In New Zealand, beef cows have long been thought to be less profitable than their dairy cow cousins and have often been described as necessary evils by their sheep farmer owners, but are needed to keep the grass 'right' for the sheep they share pastures with. Beef cows and sheep are usually farmed together.

Recent research at Lincoln University, however, has provided a number of insights into ways farmers could improve the production and efficiency of their beef herds.

This research was part of a Master of Agricultural Science degree undertaken by Craig Thomas, a veterinarian and beef farmer, studying in the Faculty of Agriculture and Life Sciences at Lincoln University. Funding for the project was providing by the Sustainable Farming Fund of the Ministry of Agriculture and Forestry.

The work was based on data collected from more than 30 mainly Canterbury beef herds over a three-year period.

The aim of the project was to find out whether there were any practical ways for beef farmers to identify and cull the least efficient heifers and cows in their herds.

"Currently, most commercial beef farmers choose the largest heifer calves for replacements and rarely cull any mature cows for poor performance," said Craig.

"My research showed that there are practical ways to determine the efficiency of individual cows and that some cows are more efficient than others year after year."

Of all the different culling strategies looked at, the most profitable system was one that involved mating more than the normal number of yearling heifers and then choosing rising three-year-old replacements for the main cow herd based on their first calving performance.

"Culling the bottom half of first calving heifers based on the calf they produce will increase net future per cow revenue by up to $30 per cow per year," said Craig.

"This is the major outcome from this research."

Identification of which calf belonged to which cow was also crucial to evaluating an individual cow's performance. Three different methods were investigated: identifying cow/calf pairing at birth, after marking or by the use of DNA collected from the cow and the calf.

Current pricing of DNA-determined parentage made the use of that technology unprofitable.

"Identification and culling of the least efficient mature cows in the herd was far less profitable than the other methods, with net future increased cattle revenue only increasing by $7-8 per cow per year," said Craig.

"A third performance recording system examined was the use of home-grown bulls which although quite profitable probably required more intensive management than most beef properties are willing to undertake."

Several of the farmers involved in the project have commented that culling heifers on their first calf has really tidied up their calf crop and they will continue using the system.