In this research communication I show the effect of various cow–calf contact systems on milk yield and milk composition during the periods when calves where allowed to suckle their dams and after the calves were separated in comparison to cows that were only machine milked throughout their lactation. Analyses were based on four different experiments, but conducted at the same research station and under comparable housing and feeding conditions. Nursing dams had contact to their calves during the whole day, during night-time or only twice per day shortly before milking. A control group of cows that had no contact to their offspring was part of every experiment. Data of the regular monthly milk recordings were analysed with linear mixed models. Results showed a significant effect of the suckling system on the machine milk yield over the whole lactation. While cows with night-time contact reached the milk production level of the control cows, cows with whole day or short-time contact still produced less milk after the calves were separated. Fat content was always lower during the suckling period but not afterwards. The significantly higher milk protein content in dams with calf contact requires further investigation. Somatic cell count in milk of nursing dams was slightly increased, probably due to the exposure of the teats to frequent suckling in addition to machine milkings. In conclusion, cow–calf contact systems influence the performance of cows during and after the suckling period but to varying degrees depending on the system adopted.

中文翻译：

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奶牛-小牛接触系统中哺乳对奶牛产奶量和奶成分的影响

在这篇研究交流中，我展示了在犊牛哺乳期和犊牛分离后，各种奶牛与犊牛接触系统对产奶量和牛奶成分的影响，与在整个泌乳期间仅使用机器挤奶的奶牛相比. 分析基于四个不同的实验，但在同一研究站和可比较的住房和喂养条件下进行。哺乳大坝在全天、夜间或挤奶前一天仅接触两次犊牛。每个实验都包含一组与后代没有接触的母牛。使用线性混合模型分析每月定期牛奶记录的数据。结果表明，哺乳系统对整个哺乳期的机器产奶量有显着影响。虽然夜间接触的奶牛达到了对照奶牛的产奶量，但全天或短时间接触的奶牛在犊牛分离后产奶量仍然较少。在哺乳期，脂肪含量总是较低，但之后则不然。与小牛接触的水坝中显着更高的牛奶蛋白质含量需要进一步调查。哺乳母马乳汁中的体细胞计数略有增加，这可能是由于除了机器挤奶外，乳头还经常受到哺乳。总之，牛犊接触系统会影响奶牛在哺乳期和哺乳期后的表现，但程度不同，具体取决于所采用的系统。虽然夜间接触的奶牛达到了对照奶牛的产奶量，但全天或短时间接触的奶牛在犊牛分离后产奶量仍然较少。在哺乳期，脂肪含量总是较低，但之后则不然。与小牛接触的水坝中显着更高的牛奶蛋白质含量需要进一步调查。哺乳母马乳汁中的体细胞计数略有增加，这可能是由于除了机器挤奶外，乳头还经常受到哺乳。总之，牛犊接触系统会影响奶牛在哺乳期和哺乳期后的表现，但程度不同，具体取决于所采用的系统。虽然夜间接触的奶牛达到了对照奶牛的产奶量，但全天或短时间接触的奶牛在犊牛分离后产奶量仍然较少。在哺乳期，脂肪含量总是较低，但之后则不然。与小牛接触的水坝中显着更高的牛奶蛋白质含量需要进一步调查。哺乳母马乳汁中的体细胞计数略有增加，这可能是由于除了机器挤奶外，乳头还经常受到哺乳。总之，牛犊接触系统会影响奶牛在哺乳期和哺乳期后的表现，但程度不同，具体取决于所采用的系统。在哺乳期，脂肪含量总是较低，但之后则不然。与小牛接触的水坝中显着更高的牛奶蛋白质含量需要进一步调查。哺乳母马乳汁中的体细胞计数略有增加，这可能是由于除了机器挤奶外，乳头还经常受到哺乳。总之，牛犊接触系统会影响奶牛在哺乳期和哺乳期后的表现，但程度不同，具体取决于所采用的系统。在哺乳期，脂肪含量总是较低，但之后则不然。与小牛接触的水坝中显着更高的牛奶蛋白质含量需要进一步调查。哺乳母马乳汁中的体细胞计数略有增加，这可能是由于除了机器挤奶外，乳头还经常受到哺乳。总之，牛犊接触系统会影响奶牛在哺乳期和哺乳期后的表现，但程度不同，具体取决于所采用的系统。