Histological Characteristics of Conjunctiva-Associated Lymphoid Tissue in Young and Adult Holstein Cattle.

The conjunctiva-associated lymphoid tissue (CALT) has been used as a target site for mucosal vaccinations in several animals. In this study, we compared the morphological features of CALT in the eyelid and third eyelid between Holstein calves and adult cows. In the eyelids, CALTs in the form of diffused lymphoid tissue (DLT) and lymphatic follicles (LF) were observed, where DLTs were dominant and LFs were scarce. The CALTs of cows comprised T-, B-cells, macrophages, and antigen-presenting cells (APCs). In particular, B-cells were dominant except in the eyelids of the calves. The epithelial layer covering the CALT is often discontinuous and lacks goblet cells. Cytokeratin18 is strongly expressed in the epithelial layer covering the CALT, except in the third eyelids of adult cows. IgA-positive cells were diffusely distributed in the lamina propria of the conjunctiva of the eyelids and third eyelids. The eyelid CALT area in calves was lower than that in adult cows. Furthermore, the CALT of calves had a lower cellularity of B-cells and a higher cellularity of macrophages than that of adult cows. These histological characteristics indicate that CALT plays a role in the mucosal immune-inductive and effector sites. Furthermore, lower cellularity of B-cells in the CALT of calves indicates that the function of CALT as a mucosal immune induction site is less developed in calves than in adult cows.

Antibody response to 1.0 and 0.5 mL doses of an inactivated bacterial vaccine against bovine respiratory disease in young Holstein calves: a field trial.

Introduction: Early vaccination of cattle with an inactivated commercial bacterial vaccine against bovine respiratory disease has been reported to increase antibody production and can alleviate the disease. However, its dosage has been little investigated in young Holstein calves. This study addresses the need to establish guide values for vaccine dosage in these animals. Material and Methods: Healthy calves received an inactivated vaccine for Histophilus somni, Pasteurella multocida and Mannheimia haemolytica intramuscularly at the ages of 1 and 4 weeks. Administered vaccine doses were 1.0 mL for the primary and booster vaccinations (1.0 + 1.0 group), 0.5 mL for the primary and 1.0 mL for the booster vaccination (0.5 + 1.0 group), or 0.5 mL for both vaccinations (0.5 + 0.5 group). Results: Differences in the vaccine responses between the 1.0 + 1.0 group and 0.5 + 1.0 group were minor. However, the number of calves with a positive vaccine response to H. somni in the 0.5 + 0.5 group was less than half of that in the 1.0 + 1.0 and 0.5 + 1.0 groups. In logistic regression analysis, although the booster vaccination dose was positively correlated with seropositivity for H. somni, the primary vaccination dose was not correlated with vaccine response. The number of calves with positive vaccine responses to M. haemolytica was low even after booster vaccination regardless of the dose. Conclusion: The dose of 0.5 mL can be used for primary vaccinations in newborn Holstein calves, but 1.0 mL may be required for booster vaccinations.

mRNA expression of immune factors by milk somatic cells from healthy Holstein lactating cows.

This study investigated the mRNA of immune factors expressed by milk somatic cells from 72 healthy lactating Holstein cows on 1 farm. Milk samples were collected aseptically from the right front mammary gland before milking. The milk samples that had a negative reaction to the California mastitis test were used to analyze the mRNA of immune factors. Cows were divided into 2 groups based on the detection of bacteria in milk samples: positive group (n = 22 cows), which showed bacteria in cultures, and negative group (n = 50 cows), which did not show bacteria in cultures. There were significant positive correlations among the relative mRNA levels of interleukin (IL)-6, IL-8, arginase 1, chemokine (C-C motif) ligand (CCL) 1, and chemokine (C-X-C motif) ligand (CXCL) 13, as well as among the relative mRNA levels of IL-10, pentraxin 3, CCL5, and CCL14. Significantly high levels of IL-1ß, IL-6, IL-8, arginase 1, Batf, CCL1, CXCL14, and toll-like receptor 4 in the positive group were discovered compared to the negative group. These results suggest that the presence of bacteria in lactating healthy dairy cows may affect mRNA levels of inflammatory mediators expressed by somatic cells.

