Effect of phase-feeding crude protein on performance and carcass characteristics of crossbred beef bulls: an application to reduce nitrogen compounds in beef cattle diets     

Paloma de Melo Amaral  Sebastião de Campos Valadares Filho  Edenio Detmann  Stefanie Alvarenga Santos  Laura Franco Prados  Lays Débora Silva Mariz  Lyvian Cardoso Alves  Ana Clara Baião Menezes  Faider Alberto Castaño Villadiego  Marco Aurélio Schiavo Novaes  Flávia Adriane de Sales Silva 《Tropical animal health and production》2014,46(2):419-425

Beef cattle (24) with an average initial body weight of 417?±?54 kg were assigned in a 2?×?2 factorial design with six repetitions. The factors studied were two levels of CP: 11 (low CP) or 13 % (high CP) in the initial feedlot phase (days 1–36) and in the final phase (days 37–72). After 36 days, half of the bulls fed with each level of CP were selected to reverse the CP level. No interaction was observed (P?>?0.05) between the level of protein in the initial and final phases on the intake of the nutrients evaluated. There was no effect (P?>?0.05) of the protein levels in the initial and final phases on intake of dry matter, organic matter, CP, non-fiber carbohydrates, and total digestible nutrients. No differences were observed among treatments (P?>?0.05) for average daily gain (X = 1.99 kg/day) and carcass traits. We conclude that it is possible to feed Holstein-Zebu crossed bulls with an average daily gain of approximately 2 kg using a fixed level of 11 % CP during the entire feedlot period, and this diet is economically viable and environmentally sound.  相似文献   

Bovine Colostrum Supplementation Does Not Influence Serum Insulin-like Growth Factor-1 in Horses in Race Training     

Clara Fenger  Thomas Tobin  Patrick Casey  John Langemeier  Deborah Haines 《Journal of Equine Veterinary Science》2014

Bovine colostrum (BC) is a commonly used food supplement in humans for both immune support and athletic performance enhancement; the latter effect has been attributed in some studies to an increase in the anabolic cytokine Insulin-like Growth Factor-1 (IGF-1). The aim of the present study was to determine the effect of BC supplementation on serum IGF-1 in racing horses. Five serum IGF-1 samples were collected from 12 horses in race training every 2 weeks over an 8-week period from November to January. Six horses received BC supplementation for 4 weeks, starting at the 2-week point. The expected seasonal IGF-1 decrease over the November to January study period was observed, but there was no effect of BC supplementation on serum IGF-1 concentrations as compared with the untreated controls.  相似文献   

A NEW BACTERIAL DISEASE OF PEARS     

Clara FM 《Science (New York, N.Y.)》1932,75(1934):111-112

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Natural selection favors a newly derived timeless allele in Drosophila melanogaster     

Tauber E  Zordan M  Sandrelli F  Pegoraro M  Osterwalder N  Breda C  Daga A  Selmin A  Monger K  Benna C  Rosato E  Kyriacou CP  Costa R 《Science (New York, N.Y.)》2007,316(5833):1895-1898

Circadian and other natural clock-like endogenous rhythms may have evolved to anticipate regular temporal changes in the environment. We report that a mutation in the circadian clock gene timeless in Drosophila melanogaster has arisen and spread by natural selection relatively recently in Europe. We found that, when introduced into different genetic backgrounds, natural and artificial alleles of the timeless gene affect the incidence of diapause in response to changes in light and temperature. The natural mutant allele alters an important life history trait that may enhance the fly's adaptation to seasonal conditions.  相似文献   

Methyltransferase recruitment and DNA hypermethylation of target promoters by an oncogenic transcription factor   总被引：1，自引：0，他引：1  

Di Croce L  Raker VA  Corsaro M  Fazi F  Fanelli M  Faretta M  Fuks F  Lo Coco F  Kouzarides T  Nervi C  Minucci S  Pelicci PG 《Science (New York, N.Y.)》2002,295(5557):1079-1082

