Effect of vitamin E and selenium on iron utilization in neonatal pigs.

Supplying adequate iron (Fe) to neonatal pigs to support normal growth and hematological and antioxidant status, while preventing iron toxicity, is a challenge for producers. Three experiments were conducted to determine the effect of frequency and route of Fe administration with or without vitamin E (E) and selenium (Se) on growth, Fe, and antioxidant status of neonatal pigs. In Exp. 1, 12 pigs from dams with reduced E status were fed a semipurified diet without added Fe from d 3 to d 14 of age. At d 6 of age, pigs received the following i.m. injections: 1) FE, 1 mL containing 200 mg of Fe (iron dextran); 2) FEE, treatment FE plus 1 mL containing 300 IU of vitamin E (d-alpha tocopherol); or 3) FESEE, 1.03 mL containing 200 mg of Fe (iron dextran), .15 mg of Se (sodium selenite), and 15 IU of vitamin E (d-alpha tocopherol). Pigs were weighed daily and blood was collected at 3, 7, and 14 d of age. From d 8 to 14, growth was depressed (P < .05) in pigs injected with FESEE. At 14 d of age, pigs injected with FE or FEE had increased (P < .05) hemoglobin (Hb) concentration. Ceruloplasmin activity (CP) was greater (P < .05) at d 7 of age than at d 3 or 14 regardless of treatment. In Exp. 2, 3-d-old pigs (n = 94) received the following: 1) FE, 200 mg Fe (iron dextran) i.m.; (2) FEE, treatment FE plus 300 IU vitamin E i.m.; 3) EFE, 300 IU vitamin E i.m. followed by 200 mg Fe (iron dextran) i.m. 24 h later; or 4) OFE, 100 mg Fe and 10 mg Cu orally. On d 21 of age, one-half of the pigs in each treatment received a second dose of their respective treatment. Blood samples (n = 60) were obtained on d 3 and 21 of age. Pigs injected with FE, FEE, or EFE had greater (P < .05) Hb at d 21 than pigs given OFE. Copper/zinc superoxide dismutase (Cu/ZnSOD) activity was greater (P < .05) at d 21 with OFE than with the other treatments. At 65 d of age, ADG did not differ among treatments. In Exp. 3, pigs (n = 150, in three farrowing groups) were injected with 200 mg of Fe (iron dextran) on d 1 or d 1 and 14. Blood samples were obtained on d 7 and 21 of age. Hemoglobin concentration on d 21 was improved equally by both treatments. Catalase and Cu/ZnSOD activities were increased (P < .05) on d 21 of the experiment compared with d 7 regardless of treatment. Growth was not affected by injection frequency. Results from these experiments indicate that one Fe injection (200 mg) for pigs from sows fed adequate vitamin E will result in adequate growth and hemoglobin concentration with today's improved genetics.     

The effects of intestinal Escherichia coli 263, intravenous infusion of Escherichia coli 263 culture filtrate and iron dextran supplementation on iron metabolism in the young pig

An experiment using 32 pigs in a 2(3) factorial arrangement of treatments was used to determine the effects on the (1) level of iron dextran supplementation, (2) iv infusion of an Escherichia coli 263 culture filtrate and (3) presence of E. coli 263 in a ligated intestinal segment, on the ability of the young pig to limit systemic Fe availability. Iron dextran was administered im 3 d postpartum. Culture filtrate was infused iv, E. coli were injected into ligated intestines and blood sampling was started at 14 d postpartum. Blood was taken every 2 h for 22 h, after which pigs were euthanized and livers, spleens and kidneys were removed. Pigs receiving 400 mg of iron dextran (HiFe) exhibited greater serum Fe (SFe) and lower total Fe-binding capacity (TIBC) than pigs injected with 100 mg Fe (LoFe). The effects of the E. coli culture filtrate infusion appeared to be associated with endotoxin-induced circulatory shock. The presence of E. coli in the intestine increased TIBC in LoFe pigs, but not in HiFe pigs. The increase in TIBC coincided with the time of maximal fluid secretion into the intestine. Intestinal E. coli also caused an increase in liver Fe content, particularly in HiFe pigs. These data suggest that intestinal E. coli can cause a shift of Fe from the plasma to the reticuloendothelial system, and pigs receiving high supplemental dosages of Fe are less able to limit the availability of Fe to microorganisms.     

