Immunomodulatory effect of Lacticaseibacillus casei CB054 supplementation in calves vaccinated against infectious bovine rhinotracheitis.

Probiotics are live microorganisms that, confer health benefits to the host when supplemented in adequate amounts. They can promote immunomodulation by inducing phagocyte activity, leukocyte proliferation, antibody production, and cytokine expression. Lactic acid bacteria (BAL) are important probiotic specimens with properties that can improves ruminant nutrition, productivity and immunity. The aim of the present study was to evaluate the immunomodulatory effect of the supplementation with Lacticaseibacillus casei CB054 in calve vaccinated against bovine infectious rhinotracheitis (IBR). Calve were vaccinated with a commercial IBR vaccine, on day 0 and received a booster dose on day 21. L. casei CB054 was orally administered (4 ×109 UFC) for 35 days, while a non-supplemented control group received Phosphate Buffer Saline (PBS). Stimulation of bovine splenocytes with L. casei CB054 markedly enhanced mRNA transcription levels of cytokines IL2, IL4, IL10 and IL17 genes. Calves supplemented with L. casei CB054 showed significantly higher (p < 0.05) specific anti-BoHV-1 IgG levels, higher serum neutralization, as well as higher mRNA transcription for IL2, IL4, IL10 and IL17 genes in Peripheral Blood Mononuclear Cells (PBMCs) comparing with control calves. Supplemented calve had an average weight gain of ∼14 kg more than non-supplemented during the experimental period. These results suggest that L. casei CB054 supplementation increase immunogenicity of a commercial IBR vaccine in cattle and improve weight gain.

Effect of administering activated lymphocytes originated from the dam on the immune cell reaction in Holstein calves.

Injection of lymphokine activated killer (LAK) cells is known as useful for activation of cellular immune system. Although the effect of LAK cells has been clarified in human or mice, this effect on function of immune cells has not been examined in calves. Healthy ten Holstein calves were injected with the LAK cells 2 days after birth (LAK Group), and another eight calves were observed as controls (Control Group). All calves received the colostrum formulation on the day of birth, and then, were inoculated with a live attenuated vaccine of bovine herpesvirus (BHV)-1 at 2 (the first vaccination) and 6 (the second vaccination) weeks after birth. Peripheral blood of their dam obtained 3 weeks before calving was used for preparation of LAK cells. Blood samples were taken prior to vaccine inoculation and 3 days after the first inoculation, as well as 3 and 6 days after the second vaccination from all calves. Numbers of CD8+ and CD21+ cells increased significantly after the second vaccination in the LAK Group compared with Control Group. The present study suggested the improved effect of injecting LAK cells originated from dams on immune cells function of young calves after BHV-1 live vaccine.

Prevalencia del virus de la rinotraqueitis infecciosa bovina en el departamento del Caquetá, Amazonía Colombiana / Prevalence of bovine infectious rhinotracheitis virus in Caquetá department, Colombian Amazon

RESUMEN La rinotraqueitis infecciosa bovina (IBR) es una enfermedad ampliamente difundida en el mundo con gran repercusión socio-económica en las ganaderías bovinas. El objetivo del presente estudio fue determinar la prevalencia de IBR en 100 hatos del departamento del Caquetá, para lo cual, se muestrearon 960 bovinos mayores de 36 meses entre enero y marzo de 2016 en predios seleccionados a partir de los criterios: a) tamaño (50-180 hectáreas), b) con más de 10 vacas en ordeño, c) disponibilidad de los productores para cooperar y d) accesibilidad de las vías. Las muestras de suero sanguíneo se remitieron al Laboratorio de Diagnóstico Clínico Veterinario del ICA y se analizaron a través la prueba Elisa de bloqueo (BHV-1) gB. Los sueros con porcentaje de bloqueo superior al 55% se consideraron positivos a anticuerpos para IBR. Se encontró alta seroprevalencia (73,13%), mayor además en machos que en hembras (p < 0,05). A nivel municipal la seroprevalencia fue mayor en los municipios de El Doncello, Puerto Rico y San Vicente del Caguán y se encontró diferencia significativa (p < 0,05) entre los nueve municipios analizados. A nivel de hatos, la prevalencia fue del 99%. En conclusión, la prevalencia del virus de la rinotraqueitis infecciosa bovina (IBR) en bovinos de doble propósito del departamento del Caquetá fue muy alta.