Cette étude a examiné l'ARNm des facteurs immunitaires exprimés par les cellules somatiques du lait de 72 vaches Holstein en lactation en bonne santé dans une ferme. Des échantillons de lait ont été prélevés aseptiquement du quartier avant droit de la glande mammaire avant la traite. Les échantillons de lait ayant eu une réaction négative au test de mammite de Californie ont été utilisés pour analyser l'ARNm des facteurs immunitaires. Les vaches ont été divisées en deux groupes sur la base de la détection de bactéries dans les échantillons de lait : groupe positif (n = 22 vaches), qui a montré la présence de bactéries lors des cultures, et groupe négatif (n = 50 vaches), qui n'a pas montré de bactéries lors des cultures. Il y avait des corrélations positives significatives entre les niveaux relatifs d'ARNm de l'interleukine (IL)-6, de l'IL-8, de l'arginase 1, du ligand de chimiokine (motif C-C) (CCL) 1 et du ligand de chimiokine (motif C-X-C) (CXCL) 13, ainsi que parmi les niveaux relatifs d'ARNm d'IL-10, de pentraxine 3, de CCL5 et de CCL14. Des niveaux significativement élevés d'IL-1ß, d'IL-6, d'IL-8, d'arginase 1, de Batf, de CCL1, de CXCL14 et de récepteur de type Toll 4 dans le groupe positif ont été découverts par rapport au groupe négatif. Ces résultats suggèrent que la présence de bactéries chez des vaches laitières saines en lactation peut affecter les niveaux d'ARNm des médiateurs inflammatoires exprimés par les cellules somatiques.(Traduit par Docteur Serge Messier).

Effect of supplementation with Saccharomyces boulardii CNCM I-1079 on vaccine response to an inactivated bacterial vaccine in young Japanese Black calves: A field trial.

Saccharomyces boulardii group (SB group) calves were fed 2.0 × 1010 CFU/day of S. boulardii in milk replacer after 2 wk of age. All calves received inactivated vaccine for Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica at 3 wk of age and 3 wk later. After vaccination, the SB group calves showed significantly higher (mean difference: 1.56-fold) antibody titer against H. somni than the control group. The number of calves with the antibody titer above the cut-off value for M. haemolytica of the SB group was significantly higher than that of the control, and the percentage was twice as high. In addition, the mRNA transcription of IL4 and IL10 in peripheral blood mononuclear cells at the booster of the SB group was significantly higher than those of the control. In conclusion, S. boulardii may have positively affected immune responses to the inactivated multi-bacterial vaccine in young calves in the field.

Les veaux du groupe Saccharomyces boulardii (groupe SB) ont reçu 2,0 × 1010 UFC/jour de S. boulardii dans du lait de remplacement après l'âge de 2 semaines. Tous les veaux ont reçu un vaccin inactivé contre Histophilus somni, Pasteurella multocida et Mannheimia haemolytica à l'âge de 3 semaines et 3 semaines plus tard. Après vaccination, les veaux du groupe SB ont montré un titre d'anticorps contre H. somni significativement plus élevé (différence moyenne : 1,56 fois) que le groupe témoin. Le nombre de veaux avec un titre d'anticorps supérieur à la valeur seuil pour M. haemolytica du groupe SB était significativement plus élevé que celui du groupe témoin, et le pourcentage était deux fois plus élevé. De plus, la transcription de l'ARNm de l'IL4 et de l'IL10 dans les cellules mononucléaires du sang périphérique lors du rappel du groupe SB était significativement plus élevée que celles du groupe témoin. En conclusion, S. boulardii peut avoir affecté positivement les réponses immunitaires au vaccin multibactérien inactivé chez les jeunes veaux au champ.(Traduit par Docteur Serge Messier).

Effect of live yeast Saccharomyces cerevisiae supplementation on immune factors in Japanese Black calves during the growth periods.

