The Northern fowl mite, Ornithonyssus sylviarum, is the most important ectoparasite of commercial poultry in North America. Feeding sulphur to layers was successfully tested as a way to control fowl mites yet still not affect the production parameters of layers.

The research was conducted by Dr Wallace Berry, S. Oates and J. Hess from Auburn University in the US.

Fowl mite infestations can reduce egg production by 10 per cent or more – bad for layers, even worse in breeders, particularly the males. They can also bite humans and cause irritation. The constant re–infestation of mites is a continual problem for the industry, said Dr Berry.

Mites in the US are currently controlled by pesticides (pyrethroids) and their use is opposed by the government. None of these insecticides kills the mite eggs, plus some residue remains.

Dr Berry pointed out that an old cure is sulphur and sulphur powder (‘flowers of sulphur’) that has been and is still used to kill mites and ticks.

Some facts on elemental sulphur:

• inexpensive
• effective on mites and other pests
• low toxicity (unlike sulphur compounds)
• resistance is less of an issue, and
• can be sprayed or dusted

Problems with dusting sulphur:

• flammable
• corrosive
• irritating
• difficulty to control dose, and
• applications are labour–intensive

The Novel Idea: Feeding Sulphur

‘Feed–through’ pesticides have been used in the poultry and livestock industry for some time, now, Dr Berry said.

Means of controlling or eliminating fowl mites without pesticide resistance or residue concerns are needed. For this reason, three levels of a granular sulphur–based miticidal treatment in the layer diet were tested as a potentially effective and safe ‘feed–through’ miticidal treatment in laying hens, without affecting production parameters.

The levels tested were: low dose, 1 pound per ton; medium dose, 3 pounds per ton and high dose, 5 pounds per ton.

The test ran for eight weeks to determine the time required for miticidal activity to become apparent, and to determine efficacy over several mite generations. Mite numbers on the hens as well as hen body weight, mortality, egg production and shell and interior egg quality were measured throughout the experiment. Mites were counted by swab test.

At the end of the experiment, hen tissues, eggs and faeces were analysed to determine the distribution and fate of the compound in the birds, eggs and waste.

Dr Berry’s research found that the miticidal treatment reduced mite numbers without altering feed intake, egg production, egg weight or eggshell quality, and it did not accumulate in hens or eggs. There was no sulphur residue.

The only effect seen was that egg albumen height decreased at the high inclusion level of sulphur.

There was a significant decrease in mites at the medium dose at six and seven weeks, he emphasised. The high dose also had some positive results.

Effect on Minerals and Ammonia

The analysis for nitrogen, phosphorus, potassium and cadmium as well as other minerals demonstrated that granular sulphur did not alter the way hens use these minerals, did not cause the hens to accumulate toxic minerals, or to lose valuable minerals, and did not alter faecal concentrations of these minerals.

As a side benefit, the compound acidified hen waste and significantly reduced ammonia emissions. This fact alone has the US poultry industry interested in this research. They are looking at doing this same research in breeders.

Dr Berry added that, to his knowledge, this is the first study of its kind to examine the potential for using a granular sulphur product as a feed–through mite control agent in laying hens.

June 2012