Beef trial highlights value of pasture management

Southland farmland 9 May 2017

This is part one of a two part series looking at the first year’s results of a B+LNZ Beef Profit Partnership trial focusing on managing pasture quality.

A project focused on driving beef productivity and profitability on grass-based systems has highlighted the value of pasture and grazing management.

Based in Northland, Beef + Lamb New Zealand’s Beef Profit from Pasture (BPP) project has been running for one year, but has already shown that there are clear productivity and profitability gains to be made from managing pasture quality and extending grazing rotation lengths.

Facilitated by AgFirst consultant Gareth Baynham, the project, which focuses predominately on bull beef, aimed to identify strategies that lifted the quantity of pasture eaten from May to December by 1000 kgDM/ha.  At a value of 30c/kgDM, this would generate an extra $300/ha. 

Last year BPP undertook two on-farm trials.  The first, on Dennis and Rachelle O’Callaghan’s Temataa Station, looked at the impact mulching, mowing and hard-grazing Kikuyu grass in April had on the performance of R2 bulls run in a cell-type grazing system between May and December.

The second, on George and Peggy Morrison’s Pukegreen property compared the performance of R2 bulls on 30 and 60-day winter rotations.

Mulching, Mowing or Hard grazing Kikuyu grass

Conclusions

  • Mowing delivers pasture growth and quality benefits at least as good as mulching
  • Managing kikuyu improves feed quality through winter but contributes to lower pasture covers

Gareth says dairy farmers in the region routinely mulch poor-quality Kikuyu grass to allow winter-active pasture species to grow, lifting the overall ME of the pasture. This on-farm trial sought to determine how this would work in a beef system. 

These three treatments were compared with pasture growth and animal performance under a control mob on a “normal” rotation with no kikuyu control.

Calves grazed the mulching/mowing treatment areas before the paddocks were either mown or mulched over two weeks in April.

In the hard-grazing treatment, dry breeding cows were used to hard-graze the area (allocated around 8-9kg DM/cow/day) in mid- April. 

In May, the bulls were stocked on the cells at 3/ha, initially on a 40-day rotation, extending out to 60-days in winter. 

Pasture covers were assessed weekly using a rising plate meter and monthly pasture quality tests taken. 

In the bull-beef system, both the mulching and mowing generated extra revenue of $300/ha. Mulching – at a cost of $100-$150/ha – was more expensive than mowing at $50-$70/ha yet the impact on pasture quality – and animal production – was the same. In this demonstration, mowing kikuyu returned around $230/ha compared to no kikuyu control and mulching returned around $180/ha more than the control. 

The hard-grazing treatment generated extra revenue of $150/ha compared to the control.

Gareth says it was pleasing to see that mowing the Kikuyu, (which has very low growth in winter and spring) was just as successful as mulching at lifting pasture quality at around half the cost.

Cows are effective at controlling Kikuyu, but are not as effective as mechanical control as the cows won’t eat the lowest quality kikuyu. 

Highlighting the trade-off between pasture quality and quantity, pasture covers in all the treatment areas remained lower than the control through winter. 

In part two we look at what impact rotation length has on pasture quality and animal productivity.

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