Effect of Nutritional Conditions on Changes in Leukocyte Populations in Japanese Black Calves

Comparative study of different liquid diets for dairy calves and the impact on performance and the bacterial community during diarrhea

The liquid diet composition can affect dairy calves' performance and diarrhea incidence. The effect of three liquid diets on performance, incidence of diarrhea, and microbial community during diarrhea occurrence in dairy calves were evaluated. At birth, 35 dairy calves (20 male and 15 female) were randomly assigned to one of three treatments-refrigerated whole milk (WM), acidified whole milk (AWM), and milk replacer (MR). Intake, fecal score, and rectal temperature were evaluated daily, and performance and blood parameters were evaluated weekly during the preweaning period. Fecal samples from diarrheic calves were collected, and one initial and one final sample for each episode were selected. The bacterial community was assessed by sequencing the V3-V4 region of the 16S rRNA gene on the Illumina MiSeq platform and analyzed using the DADA2 pipeline. Calves fed WM had higher body weight at weaning, average daily gain, body measurements, and concentration of blood metabolites. The AWM-fed calves had a lower rectal temperature and fever days. Moreover, the MR-fed calves had lower beta-hydroxybutyrate concentration and a higher incidence of diarrhea. The fecal bacterial community of diarrheic calves showed dissimilarity among the AWM and the other treatments. At the compositional level, we observed a higher abundance of Fusobacterium and Ruminococcus genera (AWM), Prevotella (WM), and Lactobacillus (MR). In the AWM and MR diarrheic calves' feces, we also observed some beneficial bacterial genera. The performance and incidence of diarrhea of dairy calves were influenced by the liquid diet consumed and the bacterial composition of diarrhea.

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.

Characterization of a variant CD4 molecule in Japanese Black cattle

Monoclonal antibodies (mAbs) that recognize cluster of differentiation (CD) molecules on lymphocytes are useful tools for the study of different lymphocyte subsets in flow cytometry (FCM) analysis. CD4 is a glycoprotein found on the surfaces of helper T cells, monocytes, macrophages, and dendritic cells. In this study, we describe Japanese Black (JB) calves in a farm whose peripheral blood mononuclear cells (PBMCs) did not react with a CD4-specific mAb. To identify calves with PBMCs with low mAb reactivity, PBMCs from 21 JB calves (1-12 months of age) bred at the same farm were examined using two different bovine CD4 mAbs (clones #CC8 and #CACT138A). FCM analysis indicated that the calves fell into two groups based on reactivity against the two mAbs, i.e., double-positive (DP) calves, whose PBMCs were recognized by both mAbs clones, and single-positive (SP) calves, whose PBMCs were only recognized by #CACT138A. PBMCs from seven calves were not recognized by #CC8, although they had normal reactivity with another mAb, #CACT138A. Sequencing analysis of the CD4 gene in these calves revealed four nucleotide substitutions (G918 T, A930C, G970A, and G1074A) in the coding region in the SP group when compared to the DP group. Three of the four mutations were associated with amino acid substitution (Q306H, K310 N, and A324 T). The substitution at A324 T was located in the D4 domain of CD4 gene. Homology modeling based on the amino acid sequences revealed that the surface structure of this part of the molecule was significantly different between the SP and the DP groups. Therefore, the epitope recognized by the #CC8 CD4 mAb was altered in calves with this genetic mutation, and this led to the low reactivity of the PBMCs from calves in the SP group aginst the #CC8 mAb. In conclusion, this is the first study to identify CD4 variants in JB cattle. We confirmed that the variants did not affect lymphocyte functions, such as mitogen stimulation or lipopolysaccharide-induced cytokine gene expression.

Comparison of Two Different Nutritive Conditions against the Changes in Peripheral Blood Mononuclear Cells of Periparturient Dairy Cows

To clarify the relationship between cellular immune status and nutritive condition in periparturient dairy cows, feeding content, blood profiles, and immune condition were observed in cows from two dairy herds with different types of feed content. Immunological analyses such as leukocyte population and peripheral blood mononuclear cell (PBMC) mRNA of IFN-gamma, TNF-alpha, IL-4, and IL-10, quantified by real-time RT-PCR were performed. With regard to feed content during dry periods, there were six cows in the herd with insufficient non-structural carbohydrate (NFC) intake (group I) and six cows in the herd with sufficient NFC intake (group II). Significantly lower levels of blood glucose were observed in group I between weeks -12 and 16 compared with group II. Serum cholesterol level was significantly lower in group I between weeks 2 and 10 than in group II. The numbers of CD3+ and CD4+ T cells in group I were significantly lower than those in group II in weeks 6 and 14. The numbers of CD21+ B cells were significantly lower in group I than in group II in weeks -16, -12, 2, and 10. On the other hand, the CD4+/CD8+ ratio in group II was significantly higher than group I between weeks 2 and 14. The IFNgamma/IL-4 mRNA rate in group I was significantly lower than group II in week 6. We concluded that cellular immune depression occurrs after calving in dairy cows with low nutritional status in the periparturient period.