A shortened, easier to read version of Nutrient Content and Digestibility of Saskatchewan Range Plants is now available.
The report is based on a three-year study conducted by the Grazing and Pasture Technology Program in co-operation with Agriculture Canada’s Semi-Arid Prairie Agriculture Research Centre in Swift Current, Sask.
Author and program manager Zoheir Abouguendia said the study tracked nutrient content and digestibility of Saskatchewan range plants over one year. The analysis addressed different growth forms, such as grasses and shrubs, and the final report provides region-specific data based on sampling of plants in typical grazing areas in the brown, dark brown, black and grey soil zones of the province.
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“And, regardless of the growth form, species or location, the nutrient content and organic matter digestibility levels showed marked seasonal differences,” said Abouguendia. “In general, the highest (organic matter digestibility), protein content and phosphorus levels occurred early in the growing season.”
He said nutrient content and digestibility varied among growth forms and among species within growth forms.
From June to October, for example, forbs, which are broad-leaved herbs, had the highest digestibility of all the growth forms sampled. Cool-season grasses and grass-like plants had slightly higher digestibility than the browse species and the warm-season grasses during the earlier part of the growing season.
Early in the growing season, protein and phosphorus content was highest for forbs and lowest in grasses and grass-like plants. Browse species generally exhibited intermediate protein and phosphorus levels, and these levels continued to be higher than grasses and grass-like plants during the dormant season.
Abouguendia said the study indicated that protein is the best indicator of forage quality and that protein is limiting during much of the year.
“Producers need such information to decide when to supplement, what kind of supplements are needed and how much to supplement.”
The study indicated protein and phosphorus supplements are generally needed in late fall, winter and early spring. Phosphorus supplements may also be needed during the growing season to satisfy the needs of lactating cows and growing animals such as steers.
Abouguendia said the high fibre content of most range plants during the dormant season makes protein supplements necessary for proper animal performance. Adding protein or nitrogen to the diet at that time stimulates rumen microbes to digest the high fibre material more effectively. This causes more rapid rate of passage, greater forage intake and improved performance.
“But based on the study, the need for protein and phosphorus supplements can be minimized by selecting fields containing plants that are high in protein and phosphorus, such as palatable shrubs and forbs.”
Identification important
Because of variations in nutrient content and digestibility, it is important to identify the main species and their proportions in each field in order to make efficient use of the available nutrient supply during the season and the year and across the landscape, said Abouguendia.
“For example, fields dominated by cool-season grasses should be used before those dominated by warm-season plants. Cool-season plants often reach their peak nutrient content earlier. Cool-season plants also have higher nutrient content and greater digestibility during the growing season so they are more suitable for lactating and growing animals than warm-season grasses,” said Abouguendia.
The Nutrient Content and Digestibility of Saskatchewan Range Plants project was supported by Saskatchewan Agriculture’s agriculture development fund.
In Saskatchewan, the report is available from grazing and pasture technology program agrologists.
For more information, contact: Zoheir Abouguendia, manager Grazing and Pasture Technology Program, Box 4752, Regina, Sask., S4P 3Y4, phone: 306-757-9499, fax: 306-569-8799.
