Why chicken litter is not the source of velvet leaf infestation

There has been commentary recently, particularly in the Waikato area and in the South Island, about velvet leaf infestation.

Some parties have attempted to put the blame for its appearance on farms on use of chicken litter or any fertiliser sourcing from meat chicken or layer hen farms.

The argument being used by certain parties is that viable weed seeds from imported grains which allegedly contain velvet leaf survive the milling process and then are spread when the litter or fertiliser using layer faeces is spread on  properties, particularly arable farms.

Below is a flow chart setting out the process that is followed by feed mills, and written information in italics. The key requirement is to ensure that viable seeds do not survive the milling process. The non-viability is achieved by grinding the grains and /or applying a heat treatment process. Feed mill companies are required to undertake tests to show that viable seeds have not survived, and to keep the results of those tests for a period of time, and to have them available for audit at any time by the Ministry for Primary Industries.

Processing of Grain

  • Grinding & micro-sampling
  • Heat treatment
  • Micro-testing finished product
  • Testing for viable seeds in finished products.

Heat-treatment is to a minimum 70-90 degrees C. (The grain is heat-treated in a conditioner chamber with steam).

Sampling and testing for weed seed survival viability (monthly).

All feed companies that are members of the NZFMA (New Zealand Feed Manufacturers Association – comprising all companies who supply feed for meat chicken companies, who then supply chicken litter and layer hens ) have not had positive results for viable seeds after the conditioning process. All imported grain used in feed is treated this way.

Process flow chart for grains