ABSTRACT Infectious bovine rhinotracheitis (IBR) is a disease widely spread throughout the world with great socio-economic impact on bovine livestock. The objective of this study was to determine the prevalence of IBR in 100 herds in Caqueta department, for which 960 cattle older than 36 months between January and March 2016 were sampled in farms selected from the criteria: a) size (50-180 hectares), b) with more than 10 cows in milking, c) availability of producers to cooperate and d) accessibility of roads. Blood serum samples were sent to the ICA veterinary clinical diagnostic laboratory and analyzed using the Elisa blocking test (BHV-1) gB, where sera with blocking percentage greater than 55% were considered as positive for IBR antibodies. High seroprevalence was found (73.13%), being higher in males than in females (p < 0.05). At municipal level, seroprevalence was greater in El Doncello, Puerto Rico and San Vicente del Caguán municipalities, significant difference (p<0.05) was found between the nine municipalities analyzed. At herd level prevalence was of 99%. In conclusion the prevalence of Infectious Bovine Rhinotracheitis (IBR) virus in dual-purpose cattle of Caquetá department was very high.

Immune memory induced by intranasal vaccination with a modified-live viral vaccine delivered to colostrum fed neonatal calves.

Bovine respiratory disease (BRD) remains a major health problem despite extensive use of vaccines during the post-weaning period. Apparent vaccine failure is attributed, in part, to primary vaccination during the period of greatest risk for BRD, providing inadequate time for onset of protective immunity. The current study investigated whether intranasal (IN) vaccination of 3-6 week old calves with a modified-live viral (MLV) vaccine induced sufficient immune memory to prevent respiratory disease and accelerate onset of protective immunity 5 months later. Vaccine groups included naïve controls, a single IN vaccination at 3-6 weeks of age, primary IN vaccination at 6 months, and either an IN or subcutaneous (SC) booster vaccination at 6 months (n = 10/group). All calves were challenged with BHV-1 four days after vaccination at 6 months of age. Primary IN vaccination at 6 months did not significantly reduce clinical disease but significantly (P < 0.01) reduced virus shedding. A single IN vaccination at 3-6 weeks of age significantly (P < 0.05) reduced weight loss but did not reduce fever or virus shedding. Both IN and SC booster vaccinations, significantly (P < 0.01) reduced clinical disease but virus shedding was significantly (P < 0.001) reduced only by IN booster vaccination. Reduction in virus shedding was significantly (P < 0.01) greater following booster versus primary IN vaccination at 6 months. All vaccination regimes significantly (P < 0.01) reduced secondary bacterial pneumonia and altered interferon responses relative to naïve controls. Only IN booster vaccination significantly (P < 0.05) increased BHV-1 specific IgA in nasal secretions. These results confirm primary MLV IN vaccination at 3 to 6 weeks of age, when virus neutralizing maternal antibody was present, induced immune memory with a 5 month duration. This immune memory supported rapid onset of protective immunity four days after an IN booster vaccination.

Antibody Responses to Bovine Alphaherpesvirus 1 (BoHV-1) in Passively Immunized Calves.

To date, in countries where infectious bovine rhinotracheitis (IBR) is widespread, its control is associated with deleted marker vaccines. These products lack one or more genes responsible for the synthesis of glycoproteins or enzymes. In Europe, the most widely used marker vaccine is one in which glycoprotein E (gE-) is deleted, and it is marketed in a killed or modified-live form. Using this type of immunization, it is possible to differentiate vaccinated animals (gE-) from those infected or injected with non-deleted (gE+) products using diagnostic tests specific for gE. The disadvantage of using modified-live gE-products is that they may remain latent in immunized animals and be reactivated or excreted following an immunosuppressive stimulus. For this reason, in the last few years, a new marker vaccine became commercially available containing a double deletion related to genes coding for gE and the synthesis of the thymidine-kinase (tk) enzyme, the latter being associated with the reduction of the neurotropism, latency, and reactivation of the vaccine virus. Intramuscularly and intranasally administered marker products induce a humoral immune response; however, the mother-to-calf antibody kinetics after vaccination with marker vaccines is poorly understood. This review discusses several published articles on this topic.

Determining bovine viral diarrhea and infectious bovine rhinotracheitis infections in dairy cattle using precolostral blood.

