04/01/2022
Research is underway to examine the effect of applying a mineral clay to the floor of sheep pens, on reducing ammonia risks on live export ships.
The University of New England (UNE) is conducting the trial as part of its project partnership with the Livestock Export Program (LEP). It is the latest in a series of trials to understand the interaction between stocking density, ammonia gas generation and bedding, and how that affects sheep and cattle welfare.
Zeolite, a mineral clay mined in NSW, is commonly used in the poultry and dairy industries as either a feed additive or spread in sheds and bedding, to reduce ammonia production.
In this experiment, the zeolite was applied to the floor of five large animal respiration chambers. Each chamber housed nine sheep, equivalent to an allometric stocking density of k=0.33. The aim was to determine zeolite’s effect on the ammonia being released from the pad over a period of 21-days. An additional five chambers contained the same number of sheep but had no zeolite applied, as a comparison.
Following a series of microchamber experiments to determine an appropriate dose rate, the zeolite (4-6mm particle size) was applied to the chambers at 2kg per square metre in a single application before the trial began.
Daily measurements were taken on the pad condition, evaporation, feed and water intake by the sheep, temperature, humidity, and gas emissions from the pad (ammonia, oxygen, carbon dioxide and methane). Air ammonia measurements were recorded with a stationary hand-held device in the chamber throughout the experiment, while continuous video footage was recorded to allow an assessment of the animals’ behaviour. In addition, stratification measurements were taken at five different heights above the pad each morning and afternoon to monitor the release of ammonia into the air.
At the end of the trial, multiple core samples of the pad from each chamber were taken to measure pH, ammonium and moisture. One of the cores was sliced into multiple layers to see the strata effect of the above measures from the floor to the top of the pad. More than three tonnes of manure were manually removed and weighed at the end of the experiment.
In this experiment, the zeolite was applied as a single on-floor application before the sheep were moved into the pens. This was to ensure the trial could be replicated under industry conditions, with the potential to apply zeolite prior to loading, in specific areas of the ship with poorer ventilation or where ammonia risks may be higher.
There is also potential for it to be used as a spot treatment, applied to pens that are degrading faster than others.
This trial was undertaken in consultation with the project partnership working group, made up of experienced exporters, an Australian Accredited Veterinarian, a representative from the department, an independent technical/scientific advisor, and representatives of LiveCorp and MLA. They meet at least quarterly; more often if required.
The results will add to the causal web being developed by UNE, seeking to show and quantify the interactions between stocking density, bedding and ammonia. This will help to identify effective strategies to minimise welfare risks to livestock and personnel on ships.