The aim of this study was to investigate changes in expression levels of immune factors of peripheral blood mononuclear cells (PBMC) after oral supplementation of live yeast Saccharomyces cerevisiae to healthy Japanese Black (JB) calves. This study examined JB calves (N=28): 14 calves (SC Group) received 10 g/calf/day of Saccharomyces cerevisiae (SC) (Acti-Saf Sc 47), and the other calves did not receive supplement (Control Group). Blood samples were collected 9 times during experimental period (1, 2, 3, 4, 5, 6, 7, 8 and 9 months of age), and analyzed for cytokines and chemokines mRNA expression of PBMC using Real-time PCR. The level of beta Hydroxybutanoic acid (BHB) in the SC Group was significantly high at 7 and 8 months of age compared to that in the Control Group. Lymphocyte counts in the SC Group were significantly higher at 2 and 5 to 6 months of age compared to the Control Group. Significant differences were found for IL-12p40 level at 4, 7 and 9 months of age, and for IFN-γ level at 6, 7 and 8 months of age. The level of CXCR3 was significantly higher at 6 to 7 months of age by dietary SC supplementation. These results indicated that SC supplementation improved the cellular immune responses of JB calves.

Field Trial of Antibody Response To Inactivated Bacterial Vaccine in Young Holstein Calves: Influence of Animal Health Status.

Introduction: Bovine respiratory disease (BRD) is one of the primary causes of death in young calves. Vaccination against infection by the common bacteria causing BRD is possible; however, the physical condition of the young calves that enables antibody production when stimulated by early immunisation remains to be elucidated. Material and Methods: Healthy young female Holstein calves on a commercial dairy farm were fed a colostrum replacer and administered primary and booster immunisations with an inactivated vaccine against the bacterial pneumonia agents Histophilus somni, Pasteurella multocida and Mannheimia haemolytica. At each immunisation, the body weight and height at the withers were measured and the body mass index (BMI) was calculated. Blood was sampled immediately before immunisation and 3 weeks following the booster. The calves were divided into positive and negative groups based on the antibody titre at the final blood sampling. Maternal antibody titres at the primary immunisation and BMI, nutritional status and oxidative stress at both immunisations were compared between the two groups. Results: Antibody titre at the primary and BMI at both immunisations were significantly higher in the positive than in the negative group (P < 0.05). Additionally, serum gamma globulin was significantly higher in the positive group (P < 0.05), indicating a strong correlation between maternal antibody and serum gamma globulin levels. Conclusion: Elevated maternal antibody titre and higher BMI are positive factors for successful early immunisation, for which suitable colostrum may also be fundamental in young calves administered inactivated vaccines.

Effects of intra-articular inoculation with Mycoplasma bovis on immunological responses in calf joints.

Mycoplasma arthritis that caused by Mycoplasma bovis exhibit severe lameness. This disease is difficult to cure with antibiotics, but the detailed pathological mechanisms have not been fully clarified. In this study, we examined the effects of intra-articular inoculation with M. bovis on immunological responses in calf joints. We inoculated three calves each with M. bovis or phosphate buffer saline (control) into the right stifle joint and dissected them at 15 days postinoculation. Mycoplasma bovis-inoculated calves exhibited swelling of the stifle joint, increases in synovial fluid, fibrin deposition, and cartilage thinning. Intracellular M. bovis was detected in synovial tissues analyzed by immunohistochemistry and transmission electron microscopy. Messenger RNA expressions of interleukin (IL)-1ß, IL-6, IL-8, IL-12p40, and IL-17A in synovial fluid cells and synovial tissues from M. bovis-inoculated calves were significantly higher than those from control calves. Protein levels of these cytokines in synovial fluid from M. bovis-inoculated calves were markedly higher than those from control calves. Our study clarified that inoculation with M. bovis into the stifle joint induced the production of inflammatory cytokines by synovial fluid cells and synovial tissues, causing a severe inflammatory response in joints. Additionally, M. bovis could invade cells in synovial tissues, which may have aided it in evading antibiotics and host immune surveillance.

Changes in mRNA of immune factors expressed by milk somatic cells of Holstein cows with hypocalcemia after calving.