The objective of this study was to determine if precolostral blood samples are useful to detect apparent fetal infections with bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses. A convenience sample of 317 sera from 50 Canadian herds was used in the study. Antibody level was measured using 2 commercial IBR and BVD ELISA kits. Precolostral status of sera was confirmed on 304 samples using serum gamma-glutamyl transferase activity. Postcolostral serum samples yielded a higher proportion of positive results to IBR (OR = 86; 95% CI: 17.8 to 415.7) and BVD (OR = 199.3; 95% CI: 41.7 to 952.3) than did precolostral samples. All positive precolostral serum samples (n = 7 of 304) originated from calves born to vaccinated cows. Postcolostral positive serum samples (n = 11 of 13) originated mostly (60%) from calves born to non-vaccinated cows. Precolostral serum sampling can detect apparent fetal infections in a herd.

Utilisation du serum précolostral pour le dépistage de la diarrhée virale bovine (BVD) et rhinotracheite infectieuse bovine (IBR) dans les troupeaux laitiers. L'objectif de cette étude était d'évaluer l'utilité du prélèvement de sérum précolostral de nouveaux nés pour détecter des infections foetales apparentes par IBR et BVD dans un troupeau. Un échantillonnage de convenance de 317 sérums, prélevés de 50 troupeaux canadiens, a été utilisé. Les niveaux d'anticorps des sérums ont été mesurés en utilisant 2 trousses ELISA (IBR et BVD). Le statut précolostral a été confirmé pour 304 échantillons par la mesure de l'activité sérique des gamma glutamyl transférases. Une plus grande proportion de résultats positifs à IBR (RC = 86; IC 95%: 17,8 à 415,7) et BVD (RC = 199,3; IC 95 %: 41,7 à 952,3) a été observée parmi les échantillons postcolostraux que parmi les précolostraux. Tous les échantillons précolostraux positifs (n = 7/304) provenaient de veaux nés de mères vaccinées. Les échantillons postcolostraux positifs (n = 11/13) étaient majoritairement (60 %) prélevés à partir de veaux nés de mères non vaccinées. Le prélèvement de sérum précolostal peut détecter des infections foetales apparentes dans les troupeaux.(Traduit par les auteurs).

Effect of dietary boron on physiological responses in growing steers inoculated with bovine herpesvirus type-1.

Thirty-six Angus and Angus×Simmental steers were fed one of three dietary treatments; (1) control (no supplemental B), (2) 5 mg supplemental B/kg, and (3) 15 mg supplemental B/kg for 47 days to determine the effects of dietary boron (B) on disease resistance following an inoculation with bovine herpesvirus type-1 (BHV-1). On day 34 of the study steers were inoculated intranasally with BHV-1. Rectal temperatures began to elevate at day 2, and plasma tumor necrosis factor-α concentrations increased (P<0.05) by day 2 following BHV-1 inoculation. Plasma acute phase proteins were increased (P<0.01) while plasma interferon-γ was decreased (P<0.05) by day 4 post-inoculation. Supplementation of B increased (P<0.001) plasma B concentrations in a dose-responsive manner. However, dietary B did not affect the duration and severity of clinical signs of BHV-1 and had minimal effects on plasma acute phase proteins and cytokines.

Effect of dietary lipoic acid on metabolic hormones and acute-phase proteins during challenge with infectious bovine rhinotracheitis virus in cattle.

OBJECTIVE: To determine the effect of dietary supplemental lipoic acid (LA) on serum concentrations of metabolic hormones and acute-phase proteins of steers challenged with infectious bovine rhinotracheitis virus (IBRV). ANIMALS: 32 steers. PROCEDURES: Steers were randomly assigned to 4 treatments: negative control (NC; no LA, no IBRV challenge), control (CON; no LA, IBRV challenge), 16 mg of LA/kg of body weight (BW)/d plus IBRV challenge (LA16), and 32 mg of LA/kg of BW/d plus IBRV challenge (LA32). Following a 21-day adaptation period, CON, LA16, and LA32 steers received IBRV (2 mL/nostril [day 0]); NC steers received saline (0.9% NaCl) solution. Blood samples, nasal swab specimens, BW, and rectal temperatures were obtained 0, 1, 3, 5, 7, 14, and 21 days after challenge. Serum was analyzed for concentrations of haptoglobin, amyloid-A, leptin, and anti-IBRV antibodies. RESULTS: Steers fed LA32 began gaining BW by day 7, whereas BW of CON and LA16 steers declined. Serum haptoglobin concentration of LA32 steers was lower than that of CON and LA16 steers on day 7. Serum neutralization titers for 30 of 32 steers were negative for anti-IBRV antibodies before challenge; however, all steers (including NCs) had antibodies on day 21. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that LA supplementation augmented certain aspects of the immune response; LA32 steers had a more rapid recovery from IBRV viral challenge than did others.

