Daily or weekly rotational feeding of Bovatec®- and Rumensin®/Tylan® to cattle on a steam-flaked corn finishing ration

One hundred sixty-five crossbred steers averaging 823 lb were utilized to evaluate the daily or weekly rotational feeding of ionophores. Treatments were (g/ton of feed, 90% dry basis): 1) Bovatec (B; 30), 2) Rumensin plus Tylan (RT; 25 and 10, respectively), 3) treatments one and two in a daily rotation (D), and 4) treatments one and two in a weekly rotation (W). Steers fed RT consumed less (P\u3c.05) dry matter than B, D\u3eor W steers. No differences (P\u3e.15) in daily gain were observed, suggesting that the increased consumption by B, D) and W steers was accompanied by an al teration in passage rate and/or other kinetics of digestion, such that additional consumption was poorly utilized. Thus, RT steers gained 3.9% more efficiently (P=.06) than B steers and numerically more efficiently than D or W steers. No differences were observed among treatments for carcass quality or yield. Performance of D and W steers did not differ from that predicted by the performance of steers fed B and RT fed separately, indicating no synergism from alternate feeding of ionophores in this study

Utilization of dried bakery product by finishing beef steers

One hundred forty-four medium-framed crossbred steers averaging 857 lb were used to evaluate steer performance and determine net energy (NE) values of finishing diets that included dried bakery product (DBP). DBP replaced corn in the control diet at 15 or 30% of dietary DM. DM intake was depressed 6.5% by inclusion of 30% DBP. No differences in daily gain (P>.3) or feed efficiency (P>.9) were observed by replacing corn with DBP. Dietary values of NEm and NEg, calculated from animal performance, were not affected (P>.7) by the inclusion of DBP. Kidney, pelvic, and heart fat (KPH) (P<.05) and 12th rib fat thickness (P<.1) were increased linearly with inclusion of DBP, whereas other carcass characteristics were unaffected. These data indicate the DBP (10% rice hulls included) has an energy value similar to that of corn grain, although the optimal inclusion level of DBP appears to be below 30% of dietary DM

Optimal urea level in corn-based finishing diets containing alfalfa as the roughage source

One hundred medium-growth potential, crossbred yearling steers (766 lb) were used to identify the optimal level of urea in finishing diets, based on growth and carcass traits. The corn-base d diets had no urea o r contained .35, .70, 1.05, or 1.40% urea (dry matter basis) and no other supplemental protein. Alfalfa hay (10% of DM) was the roughage source and contained 16% crude protein. Feed efficiency and gain were improved by .35% urea, with little improvement from higher additions. Regression analysis indicated that the optimal level of urea for gain and feed efficiency was .5% of dietary dry matter. Hot carcass weight and dressing percentage responded quadratically, being highest for steers receiving .7 and 1.05% urea. Fat thickness and yield grade responded cubically to the addition of urea; these traits were also highest for steers receiving .7 and 1.05% urea. Loineye area decreased linearly with increased urea in the diet. Marbling scores and KPH fat were unaffected by urea addition. The increased growth, carcass weight, and finish, with no improvements in loineye area, indicate that urea enhance d diet digestibility but did not increase metabolizable protein supply. Optimal urea levels (.5%) were less than those previously indicate d for diets containing prairie hay as the roughage source (.9%), suggesting that alfalfa may supply a portion of the rumen degradable nitrogen requirement when utilized as a source of roughage in high grain diets

Comparison of Synovex-S® and steer-oid® in finishing yearling steers

Synovex-S (SS) and STEER-oid (SO) were compared in a 122-d finishing study. No differences were observed over the entire study for animal performance or carcass traits. However, in the final period (d 91-122), steers implanted with SO gained 8.4% faster (P=.17) and 8.7% more efficiently (P=.10) than steers implanted with SS, suggesting that estradiol payout in this period was less diminished for SO implants. The importance of this finding is unknown, because it is generally recommended that steers fed for longer periods of time be reimplanted midway through the finishing period to maintain maximal implant response

