Tuesday, July 5, 2022

US scientist’s NZ claims rejected

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An American scientist who says New Zealand soils and animals are sick from overuse of nitrogen fertilisers is being challenged by scientists from this country. Dr Arden Andersen completed recently a $500-a-ticket road show in the North and South Island, with up to 100 delegates attending his Soils, Science and Food seminars. Andersen said NZ farmers were overdosing on urea use by three to four times, resulting in excess levels passing through to milk. 

He also cited the recent DCD residue issue, saying the chemical was an antibiotic that threatened to breed a strain of resistance into the human population.

However, his comments have drawn the ire of University of Waikato professor of agribusiness Dr Jacqueline Rowarth.

“There is confusion by Dr Andersen about that. DCD is also the short name for dermcidin, produced in sweat glands and variously described as antimicrobial or antibiotic because it kills organisms on the skin,” Rowarth said.

“In contrast dicyandiamide, also termed DCD, is applied to pasture. The DCD measure in very low quantities in milk powder is not an antibiotic, and antibiotic resistance will not appear in children after drinking reconstituted milk powder.”

But Andersen was adamant DCD was an antibiotic and said Rowarth was “playing with semantics”.

He also said that because of overuse of urea NZ milk had three to four times the milk urea nitrogen (MUN) of that in the United States.

However, Rowarth cited research indicating NZ herds operated in a similar range to housed US herds for this indicator of “waste” or bypass nitrogen.

Rowarth also refuted another of Andersen’s assertions, that nutritious milk would result only from having balanced soil nutrition, which is lacking in NZ.

She said the nutritional quality of NZ milk was monitored and had shown to have a higher ratio of Omega 3 to Omega 6 fatty acids than standard US milk.

This is a ratio US organic milk suppliers aspire to and is highlighted as being more nutritious, giving NZ a fundamental advantage.

But Andersen said Rowarth’s comparison to US milk needed to be compared to high-quality organic US producers and would be found wanting.

Andersen also pointed to elevated MUN levels cited in DairyNZ work and the finding it was relatively common for pasture-fed cows to have significantly higher MUN levels than the average range.

However, that work also found NZ cows were tolerant to high blood and milk nitrogen levels and the benefits of using nitrogen to grow more feed outweighed the potential negative of higher nitrogen levels.

Andersen has drawn fire from scientists in the past over claims about conventional farming systems delivering lower-quality protein products and unhealthy animals.

On a visit in 2007 he cited data from DairyNZ and Waikato Technical Institute to claim NZ farmers were growing less grass now than in the early 1980s.

This was discounted by NZ scientists, who expressed grave concerns over his data when their data indicated an average increase in the drymatter consumption of NZ dairy cows of 20% over 10 years.

Andersen also says pasture sugar, or “brix” levels, are a more accurate indicator of when pastures are suitable for grazing.

But Dr John Roche, principal scientist at DairyNZ, has discounted the use of brix to indicate a pasture’s feed value. His research has shown no effect on milk production when energy was supplied either as fibre or as sugar and starch.

However, Andersen is adamant brix level is an effective indicator of pasture quality.

“No question about it. I have data off farms in NZ following my system that have 14% lower costs and 30% increases in profitability.”

Andersen has written books including Real Medicine Real Health, linking agriculture and particularly soil fertility to human health.

Dr Doug Edmeades, a long-time critic, concedes there is a link between human and animal health to soil in specific cases such as bush sickness (cobalt deficiency) but it is not generally true.

Edmeades dismisses Andersen’s claims that conventional farming systems have depleted minerals and compromised food resources.

“Before the introduction of Western farming practices many of our soils were depleted in minerals. A national survey has shown, with some exceptions, the quality of NZ soils is very good. People, at least in the Western world, are healthier than ever before, as indicated by longevity statistics.”

Andersen’s doctorate is listed as being held in osteopathics, while he also holds a Bachelor in Agriculture-Agricultural Education from Arizona State University. He also has a PhD in agricultural biophysics from Clayton University in Georgia. 

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