Effects of β-glucan extracted from Saccharomyces cerevisiae on humoral and cellular immunity in weaned piglets

Abstract

Twenty-four barrows were used to investigate the effects of β-glucan on immune function in weaned piglets. Pigs (8.09 ± 0.20 kg, 28 d of age) were fed a diet without or with supplemented β-glucan (50 mg/kg feed). All pigs were injected with ovalbumin (OVA) on day 14 to investigate their humoral immune response. On day 28, lymphocytes were isolated from all pigs to determine the effects of β-glucan on cellular immunity of pigs in vitro. Lymphocytes from six pigs of each group were incubated with 16 μg lipopolysaccharide (LPS) per ml culture medium, the remainder with an equivalent volume of culture medium alone. Samples were collected at 0, 3, 6, 12, 18, 24, and 48 h after LPS addition for determination of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10). On day 31, six pigs of each group were injected with either LPS (25 μg/kg BW) or an equivalent amount of sterile saline. Blood samples were collected at 3 h after LPS injection for analysis of IL-6, TNF-α, and IL-10 in plasma. The results indicated that dietary β-glucan enhanced pig antibody response to OVA only in the first week after injection. In vitro, the increases of IL-6 and TNF-α in culture medium were partially dampened in pigs supplemented with β-glucan when their lymphocytes were incubated with LPS, whereas the increase of IL-10 was potentiated. In vivo, dietary β-glucan attenuated the increase of plasma IL-6 and TNF-α, and enhanced the increase of plasma IL-10 when pigs were challenged with LPS. These results demonstrate that β-glucan can improve the humoral immunity of pigs and modulate cellular immunity of pigs by mitigating the elevation of pro-inflammatory cytokines and enhancing the increase of anti-inflammatory cytokines after an immunological challenge.     

On the distribution and metabolism of Fusarium-toxins along the gastrointestinal tract of endotoxaemic pigs

The aim of this study was to investigate the potential modulatory effect of E. coli lipopolysaccharides (LPS) on residues of deoxynivalenol (DON), de-epoxy-deoxynivalenol (DOM-1), zearalenone (ZEN) and its metabolites α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), zearalanone (ZAN), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL) after pre- or post-hepatic administration along the gastrointestinal axis. Fifteen barrows were exposed to a naturally mycotoxin contaminated diet (4.59 mg DON/kg feed and 0.22 mg ZEN/kg feed) and equipped with jugular (ju) and portal (po) catheters. On sampling day (day 29), the barrows were infused with LPS or a control fluid (LPS, 7.5 µg/kg body weight; control, 0.9% NaCl) either pre- or post-hepatically, resulting in three infusion groups: CON_ju-CON_po, CON_ju-LPS_po and LPS_ju-CON_po. At 195 min relative to infusion start (210 min post-feeding), pigs were sacrificed and content of stomach and small intestine (proximal, medial and distal part) as well as faeces were collected. In all LPS-infused animals, higher amounts of dry matter were recovered irrespective of LPS entry site suggesting a reduced gastric emptying and a decreased gastrointestinal motility under endotoxaemic conditions. DON metabolism in the gastrointestinal tract (GIT) remained unaltered by treatments and included an increase in the proportion of DOM-1 along the GIT, particularly from distal small intestine to faeces. Variables describing ZEN metabolism suggest a stimulated biliary release of ZEN and its metabolites in LPS-infused groups, particularly in the LPS_ju-CON_po group. In conclusion, the GIT metabolism of ZEN was markedly influenced in endotoxaemic pigs whereby a jugular induction of an acute phase reaction was more effective than portal LPS infusion hinting at a strong hepatic first-pass effect.     

Insulin-like growth factor-I feedback regulation of growth hormone and luteinizing hormone secretion in the pig: evidence for a pituitary site of action