The physiological and production effects of increased dietary intake of vitamins E and C in feedlot cattle challenged with bovine herpesvirus 1.

The physiological and production effects of feeding additional vitamin E and ruminally protected vitamin C were examined in cattle challenged with bovine herpesvirus 1 (BHV 1). Forty-eight individually penned 6-mo-old Angus and Angus crossbred heifer calves with a mean BW of 151 kg were allocated randomly to four diets in a 2 x 2 factorial arrangement of treatments. Pelleted diets provided either 15 or 185 IU/kg of DM of vitamin E, with or without 3.7 g of ruminally protected vitamin C/kg of DM. Blood samples were taken at start of the experiment and at wk 4, 5, and 6. At the start of wk 5, half of each of the dietary groups was challenged with BHV 1. Feeding additional vitamin E was associated with greater (P < 0.001) mean plasma alpha-tocopherol. In contrast, feeding ruminally protected vitamin C was not associated with greater (P = 0.59) mean plasma ascorbate concentration; however, feeding ruminally protected vitamin C was associated with lower (P = 0.03) mean blood total superoxide dismutase (Cu/Zn SOD and Mn SOD) concentration. Calves fed additional vitamin E had greater (P = 0.05) mean plasma beta-carotene concentrations. There were interactions between dietary intake of vitamins E and C with respect to serum ceruloplasmin concentration (P = 0.01) and G:F (P = 0.05). Bovine herpesvirus 1 challenge was associated with lower white cell count (P = 0.007), lymphocyte count (P < 0.001), and DMI (P = 0.03). Feeding additional vitamin E to calves challenged with BHV 1 was associated with a lower (P = 0.03) serum ceruloplasmin concentration. There was a non-significant trend towards an interaction (P = 0.06) between the feeding of vitamins E and C, with virus-challenged calves fed additional vitamin E alone having greater plasma retinol concentrations. The feeding of vitamins E and/or C in calves challenged with BHV 1 was associated with alterations in the concentrations of other antioxidants. More severe disease may have translated these cellular effects to changes in health and performance.

Latency and reactivation of a glycoprotein E negative bovine herpesvirus type 1 vaccine: influence of virus load and effect of specific maternal antibodies.

The effects of the vaccination of neonatal calves with a glycoprotein E (gE)-negative bovine herpesvirus type 1 (BHV-1) were investigated in naïve and passively immunised calves either with the recommended dose or a 5-fold concentrated one. After inoculation (PI), all calves excreted the virus vaccine except three passively immunised calves inoculated with the lower titre. No antibody response could be detected in passively immunised calves, whatever the dose used, and they all became BHV-1 seronegative and remained so after dexamethasone treatment (PDT). Nevertheless, as shown by a gamma-interferon assay, all calves that excreted the vaccine PI developed a cell-mediated immune response and a booster response was observed PDT, suggesting viral reactivation. The vaccine virus was recovered PDT from nasal secretions in two calves and BHV-1 DNA were detected in trigeminal ganglia from five calves belonging to all inoculated groups. The results show that the BHV-1 gE-negative vaccine can establish latency not only in naïve but also in passively immunised neonatal calves after a single intranasal inoculation. Moreover, this study shows for the first time that the gE-negative vaccine, when used in passively immunised calves, can lead to seronegative vaccine virus carriers.

Adjuvant effects of sulfolipo-cyclodextrin in a squalane-in-water and water-in-mineral oil emulsions for BHV-1 vaccines in cattle.