Effect of injected and dietary iron in young pigs on blood hematology and postnatal pig growth performance

The relationship of injected Fe doses on blood hematology and pig growth performance during both preweaning and postweaning periods was studied. In Exp. 1, the effect of BW of 347 pigs injected with 200 mg of Fe (dextran) intramuscularly (i.m.) at birth on hemoglobin (Hb) and percent hematocrit (Hct) at weaning was assessed. As BW increased there was a decline (P < 0.01) in Hb and Hct. In Exp. 2, Fe injection doses and timing of injected Fe on blood hematology and pig growth were evaluated. Injections were as follows: 1) 200 mg of Fe at birth; 2) 300 mg of Fe at birth; or 3) 200 mg of Fe at birth + 100 mg of Fe at d 10. A total of 269 pigs were allotted within litter to 3 treatments. The 2 greater quantities of injected Fe (i.e., 300 or 200 + 100 mg of Fe) had similar but greater (P < 0.05) Hb and Hct values than pigs receiving 200 mg of Fe, but growth rates were similar at weaning. The effects of injecting 200 mg of Fe at birth and either saline or 100 mg of Fe at 10 d of age were investigated in Exp. 3. Weaned pigs of each group were fed diets with 0, 80, or 160 mg/kg of added Fe for 35 d as a 2 × 3 factorial arrangement with 12 replicates (n = 360 pigs) in a randomized complete block design (RCB). The innate Fe contents of diets averaged 200 mg/kg. The greater Fe injection group (200 + 100 mg) had greater (P < 0.01) Hb and Hct values through 14 d postweaning (P < 0.05) and greater (P < 0.01) Hct values through 21 d postweaning. As dietary Fe increased, Hb was greater only at d 14 (P < 0.05 4), whereas Hct increased linearly to d 35 (P < 0.01) postweaning. Dietary Fe resulted in linear increases (P < 0.01) in ADG from d 21 to 35 and d 0 to 35. In Exp. 4, 3 dietary Fe (80, 160, and 240 mg/kg of diet), 2 injected Fe treatments (200 or 300 mg of Fe) at birth, and birth BW (<1.5 or ≥1.5 kg) were evaluated as a 2 × 2 × 3 factorial arrangement of treatments in a RCB design with 6 replicates (n = 280 pigs). The 300 mg of Fe injection group had lighter BW in both birth BW groups, with a birth BW × injected Fe interaction (P < 0.01). This resulted in the lighter birth BW pigs receiving 200 mg of Fe having greater BW gains to 240 mg/kg of dietary Fe, whereas light birth BW pigs injected with 300 mg of Fe plateaued at 160 mg/kg of Fe. Pigs in the heavy birth BW group injected with 200 or 300 mg of Fe at birth responded similarly to dietary Fe postweaning. These results indicate that blood Hb and Hct were affected by pig BW at weaning, but the additional 100 mg of Fe i.m. at 10 d of age increased blood hematology and that Fe injected preweaning affected initial postweaning performance.     

Effects of neonatal iron status, iron injections at birth, and weaning in young pigs from sows fed either organic or inorganic trace minerals

Second-parity sows (n = 7) were fed diets containing organic or inorganic trace minerals, and their progeny (n = 68) were used to determine the Fe status of pigs at birth and nursing and postweaning phases. The experiment comprised 2 parts, in which the first experiment was a 2 x 2 factorial arrangement. Sow trace mineral (organic vs. inorganic) was the first factor evaluated, and the injection of Fe (0 or 200 mg) to neonatal pigs within litter was the second factor. In Exp. 2, half the pigs in each litter from each neonatal Fe injection group were injected with Fe (0 vs. 200 mg) at weaning as an added factor in a 2 x 2 x 2 factorial arrangement in a split-split-plot design. Weanling pigs were fed diets fortified with 90 mg/kg of Fe (sulfate), but the analyzed indigenous and fortified Fe content was 170 mg/kg. Pigs in both experiments were bled at periodic intervals to determine hemoglobin (Hb) concentration, percentage of hematocrit (Hct), and ceruloplasmin oxidase activity. Neonates and d-2 pigs from sows fed organic trace minerals had lower (P < 0.05) Hb concentrations compared with sows fed inorganic trace minerals, but they had similar percentages of Hct values. Blood Hb seemed to remain lower throughout the nursing period when sows were fed organic vs. inorganic Fe. Pigs without Fe injection had decreased ADG (P < 0.05) from 0 to 7 and 7 to 17 d than pigs injected with Fe. Although Hb values increased when neonatal pigs received Fe injection, they were somewhat lower when sows were fed the organic Fe. Ceruloplasmin oxidase activity was low at birth, increased to weaning in each treatment group, and was greater in pigs without Fe injection at d 13 (P < 0.05) and those from sows fed organic minerals at d 17 (P < 0.01). In Exp. 2, when the Fe-fortified diet was fed, BW and ADG responses were both greater (P < 0.01) to 28 d postweaning when neonates had received Fe injections. Neonates not injected with Fe at birth but injected at weaning had greater ADG, Hb, and Hct values, whereas pigs injected with Fe did not respond to Fe injection at weaning, which resulted in interactions (P < 0.05) in those criteria at most measurement periods. The results indicated a reduced Fe bioavailability when sows were fed the organic Fe source, but this may also have been due to the greater Fe need, lowered Fe status, or both, of the sow because of the greater number of pigs farrowed and heavier litter weights at parturition and weaning. The results also indicated that Fe injections at birth may be critical to achieving maximum pig growth response to weaning. There was no apparent advantage to injecting Fe at weaning when neonatal pigs received Fe injections.     