Implant strategies for finishing calves

Two hundred-sixteen Angus and Angus-cross steer calves (690 lb) were used in a 129- day finishing study to evaluate different implant strategies, including an experimental new implant for feedlot cattle that contains 28 mg of estradiol benzoate and 200 mg of trenbolone acetate (EBTBA). Treatments were 1) nonimplanted control, 2) implanted and reimplanted with Synovex-Sfi, 3) single initial implant with EBTBA, 4) single initial implant with Revalor-Sfi, 5) implanted with Synovex-S and reimplanted with EBTBA, and 6) implanted and reimplanted with EBTBA. Initial implants and reimplants were administered on day 0 and 63, respectively. All implant treatments increased feed intake, slaughter and carcass weights, and rate and efficiency of gain. Compared with other implant treatments, the use of EBTBA as a reimplant treatment (trts 5 and 6) resulted in improved (P<.08) rate and efficiency of gain and heavier carcass weights (P<.07). However, only 58.3% of cattle in trts 5 and 6 graded Choice vs. 86.1% for controls and 80.6% for steers implanted twice with Synovex-S (P<.07). Carcasses were more masculine (P<.07) for steers in trts 5 and 6 than for nonimplanted controls, steers implanted with Revalor-S, and steers implanted twice with Synovex-S. Performance of steers implanted once with EBTBA did not differ from that of steers implanted once with Revalor-S or twice with Synovex-S, but carcasses were more masculine (P<.07) for EBTBA vs. Revalor-S steers. Implant treatment did not affect meat tenderness, as measured by Warner-Bratzler shear force determinations. Single EBTBA or Revalor-S implants resulted in performance and carcass traits similar to those resulting from implanting twice with Synovex-S

Puberty and breeding performance of beef heifers developed at different rates of gain

Crossbred heifers (546 lb initial body weight) were developed in drylot and limit-fed a corn, corn silage diet to gain .5 (n = 14), 1.0 (n = 15), 1.5 (n = 14), or 2.0 lb/d (n = 15) from Dec. 7, 1992 until the onset of the breeding season, May 3, 1993. Actual daily gains averaged 1.0, 1.4, 1.8, and 2.1 lb/d, respectively. Age at puberty was not affected by feeding treatment. At the onset of the breeding season, nutritional treatment had a linear effect on body condition score, ribeye fat thickness (both P<.01), and reproductive tract score (P<.05), all increasing with increasing rate of gain. Nutritional treatment had a quadratic effect on pelvic area (P<.05), which averaged 190.6, 201.6, 206.5, and 205.3 cm2 for heifers fed to gain .5, 1.0, 1.5, and 2.0 lb/d, respectively. At the conclusion of the development period, estrus was synchronized, and heifers were inseminated artificially at estrus for 45 days and, if open, mated naturally for another 17 d. Overall pregnancy rates were similar among heifers fed to gain .5, 1.0, and 1.5 lb/d (92.9, 93.3, and 92.9%, respectively), and all tended to be greater (P<.09) than the rate for heifers fed to gain 2.0 lb/d (66.7%). In summary, NRC recommendations underestimated gain of limit-fed heifers at lower predicted rates of gain. Thus, even though heifers fed to gain only .5 lb/d had lower body condition scores and reproductive tract scores at the onset of the breeding season, their actual body weight gains (1.0 lb/d) were sufficient for normal onset of puberty and subsequent conception. In addition, heifers fed to achieve relatively high rates of gain (2.0 lb/d) during development may have had impaired fertility

Increasing levels of grain supplementation for intensive-early stocked steers: three-year summary

