The combined effects of milking frequency and feeding level on dairy goat welfare and milk emission characteristics in late lactation

摘要

This study investigated the combined effects of once-daily milking and feeding level (ad libitum or adjusted) on goat welfare and milk emission characteristics in late lactation. Forty dairy goats housed in individual pens were managed under twice-daily milking and fed ad libitum during a pre-experimental period (2 weeks). The experiment was then divided into two successive periods: a 1-week period of milking frequency reduction and a 3-week period of feed adjustment. During the first period, half the goats were managed under once-daily milking. During the second period, half the goats of each type of milking treatment was fed ad libitum, whereas the other half received a quantity of feed adjusted weekly to milk production. The following measurements were taken for all goats: milk yield, dry matter intake (DMI), somatic cell count (SCC), plasma cortisol concentrations before morning milking, milk flow parameters [latency (i.e., the time from teat cup attachment to first measurement of the milk with a jar), the maximum milk flow rate (MAXFR) and the time taken to reach this maximum (TMAX)] and goat behaviour at morning milking (number of goats ruminating, back hunching, foot moving or kicking at milking). In addition, the time-budget (time spent drinking, eating, standing, lying or climbing) of 16 goats was measured by video recording. Milk yield was reduced by once-daily milking (18 and 21% in the first and the second period, respectively) but not by feed adjustment. DMI was reduced by once-daily milking (12%) only during the second period or by feed adjustment (28%) during the same period. Both SCC and latency were not modified by once-daily milking nor feed adjustment. MAXFR was increased by once-daily milking but not modified by feed adjustment. TMAX was increased by once-daily milking only during the first period and reduced by feed adjustment during the second one. The time spent eating was reduced by once-daily milking or feed adjustment during the second period, in agreement with the reduction in DMI in this period. There were no effects of milking frequency or feeding level on plasma cortisol concentrations, the behaviour at morning milking or the time spent drinking, standing, lying or climbing. No welfare impairment was demonstrated under our experimental conditions in late lactation dairy goats under a once-daily milking management strategy whatever the feeding level.