Ron Torell
Back to Basics:
Washy grass
Do you know the difference between a puppy and a rancher? A puppy grows up and quits whining!
Seems you cannot satisfy agriculture people when it comes to moisture. We want moisture, but then whine about the results. Take for example this past spring. June brought more than 4 inches (in.) of moisture to the desert of the Great Basin region. This added moisture was accompanied by cooler-than-normal temperatures, making for ideal growing conditions. These ideal growing conditions produced an abundance of green grass. Out came the whining about washy feed, rain-damaged hay, weeds and increased fuel load for fire. It seems we just cannot stand prosperity.
In this issue of "Back to Basics," let's discuss "washy feed."
Wishy-washy
Washy feed is a term used in reference to forage of diluted nutritional quality yet generally higher volume. Very fast-growing feed often results in high-moisture-content, low-dry-matter, washy feed.
Percent crude protein (CP) and total digestible nutrients (TDN) are often used as indicators of feed quality. The crude protein percentages represent the amount of nitrogen in forage and are lumped together when computing rations for livestock. TDN is a calculated figure representing the sum of all the digestible organic nutrients in the feed and is a good estimate of energy. Rapidly growing grass may actually result in reduced protein and energy levels. With more aboveground forage mass, the amount of nitrogen and energy in the leaves is diluted, or washed out, resulting in reduced protein and energy levels.
Researchers from Oregon State University (OSU) published a paper in the Journal of Range Management titled, "Nutritional Dynamics of 7 Northern Great Basin Grasses." In this professional paper, researchers very clearly documented reduced forage quality and increased forage volume for seven Great Basin grasses on wet years vs. dry years. This paper compared 1992, a dry year (about 9 in. of moisture; good forage quality, but low quantity), to 1993, a great water year (about 17 in. of moisture; washy, low-quality forage, but high quantity). Researchers in Idaho and Arizona showed similar results.
This research reinforces what the old-timers already knew: Washy, weak grass often occurs during wet years.
Relative to washy grass and its effect on weight gains of calves and yearlings and pregnancy rates of cows, local sales representatives for the two leading satellite auctions and several practicing large animal veterinarians reinforce what the old-timers have always told us: Shipping weights of calves and yearlings and pregnancy rates of cows are generally better on moderately dry years than on washy grass years. This is particularly true if stocking rates are increased on wet years to compensate for the increased volume of grass produced.
Pitfalls of lush grass
Is washed-out grass a bad thing? It depends. Do we want a greater volume of weaker grass or less volume of stronger grass? More grass could equate to increased stocking rate on a particular allotment. With increased stocking rates one could manage more cattle on the same acreage, potentially producing more pounds of beef per acre. Granted, per-head production may be lower, but total pounds of beef produced per acre may be higher.
One certainly has to consider the long-term health and well-being of the plant in this decision. Wet years are good for the long-term survivability and thriftiness of perennial grasses.
Does washy feed turn hard when dry? Yes, early spring growth, washy green grass can be as high as 80% moisture. As the plant matures and goes to seed, moisture leaves the standing plant, and the forage will dry up and harden. However, for the same reasons stated above, this dry standing grass would have more volume yet less quality than dry grass in lower-moisture years.
More food for thought: If a cow is acclimated to eating 30 pounds (lb.) per day of dry hay during the winter months, a sudden diet change to a high-moisture, washy green feed in the spring must be quite a shock to the good bugs in the rumen. Passage rate of the dry feed from mouth to anus could take as long as 72-96 hours vs. as few as 24-48 hours for lush green spring feed.
In addition to the abrupt diet change from winter feed to green feed, there is a huge feed intake change as well. In order for a cow to satisfy her dry-matter requirements, she needs to consume upwards of 100-125 lb. of as-fed high-moisture grass per day to equal the 30 lb. of dry feed she was receiving during the winter months. In some cases, the cow may not be able to consume enough wet, lush feed to satisfy her dry-matter requirements.
Dry-matter content and passage rate would partially explain the springtime lag in production and huge change required to adapt rumen bugs to this lush feed. Some research has shown that the addition or availability of a low- to medium-quality dry grass hay may accelerate weight gains on cattle grazing lush feed by satisfying the animal's dry-matter requirements.
Interestingly, many areas in the East and South receive in excess of 30-40 in. of moisture annually. Cattle grazing theses areas of abundant feed are often thin, yet belly deep in grass year-round. Many ranchers supplement protein and energy in these higher-precipitation zones. This tells us they must have washy grass. Thus, the authors conclude that the desert is a good place to live, as we have strong grass on dry years and most of our years are dry. When we do get plenty of rain, resulting in large volumes of grass, we complain about the grass being washy.
As always, if you would like to discuss this article or simply would like to talk cows do not hesitate to contact Torell at 775-738-1721; Bohnert at 541-573-8910; or Sprinkle at 928-474-4160.
References:
Ganskopp, D. and D. Bohnert, 2003. Mineral concentration dynamics among 7 northern Great Basin grasses. J. Range Manage. 56: 174-184.
Ganskopp, D. and D. Bohnert, 2001. Nutritional dynamics of 7 northern Great Basin grasses. J. Range Manage. 54:640-647.
George, M., Nader, G., Mcdougland, N., 2001 Annual Rangeland Forage Quality. University of California Rangeland Management Series 8022.