The antibody and cell mediated immune responses induced by BHV-1 were analysed in cattle after vaccination and challenge exposure to the virulent strain LA of BHV-1. Animals were vaccinated intramuscularly (IM) with inactivated virus vaccines against BHV-1 containing either a water in mineral oil adjuvant (W/O), a water in mineral oil adjuvant plus Avridine (W/O+Avridine) or sulfolipo-cyclodextrin in squalane in-water emulsion (SL-CD/S/W). No significant differences were registered in the antibody response induced by the three evaluated vaccines. However, the BHV-1 specific cell-mediated immunite response was stronger and appeared earlier when SL-CD/S/W was included in the formulation. The efficacy of the vaccines was also evaluated after intranasal challenge of the calves with a virulent BHV-1 LA strain. Animals vaccinated with SL-CD/S/W had reduced virus excretion and clinical symptoms compared with the mock-vaccinated animals. Comparison of levels of BHV-1 specific IgG2 and IgG1 with virus shedding revealed that, regardless of the adjuvant administered, animals showing BHV-1 specific IgG2/IgG1 ratios higher than 1 were those with a significant lower number of individuals shedding virus. Additionally, animals vaccinated with SL-CD/S/W presented no post-vaccinal reactions. These factors, combined with the higher efficacy and the ease of manipulation of the biodegradable oil, makes the vaccine formulated with this new adjuvant an important contribution for the veterinary vaccines industry.

Effect of shipping and chromium supplementation on performance, immune response, and disease resistance of steers.

Forty-eight Angus crossbred steers (263 +/- 2 kg initial BW) were blocked by weight and randomly assigned within weight group to treatment. Treatments consisted of control or .4 mg of supplemental Cr as Cr-nicotinic acid complex/kg of DM. Steers were fed diets containing 90% corn silage (DM basis) and 10% of a soybean meal-mineral-vitamin supplement. After 56 d on the dietary treatment, half of the steers in each treatment were transported 343 km and unloaded in an unfamiliar location. The next day, d 58, shipped steers were returned to the feedlot (50 km). On d 58 after shipped steers were returned to the feedlot, all steers were inoculated with infectious bovine rhinotracheitis virus (IBRV) intranasally. Average daily gain from d 0 to 80 was increased (P < .10) by supplemental Cr. There was a shipping x time interaction for serum cortisol concentrations. Shipping increased (P < .02) serum cortisol on d 58, but 7 d after transport there were no effects of shipping on serum cortisol. Transportation increased (P < .05) the ratio of neutrophils to lymphocytes. Supplemental Cr did not affect rectal temperature after the IBRV challenge or the antibody response to IBRV or porcine red blood cells. Immunoglobulin G antibody response to porcine red blood cells was decreased (P < .09) by shipping. Supplemental Cr as Cr-nicotinic acid improved ADG of growing steers, regardless of whether they had been stressed by shipping. Supplemental Cr did not affect any of the immune responses that were measured.

Effects of copper deficiency and copper deficiency coupled with high dietary iron or molybdenum on phagocytic cell function and response of calves to a respiratory disease challenge.

A study was conducted to determine the effects of supplementing a diet marginally deficient in copper (Cu) with iron (Fe), molybdenum (Mo), or Cu on phagocytic cell function and disease resistance of calves. Thirty-one calves were born to heifers fed a corn silage-based diet containing 4.5 mg of Cu/kg. Treatments consisted of 1) control (CON; no supplemental Cu, Fe, or Mo), 2) 600 mg of Fe added/kg (FE), 3) 5 mg of Mo added/kg (MO), or 4) 10 mg of Cu added/kg of DM (CU). Activity of superoxide dismutase was lower (P < .06) in neutrophils from MO vs CON or CU calves at 170 d of age. bactericidal activity of neutrophils from MO calves tended (P = .15) to be lower compared with those from CU calves at 70 d of age. Calves were inoculated intranasally with live infectious bovine rhinotracheitis virus (IBRV) 2 d after weaning, followed by intratracheal administration of Pasteurella hemolytica 5 d later. Iron- and Cu-supplemented calves exhibited higher (P < .01) body temperatures and lower (P < .06) feed intakes following IBRV inoculation compared with CON and MO calves. Copper-supplemented calves had higher levels of plasma tumor necrosis factor (TNF) than MO calves at weaning (P < .05) and tended to have higher plasma TNF (P = .11) than FE and MO calves 5 d after IBRV inoculation. These data indicate that dietary levels of Mo and Cu can affect body temperature and feed intake responses to disease by affecting TNF and perhaps other cytokines.

Immune response and disease resistance of calves fed chromium nicotinic acid complex or chromium chloride.

