Kontext

Position – a group of three farmers is seeking to take an innovative and collaborative approach to improving output of their dairy herds through genetic selection and advanced reproductive techniques.  The process of genetic improvement in dairy cattle is undertaken on the basis of selecting the most highly rated bulls to cross with the most productive cows in any given herd.  Bull selection is influenced by the traits that are deemed to be the most desirable for a particular management system and location. Thereafter the most promising heifer calves are selected to replace cows already in the herd.  The three farmers concerned all manage low input spring block calving herds.  In a spring calving herd, it is critical to maintain a tight calving pattern so it is typical to first artificially inseminate (AI) the cows using specially selected bulls and then to sweep up the remaining cows which have not conceived with a live beef bull.  Typical rates of successful AI conception run at 65%.  It is the female calves of the ‘AI-ed’ cows (around half of the 65%) which are used to produce replacement heifers.  Due to calf mortality and morbidity this effectively means most of the female calves are used as replacements and the opportunity for genetic selection of females is low.