Changes in immune factors expressed by milk somatic cells from Holstein cows with hypocalcemia after calving were investigated in this study. Fourteen multiparous Holstein cows after their 3rd or 4th calving in one farm were used. The cows were divided into 2 groups: 7 cows needing treatment due to onset of hypocalcemia (hypocalcemia group; age = 5.53 ± 0.27 years, parity = 3.14 ± 0.14) and 7 cows without health problems (control group; age = 5.88 ± 0.31 years, parity = 3.57 ± 0.26). Milk samples were collected aseptically using a cannula and mRNA of immune factors expressed by milk somatic cells were analyzed. Milk samples (50 mL) were collected from the right rear mammary gland of cows before milking at day 1 and weeks 1, 2, 4, and 8 after calving. All milk samples showed a negative reaction to the California Mastitis Test. Levels of relative interleukin (IL)-6 and cathelicidin in the hypocalcemia group were lower than those in the control group in weeks 1 to 8. A significant difference in relative IL-6 levels was found in week 4 (P < 0.05). These results suggest that levels of IL-6 expressed by milk somatic cells may be affected by hypocalcemia in dairy cows.

Dans la présente étude les modifications des facteurs immunitaires exprimées par les cellules somatiques du lait de vaches Holstein présentant une hypocalcémie après le vêlage ont été examinées. Quatorze vaches Holstein multipares après leur 3e ou 4e vêlage provenant d'une ferme ont été utilisées. Les vaches ont été réparties en deux groupes : sept vaches nécessitant un traitement en raison de l'apparition d'une hypocalcémie (groupe hypocalcémie; âge = 5,53 ± 0,27 ans, parité = 3,14 ± 0,14) et sept vaches sans problème de santé (groupe témoin; âge = 5,88 ± 0,31 ans, parité = 3,57 ± 0,26). Des échantillons de lait ont été prélevés de manière aseptique à l'aide d'une canule et l'ARNm des facteurs immunitaires exprimés par les cellules somatiques du lait a été analysé. Des échantillons de lait (50 mL) ont été prélevés dans la glande mammaire arrière droite des vaches avant la traite au jour 1 et aux semaines 1, 2, 4 et 8 après le vêlage. Tous les échantillons de lait ont montré une réaction négative au California Mastitis Test. Les niveaux relatifs d'interleukine (IL)-6 et de cathélicidine dans le groupe hypocalcémie étaient inférieurs à ceux du groupe témoin au cours des semaines 1 à 8. Une différence significative des taux relatifs d'IL-6 a été observée à la semaine 4 (P < 0,05). Ces résultats suggèrent que les taux d'IL-6 exprimés par les cellules somatiques du lait peuvent être affectés par l'hypocalcémie chez les vaches laitières.(Traduit par Docteur Serge Messier).

Field Trial of Primary and Booster Dose of Inactivated Vaccine Against Bovine Respiratory Bacteria in Young Holstein Calves.

INTRODUCTION: The objective of this research was to evaluate the antibody response to multiple doses of an inactivated mixed vaccine against Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica, and to investigate the influence of age at time of vaccination in the field. MATERIAL AND METHODS: Healthy female Holstein calves received the vaccine at the age of 5-12 days and 2, 3, or 4 weeks later in the first experiment or at 1, 2, or 3 weeks of age and 4 weeks later in the second. Blood samples were collected at each vaccination and 3 weeks after the booster dose. Based on the antibody titres after the vaccinations, calves were divided into positive and negative groups for each of the bacteria. Calves in the control group were vaccinated only once at the age of 19-26 days. RESULTS: Antibody titres against H. somni and P. multocida were significantly increased by the booster. After the second vaccinations, the titres against each bacterium were higher than those of the control group, and the M. haemolytica-positive percentage in calves with high maternal antibody levels (MAL) exceeded that in calves with low MAL. In the first experiment, a majority of the M. haemolytica-positive calves tended to have received the primary dose at seven days of age or older. CONCLUSION: A booster dose of the inactivated bacterial vaccine in young Holstein calves increased antibody production and overcame the maternal antibodies. Calves should be vaccinated first at seven days of age or older.

Cytokine levels of peripheral blood mononuclear cells in the clinical cases of Holstein calves infected with Mycoplasma bovis.