Three experiments (EXP) were conducted to determine the role of insulin-like growth factor-I (IGF-I) in the control of growth hormone (GH) and LH secretion. In EXP I, prepuberal gilts, 65 ± 6 kg body weight and 140 days of age received intracerebroventricular (ICV) injections of saline (n = 4), 25 μg (n = 4) or 75 μg (n = 4) IGF-I and jugular blood samples were collected. In EXP II, anterior pituitary cells in culture collected from 150-day-old prepuberal gilts (n = 6) were challenged with 0.1, 10 or 1000 nM [Ala15]-h growth hormone-releasing hormone-(1-29)NH2 (GHRH), or 0.01, 0.1, 1, 10, 30 nM IGF-I individually or in combinations with 1000 nM GHRH. Secreted GH was measured at 4 and 24 h after treatment. In EXP III, anterior pituitary cells in culture collected from 150-day-old barrows (n = 5) were challenged with 10, 100 or 1000 nM gonadotropin-releasing hormone (GnRH) or 0.01, 0.1, 1, 10, 30 nM IGF-I individually or in combinations with 100 nM GnRH. Secreted LH was measured at 4 h after treatment. In EXP I, serum GH and LH concentrations were unaffected by ICV IGF-I treatment. In EXP II, relative to control all doses of GHRH increased (P < 0.01) GH secretion. Only 1, 10, 30 nM IGF-I enhanced (P < 0.02) basal GH secretion at 4 h, whereas by 24 h all doses except for 30 nM IGF-I suppressed (P < 0.02) basal GH secretion compared to control wells. All doses of IGF-I in combination with 1000 nM GHRH increased (P < 0.04) the GH response to GHRH compared to GHRH alone at 4 h, whereas by 24 h all doses of IGF-I suppressed (P < 0.04) the GH response to GHRH. In EXP III, all doses of IGF-I increased (P < 0.01) basal LH levels while the LH response to GnRH was unaffected by IGF-I (P > 0.1). In conclusion, under these experimental conditions the results suggest that the pituitary is the putative site for IGF-I modulation of GH and LH secretion. Further examination of the role of IGF-I on GH and LH secretion is needed to understand the inhibitory and stimulatory action of IGF-I on GH and LH secretion.     

Effect of dietary crude protein levels in a commercial range, on the nitrogen balance, ammonia emission and pollutant characteristics of slurry in fattening pigs

An experiment was conducted to investigate the effect of dietary levels of crude protein (CP), close to the range used commercially and to the European Commission recommended values, on the nitrogen (N) balance, ammonia (NH(3)) emission and pollutant characteristics of the slurry from growing and finishing pigs. Three feeding programmes with different CP levels were compared during the growing and the finishing periods of fattening. Diets were formulated to be isoenergetic and for the digestible lysine : metabolisable energy ratio to be similar in all the diets for each phase, but differed in CP concentration (160, 150 and 140 g CP/kg for the growing phase and 155, 145 and 135 g CP/kg for the finishing phase). Faeces and urine from barrows (eight replicates per diet) allocated in metabolism cages were collected separately for 5 days to calculate the N balance and for 2 days to measure NH(3) emission in a laboratory system for 240 h. Excreta were analysed for pH, volatile fatty acids (VFA), total N, electrical conductivity (EC), total solids (TS), volatile solids (VS), biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD) and NH(4)-N reduction of dietary CP content led to a linear decrease of urinary (P < 0.05) and total (P < 0.05) N excretion, and N excretion/feed intake (P < 0.001). The emission of NH3 was similar in all diets (P > 0.05) during the 240 h of study. However, in the growing phase, the NH(3)-N level in slurry was lower (P < 0.05) for the low-CP diet. In addition, the CP level had no significant effect (P > 0.05) on total VFA, EC, TS, VS, COD or BOD(5) contents of excreta. These parameters were higher (P < 0.05) in slurry from the finishing phase than from the growing phase. However, NH(4)-N in the slurry decreased (P < 0.05) by 20.3% and 28.4% when the CP level was decreased by 9.30 or 21.40 g/kg, respectively. It is concluded that lowering dietary CP levels even by small amounts and using CP levels close to these used in commercial diets and close to the European Commission recommended values will decrease urinary and total N excretion in the slurry of growing-finishing pigs. The slurry from finishing pigs is more concentrated than that from growing pigs.     

