# Variants in Nucleotide Sequences; Gene Expression; and Hematological, Immune, and Antioxidant Biomarkers Linked to Pneumonia Risk in Holstein Calves

## TL;DR

This study identifies genetic and immune markers in calves that are associated with pneumonia risk, offering a potential strategy for reducing the disease through selective breeding.

## Contribution

The study reveals novel associations between nucleotide sequence variants, gene expression, and immune/antioxidant biomarkers linked to pneumonia in calves.

## Key findings

- Pneumonic calves showed significant differences in hematological, immunological, and antioxidant biomarkers compared to healthy calves.
- Genes like IL1α, IL-1β, IL-6, IFN-γ, and TNF-α were upregulated in pneumonic calves, while IL10, PRDX6, ATG7, and NDUFS6 were downregulated.
- Nucleotide sequence differences in immunity and antioxidant genes were observed between pneumonic and healthy calves.

## Abstract

Pneumonia is a serious problem that influences the health and productivity of calves and results in various losses. This work aimed to examine the immunological and antioxidant responses, as well as genetic and molecular differences, in calves that are prone to pneumonia. Out of the 225 calves, 180 Holstein calves had respiratory symptoms, while 45 cases seemed to be healthy. Blood was collected from the diseased and apparently healthy calves for CBC and RNA extraction. The pneumonic calves had significantly different hematological, immunological, and antioxidant blood levels; expression patterns; and SNPs of genes related to immunity and antioxidants when compared to healthy calves. These findings offer a practical strategy for reducing the incidence of pneumonia in calves by selective breeding based on genetic markers.

Pneumonia is a major issue that affects calves’ health and performance and causes numerous losses despite treatment. Investigating genetic and molecular differences, as well as immunological and antioxidant responses, in calves at risk for pneumonia was the aim of this study. A total of 225 calves were studied, including 180 Holstein calves with respiratory signs and 45 calves that were apparently healthy. Blood samples were collected for CBC, RNA extractions, and immunological and antioxidant analysis. In contrast to the control group, the pneumonic one showed a considerable (p < 0.05) increase in the expression levels of cytokines and antioxidant genes IL1α, IL-1β, IL-6, IFN-γ, TNF-α, and NOX4. In contrast, the values of IL10, PRDX6, ATG7, and NDUFS6 were in the opposite range. The pneumonic and healthy calves were found to differ in the nucleotide sequences of the genes under analysis. In pneumonic calves, a substantial (p ˂0.05) reduction was detected in RBCs, Hb count, PCV%, and lymphocytes count, and a notable (p ˂ 0.05) increase in WBCs and neutrophil count was correlated with healthy control calves. The findings of the serum profile showed that there was a meaningful (p ˂ 0.05) rise in the serum values of IL-1α, IL-1β, IL-6, TNF-α, IFN-γ, and MDA, with significant reductions in the SOD, GSH, TAC, and IL-10 in the pneumonic compared to the healthy calves. Our results provide valuable information about the nucleotide sequence, gene expression, and serum profile differences of putative indicators for pneumonia in calves. This could be applied in monitoring calves’ pneumonia through the discriminate breeding of naturally resistant animals.