0001). Microscopic agglutination (MA) titres at the same time in the unvaccinated heifers ranged from 32 to 4096 while those vaccinated at calfhood ranged from 32 to 64. Adult vaccination of infected animals did not significantly reduce leptospiruria . Prior to adulthood vaccination, 9 of 19 heifers had leptospiruria , in comparison to 4 of 15 after adulthood vaccination. At the same sampling periods 15 of 22 controls had leptospiruria in comparison to 4 of 9 subsequently tested.     

Effect of vaccination with a monovalent Leptospira interrogans serovar hardjo type hardjo-bovis vaccine on type hardjo-bovis infection of cattle.

Effectiveness of 2 concentrations of a monovalent vaccine containing Leptospira interrogans serovar hardjo type hardjo-bovis was evaluated for protection of heifers from infection with type hardjo-bovis. Nine heifers were given 2 doses of low-dose vaccine (8.32 x 10(8) cells/dose); 9 heifers were given 2 doses of high-dose vaccine (8.32 x 10(9) cells/dose); and 1 steer and 1 heifer were maintained as nonvaccinated controls. Groups of vaccinated cattle were challenge-exposed with serovar hardjo type hardjo-bovis at 7 (n = 6), 11 (n = 6), or 15 (n = 6) weeks after completion of vaccination. All cattle were challenge-exposed by conjunctival instillation of 1 x 10(5) hardjo-bovis cells on 3 consecutive days. Both control and all vaccinated cattle became infected and shed serovar hardjo type hardjo-bovis in their urine. Leptospires were detected in 15 of 16 (94%) urine samples from control cattle and in 124 of 143 (87%) samples from vaccinated cattle. Leptospires were detected in kidneys of 17 of 18 vaccinated cattle and 2 of 2 control cattle and in the uterus or oviducts of 13 of 18 vaccinates and the 1 control heifer.     

Progesterone concentrations in beef heifers bred at puberty or third estrus

Peripheral serum progesterone concentrations were evaluated in beef heifers following breeding collected on d 6 +/- 1, 9 +/- 1 collected on d 6 +/- 1, 9 +/- 1 and 12 +/- 1 (estrus = d 0) after the puberal estrus of all heifers and after the third estrus of E3 heifers. Progesterone concentrations were higher (P less than .05) for heifers in E1 compared with heifers in E3 on d 6, 9 and 12 after breeding to a fertile bull. Progesterone concentrations on d 6, 9 and 12 did not differ (P greater than .10) between pregnant heifers in E1 and E3; however, non-pregnant heifers in E1 had higher (P less than .05) concentrations of progesterone compared with non-pregnant heifers in E3 on each day. Concentrations of progesterone did not differ (P greater than .10) between non-pregnant heifers in E1 and heifers of E3 during their puberal cycle. Pregnant heifers in E1 and E3 had higher (P less than .05) concentrations of progesterone on each day than non-pregnant heifers in their respective treatments. There were no interactions (P greater than .10) between treatment, pregnancy status and day-of-estrous cycle for concentrations of progesterone. Results of this study indicated that luteal function differed between heifers that failed to conceive at their puberal estrus and heifers that failed to conceive at third estrus. However, concentrations of progesterone did not differ between heifers that conceived at puberal or third estrus. The relationship of changes in luteal function from the puberal through the third estrous cycle and pregnancy is not clear.     

Vaccination studies for the control of campylobacteriosis in Jamaican cattle

Following the first diagnosis of campylobacteriosis in Jamaican cattle a field study was undertaken to determine the pathogenicity of Campylobacter fetus subspecies venerealis Jam (Jamaican strain) and to evaluate the effectiveness of vaccination in controlling the disease. A total of 46 nonpregnant yearling heifers and four two-year-old bulls were used in two separate experiments. The results showed that C fetus subspecies venerealis Jam readily colonised the reproductive tract of susceptible heifers and persisted in some animals (68 per cent of unvaccinated and 33 per cent of vaccinated animals) for the duration of the experiment. Pregnancy was confirmed in 13 of 18 (72 per cent) culture-negative heifers but in only eight of 28 (29 per cent) of the heifers with two or more positive cultures. Vaccination appeared to be curative because 44 per cent of vaccinated heifers were cleared of infection whereas 85 per cent of unvaccinated, inoculated heifers remained infected for at least 17 weeks. Vaccination improved the fertility level of the infected heifers threefold. Infection was not established in vaccinated bulls used for breeding infected heifers.     