The immune related factors of peripheral blood mononuclear cells (PBMC) were analyzed in the clinical cases with Mycoplasma (M.) bovis infection. Seventy-eight Holstein calves in one farm were used. These calves were divided into three groups; the calves with M. bovis infection of poor outcome after treatment (Non-Recovery Group), the calves with M. bovis infection recovered (Recovery Group) and clinically healthy calves (Control Group). Blood samples were collected at days of the first medical treatment and the final treatment or euthanasia. IL-17A levels in the Non-Recovery Group were higher than those in the Recovery Group on both days. Our result suggested that the IL-17A of PBMC is an important factor to affect outcome of the calves with M. bovis infection.

Relationship Between mRNA of Immune Factors Expressed by Milk Somatic Cells and Bacteria Present in Healthy Lactating Holstein Cows.

INTRODUCTION: The characteristics of immune factors in somatic cells from lactating dairy cows and their association with commensal bacteria in normal milk have not been clarified. This study investigated the relationship between the pathogenic bacteria in milk and somatic cell immune factors in healthy lactating cows. MATERIAL AND METHODS: In total 44 healthy Holstein cows were studied on one farm. Milk samples were collected aseptically using a cannula and these samples were cultured for detection of bacteria and analysis of mRNA of immune factors expressed by somatic cells. Cows were divided into two groups based on the microbial status of their milk samples: 12 cows showed bacteria in cultures (positive group), and the other 32 cows did not (negative group). RESULTS: The mRNA levels of IL-6, lactotransferrin, and cathelicidin expressed by somatic cells after milking decreased significantly compared to those before milking in both groups (P < 0.05). There were significantly lower mRNA levels of IL-6 and cathelicidin in the positive group compared to those in the negative group before milking. CONCLUSION: These results suggest that mRNA levels of IL-6 and cathelicidin expressed by the somatic cells may be affected by the presence of bacteria in healthy lactating dairy cows.

Effect of yeast cell wall supplementation on production performances and blood biochemical indices of dairy cows in different lactation periods.

AIM: This experiment was conducted to determine the effect of yeast cell wall (YCW) supplementation on production performances and blood biochemical indices such as liver enzyme activities, energy metabolites, and electrolyte concentrations of dairy cows in different lactation periods (LP). MATERIALS AND METHODS: Thirty-two lactating Holstein cows were assigned into 2×2 factorial arrangement, in which the factors were the treatment (TM) (control [n=16] vs. YCW [n=16]) and the LP (early lactation [n=14] vs. mid-lactation [n=18]). The cows with day in milk (DIM) <120 (81±7 DIM) were defined as early lactating cows, whereas the cows with DIM >120 (179±5 DIM) were assumed as mid-lactating cows. The YCW (SafMannan; Phileo, Lesaffre Animal Care, France) was used as the dietary supplement (10 g/cow/day) in this experiment. The statistical analysis of the data was performed by the two-way analysis of variance using the general linear model procedure to determine the main effects (TM and LP) and their interaction (TM×LP) on production performances and blood biochemical parameters of experimental cows. RESULTS: No significant effects (p>0.05) of YCW supplementation on production performances and blood biochemical indices of cows in TM groups (control vs. YCW) were observed; however, some obvious effects were detected in LP (early- and mid-lactation). Milk and milk component yield of cows in early lactation were significantly higher (p<0.05) than in mid-lactation, whereas somatic cell count and milk urea nitrogen were not different (p>0.05) with the YCW supplementation. The higher level (p<0.05) of serum albumin was found in mid-lactating cows after YCW supplementation. Before the experiment, the higher (p<0.05) non-esterified fatty acid (NEFA) and NEFA/total cholesterol (T-Cho) ratio, and the lower (p<0.05) calcium (Ca) concentration were observed in early lactating cows comparison with mid-lactating cows; however, there were not different after YCW supplementation. CONCLUSION: The positive effects of YCW supplementation on milk and milk component yields, energy metabolite, especially NEFA and NEFA/T-Cho ratio and Ca concentration were observed in early lactating cows rather than mid-lactating cows.

Effect of Mycoplasma bovis on expression of inflammatory cytokines and matrix metalloproteinases mRNA in bovine synovial cells.

