Heifers injected with 10(8) (n = 40), 10(9) (n = 39), or 10(10) (n =39) colony-forming units of Brucella abortus strain 19 were conjunctivally exposed to 10(7) colony-forming units of strain 2308 during gestation. At parturition, milk from each quarter of the udder, a piece of placenta, and 2 swab specimens of the uterus from the dam plus a swab specimen of the rectum from each calf were cultured for Brucella. If the calf was dead or died, additional specimens of lung, stomach contents, and a mediastinal lymph node also were cultured. Days in gestation was determined for each heifer, using data from rectal palpation after breeding and crown-rump length and weight of calf at parturition, with the median value used for data analysis. In each vaccine dosage group, the proportion (%) of heifers developing brucellosis increased as days in gestation at exposure increased. Strain 2308 was isolated from 3 (11%) of 26, 16 (25%) of 64, and 18 (64%) of 28 heifers that were grouped as less than 121, 121 to 150, and greater than 150 days in gestation at time of exposure, respectively. Thirty-two (86%) of the 37 infected heifers were less than 260 days in gestation at parturition, and calves were premature. Heifers with premature calves were more likely to be infected, and tissues were more likely to yield multiple isolations of strain 2308, regardless of days in gestation at exposure or of days after exposure to parturition. Days after exposure to premature parturition of infected heifers ranged from 35 to 110.

Four virgin heifers were experimentally inoculated intravaginally with 7 X 10(6) Tritrichomonas foetus, and 2 heifers served as uninfected controls. The durations of infection were 13, 20, 21, and 28 weeks, respectively. An ELISA that used whole T foetus antigen was used to detect anti-T foetus immunoglobulins (IgA, IgG1, IgG2, and IgM) in vaginal, cervical, and uterine secretions, and sera during the course of infection. The vaginal and cervical antibody responses were characterized by significantly increased T foetus-specific IgA and IgG1 at 7 to 9 weeks of infection, whereas uterine IgA and IgG1 responses peaked at 10 to 12 weeks. The antibody response in serum was predominantly of the IgG1 and IgG2 subclasses. In all reproductive tract regions, IgA persisted at least until the time of T foetus clearance, and usually longer. The next most persistent isotype was IgG1, lasting longest in the vagina, then cervix, and for the shortest time in the uterus. In local secretions, IgG2 was seen only transiently, increasing at weeks 13 to 15 in the vagina, and at weeks 10 to 12 in the cervix. Little IgM, relative to that present before infection, was detected in any secretion or serum, although cervical secretions had the greatest amount. Eight to 12 weeks after clearance, the 4 experimental heifers were inoculated intravaginally with 1 x 10(5) T foetus, transient infections (2 to 3 weeks' duration) were established in only 2 of 4 heifers, as determined by culturing of reproductive tract secretions. The lag times of antibody responses during this reinfection were shorter than in the initial infection, and ELISA optical densities were at least as high as during the primary infection, suggesting an anamnestic response.

Heifers were inoculated IV with 1 of 4 modified-live bovine herpesvirus-1 vaccinal strains against infectious bovine rhinotracheitis (2 heifers/strain) on postbreeding day (PBD) 14. The effect of infection on fertility was monitored by plasma progesterone assay at 1- to 3-day intervals from the time of virus exposure until PBD 60. Infertility was detected in 4 of 8 inoculated heifers. In 2 heifers, progestrone concentrations decreased to values indicative of estrus within 10 days after inoculation (PBD 24). The 2 other heifers had evidence of embryonic death on PBD 40 and 42. Two control heifers inoculated with culture medium from noninfected cells maintained their pregnancies.

Introduction: Bovine viral diarrhoea (BVD), caused by the bovine viral diarrhoea virus (BVDV), is one of the most important diseases of cattle worldwide. The purpose of the study was to determine the BVDV infection status in a dairy herd vaccinated against BVD. Before vaccination started in 2008, there had been no prior identification or the removal of the possible source of infection (persistently infected animals). It was expected that vaccination itself would enable the elimination of viral shedders on a long term basis. Material and Methods: Serological screening for antibodies against BVDV with determination for antibodies titres, BVDV antigen, and the presence of the viral genome with phylogenetic analysis of positive samples in the herd were performed, despite the lack of any clinical problems indicating possible presence of BVDV infection. Results: 19 individuals persistently infected with BVDV were identified among calves and heifers but not in adult cattle. All virus shedders were antibody negative and the genotype of isolated virus was BVDV-1b, indicating a single source of infection. The vaccine used in the herd was composed of BVDV-1a strain. In each of the tested cowsheds, antibody titres against BVDV-1b were higher than against BVDV-1a (median values). Conclusion: Despite a long-lasting vaccination programme and relatively high sequence homology of vaccinal and field strains of BVDV (83.6%), it was not possible to avoid transplacental infections of foetuses and the birth of persistently infected calves from vaccinated heifers although the protection against clinical disease was accomplished.