Effects of beta-glucan extracted from Saccharomyces cerevisiae on humoral and cellular immunity in weaned piglets

Twenty-four barrows were used to investigate the effects of beta-glucan on immune function in weaned piglets. Pigs (8.09 +/- 0.20 kg, 28 d of age) were fed a diet without or with supplemented beta-glucan (50 mg/kg feed). All pigs were injected with ovalbumin (OVA) on day 14 to investigate their humoral immune response. On day 28, lymphocytes were isolated from all pigs to determine the effects of beta-glucan on cellular immunity of pigs in vitro. Lymphocytes from six pigs of each group were incubated with 16 microg lipopolysaccharide (LPS) per ml culture medium, the remainder with an equivalent volume of culture medium alone. Samples were collected at 0, 3, 6, 12, 18, 24, and 48 h after LPS addition for determination of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interleukin-10 (IL-10). On day 31, six pigs of each group were injected with either LPS (25 microg/kg BW) or an equivalent amount of sterile saline. Blood samples were collected at 3 h after LPS injection for analysis of IL-6, TNF-alpha, and IL-10 in plasma. The results indicated that dietary beta-glucan enhanced pig antibody response to OVA only in the first week after injection. In vitro, the increases of IL-6 and TNF-alpha in culture medium were partially dampened in pigs supplemented with beta-glucan when their lymphocytes were incubated with LPS, whereas the increase of IL-10 was potentiated. In vivo, dietary beta-glucan attenuated the increase of plasma IL-6 and TNF-alpha, and enhanced the increase of plasma IL-10 when pigs were challenged with LPS. These results demonstrate that beta-glucan can improve the humoral immunity of pigs and modulate cellular immunity of pigs by mitigating the elevation of pro-inflammatory cytokines and enhancing the increase of anti-inflammatory cytokines after an immunological challenge.     

Effect of temperature level on thermal acclimation in Large White growing pigs

The effect of temperature level (24°C, 28°C, 32°C or 36°C) on performance and thermoregulatory response in growing pigs during acclimation to high ambient temperature was studied on a total of 96 Large White barrows. Pigs were exposed to 24°C for 10 days (days -10 to -1, P0) and thereafter to a constant temperature of 24°C, 28°C, 32°C or 36°C for 20 days. Pigs were housed in individual metal slatted pens, allowing a separate collection of faeces and urine and given ad libitum access to feed. Rectal (RT) and cutaneous (CT) temperatures and respiration rate (RR) were measured three times daily (0700, 1200 and 1800 h) every 2 to 3 days during the experiment. From day 1 to 20, the effect of temperature on average daily feed intake (ADFI) and BW gain (average daily gain, ADG) was curvilinear. The decrease of ADFI averaged 90 g/day per °C between 24°C and 32°C and 128 g/day per °C between 32°C and 36°C. The corresponding values for ADG were 50 and 72 g/day per °C, respectively. The 20 days exposure to the experimental temperature was divided in two sub-periods (P1 and P2, from day 1 to 10 and from day 11 to 20, respectively). ADFI was not affected by duration of high-temperature exposure (i.e. P2 v. P1). The ADG was not influenced by the duration of exposure at 24°C and 28°C groups. However, ADG was higher at P2 than at P1 and this effect was temperature dependent (+130 and +458 g/day at 32°C and 36°C, respectively). In P2 at 36°C, dry matter digestibility significantly increased (+2.1%, P < 0.01); however, there was no effect of either duration or temperature on the digestibility of dry matter at group 24°C and 32°C. RT, CT and RR were measured three times daily (0700, 1200 and 1800 h) every 2 to 3 days during the experiment. Between 28°C and 36°C, RT and CT were lower during P2 than during P1 (-0.20°C and -0.23°C; P < 0.05), whereas RR response was not affected by the duration of exposure whatever the temperature level. In conclusion, this study suggests that the effect of elevated temperatures on performance and thermoregulatory responses is dependent on the magnitude and the duration of heat stress.     

Effects of two different anaesthetics on serum concentrations of cortisol and luteinizing hormone in barrows and gilts