During the initial 3 years of a 4-year experiment, average daily gain tended to increase in direct proportion to increasing levels of grain sorghum supplementation (2.3, 2.5 and 2.7 lb gain per day for the control and 2 and 4 lb supplement per day, respectively). The amount of grass remaining in the pastures at the end of the growing season (October 1) was greater in each of the 3 years when cattle were supplemented at 4 lb/day. During the 2 years (1989 and 1990) that feedlot performance was monitored, level of supplementation for grazing steers did not influence subsequent feedlot gain or efficiency

Supplemental chromium and revaccination effects on performance and health of newly weaned calves

Two trials were conducted to evaluate the effects of chromium (Cr) supplementation (4 mg/hd/day in a yeast form) or no supplementation, with or without revaccination with a modified live viral vaccine at 9 days postweaning o n performance, health, and ability to withstand an IBR challenge infection. In Trial 1, Cr supplementation had no effect on performance of newly weaned calves in a 28-day receiving study, but reduced the incidence of respiratory disease by 37%. Revaccinati on depressed dry matter intake and had no effect on animal health. In trial 2, blood plasma levels of cortisol and ACTH (stress hormones ) were measured at 6 and 26 days postweaning. Cortisol levels were unaffected by treatment or by time after weaning. Plasma ACTH conc e ntrations were lower at 26 vs 6 days postweaning, and were reduced at 26 days by revaccination. Despite some slight differences in rectal temperature, treatment did not appear to affect the animals\u27 ability to withstand a live IBR challenge. We concluded that supplemental Cr was beneficial in reducing the incidence of bovine respiratory disease, although mediation of stress hormones was not involved. Revaccination of newly weaned calves with a modified live viral vaccine showed no performance or health benefit

A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey IV: Discovery of Seven Additional Quasars

We present the discovery of seven quasars at z>5.7, selected from ~2000 deg^2 of multicolor imaging data of the Sloan Digital Sky Survey (SDSS). The new quasars have redshifts z from 5.79 to 6.13. Five are selected as part of a complete flux-limited sample in the SDSS Northern Galactic Cap; two have larger photometric errors and are not part of the complete sample. One of the new quasars, SDSS J1335+3533 (z=5.93), exhibits no emission lines; the 3-sigma limit on the rest-frame equivalent width of Ly alpha+NV line is 5 A. It is the highest redshift lineless quasar known, and could be a gravitational lensed galaxy, a BL Lac object or a new type of quasar. Two new z>6 quasars, SDSS 1250+3130 (z=6.13) and SDSS J1137+3549 (z=6.01), show deep Gunn-Peterson absorption gaps in Ly alpha. These gaps are narrower the complete Gunn-Peterson absorption troughs observed among quasars at z>6.2 and do not have complete Ly beta absorption.Comment: AJ in press, 16 pages, 3 figure

Optimization of the Observing Cadence for the Rubin Observatory Legacy Survey of Space and Time: A Pioneering Process of Community-focused Experimental Design

© 2021. The Author(s). Published by the American Astronomical Society. This work may be used under the terms of the Creative Commons Attribution 4.0 licence. https://creativecommons.org/licenses/by/4.0/Vera C. Rubin Observatory is a ground-based astronomical facility under construction, a joint project of the National Science Foundation and the U.S. Department of Energy, designed to conduct a multipurpose 10 yr optical survey of the Southern Hemisphere sky: the Legacy Survey of Space and Time. Significant flexibility in survey strategy remains within the constraints imposed by the core science goals of probing dark energy and dark matter, cataloging the solar system, exploring the transient optical sky, and mapping the Milky Way. The survey’s massive data throughput will be transformational for many other astrophysics domains and Rubin’s data access policy sets the stage for a huge community of potential users. To ensure that the survey science potential is maximized while serving as broad a community as possible, Rubin Observatory has involved the scientific community at large in the process of setting and refining the details of the observing strategy. The motivation, history, and decision-making process of this strategy optimization are detailed in this paper, giving context to the science-driven proposals and recommendations for the survey strategy included in this Focus Issue.Peer reviewedFinal Published versio