Tsiamadis V, Siachos N, Panousis N, Banos G, Kougioumtzis A, Valergakis G E
Department of Animal Production, Faculty of Veterinary Medicine, Box 393, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece.
Department of Animal Production, Faculty of Veterinary Medicine, Box 393, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece.
Theriogenology. 2022 May;184:73-81. doi: 10.1016/j.theriogenology.2022.03.002. Epub 2022 Mar 5.
The objective of this study was to evaluate the effects of subclinical hypocalcemia (SCHCa) patterns on reproductive performance in dairy cows. In a prospective observational study 916 cows from 9 herds were blood sampled on DIMs 1, 2, 4 and 8; Ca concentration was measured with atomic absorption and SCHCa was defined as Ca ≤ 2.09 mmol/L. Cluster analysis revealed 2 normocalcemic (NORM and HIGH) and five hypocalcemic (SCH-1 to 5) clusters. Cows in cluster NORM (n = 151) had mean day-to-day serum Ca (DIMs 1-8) between 2.24 and 2.41 mmol/L, and cows in HIGH (n = 167) between 2.42 and 2.53 mmol/L. Cows in SCH-1 (n = 130) and SCH-2 (n = 102) had transient and mostly mild SCHCa on day 1 and day 2, respectively. Cows in SCH-3 (n = 123) had mostly severe SCHCa on days 1 and 2, extending to day 4. Cows in SCH-4 (n = 120) and SCH-5 (n = 145) had SCHCa which culminated on days 4 and 8, respectively. Information on reproductive outcomes including pregnancy status by 120 and 200 DIM and days open were retrieved from farm records. Median (±SE) days to 1st artificial insemination (AI) until 120 DIM estimated with Kaplan-Meier analysis for cows in SCH-3, SCH-4 and SCH-5 were 100.0 ± 7.2, 109.0 ± 6.6 and 120.0 ± 3.2, respectively, and were statistically significantly higher from those in NORM and HIGH (91.0 ± 3.4 and 87 ± 3.7, respectively). Mean days (±SE) to detected pregnancy until 200 DIM estimated with Kaplan-Meier analysis for cows in SCH-3 were 161.2 ± 4.8 and were statistically significantly higher from those in clusters NORM and HIGH (155.5 ± 4.2 and 151.6 ± 4.3, respectively). The association of Ca clusters with the odds of detected pregnancy for the 1st insemination until 120 and 200 DIM was evaluated with Linear Mixed Models. Odds for pregnancy by 120 DIM did not differ among clusters, however, cows in clusters SCH-3 and SCH-5 had lower odds for pregnancy by 200 DIM compared to HIGH (OR = 0.55, P = 0.02, and OR = 0.49, P = 0.004, respectively). Covariate adjusted survival curves generated by multivariable Cox proportional hazards model revealed that: a) clusters SCH-3 and SCH-5 had the highest (36% and 38%, respectively), while NORM and HIGH the lowest (16% and 17%, respectively) proportion of cows not inseminated for the 1st time by 120 DIM, b) compared to HIGH, cows in SCH-5 had a lower hazard of pregnancy by 120 DIM (HR = 0.42, P = 0.005), c) the proportion of open cows by 200 DIM for NORM and HIGH were 57% and 47%, respectively, while for SCH-3 and SCH-5 66% and 68%, respectively, and d) compared to HIGH, SCH-3 (HR = 0.54, P = 0.008) and SCH-5 (HR = 0.50, P = 0.001) presented the lowest hazard for pregnancy by 200 DIM. In conclusion, cows that during the entire first week after calving were continuously normocalcemic had the best reproductive performance, while those of SCH-3 and SCH-5 the worst.
本研究的目的是评估亚临床低钙血症（SCHCa）模式对奶牛繁殖性能的影响。在一项前瞻性观察研究中，对来自9个牛群的916头奶牛在产后第1、2、4和8天进行血样采集；采用原子吸收法测定钙浓度，将SCHCa定义为钙≤2.09 mmol/L。聚类分析显示有2个正常血钙（NORM和HIGH）聚类以及5个低钙血症（SCH-1至5）聚类。NORM聚类（n = 151）的奶牛产后第1至8天的每日血清钙平均值在2.24至2.41 mmol/L之间，HIGH聚类（n = 167）的奶牛在2.42至2.53 mmol/L之间。SCH-1聚类（n = 130）和SCH-2聚类（n = 102）的奶牛分别在产后第1天和第2天出现短暂且大多为轻度的SCHCa。SCH-3聚类（n = 123）的奶牛在产后第1天和第2天大多出现严重的SCHCa，并持续到第4天。SCH-4聚类（n = 120）和SCH-5聚类（n = 145）的奶牛分别在产后第4天和第8天出现SCHCa高峰。从农场记录中获取繁殖结果信息，包括产后120天和200天的妊娠状态以及空怀天数。采用Kaplan-Meier分析估计，SCH-3、SCH-4和SCH-5聚类的奶牛到产后120天首次人工授精（AI）的中位（±SE）天数分别为100.0 ± 7.2、109.0 ± 6.6和120.0 ± 3.2，与NORM和HIGH聚类（分别为91.0 ± 3.4和87 ± 3.7）相比，差异具有统计学意义。采用Kaplan-Meier分析估计，SCH-3聚类的奶牛到产后200天检测到妊娠的平均天数（±SE）为161.2 ± 4.8，与NORM和HIGH聚类（分别为155.5 ± 4.2和151.6 ± 4.3）相比，差异具有统计学意义。采用线性混合模型评估钙聚类与产后120天和200天首次授精检测到妊娠几率的关联。产后120天各聚类的妊娠几率无差异，然而，与HIGH聚类相比，SCH-3和SCH-5聚类的奶牛到产后200天的妊娠几率较低（OR分别为0.55，P = 0.02；OR为0.49，P = 0.004）。多变量Cox比例风险模型生成的协变量调整生存曲线显示：a）SCH-3和SCH-5聚类在产后120天未首次授精的奶牛比例最高（分别为36%和38%），而NORM和HIGH聚类最低（分别为16%和17%）；b）与HIGH聚类相比，SCH-5聚类的奶牛到产后120天的妊娠风险较低（HR = 0.42，P = 0.005）；c）产后200天NORM和HIGH聚类的空怀奶牛比例分别为57%和47%，而SCH-3和SCH-5聚类分别为66%和68%；d）与HIGH聚类相比，SCH-3（HR = 0.54，P = 0.008）和SCH-5（HR = 0.50，P = 0.001）到产后200天的妊娠风险最低。总之，产犊后第一周内血钙持续正常的奶牛繁殖性能最佳，而SCH-3和SCH-5聚类的奶牛最差。