To determine if administration of the anaesthetic cocktail, telazol-ketamine-xylazine (TKX) and pentothal (PEN) decreases serum concentrations of luteinizing hormone (LH) in pigs, the following experiment was performed. On day 1, eight gilts and six barrows of similar weight (75 kg) were anaesthetized with TKX (1 mL/22.5 kg body weight [BW] intramuscularly) and indwelling jugular catheters were inserted. On days 2, 6 and 8 blood samples were taken every 20 min, for 4 h before pigs were administered saline (day 2) or anaesthetized with TKX (day 6) and PEN (8.9 mg/kg BW intravenously, day 8). Blood samples were taken every 20 min for 4 h following administration of saline and anaesthetics. Mean serum concentrations of LH and cortisol did not differ (P > 0.05) within barrows or gilts from before administration of saline (day 2) to following saline administration. Mean serum concentrations of LH and cortisol were not different (P > 0.05) within barrows and gilts before administration of TKX (pre-TKX) or PEN compared with day 2 samples. Following administration of TKX (post-TKX), mean serum concentrations of LH decreased (P < 0.05) and remained decreased for 140 min, while mean serum concentrations of cortisol increased (P < 0.05) post-TKX and remained elevated for 140 min. In gilts, mean serum concentrations of LH did not differ (P > 0.05) from pre- to post-TKX. However, mean serum concentrations of cortisol increased (P < 0.05) post-TKX in gilts and remained elevated for 240 min. Following administration of PEN, mean serum concentrations of LH and cortisol within barrows and gilts were not different (P > 0.05) from concentrations before administration of PEN. Administration of TKX to barrows and gilts increased serum concentrations of cortisol, but transient decreases in serum concentrations of LH were observed only in barrows, indicating gonadal status and/or sex may influence the ability of TKX to alter circulating concentrations of LH in pigs.     

Plasma kinetics and matrix residues of deoxynivalenol (DON) and zearalenone (ZEN) are altered in endotoxaemic pigs independent of LPS entry site

This study aimed to investigate a potential modulatory effect of E. coli lipopolysaccharide (LPS) on the kinetics of deoxynivalenol (DON) and zearalenone (ZEN) after pre- or post-hepatic LPS administration to unravel the putative role of the liver. Fifteen barrows were fed a diet containing mycotoxin-contaminated maize (4.59 mg DON/kg feed, 0.22 mg ZEN/kg feed) for 29 days and equipped with pre-hepatic catheters (portal vein, “po”) and post-hepatic catheters (jugular vein, “ju”), facilitating simultaneous infusion of LPS (“LPS group”, 7.5 μg/kg body weight) or 0.9% sterile NaCl solution (control, “CON group”, equivolumar to LPS group) and blood sampling. This resulted in three infusion groups, depending on infusion site: CON_ju-CON_po, CON_ju-LPS_po, and LPS_ju-CON_po. On day 29, pigs were fed their morning ration (700 g/pig) (?15 min), and blood samples were collected at regular intervals relative to infusion start. At 195 min, pigs were sacrificed and bile, urine, liquor, and liver samples collected. DON concentrations in jugular and portal blood decreased in both LPS-infused groups, whereas the ZEN concentrations increased, regardless of the treatment site. In liver tissue, a decrease of both toxin concentrations was observed in endotoxaemic pigs as well as a drop in hepatic conjugation, regardless of LPS entry site. In contrast to our hypothesis, DON and ZEN were not differently altered depending on the LPS-entry site. Neither the absorption nor the accumulation of DON and ZEN in different tissues differed significantly between animals which were infused with LPS via either the jugular or portal vein.     

Induced hyperlipaemia and immune challenge in locusts

Injections of immunogens, such as beta-1,3-glucan or lipopolysaccharide (LPS), bring about a marked hyperlipaemia with associated changes in lipophorins and apolipophorin-III in the haemolymph of Locusta migratoria. These changes are similar to those observed after injection of adipokinetic hormone (AKH). The possibility that endogenous AKH is released as part of the response to these immunogens is investigated using passive immunisation against AKH-I, and measurement of AKH-I titre in the haemolymph after injection of immunogens. The data presented show that, despite the similarity of the changes brought about by the presence of immunogens in the haemolymph to those brought about by AKH, there is no release of endogenous AKH after injection of laminarin or LPS. A direct effect of the immunogens on release of neutral lipids by the fat body cannot be demonstrated in vitro, and the mechanism by which hyperlipaemia is induced during immune challenge remains uncertain.     