Twenty-one Holstein bull calves (< 7 d of age at the initiation of the experiment) fed a milk replacer diet were used to assess the effects of supplemental Cr on immune response. Treatments consisted of milk replacer without supplemental Cr (control) or milk replacer with 0.4 ppm of supplemental Cr from CrCl3 or a Cr-nicotinic acid complex. On d 64, increases in skinfold thickness after an intradermal injection of phytohemagglutinin were measured to evaluate cell-mediated immune response. Calves supplemented with Cr-nicotinic acid complex had a greater response than did controls at 6, 12, 24, and 48 h after injection. Calves supplemented with CrCl3 had a greater response than did controls at 24 and 48 h after injection. In vitro blastogenic responses of lymphocytes to phytohemagglutinin or pokeweed mitogen and antibody response to porcine red blood cells were not affected by treatment. Following a disease challenge with an intranasal dose of infectious bovine rhinotracheitis on d 75, body temperature tended to be lower for calves supplemented with Cr-nicotinic acid complex than for control calves. Calves supplemented with either Cr source had lower serum cortisol concentrations at 5 d after challenge. Chromium supplementation enhanced cell-mediated immune function.

Recovery rate and plasma zinc and copper concentrations of steer calves fed organic and inorganic zinc and manganese sources with or without injectable copper and challenged with infectious bovine rhinotracheitis virus.

Two experiments were conducted using feeder calves in a randomized block design to determine the effects of organic and inorganic sources of Zn and Mn fed pre- and posttransit (Exp. 1 and 2) with or without injectable Cu (Exp. 2) on DMI, rectal temperature, BW changes, and plasma Zn and Cu concentrations of feedlot steers challenged with infectious bovine rhinotracheitis virus (IBRV). In Exp. 1, before weaning, all steers and their dams received the following free-choice mineral supplements: 1) control (no supplemental Zn or Mn), 2) ZnO+MnO (ZnMnO), and 3) Zn methionine+Mn methionine (ZnMnMet). In Exp. 2, 18 d before weaning and shipping, steers were allotted into two groups (22 steers/group) and fed 225 mg of Zn.steer-1 x d-1 in .9 kg of ground corn as ZnO or ZnMet. Half of the steers from each group were injected (s.c.) with 120 mg of Cu from Cu glycinate. Steers (Exp. 1 and 2) were weaned and shipped approximately 2,500 km to the feedlot, where they received the same supplements in the form of a complete diet for 34 d, during which time calves recovered from the stress due to shipment. All steers were initially sero-negative to IBRV. On d 34 (d 0 of IBRV), all steers were challenged with IBRV and DMI, rectal temperature, and BW change were monitored for 28 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of copper deficiency on tissue, blood characteristics, and immune function of calves challenged with infectious bovine rhinotracheitis virus and Pasteurella hemolytica.

Fourteen Holstein steers, averaging 30 d of age, were fed a semipurified diet (1.5 mg of Cu/kg) supplemented with 0 (-Cu) or 10 mg of Cu/kg of diet (+Cu) for 5 mo. Calves were then challenged by consecutive exposure to aerosol preparations of infectious bovine rhinotracheitis virus (IBRV) and Pasteurella hemolytica on d 0 and 7, respectively, of the 30-d study. Serum ceruloplasmin and plasma copper were higher in +Cu calves throughout the challenge period and increased in +Cu calves after microbial challenge. Heart weights were higher in -Cu calves, although weights of liver, spleen, and thymus were not different between treatments. Copper concentrations in all tissues as well as thymus zinc were higher in +Cu calves. Serum immunoglobulin M tended to be higher in +Cu calves and increased in both treatments after IBRV challenge. Serum IBRV antibody titers were higher in -Cu calves with detectable seroconversion by d 10 postinfection. In contrast, antigen-specific antibodies to P. hemolytica tended to be higher in +Cu calves on d 21. Copper status did not affect blastogenic response, but phytohemagglutinin (PHA)-stimulated blastogenesis was higher in both treatments after IBRV challenge. Repletion of lymphocyte cultures with copper chloride increased proliferative responses to PHA in both +Cu and -Cu calves, and greater responses at all levels of copper (1 to 16 micrograms/mL) were noted in -Cu calves. These results indicate that copper deficiency affects various physiological characteristics that may be important in immunological defense to pathogenic challenge.