Standardization and kinetics of in vitro bovine blood lymphocyte stimulation with bovine rotavirus

Two groups of 3-month old calves were immunized intramuscularly with attenuated bovine rotavirus and boosted 21 and 42 days later. The first group of three calves were vaccinated with live virus emulsified with incomplete Freund's adjuvant (IFA) and the second group was immunized with live virus suspended in phosphate buffered saline (PBS). Three other calves, serving as controls, were inoculated with PBS emulsified with IFA. The specific cell-mediated and antibody responses of the animals were studied. Preliminary analysis of in vitro peripheral blood lymphocyte transformation to bovine rotavirus determined optimal conditions as: 96 h culture period, 5 X 10(5) cells per culture in RPMI 1640 medium containing 10% heat-inactivated bovine fetal serum and the use of inactivated virus in the cell culture at a concentration of 5 X 10(6) median tissue culture infective dose before inactivation. Specific blastic stimulation was observed on calves immunized with the rotavirus emulsified with IFA after the second and third vaccine inoculation with stimulation index values varying from 2.00 to 5.73. Serum neutralizing antibody titers of 1/25,600 were also induced in the same calves. Calves immunized with rotavirus-PBS suspension developed a mean antibody titer of 1/1,600, but showed no specific lymphocyte stimulation. No increase in specific immune responses was detected in the control animals.     

Fluorometric measurement of IgG antibody responses in cattle vaccinated with Tritrichomonas foetus.

A photometrically-measured indirect fluorescent antibody (IFA) test was developed to measure antibody levels in three heifers vaccinated intramuscularly with two injections (two-week interval) of a vaccine containing formalin-killed Tritrichomonas foetus in oil adjuvant; a separate animal served as a nonvaccinated control. Sera were collected weekly and tested for specific IgG against T. foetus. Antibodies were detectable within two weeks of the initial injection and reached reciprocal titers as high as 7700 as estimated from previously tested reference sera. Titers peaked at six to eight weeks and remained at relatively high levels for the eleven-week study period. The fluorometric assay was easily developed and economical to perform; in addition, it more accurately estimated IgG levels than standard slide IFA tests.     

CONTROL OF REPRODUCTIVE FUNCTION OF CATTLE USING CLOPROSTENOL

Two intramuscular injections of cloprostenol were given 12 days apart to synchronise oestrus in a group of 47 heifers and following the second injection, 38 were found in oestrus in 2 to 6 days, 1 in 11 days and 8 in 22 to 27 days. The conception rate of the synchronised animals was 24 of 38 (63%). Twenty-nine heifers were given injections of cloprostenol in late pregnancy and parturition was induced with a latent period of 6 +/- 3 days when injected at 266 to 267 days. When injected at 254 to 262 days, 3 of 16 heifers (19%) were unresponsive and the remainder calved with a latent period of 12 +/- 6 days. The survival rate of calves from induced heifers was 71% with 80% survival from controls. Approximately 50% of the induced heifers, and none of the controls, retained their foetal membranes.     

Natural distemper in vaccinated and unvaccinated dogs in Warsaw

Two hundred and twenty-four dogs with clinical signs of distemper were examined for the presence of canine distemper virus (CDV) in mucous membranes by direct immunofluorescence assay. The study showed that 22% of the animals were CDV-positive. Most (33/50; 66%) of the infected dogs had never been vaccinated against distemper, whereas only 11 of 50 (22%) CDV-positive animals were immunized at least once. The difference in the infection rate between vaccinated and unvaccinated animals was statistically significant (P < 0.001), as assessed by the chi2 test. It is concluded that distemper is an important disease among dogs in Warsaw and the vaccination significantly reduces the risk of this disease.     