Performance of growing-finishing pigs fed diets containing Roundup Ready wheat (MON 71800), a non-transgenic genetically similar wheat, or conventional wheat varieties

The objective of this study was to compare growth performance and carcass and meat quality characteristics of growing-finishing pigs fed diets containing Roundup Ready wheat (MON 71800), compared with the non-transgenic genetically similar parental control wheat (MON 71900), and four commercial varieties of non-transgenic wheat (HANK, Westbred 926, Express and Zeke). The study was carried out as a split-plot design with a 2 × 6 factorial arrangement of treatments (two genders and six wheat varieties). A three-phase dietary program was used; all diets were formulated with a fixed level of wheat inclusion (70%, 80% and 85% for the Grower, Finisher I and Finisher II phases, respectively). A total of 240 commercial hybrid pigs (equal numbers of barrows and gilts) were grown from 29.5 ± 0.29 to 114.5 ± 2.23 kg live weight in single-gender pens (barrows or gilts) of five pigs (eight pens per dietary treatment) with ad libitum access to feed and water throughout the study. At the end of each dietary phase and of the test period, ultrasound measurements were taken at the 10th rib. Animals from the transgenic (MON 71800) and non-transgenic (MON 71900) treatments were harvested at the end of the study and carcass and meat quality measurements were taken. Pigs fed the six wheat varieties had similar (P > 0.05) feed intake, live weight gain, gain : feed ratio and ultrasound measures of backfat thickness and longissimus muscle area. There was a wheat variety × gender interaction (P < 0.05) for longissimus fat content. Gilts fed the transgenic wheat had higher (P < 0.05) longissimus fat content than those fed the non-transgenic control wheat; however, for barrows there was no effect (P > 0.05) of wheat variety on longissimus fat content. However, there was no effect (P > 0.05) of wheat variety on other longissimus muscle quality or composition measures. Gilts had lower (P < 0.01) feed intake, growth rate and backfat thickness, and similar gain : feed ratio (P > 0.05) compared to barrows. This study, with growing-finishing swine, suggests that the Roundup Ready wheat (MON 71800) resulted in equivalent animal performance to conventional wheat.     

Effects of conjugated linoleic acid levels and feeding intervals on performance, carcass traits and fatty acid composition of finishing barrows

Two experiments were conducted to investigate the effects of dietary conjugated linoleic acid (CLA) on performance, carcass traits, fatty acid composition and subcutaneous adipose tissue cellularity in finishing barrows. In Experiment 1, 54 crossbred barrows were allotted to one of three treatments, with six pens per treatment and three barrows in each pen. The pigs were fed a diet containing 0, 2, or 4% CLA oil for 6 weeks. Daily gain (P < 0.01) and feed efficiency (P < 0.01) improved with dietary CLA. Loin muscle area (P = 0.01) and intramuscular fat (P = 0.01) increased while 10th rib fat (P = 0.03) and last rib fat (P = 0.02) thickness decreased with increasing dietary CLA. Total CLA isomers increased (P < 0.01) with increasing dietary CLA. Myristic, palmitic and stearic acid levels were increased while oleic, linoleic, linolenic and arachidonic acid decreased in loin muscle and subcutaneous adipose tissue. In Experiment 2, barrows (n = 54) were allotted to one of two treatments with nine pens per treatment and three pigs in each pen. Pigs were fed a diet supplemented with 4% CLA for 3 or 6 weeks before slaughter. Over the entire experimental period, daily gain and feed efficiency were higher (P < 0.01) when CLA was fed for a longer period. Loin muscle area (P < 0.01) and intramuscular fat (P < 0.01) increased while backfat thickness at the 10th (P = 0.03) and last rib (P = 0.04) decreased when CLA was fed for 6 vs. 3 weeks. The number of cells in subcutaneous adipose tissue was not affected while adipocyte volume decreased (P = 0.01) with longer feeding time on dietary CLA. The increased CLA content of pork from CLA fed pigs provides the pork industry with an opportunity to provide value-added, healthful meat products for human consumption with respect to CLA intake and potential improvements in human health.     

Effect of testosterone on n-methyl-d, l-aspartate-induced growth hormone secretion in male swine

