Dairy cows in confinement and pasture-based feeding systems were compared across four spring-calving and three fall-calving replicates for differences in reproduction, mastitis, body weights, and body condition scores. Feeding systems and replicates included both Jersey and Holstein cows. Cows in confinement were fed a total mixed ration, and cows on pasture were supplemented with concentrates and provided baled hay or haylage when pasture supply was limiting. Breeding periods were for 75 d in spring or fall. Reproductive performance did not differ significantly due to feeding system or season. Jerseys had higher conception rates (59.6 vs. 49.5 +/- 3.3%) and higher percentages of cows pregnant in 75 d (78.1 vs. 57.9 +/- 3.9%) than Holsteins. Cows in confinement had 1.8 times more clinical mastitis and eight times the rate of culling for mastitis than did cows on pasture. Jerseys had half as many clinical cases of mastitis per cow as Holsteins. Only 41 +/- 5% of confinement Holsteins remained for a subsequent lactation, starting within the defined calving season compared with 51 +/- 5% of pastured Holsteins and 71 and 72 +/- 5% of Jerseys, respectively. Body weights and condition scores were generally higher for confinement cows than pastured cows, and Jerseys had higher condition scores and lower body weights than Holsteins. In summary, pastured cows had fewer clinical cases of mastitis, lower body condition scores, and lower body weights than confinement cows. Holsteins were less likely to rebreed, had more mastitis, higher culling rates, and lower body condition scores than Jerseys.
