Effect of Length of Stay in First Postpartum Pen on Health Status, Culling, Milk Component Yield, and Reproductive Performance of Multiparous Holstein Cows

The objective of the present study was to assess the effect of length of stay in first postpartum pen (LSPP) on BCS change (ΔBCS), health status, culling within the first 60 days in milk (DIM, CULL60), culling through 305 DIM (CULL305), milk yield, milk components, and reproductive performance of Holstein cows. A total of 817 multiparous Holstein cows from two farms were enrolled in cohorts of 45 to 50 cows every two weeks at 21±3 d before parturition. At calving, cows were randomly assigned to one of three LSPP groups: 7 (n = 260), 14 (n = 283) or 21 (n = 274) DIM. Within farm, cows were managed under the same pre- and postpartum feeding programs. Serum calcium (Ca) was assessed within 48 h after calving, and ΔBCS was assessed between calving and 28±3 DIM. Serum β-hydroxybutyrate was assessed at 7±3 and 14±3 DIM to assess hyperketonemia (≥1.2 mmol/L). Health events within the first 30 DIM were recorded, and cows were categorized into one of four groups: 1) non-disease (ND); 2) cows with only hyperketonemia (KET); 3) cows with hyperketonemia plus one other health condition (KET+); or 4) cows experiencing ≥1 health event excluding hyperketonemia (SICK). Cows sold or died were classified as culling to assess CULL60 and CULL305. Presence of a functional corpus luteum (CL, ≥1.0 ng/mL) was determined at 28±3 DIM using serum progesterone. Pregnancy per AI (PAI) for first service and time to pregnancy up to 305 DIM were assessed. Milk yield, milk fat, milk protein, and energy-corrected milk (ECM) were assessed at the first DHI test and up to 305 DIM. Data were analyzed using linear mixed models, generalized linear mixed models, or Cox proportional hazard models. Health status, ΔBCS, Ca, CULL60, functional CL, milk yield, milk components, and ECM at first DHI test did not differ (P > 0.05) among LSPP groups. Cows with an LSPP of 7 DIM tended (P = 0.081) to have reduced CULL305 with shorter time to pregnancy up to 305 DIM compared to cows with an LSPP of 21 DIM (P = 0.005). Compared to cows with an LSPP of 21 DIM, cows with an LSPP of 7 DIM had increased cumulative 305 DIM milk fat by 9.4% (P = 0.029) and ECM by 9.6% (P = 0.017), and tended to have increased milk protein by 8.2% (P = 0.059), whereas cows with an LSPP of 14 DIM did not differ. These findings show that ΔBCS, health status, and CULL60 were not affected by LSPP in multiparous cows. However, cows with an LSPP of 7 DIM had improved pregnancy and achieved greater cumulative milk fat and ECM yields up to 305 DIM.