StettlerLocal.com June 23, 2022 @ 6:40pm
Cooler conditions this spring did not encourage pasture or hay growth. As a result, plants are short and starting to head out. The question that is on many minds: do I cut now or wait and get higher yields?
Plants have one objective in their annual life cycle: to produce viable seed to keep the stand strong and viable. Once the seed head has emerged and is pollinated, the plants do not put more nutrients into growing more leaves or elongating the stem. Instead, as the seeds develop and mature, nutrients are diverted into the root system to expand their mass (Canada Thistle or quack grass, as examples) and fill the roots with nutrients so the existing plants can survive the winter.
Cutting plants for hay or grazing at the late vegetative stage or before flowering is recommended. Plants become stressed when cut or grazed. Removal of the seed head stimulates regrowth. Thus, second-growth occurs. However, the objective of producing viable seed is still the plants’ top priority.
The quality of forage decreases as the plants mature. In the vegetative stage, quality is high. After heading, protein and energy content decreases. Acid Detergent Fibre (ADF) and Neutral Detergent Fibre (NDF) increase over time. As fibre levels increase, energy decreases. Research done at the Northern Alberta Crop Research Centre cut 13 different grass species on a weekly basis from the five-leaf stage to full maturity (Suleiman, Journal of Range Management 52: 75-82 January 1999). They found that protein content decreased by 2% to 2.5% per week after heading. Acid Detergent Fibre (ADF) increased by 3% per week, reducing energy or Total Digestible Nutrients (TDN) content by approximately 1% to 1.5% per week.
Higher Neutral Detergent Fibre (NDF) content reduces the amount of forage an animal is able to consume on a daily basis. As a result, this reduces the amount of nutrients the animals receive on a daily basis.
The recommendation is to take the first cut early and hope for a better second cut. The rains this week should stimulate plant growth and produce a strong second cut.
Barry Yaremcio
Ruminant Nutritionist
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