A bright γ-ray flare interpreted as a giant magnetar flare in NGC 253.

Soft γ-ray repeaters exhibit bursting emission in hard X-rays and soft γ-rays. During the active phase, they emit random short (milliseconds to several seconds long), hard-X-ray bursts, with peak luminosities1 of 1036 to 1043 erg per second. Occasionally, a giant flare with an energy of around 1044 to 1046 erg is emitted2. These phenomena are thought to arise from neutron stars with extremely high magnetic fields (1014 to 1015 gauss), called magnetars1,3,4. A portion of the second-long initial pulse of a giant flare in some respects mimics short γ-ray bursts5,6, which have recently been identified as resulting from the merger of two neutron stars accompanied by gravitational-wave emission7. Two γ-ray bursts, GRB 051103 and GRB 070201, have been associated with giant flares2,8-11. Here we report observations of the γ-ray burst GRB 200415A, which we localized to a 20-square-arcmin region of the starburst galaxy NGC 253, located about 3.5 million parsecs away. The burst had a sharp, millisecond-scale hard spectrum in the initial pulse, which was followed by steady fading and softening over 0.2 seconds. The energy released (roughly 1.3 × 1046 erg) is similar to that of the superflare5,12,13 from the Galactic soft γ-ray repeater SGR 1806-20 (roughly 2.3 × 1046 erg). We argue that GRB 200415A is a giant flare from a magnetar in NGC 253.

Associations of stream geomorphic conditions and prevalence of alternative reproductive tactics among sockeye salmon populations.

In many species, males may exhibit alternative life histories to circumvent the costs of intrasexual competition and female courtship. While the evolution and underlying genetic and physiological mechanisms behind alternative reproductive tactics are well studied, there has been less consideration of the ecological factors that regulate their prevalence. Here, we examine six decades of age composition records from thirty-six populations of sockeye salmon (Oncorhynchus nerka) to quantify associations between spawning habitat characteristics and the prevalence of precocious sneakers known as 'jacks'. Jack prevalence was independent of neutral genetic structure among stream populations, but varied among habitat types and as a function of continuous geomorphic characteristics. Jacks were more common in streams relative to beaches and rivers, and their prevalence was negatively associated with stream width, depth, elevation, slope and area, but positively related to bank cover. Behavioural observations showed that jacks made greater use of banks, wood and shallows than guard males, indicating that their reproductive success depends on the availability of such refuges. Our results emphasize the role of the physical habitat in shaping reproductive tactic frequencies among populations, likely through local adaptation in response to variable fitness expectations under different geomorphic conditions.

Early warnings of regime shifts: a whole-ecosystem experiment.

Catastrophic ecological regime shifts may be announced in advance by statistical early warning signals such as slowing return rates from perturbation and rising variance. The theoretical background for these indicators is rich, but real-world tests are rare, especially for whole ecosystems. We tested the hypothesis that these statistics would be early warning signals for an experimentally induced regime shift in an aquatic food web. We gradually added top predators to a lake over 3 years to destabilize its food web. An adjacent lake was monitored simultaneously as a reference ecosystem. Warning signals of a regime shift were evident in the manipulated lake during reorganization of the food web more than a year before the food web transition was complete, corroborating theory for leading indicators of ecological regime shifts.

Evaluating the effects of supplemental B vitamins in practical swine diets during the starter and grower-finisher periods--a regional study.