Mycoplasma bovis causes chronic arthritis in calves. Mycoplasma arthritis shows severe inflammatory reactions in joints that is commonly treated with antibiotics and results in significant economic losses in the calf industry. A previous study showed that inflammatory cytokines and matrix metalloproteinases (MMPs) produced by synovial cells promote progression of the pathophysiology of bacterial arthritis. However, the mechanism underlying the pathogenesis of bovine Mycoplasma arthritis has not been fully clarified. In this study, we examined the immunologic response of bovine synovial tissue to M. bovis. We observed significant increases in expression of interleukin (IL)-1ß, IL-6, IL-8, MMP-1, and MMP-3 mRNA in synovial tissue from Mycoplasma arthritis calves compared with tissues from normal calves. Expression of IL-6, IL-8, and MMP-1 mRNA was also induced in cultured synovial cells stimulated with M. bovis, but not expression of IL-1ß and MMP-3 mRNA. In contrast, the culture supernatant of peripheral blood mononuclear cells stimulated with M. bovis induced marked increases in the expression of IL-1ß, IL-6, IL-8, MMP-1, and MMP-3 mRNA in synovial cells. Our results indicate that inflammatory cytokines and MMPs produced by synovial cells play a key role in the pathogenesis of Mycoplasma arthritis. We suggest that interactions between synovial cells and mononuclear cells in the presence of M. bovis induce expression of these cytokines and MMPs in synovial cells, resulting in severe inflammatory reactions in the joints.

Identification of an antilymphocyte transformation substance from Pasteurella multocida.

Pasteurella multocida is one of the most important bacteria responsible for diseases of animals. Crude extracts from sonicated P. multocida strain Dainai-1, which is serotype A isolated from bovine pneumonia, were found to inhibit proliferation of mouse spleen cells stimulated with Con A. The crude extract was purified by cation and anion exchange chromatography and hydroxyapatite chromatography. Its molecular weight was 27 kDa by SDS-PAGE and it was named PM27. PM27 was found to inhibit proliferation of mouse spleen cells stimulated with Con A as effectively as did the crude extract; however, its activity was lost after heating to 100°C for 20 min. PM27 did not directly inhibit proliferation of HT-2 cells, which are an IL-2-dependent T cell line, nor did it modify IL-2 production by Con A-stimulated mouse spleen cells. The N-terminal amino acid sequence of PM27 was determined and BLAST analysis revealed its identity to uridine phosphorylase (UPase) from P. multocida. UPase gene from P. multocida Dainai-1 was cloned into expression vector pQE-60 in Escherichia coli XL-1 Blue. Recombinant UPase (rUPase) tagged with His at the C-terminal amino acid was purified with Ni affinity chromatography. rUPase was found to inhibit proliferation of mouse spleen cells stimulated with Con A; however, as was true for PM27, its activity was lost after heating to 100°C for 20 min. Thus, PM27/UPase purified from P. multocida has significant antiproliferative activity against Con A-stimulated mouse spleen cells and may be a virulence factor.

Heme-binding of bovine lactoferrin: the potential presence of a heme-binding capacity in an ancestral transferrin gene.

Lactoferrin (Lf) and transferrin (Tf) are iron-binding proteins that can bind various metal ions. This study demonstrates the heme-binding activity of bovine Lf and Tf using biotinylated hemin. When both proteins were coated on separate plate wells, each directly bound biotinylated hemin. On the other hand, when biotinylated hemin was immobilized on an avidin-coated plate, soluble native Lf bound to the immobilized biotinylated hemin whereas native Tf did not, suggesting that a conformational change triggered by coating on the plate allows the binding of denatured Tf with hemin. Incubation of Lf with hemin-agarose resulted in negligible binding of Lf with biotinylated hemin. Lf in bovine milk also bound to immobilized biotinylated hemin. These results demonstrate that bovine Lf has specific heme-binding activity, which is different from Tf, suggesting that either Tf lost heme-binding activity during its evolution or that Lf evolved heme-binding activity from its Tf ancestral gene. Additionally, Lf in bovine milk may bind heme directly, but may also bind heme indirectly by interaction with other milk iron- and/or heme-binding proteins.

