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United States Department of Agriculture

Agricultural Research Service

L. Dale Van Vleck


Phone: (402) 472-6010



Dr. Van Vleck's research works with a variety of traits and sets of data to improve beef cattle and sheep through genetic selection. A major ongoing project is to develop and improve adjustment factors for weight and carcass traits which allow comparison of sires of different beef breeds. Each breed typically does a genetic evaluation but the base for each breed is different and direct comparison of the genetic evaluations of a pair of breeds is impossible. Records from USMARC can be, and are, used to develop factors to add to the genetic evaluations for each of 18 breeds so that sires of one of those breeds can be compared with sires of the other 17 breeds. A more complicated project is to estimate the effect of an animal in a pen on performance of all other animals in the pen. Thus the record of each animal contains the direct genetic effect of the animal for its own performance but also the competition effects of all penmates on that record. The challenge of models with both direct and competition genetic effects is to partition these effects from the physical effect of the pen and to estimate components of variability for the direct and competition genetic effects and also the correlation (negative, zero, or positive) between the direct and competition effects. Statistical software has been designed and developed for these and other analyses.

Last Modified: 8/13/2016
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