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Dairy Pipeline: July 2005
Charles C. Stallings
Extension Dairy Scientist,
Nutrition and Forage Quality
(540) 231-3066 email: cstallin@vt.edu
Maximizing the amount of forage in the ration not only can improve cow health but reduces the need for supplemental feeds that are typically high in phosphorus (P). For instance, soybean meal contains .7% P (dry basis) compared to .3% for alfalfa. Simply supplying more protein with alfalfa will reduce the need for more soybean meal and result in lower ration P. Also, many by-product feeds contain high concentrations of P. Feeds such as whole cottonseeds (.6%), brewers grains (.67%), and distillers grains (.83%) are good examples. Using more forage in the ration can reduce the need for these feeds. The fact that most forage is grown on the farm using recycled nutrients in manure makes it a desirable practice for net reduction of nutrients onto the farm and subsequently into the soil where accumulation can occur with possibility of water contamination. To maximize forage in the ration a complete forage analysis should be conducted every month to monitor quality and correct rations as needed. A complete analysis would include dry matter, crude protein, fiber (ADF and NDF), estimated energy, plus minerals on a less regular basis. Many reports will give protein solubility and in some cases an estimated degradability. Also a fermentation profile can be obtained with pH and acids reported for fermented feeds. This can give an idea of how complete the fermentation was and how stable it might be over time. Another measurement that is being used increasingly is NDF digestibility. This measurement can be used to more correctly estimate the energy content of the forage because fiber is an important contributor of energy in forages including corn silages. Corn silage is relatively low in P containing .26%. In order to use the maximum forage, attention is needed pre and post harvest. Forage quality needs to be measured periodically with the latest techniques available to improve the estimates of energy content, and supplementation can sometimes be reduced with no lose of milk yield.