Dr Bill Wales and the pasture consumption calculator.IT’S a dry argument that might finally have been settled.
Australian researchers have officially backed a new way of estimating dry matter (DM) consumption in dairy herds.
They believe a technique called ‘feeding systems’ is more accurate than the current system.
Janna Heard, a research scientist with the Department of Primary Industries (DPI), led the team of Victorian and WA scientists studying how farmers account for energy requirements of Australian herds.
As a result of this work, a simple computer program has been developed to help them estimate on-farm annual pasture removal and feed conversion efficiency of the milking herd. DPI Research Manager of Dairy Production Sciences Bill Wales said this could be used to benchmark farm performance over time.
“You need to measure pasture consumption accurately to make sensible decisions on purchasing expensive supplements,” he said.
“However, estimating the amount of pasture consumed is difficult and is influenced by the interrelationship between animals, plants and overall feed management.”
When researchers analysed the sensitivity of both techniques using a stylised dairy farm in Australia’s temperate zones, pasture consumption using the current approach was 8.6tDM/ha, while the feeding standards approach measured 12.44tDM/ha.
Currently many farmers use a back-calculation that assumes every 20kgDM of feed consumed annually produces 1kg milk fat.
After allowing for intake of supplements, forage consumption can be estimated from milk fat production.
“This is possibly no longer a suitable standard,” Dr Wales said.
“There have been significant improvements in the genetic potential of cows based on milk component yield, such as milk fat, and there is now a much wider range of feeding systems than when this simple calculation method was introduced.”
Seeking a more accurate technique, the researchers used a back-calculation approach which accounts for all the metabolisable energy (ME) requirements of a cow under Australian conditions, based on CSIRO findings.
“The practical implication of this is that dairy farmers might be undervaluing the contribution of pasture and overvaluing the contribution of purchased supplementary feeds to their herd’s diet,” Dr Wales said. “We feel confident the ‘feeding standards’ approach provides an improved measurement method.”
