Date of Award
Doctor of Philosophy
Robert R. Shrode
Leonard M. Josephon, R.L. Murphree, Don O. Richardson, John D. Smalling
Data recorded from a total of 5,618 calves from the herds at the Plateau Experiment Station (PES) and Tobacco Experiment Station (TES) of the University of Tennessee were available for analysis. Weight and condition score were recorded for these calves three times during their first year of life. Standard adjustment, including those to remove variation due to differences in age and sex of calf and age of dam, were made for each of these variables. In addition for the present purpose, the data were adjusted to remove variation due to differences between sires of calves.
Analysis of the adjusted data revealed that there was a significant effect of sire of fetus carried by the cow upon the performance of her currently nursed calf with respect to both variables at all three collection times in the TES data. The PES data followed a similar pattern; however, the effect on average daily gain at weaning and at a year of age was not significant.
Another analysis was performed on the same data to determine if the sex of the fetus had a similar effect; however, no such effect was revealed. Of the 6 combinations of variable and collection time at each of the two stations, sex of fetus was a significant effect in three at TES and in one at PES after adjustment to remove variation due to differences in birth weight of fetus.
In order to relate the age of the fetus to the magnitude of these effects on performance, a regression analysis of variance was performed using age of fetus as the continuous independent variable in the preweaning and weaning data. It was determined that, in the four combinations of variable and collection time, there was a significant regression on fetus age in the TES data, but in the PES data regression of condition score at preweaning and average daily gain at weaning on fetus age were not significant. The same analyses also revealed that these effects generally increased as age of fetus increased.
Shannon, David, "Sire-of-fetus effects on performance of the dam's current calf in beef cattle. " PhD diss., University of Tennessee, 1980.