Two experiments were conducted to evaluate dietary fortification levels of a B vitamin pre-mix for starter and grower-finisher pigs on subsequent performance responses. The objective was to determine whether the modern pig requires higher dietary levels of B vitamins than estimated by the NRC (1998). Both experiments added fat-soluble vitamins at the requirement levels (NRC, 1998) in all diets, whereas the B vitamins were added at 0, 100, 200, or 400% of the total NRC (1998) requirement levels for the starter and grower pig. Indigenous vitamin contributions from the feed grains were not included in the estimates. Each station used the same vitamin premixes but incorporated its own grain sources in the diets. The first experiment was conducted across 7 stations (Indiana, Ohio, Oklahoma, Michigan, Missouri, Nebraska, Texas) and involved 660 pigs in a randomized complete block design in 30 replicates. Complex nursery diets were fed in 2 phases. The first phase (0 to 14 d postweaning) and second phase (15 to 35 d postweaning) diets were formulated to Lys (total) levels of 1.50 and 1.30%, respectively. The results demonstrated no performance response to addition of B vitamins from 0 to 14 d post-weaning, but performances increased quadratically (P < 0.01) to the 100% NRC level from 14 to 35 d postweaning and for the overall 35-d period. The second experiment was conducted across 3 stations (Ohio, Nebraska, and South Dakota) and involved 216 pigs in a randomized complete block design in 10 replicates. Corn-soybean meal mixtures were fed in 3 phases formulated to total Lys levels of 1.30% (23 to 55 kg of BW), 1.00% (55 to 85 kg of BW), and 0.78% (85 to 120 kg of BW). Pig performances increased (P < 0.01) to the 100% B vitamin level from 23 to 85 kg of BW, but there was no response to any level from 85 to 120 kg of BW. Carcass measurements demonstrated a greater LM area (P < 0.01) and a lower backfat depth (P < 0.01) to the 100% B vitamin level. One station evaluated an additional treatment (3 replicates) in which each replicate was fed a fifth diet containing the 100% dietary level of B vitamins from 23 to 85 kg of BW whereupon the B vitamins were removed from 85 to 120 kg of BW. This removal did not reduce pig performance responses for the final period or for the overall period. The results demonstrated that supplementation of B vitamins at the 100% total NRC levels for starter and grower pigs was sufficient to meet their needs, and there was no further improvement to or deleterious effect to greater dietary levels.

Effects of replacing pharmacological levels of dietary zinc oxide with lower dietary levels of various organic zinc sources for weanling pigs.

Two 28-d randomized complete block design experiments were conducted to evaluate the effects of concentrations and sources of Zn on growth performance of nursery pigs. Seven stations participated in Exp. 1, which evaluated the efficacy of replacing 2,500 ppm of Zn from ZnO with 125, 250, or 500 ppm of Zn from Zn methionine. A control diet with 125 ppm of supplemental Zn was included at all stations. A total of 615 pigs were used in 26 replicates. Average weaning age was 20.6 d and the average initial BW was 6.3 kg. There were no differences in any growth response among the three supplemental Zn methionine levels fed in Exp. 1. Zinc supplementation from Zn methionine improved ADG compared with the control during all phases (P < 0.05), due primarily to an increase in ADFI. Pigs fed 2,500 ppm of Zn from ZnO gained faster (P < 0.01) than those fed the control diet during all phases, and faster (P < 0.05) than those fed supplemental Zn from Zn methionine for the 28-d experiment. Differences in gain were again due mainly to differences in feed intake. A second experiment compared five sources of supplemental organic Zn (500 ppm of Zn) with 500 and 2,000 ppm supplemental Zn from ZnO and a control (140 ppm total Zn). Six stations used a total of 624 pigs, with an average weaning age of 20.4 d and averaging 6.2 kg BW in 15 replicates. Pigs fed 2,000 ppm of Zn from ZnO gained faster (P < 0.05) than pigs fed the control or any of the 500 ppm of Zn treatments (ZnO or organic Zn). Pigs fed the 2,000 ppm of Zn from ZnO also consumed more feed than those receiving 500 ppm of Zn from ZnO or from any of the organic Zn sources (P < 0.05). Organic sources of Zn did not improve gain, feed intake, or feed efficiency beyond that achieved with the control diet. Supplemental Zn at a concentration of 500 ppm, whether in the form of the oxide or in an organic form, was not as efficacious for improved ADG as 2,000 to 2,500 ppm of Zn from ZnO.

An exceptionally bright flare from SGR 1806-20 and the origins of short-duration gamma-ray bursts.

Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. Here we report the detection of a long (380 s) giant flare from SGR 1806-20, which was much more luminous than any previous transient event observed in our Galaxy. (In the first 0.2 s, the flare released as much energy as the Sun radiates in a quarter of a million years.) Its power can be explained by a catastrophic instability involving global crust failure and magnetic reconnection on a magnetar, with possible large-scale untwisting of magnetic field lines outside the star. From a great distance this event would appear to be a short-duration, hard-spectrum cosmic gamma-ray burst. At least a significant fraction of the mysterious short-duration gamma-ray bursts may therefore come from extragalactic magnetars.

