In vivo model to study the impact of genetic variation on clinical outcome of mastitis in uniparous dairy cows

Abstract

Background: In dairy herds, mastitis causes detrimental economic losses. Genetic selection offers a sustainable tool to select animals with reduced susceptibility towards postpartum diseases. Studying underlying mechanisms is important to assess the physiological processes that cause differences between selected haplotypes. Therefore, the objective of this study was to establish an in vivo infection model to study the impact of selecting for alternative paternal haplotypes in a particular genomic region on cattle chromosome 18 for mastitis susceptibility under defined conditions in uniparous dairy cows. Results: At the start of pathogen challenge, no significant differences between the favorable (Q) and unfavorable (q) haplotypes were detected. Intramammary infection (IMI) with Staphylococcus aureus 1027 (S. aureus, n = 24, 96 h) or Escherichia coli 1303 (E. coli, n = 12, 24 h) was successfully induced in all uniparous cows. This finding was confirmed by clinical signs of mastitis and repeated recovery of the respective pathogen from milk samples of challenged quarters in each animal. After S. aureus challenge, Q-uniparous cows showed lower somatic cell counts 24 h and 36 h after challenge (P < 0.05), lower bacterial shedding in milk 12 h after challenge (P < 0.01) and a minor decrease in total milk yield 12 h and 24 h after challenge (P < 0.01) compared to q-uniparous cows. Conclusion: An in vivo infection model to study the impact of genetic selection for mastitis susceptibility under defined conditions in uniparous dairy cows was successfully established and revealed significant differences between the two genetically selected haplotype groups. This result might explain their differences in susceptibility towards IMI. These clinical findings form the basis for further in-depth molecular analysis to clarify the underlying genetic mechanisms for mastitis resistance.

Hepatic Transcriptome Analysis Identifies Divergent Pathogen-Specific Targeting-Strategies to Modulate the Innate Immune System in Response to Intramammary Infection

“…Comparison of the volcano plots from S. aureus vs. E. coli challenge (Figure 3) after challenge. The average maximum temperature of the animals was 41.8 • C (22). This strong systemic response was also reflected in the liver transcriptome.…”

“…The remaining five animals were brought to the Leibniz Institute for Farm Animal Biology in Dummerstorf, in the following referred to as FBN, to serve as a non-challenged control and to participate in a longterm model. The husbandry and sample collection of both experimental groups were previously described (20)(21)(22). For the TiHo cohort, the experiment was approved under the reference number 33.12-42502-04-15/2024 by the Lower Saxony Federal State Office for Consumer Protection and Food Safety.…”

“…Previous S. aureus challenge experiments with an analogous model had indicated no or only a moderate systemic host response (52) and no data were provided regarding liver involvement in this process. However, the fact that during the course of infection, the animals displayed an increase of body temperature with an average peak of >40.5 • C (22) demonstrates that a clinical response to the intramammary S. aureus challenge had occurred. This is also documented by a massive change in liver function observed in the hepatic gene expression analysis.…”

Allele-biased expression of the bovine APOB gene associated with the cholesterol deficiency defect suggests cis-regulatory enhancer effects of the LTR retrotransposon insertion

“…The cows investigated in this study were part of a large network project to evaluate genetic predisposition for disease susceptibility in Holstein Friesian cows. Details on the selection and management of the animals have been previously described 17 – 20 . The final cohort comprised 35 animals, seven heterozygous CDC carriers and 28 homozygous wild type CDF animals.…”

Determination of Effectiveness Bacillus Megaterium for Subclinical Cow Mastitis

“…Втрати, спричинені субклінічним маститом, дуже важко визначити кількісно. Експерти сходяться на тому, що субклінічний мастит призводить до більших фінансових втрат в стаді, ніж клінічні випадки (Klaas & Zadoks, 2018;Rohmeier et al, 2020). Також хронічний мастит -це тривалий запальний процес, з нерегулярними клінічними загостреннями.…”