JDS26031-Beiranvand et al.

Supplementary file of the paper in JDS: A randomized controlled trial evaluating postpartum delayed milking strategy and oral Ca bolus administration on production and blood metabolites of Holstein cows.
Implications: Subclinical calcium (Ca) deficiency is often considered a gateway to other calving-related 5 diseases that impose substantial economic losses on the dairy business. In this study, dairy cows supplemented or not with 2 oral Ca boluses after calving were either milked 3x per day or assigned to delayed milking for 24 and 48 h after colostrum harvest. Ca bolus administration had no effect on production performance and blood metabolites. Overall, milking withdrawal decreased daily 9 milk production during the 3 to 12 days in milk, but it did not affect the 3 monthly test day records. In addition, multiparous cows in the M48 treatment had increased blood concentrations of Ca, P and glucose and decreased those of β-hydroxybutyrate, highlighting delayed milking as a promising strategy to attenuate subclinical hypocalcemia.
in the files submitted to this repository, Table 1 shows the ingredient and composition of the diets used pre-and postpartum, and a diagram is depicted to indicate the factorial design of the experiment (Fig 1). The effects of treatments on cumulative milk production through 3 to 12 days in milk, milk composition, and milk yield on 3 consecutive monthly records of the experimental cows are shown in Fig. 2, 3, and 4, respectively.

本补充文件对应发表于《Journal of Dairy Science（JDS）》的研究论文：一项评估产后延迟挤奶策略与口服钙丸（oral Ca bolus）给药对荷斯坦奶牛（Holstein cows）生产性能及血液代谢物影响的随机对照试验。
研究启示：亚临床钙（Calcium, Ca）缺乏常被视为引发其他围产期相关疾病的诱因，此类疾病会给奶业带来巨额经济损失。本试验中，荷斯坦奶牛产后是否补充口服钙丸，同时分别采用每日3次挤奶方案，或在初乳采集后延迟24、48小时挤奶。结果显示，口服钙丸给药对奶牛生产性能与血液代谢物无显著影响。整体而言，延迟挤奶会使泌乳3至12天的日产奶量降低，但对3次月度测定日记录无影响。此外，接受M48处理的经产母牛，其血液中钙、磷及葡萄糖浓度升高，β-羟丁酸（β-hydroxybutyrate）浓度降低，这表明延迟挤奶是一种有望缓解亚临床低钙血症（subclinical hypocalcemia）的可行策略。
本仓库提交的文件中，表1展示了围产期（产前及产后）所用日粮的原料组成与营养成分，另有示意图阐明本试验的析因设计（factorial design）（图1）。各处理对试验奶牛泌乳3至12天累计产奶量、乳成分，以及连续3次月度测定日产奶量的影响，分别如图2、图3、图4所示。