Consider Undigestible Fiber in Silage Corn Products

Neutral detergent fiber digestibility (NDFD) has long been a primary consideration when evaluating corn silage for dairy rations. Continuing research at Cornell University and other leading research institutions is showing that undigested fiber content (uNDF) of corn silage can also play an important role in formulating efficient dairy rations.

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The Cornell Net Carbohydrate and Protein System (CNCPS) software was developed to predict nutrient requirements, feed utilization, animal performance, and nutrient excretion for dairy and beef cattle and sheep, using accumulated knowledge about feed composition, digestion, and metabolism.1

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A dairy farmer and their nutritional consultant can enter a number of parameters, including forage analysis and chemical composition of the feeds, information about individual animals, including pounds of milk produced per day, body weight, etc. The software then provides the dairy farmer with a list of ingredients per animal to put into the feed for each day.

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“There are several approaches used in developing the most efficient dairy ration formulations,�? says Joe Lawrence, dairy forage systems specialist, Cornell University. “This system incorporates emerging research that has been conducted over the last 10 plus years, evaluating the fiber digestibility of numerous feedstuffs, including corn silage and alfalfa. There is a direct correlation that cows that eat more produce more milk. More undigested fiber in the ration fills the cows up faster and passes through without providing any nutritional value. It is important for dairy farmers to select silage corn products with the optimal mix of NDFD and uNDF,�? Lawrence says. (Lawrence, J., Cornell University, 04/14/2017)

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“Corn products intended for grain will often have more undigestible fiber because the stalks are bred for stalk strength,�? Lawrence says. “Several commercial forage laboratories where farmers send their silage for analysis can provide both uNDF and NDFD content. uNDF is a new and emerging topic area that is important to balancing rations. The CNCPS software considers uNDF as one important factor of a balanced ration. Farmers should look at the NDFD and uNDF of any corn products they are considering planting for silage,�? Lawrence says.

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Lawrence notes that, while some corn products are more digestible than others, the growing season and weather patterns can have an effect on the fiber content of a corn product in any growing season. “It is best to look at an average uNDF for an entire trial and compare individual corn products to the average to determine the relative digestibility of an individual corn product,�? Lawrence says.

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CNCPS was most recently updated in December, 2016. The current model predicts:

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  • Energy, metabolizable protein, amino acid, and mineral requirements for maintenance, tissue deposition, and milk synthesis
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  • Intake and ruminal degradation of feed carbohydrate and protein fractions, and microbial growth
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  • Intestinal digestion and excretion
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  • Metabolism of absorbed energy, protein, and amino acids
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  • Nutrient excretion and feed requirements for individual animals an the herd
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CNCPS (and commercially available software based on CNCPS) is currently used worldwide by nutritionists to help dairy farmers develop balanced rations. In the U.S., it is used in ration balancing for about 40 percent of dairy cows. 170419083548

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