A hot, dry summer hastened the maturity and dormancy of native and improved pastures in many parts of the province, reducing both quality and digestibility of forages.
“Plants do not grow as tall as normal in dry conditions,” said beef and forage specialist Barry Yaremcio. “Fibre levels increase faster and overall energy content of the forage is reduced.
“Fibre is the most difficult part of the plant for rumen microbes to break down. Feed remains in the rumen for longer periods of time. The longer the feed is resident in the rumen, the less an animal is able to eat, resulting in lower total daily nutrient intake.”
In hot, dry conditions, less nitrogen is absorbed by the roots and transferred into the plant, resulting is less protein in the leaves. That, in turn, reduces microbial growth in the rumen and feed intake.
“Instead of pasture forage meeting protein requirements until mid- to late September, it’s possible that protein requirements of the lactating cow will not be met by mid-August,” said Yaremcio. “As result, you can expect reduced milk production and lower calf growth rates.”
More mature forages can become very hard and brittle, especially the wheatgrasses and fescues.
“It may seem from a quick drive-by inspection that there’s sufficient forage for the animals to eat,” said Yaremcio. “If cattle ignore these plants and don’t want to eat them, you should consider this material as having no feeding value and it shouldn’t be considered as a potential feed supply.”
Producers should walk their pastures to check what forages have been “left behind,” he said.
“It’s possible to have cows in overmature unpalatable grass that’s up to their knees or bellies and they are unwilling or unable to eat enough to meet nutrient requirements.”
Also watch for overgrazing as this reduces winter survival of certain species.
“Alfalfa and orchardgrass are two prime examples,” said Yaremcio. “Plant counts next spring could be substantially lower if pastures are grazed at the wrong time of year or too extensively. Overgrazing this fall may also delay plant development next spring which delays turnout, and could also reduce next year’s yield potential.”