Milk accumulation in the udder decreases milk secretion and this effect is explained as well by the effects of the quantity of milk stored in the udder as by the duration and repetition of periods of milk stasis. This experiment aimed to better understand the underlying mechanisms of decreased milk yield in response to the specific effects of the quantity of milk stored in the udder, independent from storage duration, on milk yield and composition. Sixteen Holstein cows were assigned to 4 blocks of 4 cows in a 4 × 4 Latin square design using 7-d periods, with a 4-d sampling period and a 3-d washout period. Cows were milked twice daily at approximately 0700 and 1630 h throughout the trial. Treatments consisted of 4 degrees of milk removal (100, 70, 40, and 0%) applied at one morning milking, designated M0. Effects of the quantity accumulated were studied in relation to udder distension, via measurements of the total distance between the ends of the 4 teats, and cisternal capacity, via the evaluation of cisternal area by ultrasonographic scan at 1 and 9 h after M0. The effect of the quantity accumulated was also evaluated in relation to mammary epithelium permeability by determining plasma lactose concentrations 1 h before and 4, 7, and 10 h after M0. Leaving milk in the udder at M0 decreased milk production during the M0–M1 interval in a negative curvilinear manner. As a result, M0+M1 milk yield decreased or tended to decrease significantly by −1.3, −5.3, and −12.8 kg for the 70, 40, and 0% treatments compared with the 100% treatment (41.7 ± 1.26 kg/d), respectively. Negative carry-over effects on milk yield were observed until the M3 milking only for the 40 and 0% treatments, and no differences were observed between the effects of these treatments. The total distance between teats increased significantly but to decreasing degrees during the M0–M1 interval. For the 40 and 0% treatments, cisternal area, which was increased 1 h after M0 milking, exhibited no further increase during the M0–M1 interval, suggesting cisternal distension was close to maximum. Simultaneously, lactose concentrations increased in blood plasma for only these 2 treatments, and this increase occurred earlier for the 0% treatment. It was also observed that cows presenting the earliest increases in plasma lactose concentrations during milk accumulation lost more milk in response to extended milking intervals.

乳汁在乳房中的积聚减少了乳汁的分泌，这种作用也可以通过乳汁中储藏的乳汁量的影响以及乳汁停滞期的持续时间和重复性来解释。这项实验旨在更好地了解牛奶中降低的牛奶产量的潜在机制，这些牛奶对牛奶中储存的牛奶量的特定影响（与储存时间无关）对牛奶产量和组成有特殊的影响。将16头荷斯坦奶牛按照4 x 4拉丁方形设计分配给4头奶牛，每组4头，采用7天周期，4天采样周期和3天冲刷周期。在整个试验过程中，每天大约在0700和1630 h挤奶两次。处理包括在早晨挤奶时采用4度脱奶（100％，70％，40％和0％），标记为M0。通过测量4个乳头末端之间的总距离和水箱容量，通过在M0后1和9小时通过超声扫描评估水箱面积，研究了积奶量对乳房膨胀的影响。还通过确定M0之前1小时，4、7和10小时后的血浆乳糖浓度，评估了相对于乳腺上皮渗透性的累积量的影响。在M0到M1的间隔期间，将乳汁留在M0处的乳房会以负曲线的方式降低产奶量。结果，与100％处理（41.7±1.26 kg / d）相比，70％，40％和0％处理的M0 + M1牛奶产量降低或趋于明显下降-1.3，-5.3和-12.8 kg ， 分别。在仅对40％和0％的处理进行M3挤奶之前，观察到对牛奶产量的负面残留影响，并且在这些处理之间没有观察到差异。在M0–M1间隔内，奶头之间的总距离显着增加，但程度逐渐减小。对于40％和0％的治疗，在M0挤奶后1小时，在C0到M1间隔内，没有扩大，但在C0到M1间隔期间，其胸骨面积没有增加。同时，仅这两种治疗使血浆中的乳糖浓度增加，而对于0％的治疗，这种增加发生得较早。还观察到，在牛奶积累过程中血浆乳糖浓度最早出现增加的母牛会因延长的挤奶间隔而损失更多的牛奶。这些治疗的效果之间没有观察到差异。在M0–M1间隔内，奶头之间的总距离显着增加，但程度逐渐减小。对于40％和0％的治疗，在M0挤奶后1小时，在C0到M1间隔内，没有扩大，但在C0到M1间隔期间，其胸骨面积没有增加。同时，仅这两种治疗使血浆中的乳糖浓度增加，而对于0％的治疗，这种增加发生得较早。还观察到，在牛奶积累过程中血浆乳糖浓度最早出现增加的母牛会因延长的挤奶间隔而损失更多的牛奶。这些治疗的效果之间没有观察到差异。在M0–M1间隔内，奶头之间的总距离显着增加，但程度逐渐减小。对于40％和0％的治疗，在M0挤奶1小时后，其胸骨面积在M0–M1间隔内没有进一步增加，这表明胸骨扩张已接近最大。同时，仅这两种治疗使血浆中的乳糖浓度增加，而对于0％的治疗，这种增加发生得较早。还观察到，在牛奶积累过程中血浆乳糖浓度最早出现增加的母牛会因延长的挤奶间隔而损失更多的牛奶。在M0–M1间隔内，奶头之间的总距离显着增加，但程度逐渐减小。对于40％和0％的治疗，在M0挤奶后1小时，在C0到M1间隔内，没有扩大，但在C0到M1间隔期间，其胸骨面积没有增加。同时，仅这两种治疗使血浆中的乳糖浓度增加，而对于0％的治疗，这种增加发生得较早。还观察到，在牛奶积聚期间血浆乳糖浓度最早出现增加的母牛会因延长的挤奶间隔而损失更多的牛奶。在M0–M1间隔内，奶头之间的总距离显着增加，但程度逐渐减小。对于40％和0％的治疗，在M0挤奶后1小时，在C0到M1间隔内，没有扩大，但在C0到M1间隔期间，其胸骨面积没有增加。同时，仅这两种治疗使血浆中的乳糖浓度增加，而对于0％的治疗，这种增加发生得较早。还观察到，在牛奶积聚期间血浆乳糖浓度最早出现增加的母牛会因延长的挤奶间隔而损失更多的牛奶。提示脑池扩张已接近最大。同时，仅这两种治疗使血浆中的乳糖浓度增加，而对于0％治疗，这种增加发生得较早。还观察到，在牛奶积累过程中血浆乳糖浓度最早出现增加的母牛会因延长的挤奶间隔而损失更多的牛奶。提示脑池扩张已接近最大。同时，仅这两种治疗使血浆中的乳糖浓度增加，而对于0％的治疗，这种增加发生得较早。还观察到，在牛奶积累过程中血浆乳糖浓度最早出现增加的母牛会因延长的挤奶间隔而损失更多的牛奶。