Effect of acetate Ringer's solution with or without 5% dextrose administered intravenously to diarrheic calves.

The objectives of this study were to evaluate the effects of intravenous acetate Ringer's solution, with or without dextrose, on diarrheic calves with either experimentally induced or spontaneous diarrhea. In the experimental model, diarrhea was induced in nine healthy calves by administering cold milk (below 4°C) twice a day for 2 days. The calves were randomly assigned to the isotonic saline (ISS), acetated Ringer's (AR) or acetated Ringer's with 5% dextrose (ARD) groups, with three calves assigned to each group. The calves received 80 ml/kg of their designated solution, at a flow rate of 20 ml/kg/hr. Infusion of ISS, AR and ARD were all found to be safe and effective in increasing plasma volume. Intravenous (IV) infusion of ISS resulted in the acidification secondary to dilution, while AR and ARD infusion inhibited acidification. In addition, prevention of catabolism was observed only with IV infusion of ARD. Sixteen calves with spontaneous diarrhea were enrolled in the clinical study. The calves were randomly assigned to the AR or ARD groups, with eight calves being assigned to each group. The calves received 100 ml/kg of their designated solution, at a flow rate of 25 ml/kg/hr. Intravenous infusion of AR and ARD was found to be effective in increasing plasma volume and inhibiting acidification. Only infusion of ARD prevented catabolism, but it also led to hyperglycemia. Our results suggest that a solution containing dextrose may be beneficial for wasting diarrheic calves.

Iron and Ferritin Levels in the Serum and Milk of Bovine Leukemia Virus-Infected Dairy Cows.

Iron metabolism was examined in 15 bovine leukemia virus (BLV)-infected dairy cows (2.6-7.8 years old). BLV infection was detected by measuring serum antibody titer against BLV virus antigen (gp51). The anti-BLV antibody titers of the BLV-infected cows were significantly higher in serum than in milk; a single serum-positive animal lacked detectable anti-BLV antibodies in its milk. Iron and ferritin concentrations also were significantly higher in serum than in milk. Although most of the BLV-infected dairy cows had past or present anamneses (such as inflammatory diseases, including intramammary infection), the milk ferritin concentrations of the infected cows were significantly lower than those of normal cows; serum ferritin concentrations did not differ significantly between these two groups. The anti-BLV antibody titers in milk samples showed significant correlation with serum iron concentrations. These results suggest that BLV infection affects iron homeostasis through iron metabolism in the dairy cow mammary gland.

Effect of supplemental vitamin E on the peripheral blood leukocyte population in Japanese Black calves.

We investigated the effect of supplemental vitamin E on the peripheral blood leukocyte population in Japanese Black calves. Twenty-six calves kept at the same farm were studied. They were divided into two groups; thirteen calves received 300 IU/day of vitamin E orally from 1 to 3 months of age (VE group), and the other thirteen calves did not receive the vitamin E supplement (control group). The VE group showed a higher serum vitamin E concentration at 2 and 3 months of age compared with the control group (P<0.01). The numbers of CD3(+) cells and CD4(+) cells were higher in the VE group than in the control group, and the difference was statistically significant at 3 months of age (P<0.05). The numbers of CD21(+) cells were higher in the VE group than in the control group, and the difference was statistically significant at 2 months of age (P<0.05). The numbers of CD335(+) cells tended to be higher in the VE group than in the control group. The numbers of CD8(+) cells and CD14(+) cells tended to be higher in the VE group than in the control group at 3 and 4 months of age. This study demonstrated that the supplementation of suckling Japanese Black calves with vitamin E might affect the numbers of some immune cell types in the peripheral blood.

Comparison of cytokine mRNA expression in peripheral CD4(+) , CD8(+) and γδ T cells between healthy Holstein and Japanese Black calves.

