The Innovation Centre of Ruminant Precision Nutrition and Smart Farming, Jilin Agricultural Science and Technology University, Jilin 132109, China; Department of Animal Nutrition, The University of Veterinary and Animal Sciences, Lahore 54000, Pakistan; Jilin Inter-Regional Cooperation Centre for the Scientific and Technological Innovation of Ruminant Precision Nutrition and Smart and Ecological Farming, Jilin 132109, China.
AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand.
J Dairy Sci. 2024 Jan;107(1):301-316. doi: 10.3168/jds.2023-23545. Epub 2023 Sep 13.
Chromium (Cr) has been reported to modulate blood biochemistry in dairy cows. However, there is a discrepancy in the literature regarding the effects of dietary Cr supplementation on various blood parameters. This meta-analysis aimed to evaluate the effects of Cr supplementation in dairy cows on blood glucose, insulin, glucagon, nonesterified fatty acid (NEFA), cortisol, and serum total protein (STP) concentrations. Following relevant literature data extraction, a 3-level meta-analytical random effect model was fitted to the data expressed as standardized mean difference (SMD) of outcome measures of control versus Cr-supplemented cows (i.e., difference in mean between control and treatment group or pooled standard deviation). The SMD can be categorized as having a small effect (0.20), a moderate effect (0.50), and a large effect (0.80). The meta-regression identified the potential sources of heterogeneity, including the body weight of cows, experimental duration/duration of Cr supplementation, blood sampling time (3 wk before parturition until 4 wk after parturition categorized as the transition period, else as the nontransition period), and form of Cr complexes. Blood glucose did not differ significantly between control and Cr-supplemented cows with an estimated SMD of μ = 0.0071 (95% confidence interval [CI]: -0.212 to 0.226). The effect of Cr supplementation on blood insulin was also nonsignificant with an SMD of μ = 0.0007 (95% CI: -0.191 to 0.193). Cows receiving Cr supplements had significantly higher levels of glucagon than controls (95% CI: 0.116 to 0.489), with an estimated SMD = 0.303. Combined transition and nontransition data suggest Cr supplementation did not affect the concentration of NEFA. However, in transition cows, Cr supplementation significantly decreased blood NEFA levels as compared with controls (95% CI: -0.522 to -0.0039), with estimated SMD = -0.263. The estimated SMD was μ = -0.1983 (95% CI: -0.734 to 0.337) for cortisol and -0.0923 (95% CI: -0.316 to 0.131) for total protein. In summary, Cr supplementation in the transition cows decreased NEFA concentration. Blood glucose, insulin, cortisol, and STP concentrations were unaffected. However, Cr supplementation increased glucagon concentration.
铬（Cr）已被报道可调节奶牛的血液生化指标。然而，关于日粮补充铬对各种血液参数的影响，文献中存在差异。本荟萃分析旨在评估奶牛补充铬对血糖、胰岛素、胰高血糖素、非酯化脂肪酸（NEFA）、皮质醇和血清总蛋白（STP）浓度的影响。在提取相关文献数据后，采用 3 级随机效应模型对数据进行拟合，结果以对照组与补充铬组的标准化均数差值（SMD）表示（即对照组与处理组之间的平均差异或合并标准差）。SMD 可分为小效应（0.20）、中效应（0.50）和大效应（0.80）。荟萃回归确定了异质性的潜在来源，包括奶牛体重、试验持续时间/铬补充持续时间、采血时间（分娩前 3 周至分娩后 4 周分为过渡期，其他时间为非过渡期）和 Cr 复合物的形式。对照组与补充铬组的血糖无显著差异，估计 SMD 为 μ=0.0071（95%置信区间：-0.212 至 0.226）。Cr 补充对血液胰岛素的影响也不显著，SMD 为 μ=0.0007（95%置信区间：-0.191 至 0.193）。接受 Cr 补充剂的奶牛的胰高血糖素水平明显高于对照组（95%置信区间：0.116 至 0.489），估计 SMD=0.303。合并过渡期和非过渡期的数据表明，Cr 补充剂不会影响 NEFA 的浓度。然而，在过渡期奶牛中，Cr 补充剂与对照组相比显著降低了血液 NEFA 水平（95%置信区间：-0.522 至 -0.0039），估计 SMD=-0.263。皮质醇的估计 SMD 为 μ=-0.1983（95%置信区间：-0.734 至 0.337），总蛋白为 -0.0923（95%置信区间：-0.316 至 0.131）。总之，过渡期奶牛补充 Cr 可降低 NEFA 浓度。血糖、胰岛素、皮质醇和 STP 浓度不受影响。然而，Cr 补充剂增加了胰高血糖素的浓度。
