@article{mavrogenis_dillard_robison_1978, title={GENETIC-ANALYSIS OF POST-WEANING PERFORMANCE OF HEREFORD BULLS}, volume={47}, ISSN={["1525-3163"]}, DOI={10.2527/jas1978.4751004x}, abstractNote={The genetic parameters of and interrelations among postweaning performance traits were investigated using feedlot performance records of 695 individually-fed Hereford bulls from 72 sires. The data comprise two generations of selection for weaning weight (line 1), postweaning growth rate (line 2) and a random control (line 3). Estimates of heritability from analyses of within-animal regression coefficients (regression of cumulative gain (B-WT) or feed intake (B-FEED) on the period of measurement) obtained from intermediate, 14-day measurements were higher than for total gain or total feed. Further, the heritability of the ratio of the two regressions (B-FEED/B-WT) was higher than for feed/gain. Heritabilities for B-WT, B-FEED, NEWEF (B-FEED/B-WT), PREDEF1 (total feed/B-WT)and PREDEF2 (B-FEED/total gain) were .41±.26, .52±25, .38±22, .33±.22 and .24±.21, respectively. Heritabilities of point estimates were: .23±.20, .44±.25, .26±25, .21±.23 and .49±28 for ADG (average daily gain), ADFC (average daily feed intake), FEEDEF (feed/gain), FAT(sonoray fat measurement) and FINWT (yearling weight), respectively. High and positive genetic correlations were found between ADG and ADFC (.84), FINWT and ADFC (.55), FINWT and ADG (.71) and ADFC and FEEDEF (.72). FEEDEF and ADG were lowly correlated genetically (.23), whereas FINWT and FEEDEF were genetically independent (−.02). However, the regression coefficient approach produced different results regarding the associations among gain, feed consumption and feed efficiency. The genetic correlations between B-WT and B-FEED, B-WT and NEWEF and B-FEED and NEWEF were .19, −.06 and .12, respectively. Thus the antagonistic correlations were generally reduced by this approach. These results suggest that direct selection will be necessary to improve efficiency. Selection for NEWEF is suggested. Heritability estimates from sire-son analyses were lower than those obtained from paternal half-sib correlations. Hence estimates of the covariance between direct genetic and maternal effects were negative for all traits.}, number={5}, journal={JOURNAL OF ANIMAL SCIENCE}, author={MAVROGENIS, AP and DILLARD, EU and ROBISON, OW}, year={1978}, pages={1004–1013} }
 @article{mavrogenis_robison_1976, title={FACTORS AFFECTING PUBERTY IN SWINE}, volume={42}, ISSN={["1525-3163"]}, DOI={10.2527/jas1976.4251251x}, abstractNote={Data on 211 crossbred gilts were utilized to investigate the effects of season of birth, presence or absence of boars and number of gilts per pen on age and weight at puberty. The gilts were allotted to treatments at an average age of 140 days. Gilts born in the fall reached puberty at a younger age and a lower weight (P<.01) than those born in the spring. There also was a higher incidence of "silent" estrus, (i.e., ovulation without psychic estrus) in fall-born gilts (P<.01). The presence of boars substantially reduced (P<.01) age and weight at puberty. Gilts exposed to boars had a higher incidence of "silent" estrus (P<.01) than those denied the presence of boars. Age and weight at puberty were substantially reduced (P<.01 and P<.05, respectively) in gilts grouped 30 to a pen vs those individually penned, but there was no effect of grouping on the incidence of "silent" estrus. Interactions of season of birth and boar presence and season of birth and grouping were significant. No reduction in age at puberty was achieved in fall-born gilts when exposed to boars or group penned, whereas the presence of boars and/or group size (30/pen) caused a substantial reduction in age at puberty in spring-born gilts.}, number={5}, journal={JOURNAL OF ANIMAL SCIENCE}, author={MAVROGENIS, AP and ROBISON, OW}, year={1976}, pages={1251–1255} }