The objective of this study was to evaluate the effect of late-gestation vaccination of beef heifers with 2 doses of a killed-virus (KV) vaccine containing bovine herpesvirus 1 (BoHV-1), bovine viral diarrhea virus 1 (BVDV-1), and bovine viral diarrhea virus 2 (BVDV-2) on the serum concentrations of antibody against BoHV-1, BVDV-1, and BVDV-2 in heifers and their calves and on the IgG concentration in the calves. Of the 47 pregnant beef heifers selected, 26 received 2 doses of the vaccine at 6.5 to 8 mo of gestation (at pregnancy check), and 21 received 2 doses of saline. The mean log2 serum titers of neutralizing antibody against BoHV-1, BVDV-1, and BVDV-2 before vaccination did not differ significantly between the treatment groups; however, at calving all 3 mean titers were significantly greater (P < 0.05) in the vaccinated heifers than in the control heifers. At 24 h after birth the mean serum IgG levels in the calves did not differ significantly between the 2 groups, at 30.18 and 32.28 g/L, respectively (P < 0.05); however, the mean log2 serum titers of antibody to all 3 viruses were greater in the calves nursing colostrum from the vaccinated heifers than in the calves nursing colostrum from the nonvaccinated heifers and significantly so for BoHV-1 and BVDV-1 (P < 0.001 and P = 0.009, respectively). Thus, late-gestation vaccination of beef heifers could result in a greater and more consistent deposition of specific antibodies in colostrum, reducing the variability of initial titers in calves and increasing the duration of maternal immunity.

Objective: To evaluate the efficacy of vaccination with the Leptospira interrogans serovar hardjo type hardjoprajitno component of a pentavalent Leptospira bacterin against a virulent experimental challenge with Leptospira borgpetersenii serovar hardjo type hardjo-bovis strain 203 in cattle. Animals: Fifty-five 6-month-old Holstein heifers. Procedures: Heifers that were negative for persistent infection with bovine viral diarrhea virus determined via immunohistochemical testing and negative for Leptospira interrogans serovar pomona, Leptospira interrogans serovar hardjo, Leptospira interrogans serovar grippotyphosa, Leptospira interrogans serovar bratislava, Leptospira interrogans serovar canicola, and Leptospira interrogans serovar icterohaemorrhagiae determined via microscopic agglutination assay were enrolled in the study. Two heifers were separated and used for the challenge passage. The remaining heifers were vaccinated twice with a commercial pentavalent bacterin or a sham vaccine 21 days apart and subsequently challenged with L borgpetersenii serovar hardjo type hardjo-bovis strain 203. Urinary shedding, antibody titers, and clinical signs of leptospirosis infection were recorded for 8 weeks after challenge. Results: Heifers that received the pentavalent bacterin did not shed the organism in urine after challenge and did not have renal colonization at necropsy. Heifers that were sham vaccinated shed the organism in urine and had renal colonization. Conclusions and Clinical Relevance: Results provided evidence that a pentavalent Leptospira vaccine containing L interrogans serovar hardjo type hardjoprajitno can provide protection against challenge with L borgpetersenii serovar hardjo type hardjo-bovis strain 203. It is important to demonstrate cross-protection that is vaccine specific against disease-causing strains of organisms that are prevalent under field conditions.

Objective—To evaluate serum haptoglobin concentration at feedlot arrival and subsequent performance and morbidity and mortality rates of calves that developed bovine respiratory disease. Animals—360 heifer calves and 416 steer and bull calves. Procedures—Serum samples were obtained from cattle at the time of arrival to a feedlot (day −1) and analyzed for haptoglobin concentration. In experiment 1, calves were classified into groups with a low (< 1.0 μg/mL), medium (1.0 to 3.0 μg/mL), or high (> 3.0 μg/mL) serum haptoglobin concentration and allotted into pens on the basis of group. In experiment 2, calves were classified as having or not having detectable serum haptoglobin concentrations. Results—In experiment 1, average daily gain from days 1 to 7 decreased as haptoglobin concentration increased. Dry-matter intake (DMI) from days 1 to 21 decreased with increasing haptoglobin concentration, and DMI typically decreased from days 1 to 63. Total bovine respiratory disease morbidity rate typically increased with increasing haptoglobin concentration. At harvest, no differences in carcass characteristics were observed on the basis of haptoglobin concentration. In experiment 2, cattle with measureable serum haptoglobin concentrations at arrival weighed less throughout the experiment, gained less from days 1 to 7, and had lower DMI from days 1 to 42. Overall morbidity rate was not different between groups, but cattle with detectable serum haptoglobin concentrations had higher odds of being treated 3 times. Conclusions and Clinical Relevance—Serum haptoglobin concentration in cattle at the time of feedlot arrival was not associated with overall performance but may have limited merit for making decisions regarding targeted prophylactic treatment.

Objective-To determine efficacy of a modified-live virus (MLV) vaccine containing bovine viral diarrhea virus (BVDV) 1a and 2a against fetal infection in heifers exposed to cattle persistently infected (PI) with BVDV subtype 1 b. Animals-50 heifers and their fetuses. Procedures-Susceptible heifers received a placebo vaccine administered IM or a vaccine containing MLV strains of BVDV1a and BVDV2a administered IM or SC. On day 124 (64 to 89 days of gestation), 50 pregnant heifers (20 vaccinated SC, 20 vaccinated IM, and 10 control heifers) were challenge exposed to 8 PI cattle. On days 207 to 209, fetuses were recovered from heifers and used for testing. Results-2 control heifers aborted following challenge exposure; both fetuses were unavailable for testing. Eleven fetuses (8 control heifers and 1 IM and 2 SC vaccinates) were positive for BVDV via virus isolation (VI) and for BVDV antigen via immunohistochemical analysis in multiple tissues. Two additional fetuses from IM vaccinates were considered exposed to BVDV (one was seropositive for BVDV and the second was positive via VI in fetal tissues). A third fetus in the SC vaccinates was positive for BVDV via VI from serum alone. Vaccination against BVDV provided fetal protection in IM vaccinated (17/20) and SC vaccinated (17/20) heifers, but all control heifers (10/10) were considered infected. Conclusions and Clinical Relevance-1 dose of a BVDV1a and 2a MLV vaccine administered SC or IM prior to breeding helped protect against fetal infection in pregnant heifers exposed to cattle PI with BVDV1b.