cjs-202304-0004 ArticleInAPeriodical 2023 Czech Journal of Animal Science 68 4 161-168 CodlRadim DucháčekJaromír VacekMojmír PytlíkJan StádníkLuděk VrhelMarek The influence of eating and rumination time on solids content in milk and milk yield performance of cows The aim of this study was to evaluate the effect of rumination time, eating time and season on milk yield and on milk component content in the context of milk recording. The experiment was carried out with two breeds - Czech Fleckvieh cattle and Holstein cattle - for one year. Vitalimetr 5P neck responders were used to monitor eating and rumination time. For statistical evaluation, the time of eating and rumination was divided into three groups according to the length of eating and ruminating, with each breed being categorised separately. The highest protein content, which was 3.6%, was calculated for the group with an average eating time. The fat content was highest for the group with a below-average eating time. On the other hand, the highest milk yield was statistically significantly (P < 0.01) higher in the group with the longest eating time. In terms of rumination, the trend was similar to that of the eating period. In the evaluation of the effect of rumination time, there was no difference in protein %, fat kg and fat % content. A significant (P < 0.05) increase of protein kg was observed with higher rumination time. Changes in milk yield and milk components also occurred throughout the year. During the winter months, the yield decreased, but there was an increase in milk constituent content. During the summer months, the reverse results were obtained. The findings of this study highlight the importance of evaluating eating and rumination time as a potential predictor of milk yield and milk solids content, which are important in milk monetization.