Previous research from our laboratory demonstrated that n-methyl-d, l-aspartate (NMA), a potent agonist of glutamate, increased growth hormone (GH) secretion in barrows and boars. To determine if testosterone modulates NMA-induced GH secretion, Poland China x Yorkshire swine were challenged with NMA in a model that compared GH responses in boars with those of barrows or barrows treated with testosterone propionate (TP). Boars and barrows weighing 112.6+/-1.4 kg (mean +/- SE) were fitted with indwelling jugular vein catheters. Barrows (n = 16) were given i.m. injections of TP (25 mg in corn oil) twice daily from d 0 to d 6. Boars (n = 16) and control barrows (n = 15) received twice daily injections of corn oil. On d 6, blood was sampled every 15 min for 4 h. Two h after sampling began, all animals received an i.v. injection of NMA at a dose of 2.5 mg/kg body weight. Mean testosterone concentrations (ng/ml serum) were similar (P > .1) for boars (8.1+/-0.8) and barrows receiving TP (7.3+/-0.3), but were greater in both cases (P < .05) than for barrows receiving corn oil (.2+/-.01). Prior to NMA injections, mean GH concentrations were similar (P > .1) among groups and averaged 2.7+/-.2 ng/ml serum across treatments. Serum concentrations of GH after NMA increased (P < .05) similarly among groups and averaged 6.3+/-0.3 ng/ml across treatments during the 2-h period after injection. These results were not supportive of a role for testosterone as a modulator of NMA-induced GH secretion in male swine.     

The Effects of Dietary Chromium(III) Picolinate on Growth Performance, Vital Signs, and Blood Measurements of Pigs During Immune Stress

This experiment used 24 pigs (26.0 kg) to investigate the effects of dietary chromium (Cr) on pigs challenged with lipopolysaccharide (LPS). Following 35 days of diet exposure, the immune stress treatments were: (1) phosphate-buffered saline (PBS) injection and no Cr, (2) LPS injection and no Cr, (3) LPS injection and Cr 1,000 ppb, and (4) LPS injection and Cr 2,000 ppb. At 0 h, PBS or LPS was injected intraperitoneally in each pig. During the first 12 h post-injection, pigs challenged with LPS lost 951 g, while the PBS group gained 170 g (p?<?0.001). Compared with the PBS group, LPS-challenged pigs consumed less feed (p?<?0.01) during the first 24 h. The LPS group had higher rectal temperature at 2 and 4 h and higher respiratory rate at 1.3 and 8.5 h than the PBS group (p?<?0.05). Plasma collected at 3 h had higher cortisol (p?<?0.001) and lower glucose (p?<?0.05) concentrations in the LPS group than the PBS group. However, supplemental Cr did not affect the response variables. Overall, the LPS challenge affects growth performance, vital signs, and plasma variables, but dietary Cr is unable to moderate stress-related effects associated with an LPS challenge.     

Ans fluorescence and electrokinetic potential of activated lymphocytes by con A or LPS in vivo

The $\text{in vivo}$ effect of Concanavalin A (Con A), or bacterial lipopolysaccharide (LPS) on mouse spleen cell populations was investigated. The membrane fluorescence changes of activated splenic lymphocytes were studied during two weeks after the injection of polyclonal immunogens. Experiments were performed with the hydrophobic fluorescent probe: 1-anilino-8-naphthalene sulphonate (ANS). The kinetic studies further indicated that the course of fluorescence changes may considerably vary depending on both immunogens. These fluorescence intensity changes would be in direct relation to the electrokinetic surface potential changes of activated lymphocytes, as assessed by the electrophoretic mobility analysis. By comparison with the inverse relationship observed in our previous study, it would be concluded that the relation (direct or inverse) between ANS fluorescence and electrokinetic potential depends on the net electrical charge of the antigens used.     

Febrile and cortisol responses induced in guinea pigs by localized peripheral inflammatory stimulation

(1) In guinea pigs, a high (100 μg/kg) or a low (10 μg/kg) dose of lipopolysaccharide (LPS) was injected into subcutaneously implanted Teflon chambers along with the prior injection of a local anesthetic (ropivacaine) or sterile saline. (2) Intra-chamber injection of the LPS alone induced fever and elevation of circulating cortisol. (3) Fever in response to the low dose of the LPS was attenuated by the pretreatment with the local anesthetic while circulating levels of cortisol were not impaired by this procedure. (4) There was a moderate increase in plasma interleukin-6 (IL-6) in response to both concentrations of locally administered LPS. The LPS did not enter the systemic circulation in measurable amounts. (5) These results favor the possibility of a participation of afferent neural as well as humoral signals (IL-6) in the manifestation of fever in this experimental model.     

