Twelve multiparous Holstein cows averaging 122 d postpartum were used in a replicated Latin square design with 21-d periods. Cows were fed diets containing either low or high soluble protein supplemented with 0 or 9 g/d of Yucca shidigera extract per cow. Dry matter intake and yields of milk, fat, 3.5% fat-corrected milk, and total solids were not affected by treatment. High soluble protein increased percentages of fat and total solids in milk but decreased percentages of crude protein and true protein in milk. Yucca shidigera extract did not affect percentages or yields of milk components, ruminal NH3 N, or urea N in milk or plasma. High soluble protein tended to increase both ruminal pH and concentrations of ruminal NH3 N. Yucca shidigera extract did not affect ruminal pH or NH3 N. High soluble protein increased concentrations of urea N in plasma and milk when both were measured by enzymatic assay, but differences in milk urea N measured by mid infrared reflectance spectroscopy were not significant. Neither Yucca shidigera extract nor increased ruminally undegradable protein was beneficial in this trial when fed to cows milking 30 to 35 kg/d. Concentrations of urea N in milk as measured by mid infrared reflectance spectroscopy were higher than those measured by enzymatic assay, but measurements by mid infrared reflectance spectroscopy were not as sensitive to treatment differences as were measurements by enzymatic assay.

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Zebra mussels (Dreissena polymorpha) are invasive/nuisance species first introduced into the Great Lakes region in the late 1980s. Since their introduction efforts have been underway to prevent and/or control their spread. Zebra mussel infestations can occur on submerged critical structure. For the U.S. Army Corps of Engineers (USACE) it is essential that hydraulic infrastructure are effectively and efficiently maintained to ensure proper water control and navigation. A study was conducted to determine the extent of the zebra mussel invasion on USACE districts and the impact zebra mussels have on USACE infrastructure. Consistent with available U.S. Geological Survey (USGS) data, it was found that zebra mussels are present within 24 of the 36 continental United States USACE district boundaries, although San Francisco and Galveston Districts have only isolated populations in non-USACE waters. Albuquerque and Omaha Districts appear to be the two districts most at risk for invasion. While infestations are common, 62% of the districts with USACE infested waters reported no or minimal impacts on the infrastructure or operation/maintenance costs. Those districts with impacts did not normally have cost figures readily available. It was also found that 12 districts have or have had zebra mussel monitoring programs in place. DISCLAIMER:The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

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