Genetic parameters for carcass traits and their live animal indicators in Simmental cattle

The objective of this study was to estimate parameters required for genetic evaluation of Simmental carcass merit using carcass and live animal data. Carcass weight, fat thickness, longissimus muscle area, and marbling score were available from 5,750 steers and 1,504 heifers sired by Simmental bulls. Additionally, yearling ultrasound measurements of fat thickness, longissimus muscle area, and estimated percentage of intramuscular fat were available on Simmental bulls (n = 3,409) and heifers (n = 1,503). An extended pedigree was used to construct the relationship matrix (n = 23,968) linking bulls and heifers with ultrasound data to steers and heifers with carcass data. All data were obtained from the American Simmental Association. No animal had both ultrasound and carcass data. Using an animal model and treating corresponding ultrasound and carcass traits separately, genetic parameters were estimated using restricted maximum likelihood. Heritability estimates for carcass traits were 0.48 +/- 0.06, 0.35 +/- 0.05, 0.46 +/- 0.05, and 0.54 +/- 0.05 for carcass weight, fat thickness, longissimus muscle area, and marbling score, respectively. Heritability estimates for bull (heifer) ultrasound traits were 0.53 +/- 0.07 (0.69 +/- 0.09), 0.37 +/- 0.06 (0.51 +/- 0.09), and 0.47 +/- 0.06 (0.52 +/- 0.09) for fat thickness, longissimus muscle area, and intramuscular fat percentage, respectively. Heritability of weight at scan was 0.47 +/- 0.05. Using a bivariate weight model including scan weight of bulls and heifers with carcass weight of slaughter animals, a genetic correlation of 0.77 +/- 0.10 was obtained. Models for fat thickness, longissimus muscle area, and marbling score were each trivariate, including ultrasound measurements on yearling bulls and heifers, and corresponding carcass traits of slaughter animals. Genetic correlations of carcass fat thickness with bull and heifer ultrasound fat were 0.79 +/- 0.13 and 0.83 +/- 0.12, respectively. Genetic correlations of carcass longissimus muscle area with bull and heifer ultrasound longissimus muscle area were 0.80 +/- 0.11 and 0.54 +/- 0.12, respectively. Genetic correlations of carcass marbling score with bull and heifer ultrasound intramuscular fat percentage were 0.74 +/- 0.11 and 0.69 +/- 0.13, respectively. These results provide the parameter estimates necessary for genetic evaluation of Simmental carcass merit using both data from steer and heifer carcasses, and their ultrasound indicators on yearling bulls and heifers.     

THE EFFECT OF CHALLENGE WITH VIRULENT BRUCELLA ABORTUS ON BEEF CATTLE VACCINATED AS CALVES OR ADULTS WITH EITHER BRUCELLA ABORTUS STRAIN 19 OR 45/20

SUMMARY Groups of female calves were vaccinated subcutaneously with the standard dose of Brucella abortus strain 19 (S19) or with B. abortus 45/20 (S45/20). These calves and non-vaccinated control calves were mated at 15 months of age and challenged by way of the conjunctival sac with B. abortus strain 544 (S544). The incidence of abortion, stillbirths, weakling calves and healthy calves was observed after challenge and specimens were collected for culture at parturition and slaughter. Fifteen healthy calves were born to 18 animals vaccinated with S19, 12 were born to 18 animals vaccinated with S45/20 and 2 were born to 8 animals that were not vaccinated. B. abortus was isolated from 5 of the animals vaccinated with S19, 13 of the animals vaccinated with S45/20 and 9 of the 12 animals that were not vaccinated. Only one of the 5 infected animals vaccinated with S19 was vaccinated as an adult.