This study aimed to determine if a diet change from a mixed system to a confinement system affects the milk production and composition, behavior and blood biochemistry of dairy cows. Cows were assigned randomly to one of the two treatments: cows fed with TMR (total-mixed-ration) (confined) throughout the period group fed TMR (GTMR, n = 15) and cows that changed their diet from pasture plus TMR to exclusive TMR at 70 ± 14 DIM (GCHD, n = 15). GTMR cows produced more milk and greater lactose and protein yield before the change of diet than GCHD cows (p ≤ .01), but these differences disappeared after the change. GCHD cows decreased the frequency of rumination and lying from before to after the change (p ≤ .03), but in GTMR cows no changes were observed. After diet change, GCHD cows had lower frequency of rumination and lying than GTMR cows (p ≤ .02). Before the change, GCHD cows had greater NEFA (non esterified fatty acids) concentrations than GTMR cows (p = .002). Abrupt change from a mixed system to a confined system was favorable on blood biochemical and milk variables of dairy cows. However, in relation to behavior, the cows expressed difficulties to adapt quickly to the abrupt change of system.

中文翻译：

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从奶牛的总奶量和组成，血液生化和行为方面，饮食结构从将总混合配给量和牧场混合的系统更改为限制系统（总混合配给率）。

这项研究旨在确定从混合系统到封闭系统的饮食变化是否会影响奶牛的产奶量，组成，行为和血液生化。奶牛被随机分配到两种处理方式之一：在整个TMR时段（GTMR，n = 15）期间，以TMR（总混合比）（密闭）饲喂的奶牛，以及将饮食从牧场加TMR改为独家饲喂的奶牛TMR为70±14 DIM（GCHD，n = 15）。与GCHD奶牛相比，GTMR奶牛在日粮改变之前产生了更多的牛奶，乳糖和蛋白质产量更高（p≤.01），但这些差异在改变后消失了。从改变前到改变后，GCHD奶牛降低了反刍和卧倒的频率（p≤.03），但在GTMR奶牛中未观察到变化。改变饮食后，GCHD奶牛的反刍和卧倒频率比GTMR奶牛低（p≤.02）。更改之前，GCHD奶牛的NEFA（非酯化脂肪酸）浓度高于GTMR奶牛（p = 0.002）。从混合系统到密闭系统的突然变化有利于奶牛的血液生化和乳汁变量。然而，在行为方面，奶牛表现出难以迅速适应系统突变的困难。