J.H.M. Verheijden

Wageningen University, Wageningen, Gelderland, Netherlands

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Publications (74)88.52 Total impact

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    ABSTRACT: Intermittent suckling (IS) has proven to stimulate creep feed intake in suckling piglets. This paper describes the development of feeding behaviour in three litters with high (H) and three litters with low (L) feed intake during lactation in both control (C) and IS treatment. In order to synchronize the start of intermittent suckling within a farrowing room, treatment day 0 (T0) was designated as the start of data collection. IS litters were separated from the sow for a period of 12 h/day (0930 to 2130) from T14 to weaning (T25). Feeder visits of individual piglets and nursing behaviour were analysed from continuous video recordings at 5 treatment days: T13, T16, T24, T25 and T26. A high number of CL piglets never visited the feeder during lactation; at T24, 56% of the CL piglets did not visit the feeder. On the other hand, 91% of the ISL and CH piglets and all ISH piglets visited the feeder at least once at T24. In contrast to the other groups, no increase was seen in visiting frequency during lactation in CL piglets. At T24, visiting frequency was higher in ISL than in CL piglets. So, IS stimulated piglets from low feed intake litters to visit the feeder. Between T16 and T24, total feeder time increased in piglets from all groups (P < 0.05), except in CL piglets in which no change was found (P > 0.10). Latency to first visit to the feeder after weaning did not differ between groups. It is concluded that IS stimulates piglets from litters with a low level of creep feed intake to visit the feeder during lactation, which familiarizes them with the feeder and the feed during lactation. The IS treatment does not affect feeder visiting behaviour of piglets with an anyhow high level of feed intake during lactation
    Livestock Science 02/2010; · 1.25 Impact Factor
  • 01/2010;
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    ABSTRACT: Daily separation of sows and piglets during lactation, intermittent suckling (IS), improves feed intake and postweaning adaptation in piglets. The aim of the current study was to determine how, in piglets that have been subjected to IS, age at weaning and the duration of the preceding IS period contribute to postweaning adaptation through effects on feed intake, growth, and gut characteristics. All piglets had ad libitum access to creep feed from d 7. Litters were subjected to conventional weaning (CW) or to 1 of 3 IS regimens. In CW, litters (n = 29) had continuous access to the sow until weaning (d 26, d 0 = farrowing). During IS, litters had access to the sow between 1600 and 0600 h. Litters in the IS treatments were subjected to IS 1) from d 19 onward and weaned at d 26 (IS19-7D, n = 33), 2) from d 19 onward and weaned at d 33 (IS19-14D, n = 28), or 3) from d 26 onward and weaned at d 33 (IS26-7D, n = 33). The IS19-7D regimen resulted in a relative growth check within the first 2 d after weaning similar to CW litters (72 +/- 13 and 90 +/- 7%, respectively), but in a greater piglet growth (P = 0.014) and feed intake (P = 0.001) between d 2 and 7 postweaning. Moreover, IS19-7D was not associated with a (further) reduction in villus height as observed at d 2 postweaning in CW litters. In IS piglets weaned after an extended lactation (d 33), a markedly smaller weaning-associated relative growth check was observed shortly postweaning (11 +/- 18 and 32 +/- 19% for IS19-14D and IS26-7D litters, respectively). In these litters, feed intake and growth within the first 2 d after weaning were slightly greater when piglets were subjected to IS for 2 wk (IS19-14D) rather than for 1 wk (IS26-7D; P = 0.032 and P = 0.037 for feed intake and growth, respectively). Irrespective of duration of IS, weaning at d 33 with IS was not associated with a reduction in villus height. Irrespective of treatment, plasma citrulline concentrations were reduced at d 2 and 8 postweaning compared with the values at weaning (P < or = 0.01). No correlation was observed between postweaning plasma citrulline concentrations and postweaning small intestinal villus height. This study indicates that 1 wk of IS before weaning at d 26 of lactation improves feed intake and growth between d 2 and 7 postweaning and does not result in a reduction of villus height as observed in CW piglets, although it did not prevent a profound growth check shortly after weaning. However, combining 1 wk of IS with an extended lactation improved postweaning adaptation markedly in terms of growth, feed intake, and gut characteristics. Increasing the duration of IS from 1 to 2 wk slightly improved growth and feed intake shortly after weaning, but the contribution to postweaning adaptation seemed to be relatively small compared with extending lactation.
