Optimising lactation cycles for the high-yielding dairy cow. A European perspective
ABSTRACT 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.
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ABSTRACT: The net economic value of reproductive efficiency in dairy cattle was estimated using a stochastic dynamic simulation model. The objective was to compare the economic consequences of reproductive performance scenarios ("average" and "poor") of a cow having a good reproductive performance and to explore which reproductive factors have an important impact on economic efficiency. A "good" reproductive performance scenario was defined with 1 ovulation rate (POVU(i)), 0.7 estrus detection rate (PEst), 0.7 conception rate (PCon), 0.03 incidence rate of postpartum disorders prolonging the ovarian cyclicity (CO), 0.2 incidence rate of postpartum disorders reducing conception (ME), 0.05 embryonic death rate (ED), and voluntary waiting period (VWP) of 9 wks pp (post partum). In the current situation of dairy cows in the Netherlands, an "average" reproductive scenario (0.95 POVU(i), 0.5 PEst, 0.5 Pcon, 0.07 CO, 0.27 ME, 0.07 ED and VWP of 12 wks pp) and a "poor" reproductive scenario (0.90 POVU(i), 0.3 PEst, 0.3 Pcon, 0.11 CO, 0.33 ME, 0.09 ED and VWP of 15 wks pp) were identified. A sensitivity analysis was performed by comparing changes of single effect of factors in a good and poor scenario with the average scenario. The mean net economic loss (NEL(i)) compared with the good scenario was euro 34 and euro 231 per cow per year for the average and poor reproductive performance scenario, respectively. Increasing the calving interval resulted in greater economic loss. The important factors on the cost of reproductive efficiency were the involuntary culling cost and the return of milk production. Variation in PCon, PEst, ME, ED, and VWP had large impacts on economic benefits.Theriogenology 09/2010; 74(5):835-46. · 1.96 Impact Factor