Endurance training increases LKB1 and MO25 protein but not AMP-activated protein kinase kinase activity in skeletal muscle.

LKB1 complexed with MO25 and STRAD has been identified as an AMP-activated protein kinase kinase (AMPKK). We measured relative LKB1 protein abundance and AMPKK activity in liver (LV), heart (HT), soleus (SO), red quadriceps (RQ), and white quadriceps (WQ) from sedentary and endurance-trained rats. We examined trained RQ for altered levels of MO25 protein and LKB1, STRAD, and MO25 mRNA. LKB1 protein levels normalized to HT (1 +/- 0.03) were LV (0.50 +/- 0.03), SO (0.28 +/- 0.02), RQ (0.32 +/- 0.01), and WQ (0.12 +/- 0.03). AMPKK activities in nanomoles per gram per minute were HT (79 +/- 6), LV (220 +/- 9), SO (22 +/- 2), RQ (29 +/- 2), and WQ (42 +/- 4). Training increased LKB1 protein in SO, RQ, and WQ (P < 0.05). LKB1 protein levels after training (%controls) were SO (158 +/- 17), RQ (316 +/- 17), WQ (191 +/- 27), HT (106 +/- 2), and LV (104 +/- 7). MO25 protein after training (%controls) was 595 +/- 71. Training did not affect AMPKK activity. MO25 but not LKB1 or STRAD mRNA increased with training (P < 0.05). Trained values (%controls) were MO25 (164 +/- 22), LKB1 (120 +/- 16), and STRAD (112 +/- 17). LKB1 protein content strongly correlated (r = 0.93) with citrate synthase activity in skeletal muscle (P < 0.05). In conclusion, endurance training markedly increased skeletal muscle LKB1 and MO25 protein without increasing AMPKK activity. LKB1 may be playing multiple roles in skeletal muscle adaptation to endurance training.

Variability in mixing efficiency and laboratory analyses of a common diet mixed at 25 experiment stations.

An experiment involving 25 experiment stations in the North Central and Southern regions (NCR-42 and S-288, respectively) was conducted to assess the degree of uniformity of diet mixing among stations and to assess the variability among station laboratories in chemical analysis of mixed diets. A fortified corn-soybean meal diet was mixed at each station using a common diet formula (except for vitamin and trace-mineral additions). The diet was calculated to contain 14% crude protein (CP), 0.65% Ca, 0.50% P, and 125 ppm Zn (based on 100 ppm added Zn). After mixing, samples were collected from the initial 5% of feed discharged from the mixer, after 25, 50, and 75% was discharged, and from the final 5% of discharged feed. The five samples were sent to the University of Kentucky, finely ground, and divided into subsamples. Each set of five subsamples from each station was distributed to three randomly selected stations for analysis of CP, Ca, P, and Zn (i.e., each station analyzed five diet sub-samples from three other stations). In addition, two commercial and two station laboratories analyzed composites of the five subsamples from each of the 25 mixed diets. Based on the laboratories that analyzed all diets, means were 13.5, 0.65, and 0.52%, and 115 ppm for CP, Ca, P, and Zn, respectively. Ranges of 11.8 to 14.6% CP, 0.52 to 0.85% Ca, 0.47 to 0.58% P, and 71 to 182 ppm of Zn were found among the 25 diet mixes. The coefficients of variation among the 25 diet samples for CP, Ca, P, and Zn were 4.3, 9.3, 4.1, and 17.4%, and among the 25 laboratories were 3.6, 12.5, 10.7, and 11.1%, respectively. Overall analyses of the five sub samples were, respectively, CP: 13.4, 13.6, 13.4, 13.5, and 13.4% (P < 0.06); Ca: 0.66, 0.67, 0.67, 0.66, and 0.67%; P: 0.50,0.51,0.51,0.50, and 0.50%; and Zn: 115, 116, 112, 113, and 120 ppm (P < 0.001). Diets were not uniformly mixed at all stations (station x sample No. was P < 0.08 for Ca and P < 0.01 for CP, P, and Zn). Among stations, the range of the five samples, expressed as a percentage of the mean and averaged for CP, Ca, P, and Zn, varied from +/- 1.1% (i.e., 98.9 to 101.0%) to +/- 12.9% (84.6 to 110.4%), with an overall average of +/- 5.2%. Neither type nor volume of mixers was related to mixing uniformity. The results suggest that uniformity of diet mixes varies among experiment stations, that some stations miss their targeted levels of nutrients (especially Zn), and that the variability among experiment station laboratories in analysis of dietary Ca, P, and Zn in mixed diets is quite large.