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Estrogen receptors and cell signaling     

Pietras RJ  Levin ER  Szego CM 《Science (New York, N.Y.)》2005,310(5745):51-3; author reply 51-3

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Energy resources and global development     

Chow J  Kopp RJ  Portney PR 《Science (New York, N.Y.)》2003,302(5650):1528-1531

In order to address the economic and environmental consequences of our global energy system, we consider the availability and consumption of energy resources. Problems arise from our dependence on combustible fuels, the environmental risks associated with their extraction, and the environmental damage caused by their emissions. Yet no primary energy source, be it renewable or nonrenewable, is free of environmental or economic limitations. As developed and developing economies continue to grow, conversion to and adoption of environmentally benign energy technology will depend on political and economic realities.  相似文献   

Protective effects of dexmedetomidine on small intestinal ischaemia-reperfusion injury in horses     

Ashley R. VanderBroek  Julie B. Engiles  Sabine B. R. Kästner  Veronika Kopp  Nicole Verhaar  Klaus Hopster 《Equine veterinary journal》2021,53(3):569-578

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Induction of variability in chimeric Aster cordifolius `White Elegans' through somaclonal variation     

Maria Cammareri  Angela Errico  Edgardo Filippone  Silvana Esposito  Clara Conicella 《Euphytica》2002,128(1):19-25

A protocol was developed for plant regeneration from leaf explants (laminaand petiole) of Aster cordifolius cultivar `White Elegans', which ischimeric for chromosome number and the ligulate flower colour. Explantswere cultured on MS or Gamborg's B5 medium in presence of IAA, 2,4-Dand BAP, alone or in combination. The highest frequency of shootregeneration was obtained on B5 medium supplemented with 2,4-D(0.09 mg l^-1) and BAP (1.8 mg l^-1). After the invitro rooting stage and acclimatization, 90% of plantlets survived in thegreenhouse. The regeneration process occurred by indirect organogenesisas shown by cyto-histology. The regenerants maintained the originalchimerism for chromosome number. Pink flowers instead of theexpected white ones were obtained in all regenerants. Ahypothesis for the uniform colour change is discussed. Variations weredetected in the regenerant generation (R₀) for quantitative characterssuch as capitulum and disc diameters, and number of ligulate flowers. SinceAster can be vegetatively propagated, selection of variants in R₀can provide interesting material for breeding purposes.  相似文献   

Increasing resistance to Fusarium crown and root rot in asparagus by gametophyte selection     

Ana Clara Pontaroli  Elsa Lucila Camadro 《Euphytica》2001,122(2):343-350

In garden asparagus, Fusarium crown and root rot is the main cause of crop decline. Since chemical treatments are inefficient, efforts should focus on the development of resistant cultivars to control the disease. Toxic culture filtrate (TCF) of F. oxysporum has affected asparagus pollen germination and tube growth. Consequently, gametophyte selection was evaluated to ascertain if the application of selective agents at this level could increase selection efficiency. Two susceptible pistillate plants and one tolerant and one susceptible staminate plants were used in controlled crosses. Before pollination, a drop of a germination vehicle with TCF or without it was applied to the stigmas. Some pollinated pistils were fixed and analyzed by fluorescence microscopy; the rest were left on the plant for seed production. Fifty to 200 seeds were obtained per treatment combination (staminate plant x pistillate plant x pollination vehicle). The derived plantlets were inoculated in vitroand evaluated for disease symptoms. The application of TCF to stigmas reduced pollen germination and tube growth compared with untreated controls,regardless of the genotypic combination. Pollen germination and tube growth was poorer for the tolerant staminate genotype than for the susceptible one. When the TCF was applied, the number of seeds per pollination in comparison with the controls diminished only when the susceptible genotype was the pollinator. The percentage of affected root area of the progenies obtained after applying the TCF was lower than in the controls only when the tolerant genotype was the pollinator. Increasing Fusarium resistance in asparagus by means of gametophyte selection seems feasible. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献