Automated milking systems (AMS) offer the potential to increase production and decrease labor costs, providing an option for small farms to remain competitive in today's dairy industry. The success of AMS in a pasture-based feeding system is contingent upon careful management of grazing rotation and cow traffic to entice voluntary milkings. A better understanding of how cows respond to the pasture environment is important for improving management in this context. Our first objective was to evaluate cow responses to both travel distance between paddocks, and forage species heterogeneity among paddocks. Cows increased grazing bout length (P < 0.02) and decreased bout frequency (P < 0.002) with greater traveling effort. Milk yield was not affected (P = 0.52) by distances between paddocks, however, greater overall distance walked daily decreased (P < 0.009) milk yield. Forage species heterogeneity among paddocks had no effect (P > 0.05) on behavior or milk production. Our second objective was to determine whether cows exhibit temporal preference for certain species mixtures based on predicted increases in water-soluble carbohydrates (WSCs) during evening hours. Contrary to expectation, cow preferences tended not to be based on time of day (P > 0.05), but may have been skewed by unequal biomass availability across contrasting forage species mixtures. Our final objective was to examine grazing behavior in two feeding systems, and between two cattle breeds. Cows fed partial totally mixed ration (pTMR) spent less time grazing (P < 0.01) than those not fed pTMR. United States Holsteins had greater milk yield (P < 0.01) than New Zealand Friesians. No other variables differed (P > 0.05) between feeding systems or breeds.
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