A CASE-CONTROL STUDY TO IDENTIFY FARM FACTORS AFFECTING FERTILITY OF DAIRY HERDS - UNIVARIATE DESCRIPTION OF FACTORS

Objective To identify farm factors which were associated with reproduc tive performance in dairy herds in New South Wales. Procedure A survey was administered by face to face interview to examine the responses o f producers drawn from 757 herds, which used the New South Wales Agric ulture Department Dairy Herd Improvement scheme. A case-control approa ch was used to select a total of 126 herds from the first (top group - cases) and fourth quartiles (low group - controls) for intercalving i nterval. Results We found that the estimated interval from carving to first mating was significantly different between groups (P = 0.03) and that the groups significantly differed in both their target for inter val to first mating (P = 0.02) and their perceived optimum time for fi rst mating (P = 0.04). Other factors associated with a longer intercal ving interval included, use of embryo transfer programs (P = 0.08), yo unger managers (P = 0.02), fewer breedings per day (P = 0.01), a great er number of people detecting heats (P = 0.07), but less hours spent d etecting heats while handling the cows (P = 0.11), and a failure to va ccinate bulls for campylobacteriosis (P = 0.14). Conclusions Managers of herds with poorer reproductive performance did not intend to male c attle as soon after calving as managers with better reproductive perfo rmance, were not as active in seeking veterinary advice on reproductio n, and were attempting to treat reproductive diseases and disorders th emselves.