Determination of the temporal relationship between porcine growth hormone, serum IGF-1 and cortisol concentrations in pigs

We found previously that porcine growth hormone (pGH) causes an increase in growth rate with a concurrent improvement in carcass composition in pigs. The somatomedin, insulin-like growth factor 1 (IGF-1), is though to play a major role in mediating some of the anabolic actions of GH, while the glucocorticoid hormones are potential counter-regulators of these effects. The present study was conducted to determine the temporal and dose-response relationship between GH administration and serum IGF-1 and cortisol concentrations in pigs. Twelve Yorkshire barrows, fitted with femoral artery catheters, were injected (im) with either 0, 10, 100 or 1,000 micrograms/kg pGH. Blood sampling began 40 min prior to pGH injection and was continued for 37 h. Serum GH, IGF-1 and cortisol concentrations were determined by radioimmunoassay. In control animals, serum GH concentrations ranged from 1.6 to 5.7 ng/ml over 37 h. In the animals treated with increasing doses of pGH, peak serum GH concentrations reached 28, 112 and 286 ng/ml and levels remained elevated for 4, 12 and 24 h, respectively. Serum IGF-1 concentrations were elevated by pGH after a lag time of 4 to 6 h. When the IGF-1 concentrations were integrated over time, the response appeared to be dose-dependent, with an ED50 of 710 micrograms/kg body weight (BW). Data for serum cortisol concentrations showed a great deal of individual variation. A transient increase in cortisol was observed, but only in the group treated with 1,000 micrograms pGH/kg BW. Cortisol levels returned to baseline 2 h after pGH injection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Recombinant porcine somatotropin for sows during late gestation and throughout lactation.

Two experiments were conducted to evaluate whether administration of recombinant porcine somatotropin (pST) to sows (Hampshire-Yorkshire) enhanced lactational performance. In Exp. 1, sows (n = 84) were fed a corn-soybean meal diet (17.8% CP), or a similar diet with 8% added fat, from d 108 of gestation to d 28 of lactation. Half of the sows fed each diet were injected with 6 mg/d of pST from d 108 of gestation to d 24 of lactation. Diets were fed at 2.27 kg/d from d 108 of gestation until farrowing and then were self-fed during lactation. By d 3 of lactation, litter size was standardized at 8 to 10 pigs per litter. Treating sows with pST resulted in a 10-fold increase (P less than .001) in serum somatotropin at 4 h postinjection. Serum glucose was increased (P less than .01) and serum triglycerides, creatinine, and urea N were decreased (P less than .01) by pST. During the summer, apparent heat stress occurred in pST-treated sows, resulting in 14 deaths. Most (10) of the deaths occurred just before, during, or shortly after farrowing. Fewer (P less than .08) deaths occurred when pST-treated sows were fed the diet with added fat. Sows treated with pST consumed less feed (P less than .10) and lost more backfat (P less than .10) during lactation than controls. Increasing the dietary fat did not prevent these changes. Weaning weights of pigs and milk yield of sows (estimated by deuterium oxide dilution) were not affected by pST treatment. In Exp. 2, sows (n = 42) were injected weekly with 0 or 70 mg of pST on d 3, 10, 17, and 24 of lactation. Litters were standardized by d 3 at 8 to 10 pigs, and sows were fed the same control (low fat) diet as in Exp. 1. Sows treated with pST consumed less feed and lost more weight and backfat during lactation than untreated sows. Litter size, average pig weaning weights, and milk yield were not influenced by pST treatment. These data indicate that a 6-mg daily injection of pST from 6 d prepartum to d 24 of lactation or a 70-mg weekly injection of pST from 3 d postpartum to d 24 of lactation does not increase milk production in lactating sows.     