Conjugated linoleic acid can prevent tumor necrosis factor gene expression by inhibiting nuclear factor binding activity in peripheral blood mononuclear cells from weaned pigs challenged with lipopolysaccharide

Twenty-four weanling barrows were fed corn-soybean diets supplemented with 2% conjugated linolenic acid (CLA) or soybean oil. On day 14 and 21, pigs were injected intraperitoneally with lipopolysaccharide (LPS) or sterile saline. Plasma samples were collected 2h after injection. Peripheral blood mononuclear cells (PBMC) were also collected on day 21, 2 h after injection to determine tumor necrosis factor-alpha (TNF-alpha) production and its mRNA expression. The results indicate that dietary CLA inhibited the production of TNF-alpha by pig PBMC both at the protein and mRNA expression level. In a second experiment, PBMC, collected from a healthy pig, were incubated with either c9,t11-CLA or t10,c12-CLA, or without CLA and stimulated with LPS. Both CLA isomers inhibited LPS-stimulated TNF-alpha production and expression, which may be partially due to inhibition of the binding activity of nuclear factor-kappaB. The t10,c12 isomer was more effective than the c9,t11-CLA isomer in reducing TNF-alpha levels and nuclear factor-kappaB activation.     

Serum concentrations of melatonin during scotophase and photophase in 3, 4, 5 and 6 months old gilts and barrows

One-hundred-twenty prepubertal crossbred gilts (Hampshire x Duroc) x (Yorkshire x Landrace) were removed from the nursery at 68.7+/-0.4 days of age and 23.6+/-0.9 kg body weight and relocated to a conventional grower-finisher unit. In addition, 60 barrows of similar genetics were relocated from the nursery at 71.0+/-0.5 days of age and 27.4+/-0.5 kg body weight to the same building. Twelve mature anestrous ewes that weighed 77.0+/-2.4 kg were assigned randomly to one of four pens of equal dimensions among the pens containing pigs. Ewes were included in this study to serve as positive controls since their secretory profiles of melatonin are well characterized. All pigs were bled by jugular venipuncture at approximately 3, 4, 5 and 6 months of age. At each age in the pigs and the mature ewes, a single sample was obtained during photophase and scotophase. Illumination intensity during the period of incandescent lighting averaged 220 1x. Blood collection was initiated approximately 4 h after sunrise and 3.5-4 h after sunset. The proportion of animals that exhibited a nocturnal rise in melatonin (MEL) was similar (P > 0.05) between gilts and barrows, but was higher (P < 0.002) in ewes than in pigs at each age examined. A greater proportion (P = 0.007) of 3 month old barrows had a nocturnal rise of MEL than any other age of barrow. Similarly, there was a tendency (P = 0.06) for more 3 month old gilts to exhibit a nocturnal increase in serum MEL than 4, 5 or 6 month old gilts.     

Immunocastrated male pigs: effect of 4 v. 6 weeks time post second injection on performance,carcass quality and meat quality

Immunocastration or vaccination against boar taint can be used as alternative for surgical castration of male piglets. The vaccine is administrated twice. After the second vaccination (V2), the pigs behave like barrows instead of boars and their feed intake increases which may result in a lower lean meat percentage. The timing of V2 is therefore crucial to find the right balance between the advantages of entire males and barrows. In this study, we evaluated the effect of time post second injection within the advised time frame (4 v. 6 weeks before slaughter) on behaviour, performance, carcass and meat quality of immunocastrated male pigs. In total, 180 animals (hybrid sow×Piétrain): 60 gilts, 60 male pigs vaccinated 6 weeks before slaughter (IM-6) and 60 male pigs vaccinated 4 weeks before slaughter (IM-4), all slaughtered at comparable slaughter weights. After 20 weeks of age, IM-6 showed more inactive behaviour at the expense of playing and aggressive behaviour. Daily feed intake (DFI), daily gain (DG) and feed conversion ratio (FCR) did not differ significantly between IM-6 and IM-4. Gilts had a lower DFI and DG in the late finishing phase and a higher FCR overall compared with both IM groups. Gilts showed a higher lean meat content compared with both IM groups. Earlier vaccination increased dressing percentage, which could partly be explained by the lower weight of the gastrointestinal tract, but not by testes weight. Meat quality traits and palatability did not differ significantly between IM-6 and IM-4. Vaccination of immunocastrates at 6 compared with 4 weeks before slaughter improved the calmness in the stable and the dressing percentage, while maintaining performance and carcass characteristics.     

