The objective of this cross-sectional study was to assess the variability of plasma folate and vitamin B12 concentrations in lactating Holstein cows across the United States and Canada. We also evaluated the effect of diet composition and cow characteristics on folate and vitamin B12 plasma vitamin concentrations. A total of 22 and 24 US and Canadian dairy herds were enrolled, totaling 427 and 476 cows at 10 to 197 days in milk across all US and Canadian herds, respectively. Blood samples were taken to analyze plasma folate and vitamin B12 concentrations, and ingredients of the diet were collected to determine nutrient composition. To reduce the number of interdependent variables in the analysis of the association of diet composition with plasma vitamin concentrations, we conducted a principal component analysis. Plasma folate concentrations were lower for US cows [13.4 ng/mL, 95% confidence interval (CI): 12.7-14.2] than for Canadian cows (14.5 ng/mL, 95% CI: 13.7-15.2), and the opposite was observed for plasma vitamin B12 concentrations (US 206 pg/mL, 95% CI: 192-221; Canada 170 pg/mL, 95% CI: 159-181). The highest plasma concentrations of both vitamins were observed in the Northwest region of the United States (Oregon and Washington). Cows in California had the lowest plasma folate concentrations, and cows in Québec and New York State had the lowest plasma vitamin B12 concentrations. Plasma folate concentrations were higher for multiparous than for primiparous cows and plasma vitamin B12 concentrations progressively increased from parity 1 to 3 and higher. For both studied vitamins, plasma concentrations were lower at 0 to 55 than at 56 to 200 days in milk. Of 3 principal components, the one associated with dietary carbohydrates was significantly correlated with plasma folate and vitamin B12 concentrations. Indeed, plasma folate concentrations decreased with dietary fiber concentrations (i.e., neutral and acid detergent fibers and lignin) and increased with dietary nonfiber carbohydrate concentrations. We obtained the opposite results for plasma vitamin B12 concentrations. Both multivariable models explained 41% (pseudo-R2) of the variation in plasma folate and vitamin B12 concentrations. Information gathered in this study is the first step toward determining sources of variation in plasma folate and vitamin B12 concentrations, as well as the vitamin status of cows.

中文翻译：

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在美国和加拿大，日粮组成对荷斯坦奶牛血浆叶酸和维生素B12浓度影响的横断面研究。

这项横断面研究的目的是评估美国和加拿大泌乳荷斯坦奶牛血浆叶酸和维生素B12浓度的变化。我们还评估了日粮组成和奶牛特性对叶酸和维生素B12血浆维生素浓度的影响。在美国和加拿大的所有牛群中，总共有22和24个美国和加拿大的奶牛在10至197天的牛奶中分别招募了427和476头奶牛。采集血液样本以分析血浆叶酸和维生素B12的浓度，并收集饮食成分以确定营养成分。为了减少饮食组成与血浆维生素浓度相关性分析中相互依赖变量的数量，我们进行了主成分分析。美国母牛的血浆叶酸浓度较低[13.4 ng / mL，95％置信区间（CI）：12.7-14.2]，低于加拿大母牛的血浆叶酸浓度[14.5 ng / mL，95％CI：13.7-15.2]，但观察到相反血浆维生素B12的浓度（US 206 pg / mL，95％CI：192-221;加拿大170 pg / mL，95％CI：159-181）。在美国西北部地区（俄勒冈州和华盛顿州）观察到两种维生素的最高血浆浓度。加利福尼亚州的奶牛血浆叶酸浓度最低，魁北克和纽约州的奶牛血浆维生素B12浓度最低。多胎产妇的血浆叶酸浓度高于初产奶牛，血浆维生素B12的浓度从平价1逐渐增加到3。对于两种维生素 牛奶中0至55天的血浆浓度低于56至200天时的血浆浓度。在3种主要成分中，一种与膳食碳水化合物相关的成分与血浆叶酸和维生素B12浓度显着相关。实际上，血浆叶酸浓度随膳食纤维浓度（即中性和酸性洗涤剂纤维和木质素）降低而随膳食非纤维碳水化合物浓度升高而升高。对于血浆维生素B12浓度，我们获得了相反的结果。两种多变量模型均解释了血浆叶酸和维生素B12浓度变化的41％（伪R2）。这项研究中收集的信息是确定血浆叶酸和维生素B12浓度以及奶牛维生素状况变化来源的第一步。与饮食碳水化合物有关的一种与血浆叶酸和维生素B12的浓度显着相关。实际上，血浆叶酸浓度随膳食纤维浓度（即中性和酸性洗涤剂纤维和木质素）降低而随膳食非纤维碳水化合物浓度升高而升高。对于血浆维生素B12浓度，我们获得了相反的结果。两种多变量模型均解释了血浆叶酸和维生素B12浓度变化的41％（伪R2）。这项研究中收集的信息是确定血浆叶酸和维生素B12浓度以及奶牛维生素状况变化来源的第一步。与饮食碳水化合物有关的一种与血浆叶酸和维生素B12的浓度显着相关。实际上，血浆叶酸浓度随膳食纤维浓度（即中性和酸性洗涤剂纤维和木质素）降低而随膳食非纤维碳水化合物浓度升高而升高。对于血浆维生素B12浓度，我们获得了相反的结果。两种多变量模型均解释了血浆叶酸和维生素B12浓度变化的41％（伪R2）。这项研究中收集的信息是确定血浆叶酸和维生素B12浓度以及奶牛维生素状况变化来源的第一步。血浆叶酸浓度随膳食纤维浓度（即中性和酸性洗涤剂纤维和木质素）降低而随膳食非纤维碳水化合物浓度升高而升高。对于血浆维生素B12浓度，我们获得了相反的结果。两种多变量模型均解释了血浆叶酸和维生素B12浓度变化的41％（伪R2）。这项研究中收集的信息是确定血浆叶酸和维生素B12浓度以及奶牛维生素状况变化来源的第一步。血浆叶酸浓度随膳食纤维浓度（即中性和酸性洗涤剂纤维和木质素）降低而随膳食非纤维碳水化合物浓度升高而升高。对于血浆维生素B12浓度，我们获得了相反的结果。两种多变量模型均解释了血浆叶酸和维生素B12浓度变化的41％（伪R2）。这项研究中收集的信息是确定血浆叶酸和维生素B12浓度以及奶牛维生素状况变化来源的第一步。两种多变量模型均解释了血浆叶酸和维生素B12浓度变化的41％（伪R2）。这项研究中收集的信息是确定血浆叶酸和维生素B12浓度以及奶牛维生素状况变化来源的第一步。两种多变量模型均解释了血浆叶酸和维生素B12浓度变化的41％（伪R2）。这项研究中收集的信息是确定血浆叶酸和维生素B12浓度以及奶牛维生素状况变化来源的第一步。