Table 2 Summary of the six most significant clusters obtained from DAVID functional annotation cluster analysis of the DEG in the modules which were significantly positively or negatively correlated to lactation number in primiparous (PP) cows, indicating either lower or higher gene expression in older multiparous MP > 3 cows

Cluster 1: Enrichment Score: 16.18

Cluster 1:Enrichment Score: 29.73

• Krueppel-associated box

• Zinc finger C2H2-type/integrase DNA-binding domain

• Zinc finger, C2H2

• Nucleic acid binding

• Zinc finger, C2H2-like

• KRAB

• ZnF_C2H2

• Regulation of transcription, DNA-templated

• Metal ion binding

• Membrane

• Transmembrane helix

• Transmembrane

• integral component of membrane

Cluster 2: Enrichment Score: 7.01

Cluster 2: Enrichment Score: 19.87

• Zinc-finger

• Metal ion binding

• Zinc

• Metal-binding

• Signal

• Disulfide bond

• Glycoprotein

• Signal peptide

• Glycosylation site: N-linked (GlcNAc...)

• Disulfide bond

Cluster 3: Enrichment Score: 6.83

Cluster 3: Enrichment Score: 7.32

• Transcription regulator SCAN

• Retrovirus capsid, C-terminal

• SCAN

• Transmembrane region

• Topological domain: Cytoplasmic

• Topological domain: Extracellular

Cluster 4: Enrichment Score: 5.05

Cluster 4: Enrichment Score: 3.94

• Nucleotide binding

• Nucleotide-binding, alpha-beta plait

• RNA recognition motif domain

• RRM

• Glycolysis / Gluconeogenesis

• Glycolysis

• Glycolytic process

• Carbon metabolism

• Biosynthesis of amino acids

Cluster 5: Enrichment Score: 2.02

Cluster 5: Enrichment Score: 3.70

• BTB/POZ fold

• BTB/POZ-like

• BTB

• C-type lectin fold

• C-type lectin-like

• C-type lectin

• CLECT

• C-type lectin, conserved site

Cluster 6: Enrichment Score: 1.88

Cluster 6: Enrichment Score: 3.28

• Immunoglobulin-like domain

• Immunoglobulin-like fold

• Immunoglobulin subtype 2

• Immunoglobulin I-set

• Immunoglobulin subtype

• IGc2

• IG

• Immunity

• Innate immunity

• Innate immune response