The article headlined "Lift production but not at cows' expense" which featured in the Otago Daily Times on May 25, mistakenly quoted me at the Telford Open Day as saying the New Zealand average for pasture eaten was 12,000 tonnes, instead of 12 tonnes DM per hectare (12,000 kg DM/ha), and that Lincoln University was sitting above average at 15,000 tonnes, instead of 15 tonnes DM/ha (15,000kg DM/ha).
This was subsequently corrected by the paper, but expressed as 12 tonnes/cow and 15 tonnes/cow.
Jock Allison, of Dunedin, has quite rightly pointed out that New Zealand dairy cows cannot eat that much, so I hope the following clears up any misunderstanding and reiterates an important point about pasture management.
"Pasture eaten" is a measure of how much pasture grown on the milking platform is being eaten by cows to produce milk, and is measured in kilograms of dry matter per hectare (kg DM/ha) or tonnes per hectare (tonnes/ha).
It is calculated as: pasture eaten (kg DM/ha) = milksolids (ms)/ha x kg DM/kg ms, less imported feed (kg DM/ha).
The kg DM/kg ms is the annual amount of feed required for a cow at a specific liveweight and milksolid production level, assuming the average metabolisable energy (ME) of feed eaten is 11 megajoules ME/kg DM.
Pasture eaten is an indication of how much of the feed grown on the milking platform is used (eaten) by the cows, and also indicates how much of the production is obtained from imported feed.
Grass is generally the cheapest form of feed.
Farm profitability can be improved by increasing pasture eaten rather than by importing feed.
Improved pasture management, as well as increased pasture grown and quality, will contribute to increasing pasture eaten.
At the Telford open day, pasture eaten was calculated at 13 tonnes DM/ha (13,000kg DM/ha).
That compared with a New Zealand average of 12 tonnes DM/ha (12,000kg DM/ha), and to the Lincoln University farm of above 15 tonnes DM/ha (15,000kg DM/ha).
This was used to demonstrate the relevance of the information collected by Telford from weekly farm walks and displayed on the South Island Dairying Development Centre website.
This information included average pasture cover, rotation length, milksolids production (ms/cow and ms/ha), soil temperatures, rainfall, pasture growth rates, supplements and nitrogen used.
Telford farm manager Zac Haderbache put the pasture covers into a feed wedge to help with pasture management decisions and to ensure pasture use was maximised.
This also helped with maintaining high quality pasture by keeping grazing residuals below 1500kg DM.
With a payout prediction of $4.55 for 2009-10, farm working expenses need to be carefully monitored.
DairyNZ forecasts farm working expenses at $2.90 a kg ms for 2009-10, down from $3.70 in 2007-08, and $3.25 in 2008-09.
Interest and rent are predicted at $1.20 a kg ms.
At a predicted $4.55 payout, there is little remaining for personal expenses, farm maintenance and plant replacement.
So, with this in mind, reduce costs by increasing pasture eaten.
- Caroline Hadley
DairyNZ consulting officer, South Otago