Animal Health 1

摘要

Our objectives were to evaluate the association of subclinical hypocalcemia(SCH) duration with the risk of early lactation negative eventsand milk production. Data from a cohort of 407 Holstein cows in 2herds in NY were used. Primiparous (P) and multiparous (M) cows wereclassified into 1 of 4 groups based on postpartum plasma total Ca (tCa):normocalcemic (NC; [tCa]P > 2.15 mmol/L at 1 and 2 DIM, n = 67; [tCa]_M > 1.77 at 1 DIM, > 2.20 mmol/L at 4 DIM, n = 109); transient SCH(tSCH; [tCa]P ≤ 2.15 at 1 DIM, > 2.15 mmol/L at 2 DIM, n = 25; [tCa]_M ≤ 1.77 at 1 DIM, > 2.20 mmol/L at 4 DIM, n = 50); persistent SCH(pSCH; [tCa]_P ≤ 2.15 mmol/L at 1 and 2 DIM, n = 33; [tCa]_M ≤ 1.77at 1 DIM, ≤ 2.20 mmol/L at 4 DIM, n = 34); or delayed SCH (dSCH;[tCa]_P > 2.15 at 1 DIM, ≤ 2.15 mmol/L at 2 DIM, n = 19; [tCa]_M > 1.77at 1 DIM, ≤ 2.20 mmol/L at 4 DIM, n = 70). Evaluated outcomes weredevelopment of a negative event (NEG; hyperketonemia at 3, 5, 7, and/or 10 DIM, metritis, or displaced abomasum or herd removal within 60DIM) and average milk yield per d across the first 10 wk of lactation.Multivariable Poisson models were used to analyze the NEG outcomeand generalized linear mixed models for milk yield. Both P and M cowswith tSCH were no more likely to have a NEG event than NC cows (riskratioP (RR) = 1.3, 95% CI = 0.5 to 3.2; RRM = 1.4, 95% CI = 1.0 to 2.1).However, P and M pSCH cows were 4.1 (95% CI = 2.1 to 7.9) and 1.8(95% CI = 1.2 to 2.7), and dSCH cows 3.2 (95% CI = 1.5 to 7.0) and 1.8(95% CI = 1.4 to 2.6) times more likely to have a NEG event than NCcows, respectively. Both P and M cows with tSCH produced more milkper d than NC, pSCH, or dSCH cows across the first 10 wk of lactation.Primiparous cows averaged 28.5 ± 0.7, 31.9 ± 1.1, 29.7 ± 0.9, and 28.7± 1.2 kg per d for NC, tSCH, pSCH, and dSCH cows, respectively, andM cows averaged 44.6 ± 0.7, 49.1 ± 1.1, 46.4 ± 1.3, and 41.4 ± 0.9 kgper d for NC, tSCH, pSCH, and dSCH, respectively. Our results suggestthat cows with tSCH adapt better to early lactation, develop fewerNEG events, and produce more milk than NC, pSCH, or dSCH cows.Primiparous or M cows with pSCH or dSCH are at an increased risk forearly lactation NEG events and reduced milk production.