Japanese Black (JB) calves are more susceptible to infectious diseases compared to Holstein (Hol) calves. To clarify the immunological differences between JB and Hol calves, expression of cytokine messenger RNA (mRNA) was examined using peripheral CD4(+) , CD8(+) and γδ T cells. Healthy calves, 24 from each species, were examined. Blood samples were obtained from calves at 1 week, 1 month and 3 months old, eight calves for each age of each species. Peripheral blood mononuclear cells were stimulated with phytohemagglutin (PHA), and T cell subsets were isolated by positive selection using magnetic cell sorting (MACS). Levels of interlekin (IL)-2, IL-4, IL-10 and interferon (IFN)-γ mRNA in three T cell subsets were analyzed. WC1-N1(+) γδ T cell percentages were significantly lower in JB calves at 1 week and 1 month of age compared to Hol calves. In addition JB calves had significantly lower IL-2, IL-10 and IFN-γ mRNA in WC1-N1(+) γδ T cells at 1 and 3 months of age, whereas there were no significant differences in cytokine mRNA of CD4(+) and CD8(+) cells between the two groups. Decreased cytokine mRNA and cell number of peripheral γδ T cells may affect negatively on the immune system of JB calves.

Changes in leukocyte populations of cows with milk fever or displaced abomasum after calving.

Most of the metabolic diseases of dairy cows occur within the first 2 wk after calving, and cows with a metabolic disease are prone to infectious diseases. Although metabolic diseases are generally recognized as a risk factor for infectious diseases owing to the associated decrease in immune function, the difference in immune status between cows with milk fever (MF) or displaced abomasum (DA) during the lactation period has not been clarified. Therefore, the peripheral blood leukocyte populations in 38 multiparous Holstein cows from 1 herd were analyzed after calving. The cows were divided into 3 groups according to health: 21 cows that remained clinically healthy throughout the experimental period (control group), 9 cows that had MF on the day of calving, and 8 cows with an onset of DA within 4 wk after calving. The T- and B-cell numbers were lowest at week 0, and they increased gradually after calving. There was no significant difference between the 3 groups in the number of each subset of leukocytes on the day of calving, but the number of CD8⁺ T-cells was significantly lower in the MF and DA groups than in the control group at week 1. The numbers of CD4⁺, CD8⁺, and WC1⁺ T-cells tended to be lower in the DA group than in control group from weeks 4 to 12, a tendency not observed in the MF group. These data suggest that when cows have DA around the time of calving, their lymphocyte numbers remain lower until 12 wk after calving.

La plupart des maladies métaboliques des vaches laitières se produisent à l'intérieur des 2 premières semaines après le vêlage, et les vaches avec une maladie métabolique sont sujettes aux maladies infectieuses. Bien que les maladies métaboliques soient généralement reconnues comme un facteur de risque pour les maladies infectieuses à cause de la diminution de la fonction immunitaire qui y est associée, la différence dans le statut immunitaire entre des vaches avec une fièvre du lait (MF) ou un déplacement de caillette (DA) durant la période de lactation n'a pas été clarifiée. Ainsi, les populations des leucocytes du sang périphérique de 38 vaches Holstein multipares provenant de un troupeau ont été analysées après le vêlage. Les vaches ont été divisées en trois groupes selon leur état de santé : 21 vaches qui sont demeurées cliniquement saines durant toute la durée de la période expérimentale (groupe témoin), 9 vaches qui ont eu une MF le jour du vêlage, et 8 vaches avec un début de DA dans les 4 sem après le vêlage. Le nombre de cellules T et B étaient à son plus bas la semaine 0, et il a augmenté graduellement après le vêlage. Il n'y avait pas de différence significative entre les trois groupes dans le nombre de chaque sous-groupe de leucocytes le jour du vêlage, mais le nombre de cellules T CD8+ était significativement plus faible dans les groupes MF et DA que dans le groupe témoin à la semaine 1. Le nombre de cellules T CD4+, CD8+ et WC1+ avaient tendance à être plus faible dans le groupe DA que dans le groupe témoin à partir de la semaine 4 jusqu'à la semaine 12, une tendance non observée dans le groupe MF. Ces données suggèrent que lorsque les vaches ont un DA durant la période du vêlage, leurs dénombrements lymphocytaires demeurent faibles jusqu'à 12 sem après la mise-bas.(Traduit par Docteur Serge Messier).