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March 2010 Archive for Animal Health & Nutrition

RSS By: Rick Lundquist, Dairy Today

Rick Lundquist is an independent nutrition and management consultant based in Duluth, Minn. He provides livestock production advice.

Forage Fragility as a Measure of Effective Fiber

Mar 26, 2010

By Rick Lundquist, Ph.D.

 

Feeding cows is part science and part art. Nutritionists and dairy producers who know and study cows recognize that the art of feeding cows is the intangible that can’t be predicted by a computer program. Nutritional science continues to attempt to explain the art of feeding. Fiber digestion is one area that challenges nutritional science.

 

Dr. Dave Mertens of the U.S Dairy Forage Research Center defines physically effective NDF (peNDF, neutral detergent fiber) as the fraction of NDF that stimulates chewing and helps form the “rumen mat.” The “rumen mat” retains feed particles in the rumen, which increases their digestibility and can affect rumen pH, butterfat, acidosis and feed efficiency.

 

Physically effective NDF is measured by dry sieving the forage and measuring the portion of particles retained on the sieve. Diets with 21% to 24% peNDF of dry matter appear to promote the highest efficiency of 4% fat corrected milk production. But peNDF doesn’t explain all of the variation in chewing time. For example, we know that cows have to chew longer to process the same amount of NDF from oat straw compared to alfalfa.

 

Dr. Rick Grant of the Miner Agricultural Research Institute has attempted to take the prediction of fiber digestibility one step farther by measuring forage fragility. Fragility is defined as the relative rate at which forage is reduced in particle size during chewing. Alfalfa NDF is more fragile than oat straw NDF. Brown midrib corn silage contains highly fragile NDF.  

 

Fragility is measured in the lab by subjecting the forage to a ball mill filled with ceramic balls that mimic the grinding action of molars. Theoretically, a fragility factor combined with peNDF will better predict cow chewing responses. Their lab has conducted experiments that tend to confirm this. Diets were formulated to supply similar amounts of NDF from either wheat straw or grass hay. The grass hay and straw had similar peNDF’s (similar particle size), but the grass fiber had much higher fragility and had greater NDF digestibility than the straw. The straw diet resulted in about 30 minutes more rumination time per day than the grass diet.

 

For now, NDF digestibility is probably the best predictor of chewing and rumination time for most forages.  Fragility and peNDF may help improve this prediction. But, there’s still some art in feeding cows.

 

Rick Lundquist is an independent nutrition and management consultant based in Duluth, Minn. Contact him at siestadog@aol.com.

 
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This column is part of the Dairy Today eUpdate newsletter, which is delivered free to your inbox every Tuesday morning. Dairy Today eUpdate provides the latest in dairy markets, policy, management and production, and news. Click here to sign up.  

Australian Dairy Conference: No Worries Down Under, Opportunities in China

Mar 01, 2010

by Rick Lundquist, Ph.D.

As a participant in the Australian Dairy Conference last week, I became immersed in the Aussie dairy industry and culture.

While I told a tale of depleted equity and continued uncertainty in the U.S. industry, the Aussies seemed to have a more “no worries” attitude about the future of the dairy world, despite a 10-year drought in their country and wobbly prices this past year. They see 2009 as a “dag on a sheep’s tail”; in other words, something to scrape off and move on. 

 

We heard from the Chinese, who are looking nowhere but up for dairy consumption in China. There’s a famous old Chinese saying, we were told, that goes, “The masses regard food as their heaven.”

Dairy consumption in China is increasing despite the melamine scandal. They are looking for high-quality milk and dairy products from foreign countries. They are also rapidly building their own industry. They need technology, and they also need heifers from other countries. I stated in my last column that U.S. agriculture is becoming dependent on China, but there are opportunities there too, if we take advantage of them.

 

We also heard from Australian dairy producers. Theirs are primarily grazing operations. Some are feeding partial mixed rations (PMRs) to supplement the grass. Only a few are feeding TMRs in confinement. They know how to raise high-quality grass in Australia; sometimes too good. Subacute rumen acidosis (SARA) caused by high quality grass is a problem. They don’t feed as much silage as we do, but I saw the best preserved silage I’ve ever seen in Oz: corn silage treated with L. buchneri inoculant, covered with Silostop film and shade cloth. It had absolutely no spoilage layer on top.

 

One thing I came back with is an appreciation for the dairy industry as a whole. For the most part, dairy farmers, regardless of where they’re from, do this because they love cows and they love what they do. Whether they’re from Australia or the U.S., they just want a decent return on their investment so they can continue to do what they love.

 

The world still looks to the U.S. dairy industry for technological advances and solutions to problems. The Chinese milk price is 50% higher than ours, but they still are unprofitable. We can compete with anyone in the world, due to our feed growing capabilities, technology and management. The world is continuing to get smaller, but this may be a good sign for our dairy industry.   

 

Rick Lundquist is an independent nutrition and management consultant based in Duluth, Minn. Contact him at siestadog@aol.com.

 
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This column is part of the Dairy Today eUpdate newsletter, which is delivered free to your inbox every Tuesday morning. Dairy Today eUpdate provides the latest in dairy markets, policy, management and production, and news. Click here to sign up.  

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