Achieving mating weight critical to economics of "elastic" cows

29 April 2015

 When it comes to a breeding cow's ability to gain and hold weight, a group of Canterbury farmers wanted to know which type of cow was more profitable: an "elastic" cow or a "resilient" cow?

The B+LNZ Canterbury beef profit partnership group used a farmer-initiated technology transfer project to find the answer.

Elastic refers to a beef cow's ability to use summer and autumn feed surpluses to lift their body weight, then withstand some bodyweight loss over winter. Resilient refers to a cow's ability to resist losing weight during autumn and winter, when feed conditions are poor. A resilient cow is less reliant on regaining weight during summer, before mating.

The research found that elastic cows had a 10 per cent higher annual feed demand than resilient cows, but the additional demand was over late spring and early summer, when pasture was abundant and cheap.

Essentially, the elastic cow's feed demand curve fitted the hill country feed supply curve better than the resilient cow.

This improved match up of feed supply and demand is valuable from a feed quality perspective – a key driver for growing young stock and high ewe flock production – and the primary reason many farmers run beef cows.

graph shows feed demand curve of elastic cow fits hill country feed supply curve better than the resilient cow

The critical finding from the research was that the elastic cow needed to be back up to weight by mating. If this was not achieved, then the risk of lower pregnancy rates and productivity off-set the feed advantages of the elastic cow.

Key findings

  • Target optimum cow condition at mating for satisfactory reproductive rates
  •  Identify light cows at calving and preferentially feed through to mating
  • Identify cows that lose condition over winter, recover in spring, achieve acceptable liveweight at mating – then use this information to assist with culling decisions
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