@article{dillard_rodriguez_robison_1980, title={ESTIMATION OF ADDITIVE AND NON-ADDITIVE DIRECT AND MATERNAL GENETIC-EFFECTS FROM CROSSBREEDING BEEF-CATTLE}, volume={50}, ISSN={["1525-3163"]}, DOI={10.2527/jas1980.504653x}, abstractNote={Data from straightbred and crossbred cattle involving Angus, Charolais and Hereford breeds were analyzed to obtain fitted constants for each of 22 breed groups and to estimate breed additive, heterotic, breed maternal and average maternal heterosis effects for birth weight, preweaning average daily gain, weaning weight and type score. Year, sex, age of dam and age of calf at weaning, as well as the interaction herd × year, were significant sources of variation for all traits. Among breed groups, crossbred calves showed higher values than the straightbred Angus and Hereford calves for each trait studied. Charolais additive effects, expressed as a deviation from Hereford, were positive (P<.05) for birth weight, average daily gain and weaning weight. Angus additive effects for birth weight were negative (P<.01). Charolais maternal contributions to preweaning traits exceeded those of Hereford and Angus. Angus maternal effects significantly exceeded Hereford for all traits except type score. Nonadditive genetic effects were significant for daily gain, weaning weight and type score. Equations for predicting the performance of all breed groups studied and some other combinations of interest were calculated with the partial regression coefficients for each trait and the additive, heterozygotic, maternal and average maternal heterosis coefficients for each breed group. Estimates of heterosis from the predicted least-squares means were: birth weight (2.4%), daily gain (3.8%), weaning weight (3.9%) and type score (3.7%). Comparisons of the breed group model to the regression model that estimated breed additive and heterozygotic (intra-locus interaction) direct and maternal effects suggested that specific maternal heterosis, epistasis and (or) linkage may have contributed to differences among breed groups for weaning weight and average daily gain. However, these additional effects accounted for only about 1% of the variance. Thus, it appears that the regression model adequately explains the variation in the data.}, number={4}, journal={JOURNAL OF ANIMAL SCIENCE}, author={DILLARD, EU and RODRIGUEZ, O and ROBISON, OW}, year={1980}, pages={653–663} }
 @article{dillard_yusuff_robison_1978, title={MILK-PRODUCTION IN HEREFORD COWS .2. HERITABILITIES AND REPEATABILITIES}, volume={47}, ISSN={["1525-3163"]}, DOI={10.2527/jas1978.471137x}, abstractNote={Heritabilities and repeatabilities of measures of milk yield were estimated from 1,319 lactation records of 528 cows sired by 84 bulls used in two related herds of Hereford cattle. The data were collected over a period of 8 years (1968 to 1975). Estimates of milk yield were obtained at bimonthly intervals by the calf-suckling technique. The three within-lactation observations (M1, M2, and M3), the sum of the three observations (TMY) and a predicted sum of seven monthly observations (PMY) were studied. Estimates of heritability from paternal half-sib correlations were .17±.08, .29±.10, .28±.09, .44±.13 and .45±.13 for M1, M2, M3, TMY and PMY, respectively. Genetic correlations among the various measures of milk yield approximated 1.00. Repeatabilities were estimated by the intraclass correlation method from cows having at least two records. A total of 1,113 lactation records from 322 cows was included. The repeatability estimates for M1, M2, M3, TMY and PMY were .23±.03, .31±.03, .24±.03, .46±.03 and .46±.03, respectively, Repeatabilities for paired records for all possible pairs of records through the sixth lactation were calculated also. Mean repeatability values for adjacent records were .34, .40, .51, .64 and .65 for M1, M2, M3, TMY and PMY, respectively. As degree of adjacency decreased, i.e., as records were more separated by time, the repeatabilities decreased. Where records were separated by 5 years the repeatabilities were .17, .47, .32, .42 and .44 for M1, M2, M3, TMY and PMY, repectively.}, number={1}, journal={JOURNAL OF ANIMAL SCIENCE}, author={DILLARD, EU and YUSUFF, MKM and ROBISON, OW}, year={1978}, pages={137–141} }