Stimulation of pig growth performance by porcine growth hormone and growth hormone-releasing factor

The current study was undertaken to determine the effects of human growth hormone-releasing factor [hpGRF-(1-44)-NH2] on growth performance in pigs and whether this response was comparable to exogenous porcine growth hormone (pGH) treatment. Preliminary studies were conducted to determine if GRF increased plasma GH concentration after iv and im injection and the nature of the dose response. Growth hormone-releasing factor stimulated the release of pGH in a dose-dependent fashion, although the individual responses varied widely among pigs. The results from the im study were used to determine the dose of GRF to use for a 30-d growth trial. Thirty-six Yorkshire-Duroc barrows (initial wt 50 kg) were randomly allotted to one of three experimental groups (C = control, GRF and pGH). Pigs were treated daily with 30 micrograms of GRF/kg body weight by im injection in the neck. Pigs treated with pGH were also given 30 micrograms/kg body weight by im injection. Growth rate was increased 10% by pGH vs C pigs (P less than .05). Growth rate was not affected by GRF; however, hot and chilled carcass weights were increased 5% vs C pigs (P less than .05). On an absolute basis, adipose tissue mass was unaffected by pGH or GRF. Carcass lipid (percent of soft-tissue mass) was decreased 13% by GRF (P less than .05) and 18% by pGH (P less than .05). Muscle mass was significantly increased by pGH but not by GRF. There was a trend for feed efficiency to be improved by GRF; however, this was not different from control pigs. In contrast, pGH increased feed efficiency 19% vs control pigs (P less than .05). Chronic administration of GRF increased anterior pituitary weight but did not affect pituitary GH content or concentration. When blood was taken 3 h post-injection, both GRF- and pGH-treated pigs had lower blood-urea nitrogen concentrations. Serum glucose was significantly elevated by both GRF and pGH treatment. This was associated with an elevation in serum insulin. These results indicate that increasing the GH concentration in blood by either exogenous GH or GRF enhances growth performance. The effects of pGH were more marked than for GRF. Further studies are needed to determine the optimal dose of GRF to administer in growth trials and the appropriate pattern of GRF administration in order to determine whether GRF will enhance pig growth performance to the extent that exogenous pGH does.     

Physiological and immunological responses to weaning and transport in the young pig: modulation by administration of porcine somatotropin

To examine the effects of exogenous porcine (p) ST on measures of stress and immune function in weaned pigs with or without transport, pigs (20 +/- 1 d of age) received daily injections of pST (0.5 mg/kg; n = 16) or saline (n = 16) for 5 d. On d 5, a blood sample was collected immediately before injection. At 4 h postinjection, pigs were weighed, sampled for blood, injected with di-nitrophenyl-conjugated keyhole limpet hemocyanin, and weaned. One half of the pigs in each group were transported for 3 h before placement in the nursery. Pigs were weighed, and blood was collected on 1, 7, and 14 d postweaning. Statistical significance was set at P < 0.05. Serum IGF-I concentrations were increased by pST and decreased by weaning, but not affected by transport. The free cortisol index was elevated in all pigs 1 d postweaning, although less in transported versus nontransported pigs. By 7 d postweaning, the free cortisol index returned to prewean values. Serum concentrations of immunoglobulin (Ig) G increased in all pigs by 14 d postweaning, but were not affected by pST or transport. Serum IgM concentrations were elevated at 7 and 14 d postweaning. Before weaning and again 1 d postweaning, pigs treated with pST had greater concentrations of IgM than did control animals. Circulating neutrophils increased in pST-treated pigs 4 h after the final pST injection. Improved immune function in weaned pigs by pST may lead to greater health and growth in a commercial setting.     

Growth performance and carcass characteristics of pigs administered recombinant porcine somatotropin during 30 to 110 kilogram live weight

To determine growth performance during and after injection of recombinant porcine somatotropin (rpSt), crossbred Yorkshire gilts and barrows (n = 54/gender, 27 to 42 kg BW) were blocked by BW and gender (n = 3 blocks/gender). Within each block, three pigs/gender were assigned randomly to each of six pens/block. A diet containing 24.8% CP was fed ad libitum. During the live weight period of 30 to 110 kg, pigs either remained as controls (one pen/block) or were injected (i.m.) daily with rpSt (120 micrograms/kg BW) during either 30 to 60, 30 to 100, 30 to 110, 60 to 100 or 60 to 110 kg BW. Thus, three gilts and three barrows in each of three pens received each treatment. Pigs were slaughtered at either 60 kg BW (1 d after rpSt injection) or 110 kg BW (1 d, 10 d or 70 d after rpSt injection). Relative to controls, pigs injected with rpSt exhibited faster and more efficient growth during the injection period (P less than .05) but slower and less efficient growth during 10 d after cessation of injection (P less than .05). Carcasses of pigs slaughtered 1 d or 10 d after rpSt injection were leaner than controls (P less than .05), but among the pigs treated with rpSt, carcasses of pigs withdrawn from rpSt for 10 d contained more fat (P less than .05) and had a lower percentage of muscle (P less than .05) than carcasses of pigs withdrawn from rpSt for 1 d. Growth and carcass measurements were similar (P greater than .05) between controls and pigs killed 70 d after rpSt injection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma concentrations of oxytetracycline in swine after administration of the drug intramuscularly and orally in feed

Four pigs were used in a 2 X 2 crossover study to determine plasma oxytetracycline (OTC) concentration and OTC pharmacokinetic variables after IM administration of 2 OTC preparations--long acting OTC and a 100-mg of OTC/ml solution (OTC-LA and OTC-100, respectively)--at a dosage of 20 mg/kg of body weight. In a second study, 3 additional pigs were given ad libitum access to feed containing pure OTC (0.55 g/kg of feed). The mean (+/- SD) peak plasma OTC concentration after OTC-LA administration was 6.0 +/- 2.2 micrograms/ml at 30 minutes; the mean peak plasma OTC concentration after OTC-100 administration was 6.7 +/- 3.4 micrograms/ml at 90 minutes. Mean plasma OTC concentration after oral OTC administration in feed peaked at 0.4 micrograms/ml 48 hours after access to OTC-medicated feed and decreased to 0.25 micrograms/ml by the end of that study. Mean plasma OTC concentration was maintained at greater than 0.5 micrograms/ml for less than 48 hours after OTC-LA administration and for less than 36 hours after OTC-100 administration. Mean plasma OTC concentration decreased to less than 0.2 micrograms/ml by 72 hours after IM administration of either product. Calculation of area under the plasma OTC concentration-time curve (AUC) did not reveal significant difference between the 2 OTC formulations. There also was not significant difference (between OTC-LA and OTC-100) in the value of the disappearance rate constant after administration of either OTC formulation. The data did not indicate significant pharmacologic advantage of OTC-LA, compared with OTC-100, when either formulation was administered IM at a dosage of 20 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of administration of growth hormone-releasing factor to sows during late gestation on growth hormone secretion, reproductive traits, and performance of progeny from birth to 100 kilograms live weight.

The effects of growth hormone-releasing factor (GHRF) injections to sows during late gestation were investigated in two experiments. In the first one, four treatments were applied to eight catheterized sows according to two 4 x 4 Latin squares: oral administration of 2 mg of pyridostigmine, a cholinesterase inhibitor, per kilogram of BW (PYR group); i.m. injection of 50 micrograms of GHRF/kg BW (GHRF group); a combination of the pyridostigmine and GHRF treatments (PYR+GHRF); or i.m. injection of glucose (control). Pyridostigmine slightly increased the plasma concentration of growth hormone (GH). Growth hormone responses to GHRF and PYR+GHRF treatments were similar, with significantly elevated GH concentrations from 5 to 240 min after GHRF injection. In the second experiment, 36 sows were allocated to two treatments at 102 d of gestation. Until farrowing, they were injected twice daily with 50 micrograms of GHRF/kg BW (GHRF group) or isotonic glucose (control). The DM, N, fat, and energy content of 24 pigs per group was determined at weaning at 22 d. Six pigs per litter had ad libitum access to feed until slaughter at 100 kg BW and their carcasses were evaluated. Treatment with GHRF increased pregnancy duration (114.8 vs 113.6 d, P less than .05), weight of pigs at 13 d (3.69 vs 3.54 kg, P less than .05) and at weaning (5.74 vs 5.48 kg, P less than .05), and improved pig survival (86 vs 71%, P less than .05). Lipid (on a DM basis) and energy contents of the pigs slaughtered at weaning were significantly higher in the GHRF group than in the control group (14.4 vs 12.5% and 2,178 vs 2,029 kcal/kg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of growth hormone administration on vitamin D metabolism and vitamin D receptors in the pig

Twelve 36-kg pigs were given either 100 micrograms/kg porcine pituitary growth hormone (pGH) or placebo injections daily for 33 days. Serum was obtained weekly for analysis of minerals and vitamin D metabolites. On day 34, the pigs were sacrificed and renal and duodenal tissue were obtained for analysis of vitamin D receptor content (VDR). Animals treated with pGH grew faster and had a higher rate of bone accretion than did control animals. Serum concentrations of 1,25-dihydroxyvitamin D (1,25-(OH)2D) were significantly higher in pGH-treated pigs than in control pigs at all time points following initiation of treatment, with the greatest difference observed at day 28 (42.4 +/- 4.9 pg/ml in controls vs. 65.4 +/- 4.7 pg/ml in pGH-treated pigs). Serum 24,25-dihydroxy-vitamin D tended to be lower in pGH-treated pigs than in control pigs, being significantly lower on day 21 of the experiment (3.22 +/- .52 vs. 6.73 +/- 1.22 ng/ml, respectively). Serum concentrations of 25-hydroxyvitamin D and calcium were unaffected by pGH treatment. Kidneys of control pigs contained significantly more unoccupied vitamin D receptors than did kidneys from pGH-treated pigs (73.3 +/- 4.3 vs. 58.3 +/- 4.1 fmoles/mg protein). Duodenal tissue unoccupied vitamin D receptor content was similar in both pGH-treated (245 +/- 17.9 fmoles/mg protein) and control (263 +/- 21.8 fmoles/mg protein) pigs. Duodenal occupied vitamin D receptor concentration was similar in both pGH-treated (6.8 +/- .75 fmoles/mg protein) and control pigs (5.32 +/- .77 fmoles/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of boron supplementation of pig diets on the production of tumor necrosis factor-alpha and interferon-gamma

Two experiments were conducted to determine the effects of dietary B on the production of cytokines following an endotoxin challenge. In both experiments, pigs were obtained from litters generated from sows fed low-B (control) or B-supplemented (5 mg/ kg, as-fed basis) diets. In Exp. 1 and 2, 28 and 35 pigs, respectively (21 d old), remained with their littermates throughout a 49-d nursery phase and were fed either a control or B-supplemented diet. In Exp. 1, 12 pigs per treatment were moved to individual pens at the completion of the nursery phase and fed their respective experimental diet. On d 99 of the study, pigs were injected with 150 microg of phytohemagglutinin (PHA) to evaluate a local inflammatory response. Pigs receiving the B-supplemented diet had a decreased (P < 0.01) inflammatory response following PHA injection. Peripheral blood monocytes were isolated from six pigs per treatment on d 103 and cultured in the presence of lipopolysaccharide (LPS) to determine the effect of dietary B on tumor necrosis factor-alpha (TNF-alpha) production from monocytes. Isolated monocytes from pigs that received the B-supplemented diet had a numerically greater (P = 0.23) production of TNF-alpha. In Exp. 2, pigs were group housed with their littermates following the nursery phase for 43 d, after which 10 pigs per treatment were moved to individual pens. In Exp. 1 and 2, pigs were assigned randomly within dietary treatment to receive either an i.m. injection of saline or LPS on d 117 and d 109, respectively. The dose of LPS in Exp. 1 and 2 was 100 and 25 microg of LPS/kg of BW, respectively. In Exp. 1, serum TNF-alpha was increased (P < 0.01) at 2 h and tended to be increased (P < 0.11) at 6 and 24 h after injection by dietary B; however, only numerical trends existed for a B-induced increase in TNF-alpha in Exp. 2. Serum interferon-gamma (IFN-gamma) was increased (P < 0.01) at 6 h and tended to be increased (P < 0.08) at 24 h after injection in Exp. 1. In Exp. 2, dietary B also numerically increased IFN-alpha. These data indicate that dietary B supplementation increased the production of cytokines following a stress, which indicates a role of B in the immune system; however, these data do not explain the reduction in localized inflammation following an antigen challenge in pigs.     

Interrelationships of exogenous porcine growth hormone administration and feed intake level affecting various tissue levels of iron, copper, zinc and bone calcium of growing pigs

Trace mineral status was evaluated in a 2 x 3 factorial treatment array with a total of 34 barrows growing from 25 to 55 kg live weight. Treatments included three levels of feed intake (100, 80 and 60% of ad libitum intake) and exogenous pituitary growth hormone (pGH) therapy (0 and 100 micrograms/kg BW daily). Blood was collected prior to slaughter for the determination of hematocrit and serum trace metal concentrations; tissues (liver, heart, kidney, bone and muscle) were obtained when pigs were slaughtered at 55 kg. Hematocrits and serum Fe were lower in pGH-treated pigs than in controls at all levels of feed intake. Serum Cu was increased by feed restriction but was not altered by pGH therapy. The concentration of serum Zn was not affected by either treatment. Concentrations of hepatic Fe and Cu were lower in pGH-treated pigs than in controls but were higher in feed-restricted pigs than in ad libitum-fed pigs. However, the total amounts of hepatic Fe and Cu were similar in pGH-treated pigs to concentrations in controls. The concentration of hepatic Zn was not influenced by either pGH treatment or feed intake. Femur weights were marginally greater in pGH-treated pigs, probably due to elevated water content. Iron concentration in bone was higher in pGH-treated pigs than in control pigs, whereas Ca, Cu and Zn were not influenced by pGH treatment or feed restriction. Feed intake and pGH treatment did not influence the concentrations of Fe, Cu or Zn in muscle. These findings indicate that pGH therapy affects the metabolism of Fe but has little impact on the overall composition of body ash.     

