“If you took at breeding strategy and production system that uses a high proportion of feed for milk production, it will mean by default a lower proportion of feed and losses related to maintenance.”
He maintains this view has underscored much of the company’s work and is a key driver behind its New Zealand Merit Index
“While similar to Breeding Worth (BW) index the subtle difference is it is keyed at 400kg MS/cow production systems where the cost of energy and losses for maintenance and diluted against the higher milk output. Almost coincidentally you will have a cow with a reduced environmental footprint.”
Almost a decade ago Dexcel had a short-lived philosophy to have national production lifted to 400kg MS/cow/year, a good philosophy he believes.
“Really, those production gains are the low hanging fruit for the industry. With an industry average of only 340kg MS/cow … the environmental losses are just too high.”
Beatson said CRV Ambreed had its eyes wide open about the complex issue of lowering dairy herd nitrogen and methane losses, but it was a tough area to measure.
Head of LIC research and development Dr Richard Spelman said the 2012 trial of high BW cows against low for nitrogen losses highlights the potential for some genetic contribution to a lower nutrient loss footprint.
“A lot of traits we measure on animals have been sex limited, such as milk production or fertility,” he said.
“But with feed conversion efficiency and lactation, some of these traits are not limited to dams alone.”
But measuring nitrogen losses from cows can be a problem.
“Nitrogen levels can vary based on things like when the cow last ate, and we need repeated, consistent measures,” he said.
“Proxy measures like somatic cell counts are for mastitis would be good.”
The dairy industry would end up with a more environmentally friendly cow due to improved feed conversion efficiency that evolved from higher BW. Over 10 years an average BW increase of 100 should yield an additional 20kg MS.
He compares the average per cow production back in 1992-93 of 260kg MS to the 2012-13 average of 346kg MS.
“To produce the same amount of milksolids today with such a cow would require over five million cows.”
But he and Dr Jeremy Bryant of NZ Animal Evaluation point to the need for farmers to reduce stock numbers as genetic gains deliver higher-producing, more feed-efficient cows. Bryant said a rule of thumb was to allow for improved output per cow equating to reducing cow numbers by one cow/300 annually, offering another five tonnes of additional feed/300 cows/year to realise it from supplements or improved pasture species.