A lesson from flex: consider the Y chromosome when assessing Drosophila sex-specific lethals.

Bhattacharya et al. (Bhattacharya, A., Sudha, S., Chandra, H. S. and Steward, R. (1999) Development 126, 5485-5493) reported that loss-of-function mutations in the flex (female-specific lethal on X) gene caused female-specific lethality because flex(+) acts as a positive regulator of the master switch gene Sex lethal (Sxl). Sxl is essential for female development. Key to their conclusion was the ability of flex mutations to suppress the male lethality caused by Sxl(M) mutations, which inappropriately activate Sxl female-specific expression. Here we report our contrary findings that flex mutations fail to suppress even the weakest Sxl(M )alleles, arguing against the proposed regulatory relationship between flex and Sxl. Instead we show that the lethal flex phenotype depends on the absence of a Y chromosome, not on the presence of two X chromosomes. flex lethality is caused by a defect in the functioning of the X-linked rDNA locus called bobbed, since this defect is complemented by the corresponding wild-type rDNA complex on the Y.

Development of reading proficiency in English by bilingual children and their monolingual peers.

The semantic, syntactic, and graphophonic cueing techniques employed by 55 bilingual children and 39 monolingual peers when reading aloud in English were identified through miscue analysis. In contrast to earlier research in 1999 by Cline and Cozens no significant differences were found between the two groups on any of the techniques. Both bilingual and monolingual readers consistently used more graphophonic cues than syntactic or semantic cues but not significantly so. The authors discuss possible extraneous variables which may account in part for this unexpected result.

Variability among sources and laboratories in analyses of wheat middlings. NCR-42 Committee on Swine Nutrition.

A cooperative research study was conducted by members of a regional committee (North Central Regional Committee on Swine Nutrition [NCR-42]) to assess the variability in nutrient composition (DM, CP, Ca, P, Se, NDF, and amino acids) of 14 sources of wheat middlings from 13 states (mostly in the Midwest). A second objective was to assess the analytical variability in nutrient assays among 20 laboratories (labs; 14 experiment station labs and six commercial labs). Wheat middlings were obtained from each participating station's feed mill. The bulk density of the middlings ranged from 289 to 365 g/L. The number of labs that analyzed samples were as follows: DM and CP, 20; Ca, 16; P, 15; Se, 7; NDF, 10; and amino acids, 9. Each lab used its own analytical procedures. The middlings averaged 89.6% DM, 16.2% CP, .12% Ca, .97% P, 36.9% NDF, .53 mg/kg Se, .66% lysine, .19% tryptophan, .54% threonine, .25% methionine, .34% cystine, .50% isoleucine, and .73% valine. As expected, there was considerable variation in nutrient composition among the 14 sources (P < .01), especially for Ca (.08 to .30%) and Se (.05 to 1.07 mg/kg). "Heavy" middlings (high bulk density, >335 g/L), having a greater proportion of flour attached to the bran, were lower in CP, lysine, P, and NDF than "light" middlings (<310 g/L), having cleaner bran, resulting in negative correlations between bulk density and CP (r = -.61), lysine (r = -.59), P (r = -.54), and NDF (r = -.81). Each 1-percentage-point increase in CP in the wheat middlings was associated with .0235 (r2 = .61) and 2.1 (r2 = .39)-percentage-point increases in lysine and NDF, respectively. Lysine content was associated with NDF, CP, and bulk density of wheat middlings (r2 = .88). There was considerable variation among laboratories (P < .01) in analysis of all nutrients. The CV among sources (100 x sigmaS/mean) was greater than among labs (100 x sigmaL/mean) for CP, Ca, P, Se, and NDF, but the CV among labs was greater than that among sources for DM and all of the amino acids except lysine and phenylalanine.

An extracellular activator of the Drosophila JAK/STAT pathway is a sex-determination signal element.

Metazoans use diverse and rapidly evolving mechanisms to determine sex. In Drosophila melanogaster an X-chromosome-counting mechanism determines the sex of an individual by regulating the master switch gene, Sex-lethal (Sxl). The X-chromosome dose is communicated to Sxl by a set of X-linked signal elements (XSEs), which activate transcription of Sxl through its 'establishment' promoter, SxlPe. Here we describe a new XSE called sisterlessC (sisC) whose mode of action differs from that of previously characterized XSEs, all of which encode transcription factors that activate SxlPe directly. In contrast, sisC encodes a secreted ligand for the Drosophila Janus kinase (JAK) and 'signal transducer and activator of transcription' (STAT) signal transduction pathway and is allelic to outstretched (os, also called unpaired). We conclude that sisC works indirectly on Sxl through this signalling pathway because mutations in sisC or in the genes encoding Drosophila JAK or STAT reduce expression of SxlPe similarly. The involvement of os in sex determination confirms that secreted ligands can function in cell-autonomous processes. Unlike sex signals for other organisms, sisC has acquired its sex-specific function while maintaining non-sex-specific roles in development, a characteristic that it shares with all other Drosophila XSEs.

Multilingualism and dyslexia: challenges for research and practice.

Over the last two decades there has been an expansion of activity and substantial progress in research on dyslexia and research on bilingualism and multilingualism. But the study of dyslexia has generally focused on monolingual learners and the study of bilingualism has tended to focus on speakers who do not have special educational needs. This paper will review the strands of research to date that have a bearing on multilingualism and dyslexia and attempt to identify the major challenges that face researchers and teachers. A satisfactory response cannot be developed without a full understanding of the impact that dyslexia has on language learning and the impact that multilingualism has on literacy learning.

Interplanetary Network Localization of GRB 991208 and the Discovery of its Afterglow.

The extremely energetic ( approximately 10-4 ergs cm-2) gamma-ray burst (GRB) of 1999 December 8 was triangulated to an approximately 14 arcmin2 error box approximately 1.8 days after its arrival at Earth with the third interplanetary network (IPN), which consists of the Ulysses, Near-Earth Asteroid Rendezvous, and Wind spacecraft. Radio observations with the Very Large Array approximately 2.7 days after the burst revealed a bright fading counterpart whose position is consistent with that of an optical transient source with a redshift of 0.707. We present the time history, peak flux, fluence, and refined 1.3 arcmin2 error box of this event and discuss its energetics. This is the first time that a counterpart has been found for a GRB localized only by the IPN.

Further assessment of the dietary lysine requirement of finishing gilts.

A cooperative research study involving 635 gilts was conducted at eight research stations to further estimate the lysine requirement of finishing gilts. Dietary crude protein levels of the five dietary treatments ranged from 16.0 to 24.4% with calculated lysine levels of .80, .95, 1.10, 1.25, or 1.40%. Each station contributed a minimum of two replicate pens of pigs per treatment. Average initial and final weights were 53.6 and 116.4 kg, respectively. At the end of the experimental period, pigs were killed and hot carcass weight, 10th-rib fat depth, and longissimus muscle area were measured. Carcass fat-free lean percentage and fat-free lean gain were estimated from these data. Daily lysine intakes averaged 21.8, 25.9, 30.5, 34.3, and 37.8 g/d for the five treatment groups, respectively. Increasing the dietary lysine from .80 to .95% numerically increased weight gain and gain:feed, but these increases were not maintained at higher levels of dietary lysine. Overall, rate and efficiency of gain decreased (cubic, P < .01) with increasing dietary lysine. Carcasses were leaner at the two higher levels of dietary lysine as evidenced by reduced 10th rib backfat (linear, P < .01), increased longissimus area (quadratic, P < .04), and increased percentage of estimated fat-free lean (linear, P < .01). Carcass fat-free lean gain was not influenced by dietary lysine except for a small numerical improvement (P < .11) at the .95% level of dietary lysine that paralleled the improvement in body weight gain. The results indicate that the dietary lysine requirement of finishing gilts with a mean carcass fat-free lean growth rate of 306 g/d from 54 to 116 kg body weight is probably no higher than .80% of the diet to achieve maximum rate and efficiency of body weight gain and carcass lean growth rate. The results also indicate that higher dietary lysine levels may increase carcass leanness in finishing gilts, possibly due to reduced intake of NE. Whether this response is due to the effects of lysine alone, protein (i.e., other amino acids), or soybean meal is unknown.

