Delve into the influence of housing systems on digital dermatitis in dairy cows. Could genetic evaluations pave the way for enhanced bovine health across varied living conditions? Uncover the research insights here.

Imagine walking barefoot on gravel daily; the discomfort of digital dermatitis (DD) in dairy cows feels similar. This painful hoof disease significantly hampers cows’ mobility, milk production, and the economic health of dairy farms. 

The environment in which cows are housed plays a critical role in DD’s incidence and severity. Housing systems such as conventional cubicle barns (CON) and compost-bedded pack barns (CBPB) have distinct impacts on disease management. Understanding these housing-related nuances is vital for farmers and researchers working to reduce DD’s impact. 

This research utilizes detailed phenotyping data from over 2,980 observations of Holstein-Friesian and Fleckvieh-Simmental cows on ten farms. It investigates the genetic variances linked to DD stages: sick, acute, and chronic. Through genome-wide association studies (GWAS), the study identifies potential candidate genes and assesses genotype × housing system interactions. This comprehensive analysis seeks to uncover genetic factors that can inform breeding programs and enhance animal welfare, regardless of their rearing environment. 

Introduction: Understanding Digital Dermatitis in Dairy Cows

Digital Dermatitis (DD) is an infectious disease impacting the bovine foot, particularly the plantar skin bordering the interdigital cleft. This condition ranges from initial lesions to chronic, painful wounds, affecting dairy cows‘ mobility and well-being. 

The development of DD involves a mix of environmental, genetic, and management factors. Housing systems, especially conventional cubicle barns, create conditions ripe for DD, with moisture and contamination fostering pathogen growth. Nutritional imbalances, poor foot hygiene, and milking routines further increase risk. Notably, genetic predispositions also play a role; some cattle lines are more susceptible, emphasizing the need for genetic research to combat DD. 

The economic and welfare impacts of DD are significant. Economically, it causes losses through reduced milk production, higher veterinary costs, and culling of severely affected cows. Welfare-wise, the pain and lameness from DD seriously affect cattle comfort and health, raising ethical concerns in livestock management. Therefore, addressing DD with better housing, management practices, and genetic selection is crucial for sustainable dairy farming.

Exploring Housing Systems: Cubicle Barns vs. Compost-Bedded Pack Barns

Housing systems play a pivotal role in dairy productivity and cow health and welfare. The primary systems include conventional cubicle barns (CON) and compost-bedded pack barns (CBPB), each impacting the Prevalence and severity of digital dermatitis (DD). 

In CON setups, cows rest on mats or mattresses over concrete floors. This controlled environment supports restful ruminating but can worsen claw disorders due to constant exposure to manure and poor ventilation. Conversely, CBPB systems offer cows a spacious environment with composting bedding of sawdust or wood shavings, which is more comfortable and supports better hoof health by reducing pathogens through microbial activity. 

The flooring material is crucial. Concrete floors in CON systems retain moisture and manure, fostering bacteria that cause DD. CBPB systems’ drier, more sanitary bedding leads to fewer DD incidences. 

Hygiene practices, essential for DD control, differ by system. CON systems require regular scraping and washing, while CBPB systems depend on managing bedding moisture and microbial activity. Both approaches aim to reduce bacterial loads and curb DD spread. 

Cow comfort, dictated by the housing system, also affects DD prevalence. CBPB’s spacious, free-roaming environment reduces stress and improves immune function, making cows less prone to DD. In contrast, CON systems’ restrictiveness can increase anxiety and susceptibility to claw disorders. 

In summary, the choice between cubicle barns and compost-bedded pack barns significantly impacts cow health and the incidence of DD. Prioritizing comfort and hygiene in housing systems leads to healthier, more productive cows with fewer claw disorders.

Unveiling Genetic Interactions Between Housing Systems and Digital Dermatitis in Dairy Cows

The genetic study on digital dermatitis (DD) in dairy cows examined the influence of different housing systems on the disease. This research aimed to understand the interaction between cow genotypes and their environments. It focused on DD stages—DD-sick, DD-acute, and DD-chronic—in conventional cubicle barns (CON) and compost-bedded pack barns (CBPB). Herds were selected to ensure similarities in climate, feeding, and milking systems. Still, they differed in housing setups to isolate housing-specific impacts on DD. 

Using 2,980 observations from 1,710 cows and 38,495 SNPs from 926 genotyped cows after quality control, the study employed single-step approaches for single-trait repeatability animal models and bivariate models to estimate genetic parameters and correlations. GWAS identified specific SNPs and their interactions with housing systems. Heritabilities for DD stages and genetic correlations between the same traits in different housing systems were also calculated. 

Results showed higher DD prevalence in CON systems compared to CBPB. Heritabilities were 0.16 for DD-sick, 0.14 for DD-acute, and 0.11 for DD-chronic, with a slight increase in CON. Genetic correlations between the same DD traits in different housing systems were around 0.80, indicating minimal genotype × housing system interactions. Correlations among DD stages ranged from 0.58 to 0.81, showing their interconnectedness regardless of the housing system. 

GWAS results were varied for DD-acute and DD-chronic, indicating complex pathogenesis. Candidate genes affecting disease resistance or immune response included METTL25, AFF3, PRKG1, and TENM4 for DD-sick and DD-acute. SNP × housing system interactions highlighted ASXL1 and NOL4L on BTA 13 for DD-sick and DD-acute. 

For dairy farmers, these findings underline the impact of housing systems on the Prevalence and progression of DD and the potential genetic implications. Our comprehensive study provides actionable insights for dairy farmers globally. 