Effects of porcine growth hormone on glucose metabolism of pigs: I. Acute and chronic effects on plasma glucose and insulin status

The acute and chronic effects of porcine growth hormone (pGH) administration on glucose homeostasis of pigs were investigated in the present study. Twelve Yorkshire barrows (average BW = 65 kg) fitted with femoral artery catheters were allotted to three groups. Pigs received acute, intra-arterial injections of either pituitary pGH, a recombinantly derived pGH analog (ppGH or rpGH, 100 micrograms/kg BW) or saline. Acute injection of pGH did not affect fasting plasma glucose or insulin status. Pigs then were treated daily by i.m. injection for 24 d with 70 micrograms ppGH/kg BW. Serum glucose and insulin concentrations during the fed and fasted states were higher in pGH-treated than in control pigs. On d 25, an acute intra-arterial injection of ppGH (100 micrograms/kg BW) elicited increases in plasma glucose and insulin in pigs chronically treated with pGH. The area circumscribed by the glucose and insulin response curves 5 min to 7 h postinjection was 40% (P less than .005) and 177% (P less than .001), respectively, higher in ppGH-treated than in control pigs. These data indicate that pGH does increase plasma glucose and insulin in the fed and fasted states; however, this response is only observed after chronic pGH administration. In addition, pGH is capable of increasing plasma glucose and insulin acutely in the pig. This effect, however, only is observed in pigs treated chronically with pGH. The mechanisms by which pGH elicit these effects on glucose homeostasis are not known.     

Role of uteroferrin in placental iron transport: effect of maternal iron treatment on fetal iron and uteroferrin content and neonatal hemoglobin

Uteroferrin, an Fe-containing, progesterone-induced glycoprotein is involved in maternal to fetal Fe transport in swine. These studies examined the effect of im Fe injection of dam on conceptus and piglet Fe stores. In Exp. I, eight gilts were bred and assigned to either treatment I (no Fe injections) or treatment II (total of 22 mg iron-dextran/kg body weight on d 40, 45, 50, 55 and 60 of gestation) and hysterectomized on d 90 to determine whether Fe injections increased Fe stores in the conceptus. Total Fe in allantoic fluid (P less than .10) as well as uteroferrin concentration (P less than .05) and total uteroferrin (P less than .05) in placentae were greater for gilts in treatment II. In Exp. II, 19 cross-bred sows were bred and assigned to treatments I and II (d 40, 50 and 60 of gestation), as in Exp. I, and treatment III (total of 22 mg iron-dextran/kg body weight on d 90, 100 and 110 of gestation) to determine effects of treatment on hemoglobin (Hb) values of the piglets at 8 +/- 1 h and d 4 postpartum. Piglets from treatment II had higher (P less than .01) Hb at 8 +/- 1 h, but not on d 4 postpartum. Experiment III was a replication of Exp. II except that Hb values were determined at 8 +/- 1 h, d 4 and d 7 postpartum. On d 7, piglets from treatment II had higher (P less than .05) Hb, but differences at 8 +/- 1 h and d 4 were not significant (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Thyroid hormone periodicity in healthy adult geldings

Serum samples were collected from 10 healthy geldings every 4 h for three consecutive days and the triiodothyronine (T3) and thyroxine (T4) concentrations determined by radioimmunoassay. There were significant differences in the hormone concentrations related to time. The mean (+/- sd) T3 concentration peaked around 08.00 h at a level (54.06 +/- 14.02 ng/dl) significantly (P less than .001) higher than the lowest concentration (38.71 +/- 10.81 ng/dl) around midnight. Although the highest mean T3 level was 08.00 h, this value was not significantly different from the noon and 16.00 h levels. Likewise, the mean T3 level at midnight was not significantly different from the 20.00 h and 04.00 h levels, resulting in a plateau from 08.00 h to 16.00 h and a trough from 20.00 h to 04.00 h. The mean (+/- sd) T4 concentration peaked around 16.00 h at a level (2.43 +/- .81 micrograms/dl) significantly (P less than .01) higher than the lowest concentration (1.79 +/- .63 micrograms/dl) around 04.00 h.     