Influence of yeast culture on feeder calves and lambs.

Four experiments were conducted to determine the influence of yeast culture on 1) the health and performance of feeder calves, 2) the response of calves to an infectious bovine rhinotracheitis virus (IBRV) infection, and 3) nutrient utilization in lambs fasted for 3 d. In Exp. 1, 108 feeder calves were transported from Tennessee to Texas (1,600 km) and fed receiving diets containing 0 or .75% yeast culture and .35 or .69% P in a 2 x 2 factorial arrangement of treatments. In Exp. 2, 101 calves were transported 950 kg from Austin, TX to Bushland, TX and fed receiving diets containing 0, .75, 1.125, or 1.5% yeast culture. Yeast culture did not significantly affect the health or performance of calves in either experiment, although morbid calves fed yeast culture required fewer (P less than .05) days of antibiotic therapy in Exp. 2. In Exp. 3, feeder steers were fed diets containing 0 or .75% yeast culture and challenged intranasally with IBRV. Calves fed yeast culture tended to maintain heavier weights and higher DMI during IBRV infection than did steers fed the control diet. In Exp. 4, feeder lambs were fasted for 3 d and refed diets containing 0, .75, 1.125, or 1.5% yeast culture during a N and mineral balance trial. Lambs fed yeast culture had greater (P less than .08) N balance and tended to have greater Zn and Fe balance than control lambs. Results of these studies are interpreted to suggest that supplementation of morbid calves with yeast culture can have beneficial effects (fewer sick days, higher feed intakes) and that these effects may be mediated by improved N, Zn, and Fe metabolism.

Serum copper, zinc, calcium and phosphorus concentrations of calves stressed by bovine respiratory disease and infectious bovine rhinotracheitis.

The relationship between serum minerals and stress and(or) disease has not been fully evaluated in beef cattle. Two trials were conducted to determine the changes in serum Cu and Zn during market-transit stress and(or) disease. Two additional trials were conducted to determine the changes in serum Cu and Zn after inoculation with infectious bovine rhinotracheitis virus (IBRV), with one of the trials determining the changes in serum Ca and P. Trials 1 (n = 80) and 2 (n = 100) utilized calves that were handled through a normal market-transit system and transported 1,967 km to the feedlot. Trials 3 (n = 37) and 4 (n = 8) used calves that were sero-negative to IBRV and then challenged with 2.7 x 10(5) plaque-forming units of the virus. Serum samples were collected at specified intervals and serum minerals were measured for each trial. Serum Zn for morbid or IBRV-challenged calves was decreased by 34, 57, 29 and 15% (P less than .05) for the four trials, respectively, at peak morbidity. Serum Cu of morbid or IBRV-challenged calves increased 5, 15, 40 and 33% for the four trials, respectively, at peak morbidity. Feed intakes were lower during morbidity for market-transit trials and after IBRV inoculation. Lower feed intake could partially explain the decrease in serum Zn; however, when feed intake was held constant, serum Zn concentration still decreased. Serum Zn decreased and serum Cu increased during market-transit morbidity or after IBRV.

Adjuvanticity of recombinant bovine interleukin-1 beta: influence on immunity, infection, and latency in a bovine herpesvirus-1 infection.

Recombinant bovine interleukin-1 beta (rBoIL-1 beta) was administered to calves in conjunction with a bovine herpesvirus-1 (BHV-1) vaccine. All calves were immunized against BHV-1 and three groups received rBoIL-1 beta at 33, 100, or 330 ng/kg on days 1 and 15; control animals received physiological saline. All calves were challenged with BHV-1 on day 22. Total leukocytes were increased by rBoIL-1 beta, primarily by causing neutrophilia and monocytosis; CD4/CD8 ratios tended to be increased in rBoIL-1 beta-treated animals. Serum neutralizing antibody titers and cytotoxic responses against BHV-1-infected bovine kidney fibroblasts were increased and virus excretion was decreased in rBoIL-1 beta-treated calves. On days 58 and 59, control and 100 ng/kg rBoIL-1 beta-treated calves were injected with dexamethasone (.04 mg/kg). Virus excretion was less and clinical signs of BHV-1 infection were lower in rBoIL-1 beta-treated calves after dexamethasone injection. These data suggest that rBoIL-1 beta may be an effective adjuvant to BHV-1 immunization.