Genome wide association study of passive immunity and disease traits in beef-suckler and dairy calves on Irish farms

Calves with lower concentrations of immunoglobulin G (IgG) in their blood, have a greater risk of developing diseases. There is a lack of knowledge on genetic markers known to be associated with immunological variability or disease resistance. Therefore, the objective of this study was to identify SNP markers associated with passive immunity measures (serum IgG, serum protein, albumin, globulin and total protein concentrations, total solids Brix percentage, zinc sulphate turbidity units) and disease (pneumonia, diarrhoea, crude illness) traits in Irish commercial beef-suckler and dairy calves through genome wide association studies (GWAS). Genotyping was performed on DNA samples from beef-suckler (n = 698) and dairy (n = 1178) calves, using the IDBv3 chip. Heritability of passive immunity associated traits (range 0.02–0.22) and the disease traits (range 0.03–0.20) were low-to-moderate. Twenty-five and fifteen SNPs approached genome wide significance (P < 5 × 10−5) for the passive immunity and the disease traits, respectively. One SNP “ARS-BFGL-BAC-27914” reached Bonferroni genome wide significance (P < 1.15 × 10−6) for an association with serum IgG concentration in beef calves. Further work will evaluate these SNPs in larger cattle populations and assess their contribution to genomic selection breeding strategies, aimed towards producing more disease resistant livestock.

OPEN ACCESS: Insights into UK farmers' attitudes towards cattle youngstock rearing and disease

There is increased industry focus on optimised welfare, productivity and antibiotic usage in cattle youngstock, however, little is known about UK farmers' attitudes and practices in rearing calves. In this cross-sectional study, 479 farmers were surveyed online about their cattle youngstock rearing approach and outcomes. Represented were 174 dairy farmers, 255 beef suckler farmers and 50 calf rearers. Farmers showed awareness of good youngstock rearing practices such as colostrum management and housing facilities. Morbidity and mortality from diarrhoea (82%, 48%) and bovine respiratory disease (BRD) (68%, 48%) were high on farms surveyed but farmers did not frequently consult their veterinary surgeon regarding these diseases. Farmers surveyed were not always aware of the efficacy of preventative methods such as vaccination, and frequently used antibiotic treatments (27% for diarrhoea and 40% for BRD) but not diagnostics when animals had disease. Veterinary surgeons could use these insights to better understand farmers' motivations and priorities, to make communication more efficient and align goals.

Refugia: what are they and how can they be managed?

The word refugia appears commonly in the veterinary literature in relation to anthelmintic resistance, however it has its origins in ecology and crop protection. In the context of veterinary therapeutics, the reduction in exposure of target parasites, essentially through fewer treatments, can have bystander benefits too for non-target organisms, thus reducing the potential for environmental impact. Large refugia are intrinsic features of some livestock systems, for example extensive beef suckler farms, where treatments are typically infrequent, however on lowland sheep farms for instance, parasiticide treatments are typically more frequent and may involve both lambs and ewes, so management may need to be changed, for example through targeted selective treatment (TST), in order to enhance the refugia. Precision livestock farming and pen-side diagnostics can facilitate and extend the adoption of TST and other methods of refugia management.