| Summary: | Adaptivity of eating and rumination behavior are assumed to play a particular role for cows in low-input systems, because they are more frequently challenged by altering forage quality. The present study examined relations between forage quality, chewing behavior and efficiency estimates in dairy cows from Swiss zero-concentrate organic farming systems. A total of 102 Swiss Fleckvieh cows on two organic dairy farms were observed during one full production year. Each farm was visited eight times. At each visit, up to 45 cows were equipped with RumiWatch<sup>®</sup> (Itin and Hoch GmbH, Liestal, Switzerland) sensor head collars, from which eating and rumination time and the frequency of activity changes were obtained for 48 h. Milk from one complete day was analyzed individually. All offered roughages (pasture herbage, grass silages and hay) were sampled at each visit and analyzed for crude fiber, crude protein and net energy, and a feed quality score was calculated. Metabolic production efficiency was estimated based on entire lactation data, and feed efficiency was estimated based on the individual farm visits. Lactation stage and forage quality significantly affected the chewing sensor variables. Eating time increased and rumination time decreased with the improved nutritive quality of feed. Coefficients of variance of the factor animal in the sensor variables showed a contribution of the individual cow to chewing behavior. Significant correlations between chewing sensor variables and efficiency estimates were not found. In conclusion, chewing behavior under on-farm conditions in low-input dairy farms alters during lactation and during changing forage quality, with significant animal effects, indicating potential for new phenotypes, albeit with no indications for efficiency.
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