Projects (incomplete list; in random order)

Fertility in Holsteins
Fertility of Holsteins as measured by days open, non-return rates or number of inseminations per conception seems to be deteriorating. However, fertility is affected by a number of factors, including type and quality of heat detection, estrus synchronization if any, BST use, heat stress, etc. These factors are usually ignored in analyses. One can ask a question whether the fertility of Holsteins really declined dramatically, or is it reasonable with high producing cows provided management is adjusted appropriately, i.e., lactations > 305 days and longer voluntary waiting times.   This projects looks at genetics of days open through many of its components. One of the first outcomes is that voluntary waiting time needs to be at least 60 d higher for high than low

Multibreed evaluation in beef cattle

We evaluate upgrading populations of beef cattle for a number of traits, including categorical while accounting for breed differences and heterosis. We also look at international evaluation of beef cattle. Our goal is international multibreed evaluation.

Efficient yet simple animal-breeding programming in Fortran 90
Use of object-oriented and matrix operations in  Fortran 90  can lead to programs that are almost as simple as in a matrix language but as efficient as in Fortran 77.  Read a paper titled: Complex models, larger data, simpler computing? This project has resulted in a large number of application programs.

Evaluation for heat stress in dairy cattle
Whenever there is a heat stress, for example in Southeastern USA, some animals perform satisfactorily but some perform poorly. We developed a methodology to study genetics of heat tolerance using easily available weather records. This project has been described briefly in a UGA extension letter. Our studies indicate that continued selection for performance in moderate climates makes cow less heat tolerant for production and particularly reproduction. Currently, we are developing the genetic evaluation for heat tolerance for U.S. Holsteins.

Economically efficient pig breeding
Although modern pigs grow faster and have more piglets, they also have higher piglet mortality, lower sow survival, and higher susceptibility to diseases. Some claim that no real genetic progress in pigs at the commercial level over the past 10-20 years. In this project, we are looking how to select a commercial animal that would have a good balance of fitness and production. One complication is that important traits are censored and/or categorical. We also look at competition models.

Use of random regression models for a number of problems

· continuous growth,

· effect of aging on conformation scores,

· changing definition of a trait with time,

· changing genetic correlations with time.

We found that computations with random regression models can be greatly simplified if linear splines are used; one benefit is that variance components are on the same scale as in multiple trait models.

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These and other projects can benefit from your collaboration. If you are looking for a graduate school, a place for a sabbatical,  please consider the University of Georgia.

last updated  July 6, 2005