An important application of air-sea interaction research is in characterizing marine atmospheric boundary layer (MABL) properties, ducting in particular, in order to predict radar and radio ...communication conditions in the marine environment. This ongoing research project, conducted off the coast of Duck, NC, during October-November of 2015, provided an opportunity to measure EM propagation during the CASPER at-sea experimental campaigns. The measured signal is used to invert for the evaporation duct refractivity profile based on Terrain Parabolic Equation Model (TPEM) and compared to the profile predicted from NAVSLaM using concurrent meteorological and oceanographic measurements as input.
Four methods of extending lactations-in-progress were compared: ratio, multiple regression, modified regression, and regression of the remainder of the lactation on the last test. Multiple regression ...estimates and regression estimates on the last test were about equally precise. Modified regression was intermediate while errors of ratio estimates were largest. Present use of ratio extension factors results in excessively large errors in projecting short-length lactation to a 305-day basis.
Monthly weights for 548, 356, and 211 first, second, and third lactations of Beltsville Holstein were related to their milk yield, feed intake, and feed efficiency, Of the weights, those at the ...beginning and end of lactation were best for predicting yield, intake, and efficiency. Starting weight was best for estimating all traits in first lactation and for intake and yield in lactation 2. Ending weight best predicted all traits in lactation 3 and efficiency in lactation 2. First lactation weights contained more information than did those in later lactations, weights were most effective for predicting efficiency, least effective for feed intake. Higher starting weight was associated with increased milk yield and efficiency. Higher ending weight was associated with lower milk yield and efficiency.
Variation among cows in grain, forage, and total feed consumption was studied with 548 Holstein daughter-dam pairs in a single herd over 19 years. Cows were fed alfalfa hay and silage ad libitum, and ...a 15% protein grain mixture was provided to supply the difference between 115% of Morrison's net energy requirements and the estimated energy consumed in forage. Heritabilities and their standard errors for forage, grain, and total estimated net energy consumption were .19±.09, .26±.09, and .42±.10. The genetic correlation between grain consumption and milk yield was 1.0 due to the precise allocation of grain according to each cow's production. Genetic and phenotypic correlations between forage consumption and milk yield were positive but much less. Forage consumption was negatively related to gross feed efficiency. The feeding regime increased variation among cows in yield by varying the forage:grain ration. Cows varied less in total intake than in either forage or grain consumption.
A modified regression method for extending part records eliminates population or herd means of the partial lactations. Errors of prediction by the method were compared to those of extended records by ...ratio factor in two samples of data, one from Dairy Herd Improvement Association and one from the Beltsville herd. Errors of estimates by ratio factor were large, especially early in lactation. For projecting total yield from the first test, the average absolute difference from actual 305-day yield was 500kg smaller for the modified regression procedure as compared to the ratio estimate.
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