Response of postpartum beef cows to exogenous progestogens and gonadotropin releasing hormone

Plasma progesterone (P4) profile and estrous detection were used during three experiments to evaluate the effects of exogenous progestogens on the life span of gonadotropin releasing hormone (GnRH)-induced corpora lutea (CL) in postpartum (pp) beef cows. Experiment 1 utilized primiparous fall-calving cows (n = 28, trial 1); and spring-calving cows (n = 29, trial 2). On d 18 to 27 pp (d 0) all cows received intravaginal devices containing either P4 or no P4 (NP) for 5 d. On d 5 the devices were removed and calves were either removed (CR) or were present (CP) with half of the cows within steroid group. At 50 h after device removal, 500 micrograms of GnRH was given (iv) to all cows, and weaned calves were reunited with their dams. The induced CL had a normal life span (greater than 16 d) in 17 and 86% (trial 1) and 8 and 79% (trial 2) of NP and P4 cows, respectively. Calf removal did not affect (P greater than .10) the life span of the CL. In Exp. 2, spring-calving multiparous cows (d 18 to 24 pp; d 0) received either no P4 (NP; n = 19), P4 for 6 d via intravaginal devices (P4H; n = 19) or a single im injection of 300 mg P4 (P4 IM; n = 18). At 48 h after device removal or at 8 d after the injection of P4, half of the cows within steroid group received either 500 micrograms GnRH or saline. Corpora lutea had a normal life span in 0, 11, and 80% of NP, P4 IM and P4H cows, respectively, that received GnRH and in 22% of P4-saline cows. In Exp. 3, fall-calving multiparous and primiparous cows (d 25 to 31 pp) received either no progestogen (NP; n = 20), P4 via intravaginal devices for 5 d (P4H; n = 21) or melengestrol acetate (MGA; .5 mg.head-1.d-1 for 5 d orally, n = 15). At 48 d after device removal or at 72 h after the last MGA feeding, all cows received 500 micrograms GnRH. Progesterone post-GnRH injection was increased (greater than 1 ng/ml) at d 7 in 64, 100 and 100%, and remained elevated at d 14 in 11, 46 and 100% of NP, MGA and P4H cows, respectively. For all experiments plasma P4 was increased (range 2 to 5 ng/ml) when the devices containing P4 were in place, then decreased (less than 1 ng/ml) by 48 to 50 h after device removal.(ABSTRACT TRUNCATED AT 400 WORDS)     

Intensive indoor versus outdoor swine production systems: genotype and supplemental iron effects on blood hemoglobin and selected immune measures in young pigs.

The objectives of Exp. 1 were to determine the effects of production system and genotype on pig performance and health. Sows were bred, gestated, farrowed, and lactated in either an intensive indoor or an intensive outdoor production system. The three dam genotypes of pigs used in each environment were PIC Camborough-15 (C-15), PIC Camborough Blue (CB), and Yorkshire x Landrace (YL). All pigs received 100 mg of iron dextran at d 3 of age. Pigs raised in the outdoor unit had higher blood hemoglobin (Hb) concentrations on d 28 of age than pigs raised indoors (11.5 +/- .22 vs 8.16 +/- .26 g/dL, P < .0001). Outdoor-reared pigs had more white blood cells (WBC) on d 3 than indoor-reared pigs (9.7 +/- .38 vs 8.04 +/- .38 cells/microL x 10(3), P < .05), but outdoor pigs had fewer WBC on d 28 of age than indoor-reared pigs (9.8 +/- .5 vs 11.1 +/- .45 cells/microL x 10(3), P < .05). Genetic lines did not differ in plasma immunoglobulin G (IgG) concentrations at 3 or 28 d of age. Environment and age influenced pig Hb levels and WBC numbers. The objectives for Exp. 2 were to determine whether C-15-405 pigs reared outdoors or indoors needed supplemental iron or whether they would receive enough environmental iron, and how the lack of supplemental iron may impact pig Hb and immunity. Indoor and outdoor pigs received either no supplemental iron, 100 mg, or 400 mg of iron dextran on d 3 of age. Blood percentage neutrophils and neutrophil: lymphocyte ratio were lower (P < .05) indoors, and natural killer cell (NK) activity was greater (P < .05) among indoor- than outdoor-reared pigs (NK % cytotoxicity: 15.6 +/- 2.3 vs 9.7 +/- 2.3). Outdoor-reared pigs that received no injected iron had similar Hb at d 28 of age as indoor-reared pigs that received 100 mg of iron dextran (11.1 +/- .36 vs 10.7 +/- .4 g/dL, P = .59). Supplemental iron may not be necessary in an outdoor production system. Outdoor-reared pigs had lower values for some immune measures, but they had similar survival rates as indoor-reared litters.