Reproduction management of tethered cows on Norwegian dairy farms

Dairy farms in southern Norway were surveyed to obtain information regardin g reproduction management in tied herds. A total of 1613 farms were include d in the analyses. Reproductive performance during the main breeding period of the year (November 1 to February 28) was measured using the following d ependent variables: calving to first service and last service interval, num ber of artificial inseminations per cow, non-return rate at 60 days, and ca lving interval. Culling for failure to conceive was found to be associated with longer calving to first service interval, more inseminations per cow a nd lower non-return rate. More inseminations per cow and lower non-return r ate were also recorded in herds where breeding was close to calving. Oestro us checks late in the evening and frequent observations were associated wit h shorter calving to last service interval and shorter calving interval, Ca lving to last service interval was prolonged if the farmers were occupied w ith routine work while conducting oestrous checks. Manual rectal pregnancy testing was of little importance for reproductive efficiency in dairy herds with good breeding performance. More inseminations per cow occurred in her ds where oestrous checks were conducted systematically 3 and 6 weeks after service. Calving to last service interval and calving interval were shorter when only one person was responsible for the herd breeding management. (C) 1999 Elsevier Science B.V. All rights reserved.