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Birth (n = 308), weaning (n = 291), feedlot and carcass (n = 142), and yearling heifer traits (n = 139) were evaluated in F1 calves sired by Brahman (BR), Boran (BO), and Tuli (TU) bulls and born to multiparous Hereford and Angus cows. Calves sired by BR were heaviest (P < .05) at birth and largest (P < .05) for cannon bone length. Tuli crosses were smaller (P < .05) for birth weight and cannon bone length than BR and BO crosses. No significant differences were observed for gestation length among sire breeds. Brahman crosses had larger (P < .05) weaning weight, hip height, and preweaning ADG than calves sired by BO and TU. Similar trends were observed for feedlot traits. Carcasses of BR crosses were heavier (P < .05) and had less (P < .05) internal fat than those of BO and TU crosses. Tuli crosses averaged greater (P < .05) skeletal maturity than BO crosses. Tuli crosses averaged greater marbling (P < .05) than BR crosses and less (P < .05) Warner-Bratzler shear force than BO crosses. No differences were observed in longissimus muscle area, fat thickness, or yield grade among sire breeds. Heifers sired by BR were heaviest (P < .05) and tallest (P < .05) at yearling measurement. Brahman F1 heifers had larger (P < .05) pelvic height and pelvic area, due to larger skeletal frame size, than BO and TU F1 heifers. These results indicate large differences in growth and skeletal size exist among calves sired by these three breeds. Several important differences also exist for carcass quality traits, but not for carcass yield traits, among these three breeds.

Subclinical illness associated with infection is thought to reduce performance and increase production costs in feedlot cattle, but underlying components remain largely unidentified. Vaccination is frequently used in feedlot settings but producers lack metrics that evaluate the effectiveness of vaccination programs. The goal of this study was to determine if levels of serum neutralizing antibody titers were predictive of levels of vaccine protection in a commercial setting. During this four-year study, Angus-Nellore steers housed in a production feedlot setting were assigned to 1 of 3 vaccine treatments: killed vaccine (kV), modified live virus (MLV) vaccine, or no vaccine (control), and were challenged with a noncytopathic 1b field strain of bovine viral diarrhea virus. Rectal temperature and levels of circulating lymphocytes and platelets were monitored following challenge. While no animals were diagnosed as clinically ill with respiratory disease, indicators of disease (pyrexia, lymphopenia, and thrombocytopenia) were observed. The MLV treatment elicited higher antibody titers to the vaccination than the kV, and calves in the MLV treatment had higher mean titers at challenge. The year that elicited the highest antibody response to the vaccination and the year with the lowest frequency of phenotypic responses to the challenge were not concurrent. The MLV treatment had the highest proportion, 34.68%, of animals that were protected against the challenge regardless of the pre-challenge antibody titer and had the fewest number of lymphopenia cases in response to the challenge. Both vaccine treatments mitigated thrombocytopenia when compared to the control treatment, and the MLV treatment reduced lymphopenia; however, these symptoms were not completely eliminated in vaccinated animals. Pyrexia was present in 40.11% of the animals, but no difference in the frequency of cases between treatments was observed. Pre-challenge vaccination response was not indicative of the level of protection nor was anamnestic antibody response correlated with health status.

Bovine viral diarrhea virus (BVDV) plays a key role in bovine respiratory disease complex, which can lead to pneumonia, diarrhea and death of calves. Current vaccines are not very effective due, in part, to immunosuppressive traits and failure to induce broad protection. There are diverse BVDV strains and thus, current vaccines contain representative genotype 1 and 2 viruses (BVDV-1 & 2) to broaden coverage. BVDV modified live virus (MLV) vaccines are superior to killed virus vaccines, but they are susceptible to neutralization and complement-mediated destruction triggered by passively acquired antibodies, thus limiting their efficacy. We generated three novel mosaic polypeptide chimeras, designated NproE2123; NS231; and NS232, which incorporate protective determinants that are highly conserved among BVDV-1a, 1b, and BVDV-2 genotypes. In addition, strain-specific protective antigens from disparate BVDV strains were included to broaden coverage. We confirmed that adenovirus constructs expressing these antigens were strongly recognized by monoclonal antibodies, polyclonal sera, and IFN-γ-secreting T cells generated against diverse BVDV strains. In a proof-of-concept efficacy study, the multi-antigen proto-type vaccine induced higher, but not significantly different, IFN-γ spot forming cells and T-cell proliferation compared to a commercial MLV vaccine. In regards to the humoral response, the prototype vaccine induced higher BVDV-1 specific neutralizing antibody titers, whereas the MLV vaccine induced higher BVDV-2 specific neutralizing antibody titers. Following BVDV type 2a (1373) challenge, calves immunized with the proto-type or the MLV vaccine had lower clinical scores compared to naïve controls. These results support the hypothesis that a broadly protective subunit vaccine can be generated using mosaic polypeptides that incorporate rationally selected and validated protective determinants from diverse BVDV strains. Furthermore, regarding biosafety of using a live vector in cattle, we showed that recombinant human adenovirus-5 was cleared within one week following intradermal inoculation.

Postweaning, feedlot, and carcass data from crossbred calves sired by five Bos indicus breeds and one Bos taurus breed were evaluated. Data included records from F1 calves out of multiparous Hereford cows sired by Angus, Gray Brahman, Gir, Indu-Brazil, Nellore, and Red Brahman bulls. The Zebu crosses grew faster postweaning and were heavier and taller as yearlings than the Angus crosses (P < .05). Among the Zebu-sired calves, the Red and Gray Brahman crosses were faster gaining and were heavier at a year of age than the Gir, Indu-Brazil, and Nellore. The Nellore crosses were significantly taller than the Gray Brahman- and Gir-sired crosses; the Indu-Brazil and Red Brahman were intermediate. Angus crosses were lightest on and off feed but were not significantly different from Gir, and Red and Gray Brahman were heaviest (P < .05). The Nellore and Indu-Brazil were similar in initial weight, but Indu-Brazil calves were similar to Red and Gray Brahman for final weight. The Angus cross was more desirable (P < .05) in marbling score and quality grade although the Nellore crosses had the most desirable score and grade of the Zebu crosses. Gir crosses had higher skeletal maturity scores (P < .05) than Nellore, Gray Brahman, Indu-Brazil, and Angus crosses; Red Brahman crosses were intermediate Angus crosses had the lightest carcasses but not significantly lighter than the Indu-Brazil, Gir, or Nellore. Red Brahman-cross carcasses were heaviest and Gray Brahman-cross carcasses were intermediate.(ABSTRACT TRUNCATED AT 250 WORDS)