Optimising lactation cycles for the high-yielding dairy cow. A European perspective

Few investigations have been performed where effects of a planned increase of the calving interval have been elucidated. In order to study these matters, a research project has started at the Swedish University of Agricultural Sciences (SLU). The study involves researchers both at the Agricultural and Veterinary Faculties at SLU as well as from the dairy industry in Sweden. Experiments are being performed within two experimental herds (approximately 150 cows) belonging to SLU. We are now in the middle of a three-year study comparing 12- and 15-month calving intervals (herd 1) or 12- and 18-month calving intervals (herd 2), In herd 2, two milking frequencies (2 vs. 3 per day) are combined with the two calving intervals. Long-term effects on health, reproduction, milk production (including milk quality) and production efficiency are studied in detail. The plan is to study individual cows in three consecutive years. Interactions with management system and breed will also be investigated. Results from the first lactation show no significant differences in fertility between treatments. So far, milking three times per day has not given a more persistent lactation compared with milking two times a day. Some cases of salty taste of milk have been noticed. (C) 1997 Elsevier Science B.V.