Grass Seeds: Effects from paddock to plate
Grass seeds have long been an issue for many sheep graziers, costing the industry upwards of $50 million dollars in liveweight losses (can reach 50%) and carcass downgrading.
The greatest risk period for sheep to pick up grass seeds is upon us (October to January), particularly with the excellent growing seasons we’ve experienced the last few years.
It is important to be aware of the risks of grass seeds during our current spring and going into summer. Notably, merinos are more prone to damage by seeds as they have more wool on their legs and around their face, and young sheep may be most affected.
Common seed varieties that have been found in the muscle of sheep carcasses include:
Spear grass (Austrostipa sp.)
Brome grass (Bromus sp.)
Barley grass (Hordeum sp.)
Silver grass (Vulpia sp.)
Chilean Needle grass (Nassella neesiana)
Grass seeds can be picked up by sheep when they graze or become embedded into the fleece when they walk through paddocks which contain any of the species above, during the period when they are setting seed. The seed can then penetrate the skin/muscle within days.
Production losses associated with grass seed penetration include live weight losses, resulting from a reduced feed intake as the animal experiences pain, discomfort, or blindness. In some instances, as few as 25 seeds per animal has been found to cause a 50% reduction in daily weight gain. Other production losses include reduced wool production due to insufficient liveweight, reduced wool value from bitting or rubbing marks or excessive vegetable matter content, and death from secondary bacterial infections and other health exposures.
At the abattoir, carcasses with large amounts of grass seed penetration have been penalised upwards of $1 per kg and require excessive trimming resulting in carcass downgrading or condemnation.
Prevention is the best solution
Producers should consider a variety of the following prevention strategies to mitigate the effects of grass seeds in their sheep this season.
These strategies include:
Pasture and soil improvement i.e. sow strong perennial base, consider lucerne, improve soil fertility to ensure sown species outcompete weeds, apply agronomist approved herbicide treatments
Graze strategically (during normal seasons) to reduce seed set, slash paddocks during seed head development.
Apply rotational cropping practices to provide weed-free paddocks for weaners or lambs
Shear sheep before seeds set to reduce seed uptake
Finish lambs earlier or sell them to finishers
Select animals for less wool cover on the face and legs and fewer body wrinkles to reduce seed uptake.
Winning against seeds
If you are looking for more information, MLA have a great resource titled “Winning against seeds - management tools for your sheep enterprise” it can be accessed via the link below:
3D Sheep Carcass Tool
Interested in seeing how some common health conditions impact on carcass quality? Animal Health Australia have launched an interactive tool that shows the impact of six key health conditions including grass seeds. The tool can be access below: