K.R. Brown

Maternal Dietary l-Carnitine Supplementation Influences Fetal Carnitine Status and Stimulates Carnitine Palmitoyltransferase and Pyruvate Dehydrogenase Complex Activities in Swine

Effects of increasing maternal L-carnitine on carnitine status and energy metabolism in the fetus were evaluated by feeding pregnant swine a corn-soybean-based diet containing either 0 or 50 mg/kg added L-carnitine (n = 10/treatment) during the first 70 d of gestation. Carnitine, carnitine palmitoyltransferase (CPT), and pyruvate dehydrogenase complex (PDHC) activities were analyzed in tissues collected from fetuses on d 55 and 70. Maternal L-carnitine supplementation increased both fetal free and long-chain carnitine concentrations by 45% in liver and free carnitine by 31% in heart tissues but did not affect kidney tissue. Elevations in free and acylcarnitines increased with gestational age from 55 to 70 d in liver but not in heart and kidney. The increased carnitine concentrations resulted in a 45% increase in PDHC activity in heart and liver on d 70 of gestation but did not affect kidney and liver on d 55 of gestation. The increases in carnitine concentrations were accompanied by a 70% increase in hepatic CPT activity in 70-d-old fetuses, but activities in heart and kidney were unaffected. The Michaelis constant (K(m)) of CPT for carnitine in fetal tissues was not influenced by carnitine supplementation (P > 0.1). Notably, the concentrations of carnitine measured on d 70 were only 25-40% of the K(m) values in liver, 60-70% in heart, and 30-40% in kidney (P < 0.001). We conclude that carnitine ingestion during pregnancy increases fetal carnitine concentrations and stimulates heart PDHC and liver CPT activity without altering carnitine K(m).

Does menstrual cycle phase affect lung diffusion capacity during exercise

Resting lung diffusing capacity (DLCO) decreases during the early and late-follicular phases of the menstrual cycle presumably due to capillary blood volume (VC) changes; however, it is not known if these differences exist during exercise. We hypothesized that DLCO would increase during the mid-luteal phase of the menstrual cycle due to increases in VC. Eight normally menstruating females (21.4±0.7 yrs) were studied. Subjects completed a discontinuous treadmill V˙O2max test during the early-follicular (EF), late-follicular (LF), and mid-luteal (ML) phases of the menstrual cycle. Metabolic measurements were made from a breath-by-breath automated cart, and DLCO via the single-breath exhalation technique during exercise. During exercise, DLCO was lesser during EF compared to ML at 90% and 100%V˙O2max (p<0.05) (90%: 37.8±3.7 EF vs 41.6±4.0 ML, 100%: 37.7±3.7 EF vs 42.6±4.3 ML mL/mmHg/min). VC was significantly greater during the ML phase when compared to the EF at 80%, 90%, and 100%V˙O2max. These results demonstrate DLCO and VC are influenced by the menstrual cycle during heavy exercise.

Effects of feeding L-carnitine to gilts through day 70 of gestation on litter traits and the expression of insulin-like growth factor system components and L-carnitine concentration in foetal tissues.

We investigated the influence of supplemental L-carnitine on foetal blood metabolites, litter characteristics, L-carnitine concentration in skeletal muscle and insulin-like growth factor (IGF) axis components in foetal hepatic and skeletal muscle tissues at day 40, 55 and 70 of gestating gilts. A total of 59 gilts (body weight = 137.7 kg) received a constant feed allowance of 1.75 kg/day and a top-dress containing either 0 or 50 ppm of L-carnitine starting on the first day of breeding through the allotted gestation length. Foetuses from the gilts fed diets with L-carnitine tended to be heavier (p = 0.06) and the circulating IGF-II tended to be lower (p = 0.09) at day 70, compared with the foetuses from the control gilts. Insulin-like growth factor-I messenger RNA (mRNA) was lower (p = 0.05) in hepatic tissue in the foetuses collected from gilts fed L-carnitine. Free and total carnitine concentration increased (p < 0.05) in the skeletal muscle from the foetuses collected from gilts fed supplemental L-carnitine. This study showed that L-carnitine had beneficial effects on the average foetal weight at day 70 of gestation, associated with changes in the foetal IGF system.

Improved lung function following dietary antioxidant supplementation in exercise-induced asthmatics.

INTRODUCTION Oxidative stress is a characteristic of exercise-induced asthma (EIA), however antioxidant supplementation may attenuate EIA. The purpose of this study was to determine if ascorbic (AsA) and α-tocopherol supplementation would improve airway function in subjects with EIA. METHODS A single-blind randomized crossover design with eight clinically diagnosed EIA subjects (22.0 ± 0.7 year) and five healthy control subjects (28.2 ± 1.4 year) was used. Subjects consumed vitamins (V) (AsA 500 mg; α-tocopherol 300 IU) or placebo (PLA) daily for three weeks, followed by a three week washout period and then three weeks of the alternative treatment. Ten-minute treadmill tests (90% VO2peak) were performed with pulmonary function testing (forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and between 25 and 75% (FEF25-75%), and peak expiratory flow rates (PEFR)) measured pre-exercise and 1, 5, 15, and 30 min post-exercise. RESULTS Supplementation led to significant improvements at minute 5 and minute 15 in FVC; FEV1; PERF; FEF25-75% and minute 30 in FEV1 and FEF25-75% post-exercise. CONCLUSION AsA and α-tocopherol may aid the recovery of pulmonary function in subjects with EIA.

The effect of exercise training with an additional inspiratory load on inspiratory muscle fatigue and time-trial performance

The purpose was to determine the effect of moderate-intensity exercise training (ET) on inspiratory muscle fatigue (IMF) and if an additional inspiratory load during ET (ET+IL) would further improve inspiratory muscle strength, IMF, and time-trial performance. 15 subjects were randomly divided to ET (n=8) and ET+IL groups (n=7). All subjects completed six weeks of exercise training three days/week at ∼70%V̇O2peak for 30min. The ET+IL group breathed through an inspiratory muscle trainer (15% PImax) during exercise. 5-mile, and 30-min time-trials were performed pre-training, weeks three and six. Inspiratory muscle strength increased (p<0.05) for both groups to a similar (p>0.05) extent. ET and ET+IL groups improved (p<0.05) 5-mile time-trial performance (∼10% and ∼18%) and the ET+IL group was significantly faster than ET at week 6. ET and ET+IL groups experienced less (p<0.05) IMF compared to pre-training following the 5-mile time-trial. In conclusion, these data suggest ET leads to less IMF, ET+IL improves inspiratory muscle strength and IMF, but not different than ET alone.

Effects of continuous or intermittent ractopamine HCl (paylean1) use on pig growth performance in late finishing

A total of 110 barrows (PIC L210 × L42) with an initial weight of 154.4 lb were used in a 56-d feeding trial to evaluate the effects of continuously feeding ractopamine HCl (Paylean; 9 g/ton), withdrawing Paylean, or intermittent Paylean feeding on finishing pig performance. There were five experimental treatments fed the last 56 d before marketing; A) control diet (no Paylean) fed for 56 d; B) Paylean diet (9 g/ton) fed for 56 d; C) Paylean fed for 21 d, control for 14 d, then Paylean for 21 d; D) control fed for 7 d, Paylean fed for 21 d, control fed for 7 d, then Paylean fed for 21 d; and E) control fed for 35 d, then Paylean fed for 21 d. Pigs fed Paylean for 21 d then withdrawn for 7 or 14 d and then re-fed for 21 d (Treatments C and D) had similar response to those fed Paylean for only the last 21 d before market (Treatment E). Pigs fed these three treatments had final weight numerically increased by 3 to 5 lb over that of pigs continuously fed Paylean for the entire 56 d. During the period when Paylean was withdrawn (7 or 14 d), pigs lost much of the benefit that had been gained from Paylean feeding. But pigs fed Paylean again later seem to respond similarly to pigs that had never had Paylean in the diet. (

L-carnitine supplementation to gestating gilts alters the IGF axis in porcine embyronic myoblasts.

We determined the effects of supplemental L-carnitine on the insulin-like growth factor (IGF) system in porcine embryonic myoblasts (PEM) from gilts. Forty gilts (BW = 303.6 lb) were allotted to 1 of 4 treatments that were arranged in a 2 × 2 factorial, with main effects of L-carnitine (0 or 50 ppm) and day of gestation (55 or 70). All gilts were fed 3.86 lb/day and a top-dress containing either 0 or 50 ppm of L-carnitine, starting on the first day of breeding and continuing through the allotted gestation length. At d 55 or 70 of gestation, fetuses were removed for isolation of PEM from the hind-limb muscles. Real-time quantitative PCR was used to determine growth factor messenger RNA (mRNA) expression in cultured PEM at 72-, 96-, 120-, and 144-h after plating. Flow cytometry was used to analyze percentage of myogenic cells with a myoblast/myotube-specific monoclonal antibody 5.1H11, and for determination of cell cycle stage. There was no treatment differences (P>0.10) for the expression of IGF-I, IGF-II, or IGFBP-5 mRNA levels. But PEM isolated from fetuses collected from gilts fed diets with L-carnitine had lower (P = 0.08) IGFBP-3 mRNA levels, compared with levels in the controls. Myoblasts isolated from fetuses from gilts fed diets with added Lcarnitine had greater (P = 0.09; 8.8%) 5.1H11 monoclonal antibody attachment, compared with the controls, after 72 hours in culture (91.8% vs. 87.4%). Although not significant (P = 0.31), the total number of PEM in the S phase of the cell cycle was 4.7% greater in PEM collected from fetuses obtained from gilts fed diets with L-carnitine, compared with numbers from the control-fed gilts (37.5% vs. 34.2%). These data suggest that L-carnitine influences the IGF system, stage of the cell cycle, and recognition of muscle development, resulting in enhanced proliferation and delayed differentiation of PEM.

Influence of L-carnitine on litter characteristics from gilts harvested at day 40, 55, and 70 of gestation.

A total of 59 gilts were used to determine the effects of supplemental L-carnitine on reproductive performance. Experimental treatments were arranged in a 2 × 3 factorial with main effects of L-carnitine (0 or 50 ppm) and day of gestation (40, 55, or 70). All gilts received a constant feed allowance of 3.86 lb/day and a top-dress containing either 0 or 88 mg of L-carnitine, starting on the first day of breeding and continuing until the day of harvest. Total litter size, total litter weight, and crown-to-rump length of fetuses were not different (P>0.10) between treatments at any gestation length. By d 70 of gestation, average fetus weight was heavier (P = 0.06) for fetuses from gilts fed L-carnitine, compared with fetuses from gilts fed the control diet. In addition, at d 70, fetal insulin-like growth factor-II (IGF-II) concentrations were lower (P = 0.09) for fetuses from gilts fed L-carnitine than for fetuses from gilts fed the control diet. Feeding L-carnitine may have decreased fetal IGF-II, therefore increasing cell proliferation and delaying cell differentiation. These results show that providing supplemental Lcarnitine to gestating gilts has beneficial effects on average fetal weight, possibly observed because of its ability to reduce fetal IGF-II concentrations.

Influence of L-carnitine on growth and plasma IGF-I from gilts harvested at three gestation lengths.

A total of 59 gilts were used to determine the effects of supplemental L-carnitine on gilt growth and maternal insulin-like growth factor-I (IGF-I). Experimental treatments were arranged in a 2 × 3 factorial with main effects of L-carnitine (0 or 50 ppm) and day of gestation (40, 55, or 70). All gilts received a constant feed allowance of 3.86 lb/day and a topdress containing either 0 or 88 mg of Lcarnitine, starting on the first day of breeding. No differences (P>0.05) between treatments were observed for BW, estimated protein mass, or estimated fat mass at any gestation length. At d 70 of gestation, there was a numeric increase (P>0.10) in BW for the gilts fed L-carnitine, compared with those fed the control diet. At d 40 of gestation, gilts fed Lcarnitine tended to have greater (P = 0.10) backfat, compared with the gilts fed the control diet; but no differences (P>0.05) were observed in backfat on d 0, 55, or 70 of gestation. In addition, no differences (P>0.05) were observed in maternal IGF-I between treatments at any gestation length. Total and free plasma L-carnitine concentrations were similar (P>0.10) at d 0 of gestation, but concentrations were higher (P<0.01) by d 40 of gestation in the gilts fed L-carnitine. These results show that supplemental L-carnitine numerically increases BW of gestating gilts. This data represents the first part of an ongoing study, with the rest of the data being reported in subsequent publications.

Effects of intermittent usage of water-based Neomycin sulfate on the growth performance of weanling pigs.

A total of 360 weanling pigs (initially 11.4 lb and 18 ± 3 d of age, PIC) were used to determine the effects of intermittent use of water-based medication on nursery pig growth performance. Pigs were given one of eight experimental treatments: negative control (no antibiotics in the feed or water); positive control with Neo-Terramycin in the feed (140 g/ton Neomycin sulfate, 140 g/ton Oxytetracycline HCl); continuous use of either 38.0 or 75.5 mg Neomycin sulfate per L of water; use of either 38.0 or 75.5 mg of Neomycin sulfate per L of water, during weeks 1 and 3 after weaning; and use of either 38.0 or 75.5 mg Neomycin sulfate per L of water during weeks 2 and 4 after weaning. Overall (d 0 to 28 after weaning), pigs provided Neomycin sulfate in the water continuously and pigs fed the positive control diet had greater ADG (P<0.05) and ADFI (P<0.04) than did pigs provided non-medicated water and feed. Pigs fed the positive control diet tended (P<0.15) to have greater ADG than did pigs provided an intermittent supply of water-based Neomycin sulfate, but there was no difference in growth performance and feed efficiency between pigs fed the positive control diet and those provided a continuous supply of water-based Neomycin sulfate. Pigs provided a continuous supply of either dosage of Neomycin sulfate in the water had greater (P<0.05) ADG and ADFI than did pigs provided water-based Neomycin sulfate on an intermittent basis. These data demonstrate that providing neomycin in the feed or water results in a growth response, but there is no carryover effect. Thus, pig performance returns to the control level immediately after the supply of Neomycin is removed.