Prompt Optical Observations of Gamma-Ray Bursts.

The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure simultaneous and early afterglow optical emission from gamma-ray bursts (GRBs). A search for optical counterparts to six GRBs with localization errors of 1 deg2 or better produced no detections. The earliest limiting sensitivity is mROTSE>13.1 at 10.85 s (5 s exposure) after the gamma-ray rise, and the best limit is mROTSE>16.0 at 62 minutes (897 s exposure). These are the most stringent limits obtained for the GRB optical counterpart brightness in the first hour after the burst. Consideration of the gamma-ray fluence and peak flux for these bursts and for GRB 990123 indicates that there is not a strong positive correlation between optical flux and gamma-ray emission.

Functioning of the Drosophila integral U1/U2 protein Snf independent of U1 and U2 small nuclear ribonucleoprotein particles is revealed by snf(+) gene dose effects.

Snf, encoded by sans fille, is the Drosophila homolog of mammalian U1A and U2B" and is an integral component of U1 and U2 small nuclear ribonucleoprotein particles (snRNPs). Surprisingly, changes in the level of this housekeeping protein can specifically affect autoregulatory activity of the RNA-binding protein Sex-lethal (Sxl) in an action that we infer must be physically separate from Snf's functioning within snRNPs. Sxl is a master switch gene that controls its own pre-mRNA splicing as well as splicing for subordinate switch genes that regulate sex determination and dosage compensation. Exploiting an unusual new set of mutant Sxl alleles in an in vivo assay, we show that Snf is rate-limiting for Sxl autoregulation when Sxl levels are low. In such situations, increasing either maternal or zygotic snf(+) dose enhances the positive autoregulatory activity of Sxl for Sxl somatic pre-mRNA splicing without affecting Sxl activities toward its other RNA targets. In contrast, increasing the dose of genes encoding either the integral U1 snRNP protein U1-70k, or the integral U2 snRNP protein SF3a(60), has no effect. Increased snf(+) enhances Sxl autoregulation even when U1-70k and SF3a(60) are reduced by mutation to levels that, in the case of SF3a(60), demonstrably interfere with Sxl autoregulation. The observation that increased snf(+) does not suppress other phenotypes associated with mutations that reduce U1-70k or SF3a(60) is additional evidence that snf(+) dose effects are not caused by increased snRNP levels. Mammalian U1A protein, like Snf, has a snRNP-independent function.

PrP genotypes of captive and free-ranging Rocky Mountain elk (Cervus elaphus nelsoni) with chronic wasting disease.

The PrP gene encodes the putative causative agent of the transmissible spongiform encephalopathies (TSEs), a heterogeneous group of fatal, neurodegenerative disorders including human Creutzfeldt-Jakob disease, bovine spongiform encephalopathy, ovine scrapie and chronic wasting disease (CWD) of North American deer and elk. Polymorphisms in the PrP gene are associated with variations in relative susceptibility, pathological lesion patterns, incubation times and clinical course of TSEs of humans, mice and sheep. Sequence analysis of the PrP gene from Rocky Mountain elk showed only one amino acid change (Met to Leu at cervid codon 132). Homozygosity for Met at the corresponding polymorphic site (Met to Val) in humans (human codon 129) predisposes exposed individuals to some forms of Creutzfeldt-Jakob disease. In this study, Rocky Mountain elk homozygous for PrP codon 1 32 Met were over-represented in both free-ranging and farm-raised CWD-affected elk when compared to unaffected control groups.

Effects of dietary levels of selenium-enriched yeast and sodium selenite as selenium sources fed to growing-finishing pigs on performance, tissue selenium, serum glutathione peroxidase activity, carcass characteristics, and loin quality.

