Managing pastures for sheep

Ms Broughton, an independent production advisor for sheep producers in the southern parts of the state was addressing the Sheep Connect NSW webinar, an industry focused extension network funded by Australian Wool Innovation (AWI) with her topic - Perfect match - Pasture and Merinos.

Before you can know the number of ewes a particular paddock can carry and for how long, Ms Broughton said the place to start was measuring pasture quantity and pasture quality.

Ms Broughton said quantity is measured in kg/ha of dry matter (DM) which is simply the plant material which is left after all the moisture has been removed.

"We talk about the dry matter content because the moisture content is very variable according to the growth stage," she said.

"Water doesn't have any nutritional value so we take that out of the equation when assessing the feed value of the pasture."

Ms Broughton further referred to industry terms Feed on Offer (FOO) and Herbage Mass and each describes the amount of pasture available but the method of calculation is slightly different for each process.

There is a 300kgDM/ha difference between each method and Ms Broughton cautioned farmers to be aware of that difference when making their calculations similar.

"The main factors which determine your pasture quantity are height, density and dry matter percentage," she said.

"Making sure you choose the right method (of measuring DM) will really depend on the difference in those characteristics at the time of sampling."

Ms Broughton highlighted three easy to use tools to measure pasture quantity - the MLA Pasture Ruler which works on a simple relationship between pasture height and quantity: the AWI FOO library and taking your own pasture cuts.

"The pasture ruler is quick and easy and good for green actively growing, grass dominant pastures but not suitable for high legume percentage, mature or dry pastures because in those scenarios the relationship between height and density is very different," she said.

"The AWI FOO library is full of visual reference photos and measurements and is suitable for a range of pasture types and growth stages.

"It is quick and as a guide to energy and protein levels is really valuable because it is quite hard to assess otherwise."

Ms Broughton noted a lot of landholders are really good at assessing their pastures, but having the opportunity to utilise those available techniques helps and gives a common language to compare pastures.

But nothing beats taking your own measurements and pasture cuts where a sample is taken of the pasture and weighed and while it can be time consuming it is satisfying.

"It really builds up your visual assessment skills along with your own photo library similar to the AWI FOO," Ms Broughton pointed out.

"Collect photos of your different pasture types and at various stages through the growing season and you will have a really good point of visual reference.

"Pasture growth can be deceptive and people are often surprised as to how much or how little pasture there is the paddock."

There are four key terms Ms Broughton said when talking about pasture quality and they are expressed as a percentage of dry matter - digestibility, metabolizable energy, protein and fibre.

"The higher the digestibility, the higher the energy while the protein requirement depends on the stage of animal production and fibre is essential for rumen health," she said.

"Energy is the number one priority for livestock production, followed by protein, macro-minerals, micro-minerals, and vitamins in order."

Ms Broughton advised focusing on the energy and protein content of your pastures because your sheep will be in various stages of growth or reproductive cycle and naturally will have different nutritional levels.

"The lactation period, especially with twin bearing ewes, will have the maximum requirement for energy," she said.

"They will need three times more energy than a dry sheep and twice as much protein so it is a priority they get your best paddocks."

Consumption will also depend upon the quality and quantity of pasture available where Ms Broughton pointed out a sheep can eat between two and three percent of body weight in dry matter in a day.

The intake of the animal does depend on a lot of different factors and Ms Broughton noted height and length, legume percentage, variety of species and growth stage of the pasture.

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