Compensatory growth feeding strategy does not overcome negative effects on growth and carcass composition of low birth weight pigs

The aim of this study was to evaluate whether the compensatory growth feeding strategy could be a suitable solution for overcoming the negative effects on growth, carcass composition and meat quality of low birth weight pigs. Forty-two Swiss Large White barrows from 21 litters were selected at weaning and categorized into either being light (L; >0.8 and <1.3 kg) or heavy (H; >1.7 kg) birth weight pigs. From 27.8 kg BW, pigs were assigned within birth weight group to one of three feeding groups: AA: ad libitum access to the grower and finisher diet, RR: restricted access to the grower and finisher diet or RA: restricted access to the grower diet and ad libitum access to the finisher diet. At slaughter, the longissimus (LM) and semitendinosus (STM) muscles were removed from the right side of the carcass. Weight, girth and length of the STM and the LM area were determined after muscle excision. Carcass characteristics and meat quality traits were assessed. Using mATPase histochemistry, myofibre size and myofibre type distribution were determined in the LM and STM. Because of longer days on feed, total feed intake was greater (P<0.01) and feed efficiency was lower (P<0.01) in L than H barrows. Regardless of the birth weight group, AA and RA barrows grew faster (P<0.05) than RR barrows. During the compensatory growth period, RA barrows grew faster (P<0.05) than AA or RR barrows. Growth efficiency did not differ between RA and RR barrows but was greater (P<0.05) compared with AA barrows. Carcasses of L barrows were fatter as indicated by the lower (P⩽≤0.05) lean meat and greater (P⩽0.02) omental and subcutaneous fat percentage. Lean meat percentage was lower (P⩽0.05) in AA and RA than RR barrows. These differences caused by ad libitum feed access tended to be greater (feeding regime × birth weight group interaction; P<0.08) in L than H barrows. In L barrows, slow oxidative, fast oxidative glycolytic and overall average myofibre size of the LM and the fast glycolytic myofibres and overall average myofibre size of the dark portion of the STM were larger (P⩽0.03) than in H barrows. The study revealed that the compensatory growth feeding strategy was inadequate in overcoming the disadvantages of low birth weight.     

Maternal reproductive hormone levels after repeated ACTH application to pregnant gilts

Prenatal stress has been seen as a reason for reproductive failures in pig offspring mostly originated or mediated by changed maternal functions. In pregnant gilts, three experiments (EXP I-III) were conducted to characterize the effects of repeated ACTH on maternal cortisol concentrations (EXP I) and on the secretion of maternal reproductive hormones (LH, progesterone, estrone sulfate; EXP II + III). Exogenous ACTH was given six times every alternate day beginning either on day 49 (EXP I + II) or day 28 (EXP III) of pregnancy. As a result of treatment, elevated cortisol levels were observed for more than 6 h (EXP I). Plasma concentrations of LH were at low basal level (0.1-0.2 ng/ml), but showed a pulsatory release pattern both during first and second trimester of pregnancy. The number of LH pulses/6 h (L.S.M. +/- S.E.) of saline treated controls increased with ongoing pregnancy (1.4 +/- 0.1 versus 2.0 +/- 0.2 in EXP III and EXP II, respectively). After ACTH treatment the number of LH pulses did not differ between the two gestational stages (1.3 +/- 0.2 and 1.4 +/- 0.2 in EXP III and EXP II, respectively). However, differences ( P < 0.05) were obtained comparing the LH pulse number of ACTH and saline treated sows during the second trimester of pregnancy. Moreover, areas under the curve (AUC) of each LH pulse and of all LH values over the baseline were significantly reduced by treatment. The levels of progesterone increased (P < 0.05) for 150-170 min after each ACTH application both in EXP II and EXP III. The concentrations of 17alpha-hydroxy-progesterone revealed likewise a significant elevation after each ACTH injection. Throughout EXP III, estrone sulfate concentrations were found to decrease (from 2.8-16.9 ng/ml on day 28 to 0.02-0.04 ng/ml on day 38) but without differences between ACTH-and saline-treated gilts. Further data of EXP II and EXP III, e.g. number of piglets born alive, confirmed the absence of detrimental treatment effects. Thus, repeated ACTH administration with subsequent release of cortisol is able to influence the release pattern of maternal reproductive hormones. However, these findings demonstrate that stress-related effects are dependent on the stage of pregnancy. The detected changes may affect feto-maternal interactions and, as a result, fetal reproductive development.