Notably, DD prevalence was significantly higher in CON, highlighting the challenging environment of cubicle barns compared to the more welfare-oriented CBPB system. These insights are crucial as they affect animal health and have economic ramifications, including reduced milk production and increased treatment costs. 

We examined genetic evaluations across these environments and found that heritabilities for DD traits (DD-sick, DD-acute, DD-chronic) were slightly higher in the CON system. Still, overall genetic parameters remained consistent across both systems. Despite different housing practices, the genetic predisposition to DD remains relatively stable. 

Genetic correlations between different DD stages (ranging from 0.58 to 0.81) suggest a common underlying genetic resistance mechanism crucial for developing targeted breeding programs. Furthermore, GWAS pinpointed several candidate genes, such as METTL25, AFF3, PRKG1, and TENM4, with significant implications for disease resistance and immunology. 

This research underscores the importance of genotype-environment interactions, even though these were minimal in housing systems. Integrating genomic insights with practical management strategies can improve animal well-being and farm productivity as the dairy industry evolves. 

By applying these findings, dairy farmers can make informed decisions about housing systems and genetic selection, enhancing economic and animal health outcomes. This study calls for the industry to adopt evidence-based practices rooted in rigorous scientific research.

Genetic Evaluations: From Genotypes to Phenotypes

The research meticulously analyzed data from 1,311 Holstein-Friesian and 399 Fleckvieh-Simmental cows, totaling 2,980 observations across three digital dermatitis (DD) stages: DD-sick, DD-acute, and DD-chronic. This granular phenotyping clarifies how DD stages manifest in different environments. By categorizing it into conventional cubicle barns (CON) and compost-bedded pack barns (CBPB), the study highlights the environmental impact on genetic expressions related to DD. 

Quality control of 50K SNP genotypes refined the data to 38,495 SNPs from 926 cows. This dataset formed the basis for estimating genetic parameters through single-step approaches. The genetic correlations between DD traits and housing systems uncovered genotype × environment (G×E) interactions. 

Heritability estimates were 0.16 for DD-sick, 0.14 for DD-acute, and 0.11 for DD-chronic, indicating the genetic influence. Notably, these estimates and genetic variances slightly rose in the more stressful CON environment, indicating heightened genetic differentiation under challenging conditions. Genetic correlations between the same DD traits across different housing systems were around 0.80, showing minimal G×E interactions. 

Genome-wide association studies (GWAS) revealed heterogeneous Manhattan plots for DD-acute and DD-chronic traits, indicating complex biological pathways. Despite this, several shared candidate genes like METTL25, AFF3, PRKG1, and TENM4 were identified, showing their potential role in managing DD through genetic selection. 

For SNP × housing system interactions, genes such as ASXL1 and NOL4L on chromosome 13 were relevant for DD-sick and DD-acute. These findings illustrate how specific genetic markers interact with environmental factors. Overall, the minimal impact of genotype × housing system interactions supports robust genetic evaluations for DD across diverse environments, aiding broader genetic selection strategies in dairy cow populations. 

The Bottom Line

This study highlights the importance of detailed phenotyping and genetic evaluations in understanding digital dermatitis (DD) in dairy cows. By examining 1,710 Holstein-Friesian and Fleckvieh-Simmental cows in conventional cubicle barns (CON) and compost-bedded pack barns (CBPB), the research provided crucial insights into the Prevalence and heritability of DD. It found slightly higher genetic differentiation in the more challenging CON environment but minimal genotype × housing system interactions, indicating a limited impact on genetic assessments. Essential genes like METTL25, AFF3, PRKG1, and TENM4 were identified as necessary for disease resistance and immunology. 

Understanding how housing systems affect DD is crucial. It helps improve management practices to reduce DD prevalence, enhancing cow welfare and farm productivity. It also improves genetic selection by identifying traits that enhance DD resistance in specific environments, benefiting long-term herd health and sustainability. This insight is vital for today’s dairy operations and future breeding programs. 

Future research should delve into the long-term impact of housing systems on genetic traits linked to DD resistance. Exploring other environmental and management factors, like nutrition and milking routines, would offer a fuller understanding of DD. Personalized genetic interventions tailored to specific farm environments could be a game-changer in managing this disease in dairy cows.

Key Takeaways:

• The study analyzed 2,980 observations of DD stages, differentiating between DD-sick, DD-acute, and DD-chronic across two housing systems: conventional cubicle barns (CON) and compost-bedded pack barns (CBPB).
• Heritabilities for DD were slightly higher in the CON environment, suggesting a stronger genetic differentiation of the disease in more challenging conditions.
• Despite varying heritabilities, genetic correlations between the same DD traits in different housing systems were high, indicating minimal genotype × housing system interactions.
• GWAS highlighted significant candidate genes such as METTL25, AFF3, and PRKG1, which play roles in disease resistance and immunology.
• This research underscores the importance of considering housing systems in genetic evaluations to enhance disease management and improve cow welfare.

Summary: Digital Dermatitis (DD) is a severe hoof disease that affects dairy cows’ mobility, milk production, and farm economic health. Housing systems like conventional cubicle barns (CON) and compost-bedded pack barns (CBPB) have distinct impacts on disease management. CON setups, which support restful ruminating but can worsen claw disorders due to constant exposure to manure and poor ventilation, have higher DD-sick prevalence than CBPB systems (5.34%). Both approaches aim to reduce bacterial loads and curb DD spread. CBPB’s spacious, free-roaming environment reduces stress and improves immune function, making cows less prone to DD. A study found higher DD prevalence in CON systems compared to CBPB. Understanding how housing systems affect DD is crucial for improving management practices, enhancing cow welfare, and improving genetic selection.