Thursday, July 2, 2009

Takeaways: Grass Productivity by Voisin

Excellent book...lots of great info, some that I've obviously heard/known before, but a little refresher never hurts.

• The period of occupation on any given paddock should be a maximum of 6 days but should optimally be 3 days or less to avoid animals “re-grazing”, or as Voisin says “double shearing”, new growth grass. This “double shearing”, cutting the plant at a time when it has not yet renewed the reserves in its roots, will create great difficulty in the plant making new growth…it will take a very long time to attain proper height for re-grazing and indeed the lack of reserves may even be fatal to the young plant.
• Rest paddocks at least 18 days in the spring and most likely double that in the fall to allow grass sufficient time to re-grow. The easiest way to ensure this in a stocker operation is to stock with half as many calves in the fall as in the spring while keeping the same number of paddocks (double the occupation time from say ½ a day to a full day).
• Animal yields (either milk or weight gain) will be at their maximum if the animal stays on one paddock for one day. Yields decrease significantly after 3 days on the same paddock.
• “We must help the grass to grow and guide the cow in harvesting it.”
• Keep animals from having to stop grazing in order to chew the previous bite by keeping the grass short enough that further manipulation of the bite of grass is not required. Cattle grazing heavy, long grasses will sometimes take a bite, raise their head, and chew up a bite for up to 30 seconds while cattle grazing shorter grass will take 60-90 bites per minute, harvesting much more forage than those animals required to stop grazing to chew up a bite of forage.
• Cattle graze for 8 hours a day. Cattle will never graze for longer than 8 hours per day, regardless of their needs/requirements. They will not work overtime.
• Cattle ruminate for approx. 7 hours per day.
• Cattle lie down for around 12 hours per day…usually over the course of 9 rest periods for a minimum of 1 hour.
• Cattle generally take only one drink per day (when grazing lush pasture).
• Most grazing 60-90% takes place during the day, however, as temperatures increase a greater percentage is done at night.
• The first period of grazing is the longest and usually begins at sunrise…the big morning meal. This first period generally lasts around 2 hours.
• “Figures are only guides: in the end it is the eye of the grazier that decides. The grass commands; the eye of the grazier follows in its train, ready to receive its orders.”
• Rotations should start on different paddocks each year…considerable differences between the flora of the various paddocks will become evident after 2 years when starting rotation with the same paddock.
• It is important to vary the time of occupation (and thus the rest period) depending upon the speed of growth of the grass. Much less rest is needed in the spring while more is needed in the fall and much more rest time is needed in the summer.
• The flora makeup of a pasture is far more dependent on the conditions of management than on the mixture that is sown. “After 2 years for the same mixture sown, there can be either 80% or 1% clover according to the management employed.”
• Flora evolves rapidly and management conditions can effect change in sward makeup very quickly (both positive and negative)….tremendous change can occur even the very first year.

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