Impact of postpartum milking frequency on the immune system and the blood metabolite concentration of dairy cows¹

Effect of milking frequency during the first week of lactation on daily milk production over the first 14 wk of lactation. ■=cows milked once daily during the first week of lactation and then twice daily for the rest of lactation; □=cows milked twice daily throughout lactation. Milk production was lower (P<0.002) during wk 1 and tended to be lower (P=0.06) during wk 2 to 14 in cows milked once daily. Data are presented as least squares means±SEM.

Effect of milking frequency during the first week of lactation on serum NEFA (A), BHBA (B), and glucose (C) concentration in relation to the days around parturition. ■ =cows milked once daily during the first week of lactation and then twice daily for the rest of lactation; □=cows milked twice daily throughout lactation. The postpartum differences between the 2 groups were significant (P<0.05) until d 24 for NEFA and glucose, and until d 14 for BHBA. Data before calving are presented as means±SEM and data after calving are presented as least squares means±SEM.

Effect of milking frequency during the first week of lactation on serum calcium (A) and phosphorus (B) concentration in relation to the days around parturition. ■ =cows milked once daily during the first week of lactation and then twice daily for the rest of lactation; □=cows milked twice daily throughout lactation. Time points with significant difference are denoted with * (P<0.05) or † (P<0.1). Data before calving are presented as means±SEM and data after calving are presented as least squares means±SEM.

Effect of milking frequency during the first week of lactation on serum stanniocalcin (A) and leptin (B) concentration in relation to the days around parturition. ■ =cows milked once daily (1×) during the first week of lactation and then twice daily for the rest of lactation; □=cows milked twice daily throughout lactation. Leptin concentration was greater in 1× cows during the treatment period (P<0.05). Data before calving are presented as means±SEM and data after calving are presented as least squares means±SEM.

Effect of milking frequency during the first week of lactation on blood PMNL chemotaxis (A) and peripheral blood mononuclear cells proliferation (B) in relation to weeks and days around parturition. ■ =cows milked once daily during the first week of lactation and then twice daily for the rest of lactation; □=cows milked twice daily throughout lactation. Data are presented as means±SEM.

Effect of milking frequency during the first week of lactation on cytokine production: IFN-γ (A), IL-4 (B), and tumor necrosis factor-α (TNF-α, C) by lymphocytes in relation with days around parturition. ■ =cows milked once daily (1×) during the first week of lactation and then twice daily for the rest of lactation; □=cows milked twice daily throughout lactation. Time points with significant difference are denoted with * (P<0.05). Data are presented as means±SEM.