Sheep grazing serrated tussock.

THE nutritional value and risks in sheep eating weeds during Summer has been highlighted by Agriculture Victoria this week.

Agriculture Victoria livestock extension officer Raquel Waller said some Summer weeds can cause animal health issues, while others have nutritional value for sheep which may be worth considering before deciding to spray and remove them.

Ms Waller said green pick over Summer can provide protein, which is a necessary component of the sheep’s diet and is important for the digestion of the low-quality dry feed that may be on offer.

“In the absence of a Summer pasture species like lucerne, Summer weeds can be of value.

“However, it is important to know your weeds, since toxic weeds can affect the health of the flock,” she said.

A ‘Grazing value of Summer weeds’ article first published in Spring Sheep Notes 2021 outlines the nutritional value of some weeds that are potentially useful over Summer. It is a preview of the work conducted by Jess Brogden and Lisa Miller at Southern Farming Systems (SFS), and will be published in early 2022 as a Weed Fast Facts booklet on Meat & Livestock Australia’s (MLA) web hub www.mla.com.au/weeds and LESS WEEDS, BETTER PASTURE – Southern Farming Systems (sfs.org.au).

Ms Waller said the pros and cons of grazing, rather than spraying out Summer weeds in a pasture, need to be considered in terms of how it affects the preferred grasses and clover during the growing season.

“There can be competition for resources of light or shade, water and nutrients, problematic seeds for livestock, issues of toxicity and chances of success.

“For example, buried wireweed/ hogweed seed can last for up to 60 years,” she said.

“Generally, a good quality sown perennial pasture will contain 30-50 percent sown grass and 20-40 per cent subterranean clover, with annual volunteer weeds making up the rest of the pasture.

“Pastures that dry off over Summer decline in energy and protein as the plants go to seed and die off,” she said.

“High-quality pastures may still retain sufficient quality to support non-lactating animals for the duration of Summer-Autumn, but poorer quality pastures will not benefit animals.

Click here to read the ‘Grazing value of Summer weeds’ article and find more science-based information from Agriculture Victoria, including a range of tools, tables and calculators, online via the Feeding Livestock website.