Duplessis Mélissa, Girard Christiane L, Pellerin Doris, Fadul-Pacheco Liliana, Cue Roger I
Agriculture et Agroalimentaire Canada, Centre de recherche et développement de Sherbrooke, Sherbrooke, J1M 0C8, QC, Canada.
Département des sciences animales, Université Laval, Québec, G1V 0A6, QC, Canada.
JDS Commun. 2024 May 10;5(6):577-581. doi: 10.3168/jdsc.2023-0535. eCollection 2024 Nov.
Daily vitamin B (VB) requirements of humans can naturally be fulfilled by animal product consumption, especially products from ruminants because of bacteria dwelling in their rumen. Indeed, only bacteria can synthesize this vitamin. Milk is hence an excellent source of VB. This cross-sectional study was undertaken to unravel factors, such as genetic variation, diet and cow characteristics, and milk production, explaining the large variation in milk VB concentration among cows by using an integrative approach. Milk samples from 2 consecutive milkings were collected from 3,533 Canadian Holstein cows (1,239 first, 932 second, and 1,362 third and more lactations) located in 99 herds with various feeding management. For the purpose of genetic variation analysis, pedigrees were traced back for 3 complete generations for each sire and dam. A total of 10,021 identities were used in the subsequent genetic analyses. Milk VB averaged 4.2 ng/mL with a range between 0.7 and 9.0 ng/mL. Dietary fiber (NDF from forage, dietary NDF, ADF, and lignin) increased and dietary components related to energy (NFC, starch, NE, and percentage of concentrate) decreased VB in milk. Milk VB varied with DIM, with a similar pattern as milk fat and protein concentration lactation curves. Milk VB increased as age at calving increased. When disregarding the herd variance, the heritability value was 0.37, meaning that milk VB can be modified by genetic selection. The final model including factors related to the diet, animal characteristics and milk productivity, and genetic variation explained 79% (pseudo-R) of the milk VB variation. When excluding the random effect of the cow (i.e., excluding the animal and genetic relationships), the pseudo-R dropped to 43%, reinforcing the importance of genetic variation in explaining milk VB variation. To our knowledge, the present study is the most comprehensive evaluation of factors affecting milk VB variation including the greatest number of cows from various lactation stages.
人类每日对维生素B（VB）的需求可通过食用动物产品自然满足，尤其是反刍动物的产品，因为其瘤胃中存在细菌。实际上，只有细菌能合成这种维生素。因此，牛奶是VB的优质来源。本横断面研究采用综合方法，旨在揭示遗传变异、饮食和奶牛特征以及产奶量等因素，以解释奶牛之间牛奶VB浓度的巨大差异。从位于99个具有不同饲养管理方式牛群中的3533头加拿大荷斯坦奶牛（1239头头胎、932头二胎以及1362头三胎及以上胎次）连续两次挤奶中采集牛奶样本。为进行遗传变异分析，对每个父系和母系的谱系追溯了完整的3代。后续遗传分析共使用了10021个个体信息。牛奶VB平均含量为4.2 ng/mL，范围在0.7至9.0 ng/mL之间。膳食纤维（来自草料的中性洗涤纤维、日粮中性洗涤纤维、酸性洗涤纤维和木质素）增加，而与能量相关的日粮成分（非纤维性碳水化合物、淀粉、净能和精料百分比）会降低牛奶中的VB。牛奶VB随泌乳天数变化，其模式与乳脂和蛋白质浓度的泌乳曲线相似。牛奶VB随着产犊年龄的增加而增加。不考虑牛群方差时，遗传力值为0.37，这意味着牛奶VB可通过遗传选择进行改良。包含与饮食、动物特征和产奶性能以及遗传变异相关因素的最终模型解释了牛奶VB变异的79%（伪R）。排除奶牛的随机效应（即排除动物和遗传关系）后，伪R降至43%，这进一步证明了遗传变异在解释牛奶VB变异中的重要性。据我们所知，本研究是对影响牛奶VB变异因素的最全面评估，涵盖了来自不同泌乳阶段的最多数量的奶牛。