This research evaluated the efficacy of inorganic and organic Se sources for growing-finishing pigs, as measured by performance and various tissue, serum, carcass, and loin quality traits. A total of 351 crossbred pigs were allotted at an average BW of 20.4 kg to six replicates of a 2x4 factorial experiment in a randomized complete block design. Pigs were fed diets containing Se-enriched yeast (organic) or sodium selenite (inorganic), each at .05, .10, .20, or .30 mg Se/kg diet. A non-Se-fortified basal diet was a ninth treatment group. Five pigs per pen were bled initially and at 30-d intervals with serum analyzed for Se and glutathione peroxidase (GSH-Px) activity. At 55 kg BW, one pig per pen from each of three replicates was killed, and tissues were collected for Se analysis. At 105 kg BW, the remaining pigs in the three replicates were killed, carcass measurements were collected, tissues were analyzed for Se, and loin quality was evaluated for pH, drip loss, and lightness. No performance or carcass measurement benefit resulted from either Se source or dietary Se levels. Pigs had a lower serum Se concentration and GSH-Px activity when the basal diet was fed, but both increased as dietary Se level increased (P<.01). Serum GSH-Px activities were increased by pig age and reached a plateau when the diet contained approximately .10 mg Se/kg (P<.01) at d 30, and 60 of the trial, and at .05 mg Se/kg diet at d 90 of the trial. The organic Se group fed .05 and .10 mg Se/kg had serum GSH-Px activities that tended to be lower than those of pigs fed the inorganic Se source, but GSH-Px activities in both groups were similar at higher Se levels. Tissue Se contents increased linearly as the dietary Se level increased, but the increase was markedly higher when organic Se was fed, resulting in an interaction (P<.01) response. Loin drip loss, pH, and lightness were unaffected (P>.15) by organic Se source or level, but there was a trend for a higher drip loss (P = .11) and a linear (P<.01) increase in loin paleness when the inorganic Se level increased. These results indicate that neither Se source nor Se level had an effect on pig performance or carcass measurements, but organic Se source increased tissue Se concentrations. Inorganic Se may, however, have a detrimental effect on loin quality, as reflected by higher drip loss and a paler color. Using serum GSH-Px activity as the measurement criterion, the supplemental dietary Se requirement did not seem to exceed .10 and .05 mg Se/kg diet for the growing and finishing phases, respectively, when added to a basal diet containing .06 mg Se/kg.

Health and growth performance of barrows reared in all-in/all-out or continuous flow facilities with or without a chlortetracycline feed additive.

OBJECTIVE: To compare health and growth performance in barrows reared in all-in/all-out (AIAO) or continuous flow (CF) management systems. ANIMALS: 400 barrows. PROCEDURE: Barrows (approx 2 months old) were allotted to 4 replications (100 barrows each); barrows were housed in AIAO or CF rooms (10 pens/room), and 50 pigs/replicate received chlortetracycline (CTC, 110 mg/kg of feed). Barrows from each pen were slaughtered at 3, 4, 5, and 6 months old. RESULTS: Barrows in the AIAO room had greater total daily gain (TDG) and lean daily gain (LDG) than did barrows in the CF room. Addition of CTC did not improve TDG or LDG in either environment. Barrows in the AIAO room reached body weight of 104.5 kg in 169.7 days, compared with 177.3 days for barrows in the CF room. Feed-to-gain ratio was not affected by management or CTC. Lungs from barrows reared in AIAO facilities had a lower percentage of lesions than did lungs of barrows reared in CF facilities (1.74% vs 9.52%). Addition of CTC did not affect prevalence and extent of lung lesions. Extent of lung lesions was positively correlated with change in serum optical density (OD) to Mycoplasma hyopneumoniae (r = 0.35), but not with change in serum OD to Actinobacillus pleuropneumoniae. Lean growth and serum OD to M. hyopneumoniae and A. pleuropneumoniae were not correlated. CONCLUSIONS: Health and growth performance were better for barrows in an AIAO facility, compared with a CF facility, but addition of CTC to feed failed to enhance health or performance of barrows in either facility.