Variation in response to fescue toxicosis was examined in inbred and linecross mice. In Exp. 1, exposure to a 50% endophyte-infected tall fescue diet (E+) reduced ADG of males from six inbred lines, but ADG of males from one line was modestly higher on E+. Lines differed (P < .01) for reproductive organ weight, but the diet x line interaction was not significant. In Exp. 2, an apparently susceptible (C57) and an apparently resistant line (FVB) were mated to produce inbred and linecross offspring. The reduction in weight gain caused by the E+ diet did not differ significantly among the genetic groups. In Exp. 3, C57 and C57 backcrosses had smaller reductions in ADG during E+ vs control feeding periods than FVB and FVB backcrosses (P < .10). In Exp. 4, the E+ diet reduced litter size of mates of C57 males by one pup, whereas litter size of mates of FVB males was four pups larger (interaction P = .07). Neither diet, line, nor their interaction affected male reproductive organ weights or tissue proportions in testis cross-sections. In Exp. 5, the E+ diet did not affect weight gain of C57 or FVB males, but effects of the E+ diet on litter size of mates were similar to those in Exp. 4. Percentage of abnormal sperm was increased in C57 males on the E+ diet but decreased in FVB males (Exp. 5). Differences among inbred lines in susceptibility to fescue toxicosis may depend on severity of the challenge and life cycle stage when the challenge is imposed.
Blood selenium concentration at birth and growth from birth through finishing were analyzed on progeny from two birth years of Angus bulls of United States (US) or New Zealand (NZ) origin. Dams of the calves were Polled Hereford x Angus crossbreds whose sires had been selected divergently from the national sire summary to be superior (+) or inferior (-) for yearling weight EPD (G) and for total maternal effects (M) on weaning weight. There was no evidence of differences attributable to calf paternity or dam genetic group in concentration of blood selenium in calves at birth. For birth year 1988, progeny of US sires grew nonsignificantly more rapidly than progeny of NZ sires in most life-cycle phases. In 1989 calves, NZ-sired offspring grew nonsignificantly more rapidly than US-sired offspring through a year of age. Averaged across years, preweaning and postweaning growth rates were similar for calves of US and NZ paternity. Divergent selection of the calves' maternal grandsires for yearling weight EPD was successful; calves in +G groups had more rapid gains through 1 yr of age than did calves in -G groups. Also, growth rate through 4.5 mo of age was influenced by divergent selection of maternal grandsires on total maternal weaning weight EPD; calves from +M groups gained more rapidly than calves from -M groups.
Animal breeding reports in the Journal of Animal Science (JAS) and in its predecessor, Proceedings of the American Society of Animal Production, were counted and categorized. In 22 volumes of the Proceedings of the American Society of Animal Production, 155 articles had animal breeding content, of which 54% were research reports, 17% extension communications, and 28% syntheses or reviews. Several of the latter featured advice from the livestock industry to the scientific community. Thirty-one percent of articles concerned swine, whereas beef cattle, dairy cattle, and sheep each accounted for an additional 20%. In the 67 yr of JAS publication, 3,045 research papers were identified with animal breeding content, nearly half of them published since 1990. Growth in publication output was modest during the 1950s, robust in the 1960s through 1980s, moderate in the 1990s, and static in the 2000s. Important topics included genetic resource evaluation (a subject in 55% of all manuscripts), genetic parameter estimation, selection programs, and nonrandom mating systems. Maternal effects and genotype x environment interactions were featured in 17 and 15% of all manuscripts, respectively, whereas 6% dealt with a simply inherited trait. Only 4% of manuscripts included economic analysis of a breeding program or intervention. Interest in molecular biology and biometry has surged in the 1990s and 2000s. Approximately 50% of all papers involved cattle, a fifth of which concerned dairy cattle or beef x dairy crossbreds. A quarter of papers concerned swine, 15% concerned sheep, and 3% considered laboratory rodents, with the proportional contribution of sheep research decreasing across time. Authors from the Midwestern and Southern sections of the American Society of Animal Science had greater proportional contributions than Western and Northeastern section authors, and contributions of university and state experiment station authors outnumbered those of USDA-ARS authors. The proportional contribution of international authors increased across time, reaching 45% for the 2000s, as that of university and experiment station authors decreased and that of USDA-ARS authors remained fairly constant. Subjective analysis suggested substantial levels of creativity, innovation, and cooperation in JAS animal breeding research, a strong international perspective, but also a marked degree of imitation and repetition in subject matter content.
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