Comparison of Holstein and Jersey Innate Immune Responses to Escherichia coli Intramammary Infection

Intramammary growth of Escherichia coli in Holstein and Jersey cows following experimental infection. Immediately before (time 0) and at various times following intramammary infusion of 188 cfu of E. coli into one mammary quarter of 10 Holstein and 10 Jersey cows, sterile milk samples were collected and plated. The percentage of quarters in which viable bacteria were recovered is indicated (A). In those quarters in which bacteria were recovered, the mean (±SE) log₁₀ milk bacterial concentration (cfu/mL) is reported (B).

Effect of Escherichia coli IMI on Holstein and Jersey milk production. Total daily milk weights were recorded before (d −4 to 0) and following (d 1 to 11) experimental E. coli IMI of 10 Holstein and 10 Jersey cows. Mean (±SE) daily milk production is reported in kilograms. *^,#Decreased (P<0.05) compared with preinfection (d 0) production amounts of Holstein or Jersey cows, respectively; ^@differences (P<0.05) in milk production between breeds at a given time point.

Acute phase responses of Holstein and Jersey cows to intramammary Escherichia coli infection. Rectal temperatures (A) were measured and blood samples collected immediately before (time 0) and at various time points following experimental E. coli IMI of 10 Holstein and 10 Jersey cows. Plasma derived from the blood samples was assayed by ELISA for serum amyloid A (SAA; B) and LPS-binding protein (LBP; C). Mean (±SE) rectal temperatures are reported in Celsius and mean (±SE) concentrations of SAA and LBP are reported in micrograms per milliliter. *^,#Increased (P<0.05) compared with preinfection (time 0) measurements in Holstein or Jersey cows, respectively.

Effect of Escherichia coli IMI on Holstein and Jersey circulating white blood cell (WBC) counts. Blood samples were collected immediately before (time 0) and at various time points following experimental E. coli IMI of 10 Holstein and 10 Jersey cows. Blood was analyzed for total (A) and differential WBC counts (B and C). Mean (±SE) cell counts are reported in thousands per microliter. *^,#Decreased (P<0.05) compared with preinfection (time 0) cell counts of Holstein or Jersey cows, respectively.

Effect of Escherichia coli IMI on Holstein and Jersey milk SCC and BSA concentrations. Milk samples were collected immediately before (time 0) and at various time points following experimental E. coli IMI of 10 Holstein and 10 Jersey cows. Whole milk was analyzed for SCC (A and B) and milk whey assayed for BSA by ELISA (C). Mean (±SE) milk SCC are reported in millions of cells per milliliter (A) and log₁₀ cells per milliliter (B), and BSA concentrations indicated in milligrams per milliliter (C). *^,#Increased (P<0.05) compared with preinfection (time 0) concentrations in Holstein or Jersey cows, respectively; ^@differences (P<0.05) in SCC between breeds at a given time point.

Proinflammatory cytokine responses of Holstein and Jersey cows to intramammary Escherichia coli infection. Milk samples were collected immediately before (time 0) and at various time points following experimental E. coli IMI of 10 Holstein and 10 Jersey cows. Milk whey was assayed by ELISA for IL-8 (A), IL-1β (B), and tumor necrosis factor (TNF)-α (C). Mean (±SE) concentrations of IL-8 and IL-1β are expressed in picograms per milliliter and mean (±SE) TNF-α concentrations reported in nanograms per milliliter. *^,#Increased (P<0.05) compared with preinfection (time 0) concentrations in Holstein or Jersey cows, respectively; ^@differences (P<0.05) in concentrations between breeds at a given time point.

Effect of Escherichia coli IMI on Holstein and Jersey production of IL-12 and IFN-γ. Milk samples were collected immediately before (time 0) and at various time points following experimental E. coli IMI of 10 Holstein and 10 Jersey cows. The concentrations of IL-12 (A) and IFN-γ (B) in milk whey were determined by ELISA and expressed as mean (±SE) units per milliliter and picograms per milliliter, respectively. *^,#Increased (P<0.05) compared with pre-infection (time 0) concentrations in Holstein or Jersey cows, respectively; ^@differences (P<0.05) in concentrations between breeds at a given time point.