    Journal of Animal Science 08/2009; 87(10):3156-66. · 2.09 Impact Factor
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    ABSTRACT: Influenza virus infections with subtypes H1N1, H3N2 and H1N2 are very common in domestic pigs in Europe. Data on possible differences of population dynamics in finishing pigs in farrow-to-finish herds and in specialised finishing herds are, however, scarce. The presence of sows and weaned piglets on the same premises may, however, affect the exposure of finishing pigs to influenza viruses. In a longitudinal study on 14 farrow-to-finish herds and 15 finishing herds, groups of pigs were followed by repeatedly testing the same animals for antibodies against all three influenza virus subtypes (H1N1, H3N2 and H1N2). At the end of the finishing period, the seroprevalences in farrow-to-finish and specialised finishing herds were 44.3% and 62.0%, respectively for H1N1, 6.6% and 19.3%, respectively for H3N2, and 57.2% and 25.6%, respectively for H1N2. For all three subtypes, the incidence of influenza virus infections was highest at the beginning of the finishing period in farrow-to-finish herds, while the incidence of influenza virus infections was highest at the end of the finishing period in finishing herds. Respiratory disease, probably related to the influenza infections, was observed in five of these herds only, but also occurred at the beginning of the finishing period in farrow-to-finish herds and at the end of the finishing period in finishing herds. The observed differences of population dynamics of influenza virus may affect choice and timing of intervention measures.
    Veterinary Microbiology 02/2009; 137(1-2):45-50. · 3.13 Impact Factor
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    ABSTRACT: The objective of the current study was to investigate whether plasma citrulline or intestinal fatty acid-binding protein (I-FABP) concentrations might be used as longitudinal markers for small intestinal function in piglets after weaning. Plasma citrulline and I-FABP concentrations were measured longitudinally in weaned and unweaned piglets, and related to intestinal absorption values (i.e., plasma mannitol and 3-xylose concentrations in a sugar absorption test). Within each litter (n = 10), 2 piglets with a close-to-litter-average BW were selected. At 20.8 +/- 0.4 d of age, the selected piglets per litter were either weaned conventionally (CW) or remained with the sow (UNW). One day before, and 0.5, 2, 4, and 7 d after weaning of the CW piglets, the selected piglets of both groups were subjected to a sugar absorption test. After a 2-h fast, piglets were administered an oral dose of 2 mL/kg of sugar solution, containing 50 mg/kg of mannitol and 100 mg/kg of 3-xylose. One hour after administration, a blood sample was collected from a jugular vein for determination of plasma I-FABP, citrulline, mannitol, and 3-xylose concentrations. Plasma I-FABP concentration showed great variation within treatments, and no difference was observed in plasma I-FABP concentrations between the CW and UNW treatments (P = 0.63). The absorption of 3-xylose was not different between treatments (P = 0.83). Mannitol absorption, however, was less in the weaned CW piglets compared with the UNW piglets (P = 0.003), with the nadir on d 4 postweaning. Weaning also reduced plasma citrulline concentrations in the CW treatment compared with the UNW treatment (P < 0.001). On d 4 and 7 postweaning, plasma citrulline concentrations of CW piglets were less (P < 0.001 and P = 0.0013) than preweaning values. Furthermore, in the CW treatment, plasma citrulline concentrations correlated with plasma mannitol concentrations at d 4 postweaning (r = 0.89, P = 0.008) and overall (r = 0.76, P = 0.001). Based on these results, plasma citrulline concentration seems to be a possible marker for monitoring intestinal function in pigs after weaning.
    Journal of Animal Science 08/2008; 86(12):3440-9. · 2.09 Impact Factor
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    ABSTRACT: The objectives of the current study were to determine how intermittent suckling (IS) affects nursing behavior, litter activity, and general behavioral patterns during lactation, and whether IS during an extended lactation period results in behavioral patterns associated with piglet distress. Intermittent suckling was applied either with 6-h separation intervals (IS6) or with 12-h separation intervals (IS12) and was compared with the conventional treatment (CT). In the CT (n = 17 litters), sows were continuously present until weaning (d 21, d 0 = farrowing). In both IS6 and IS12, sows were separated from their litter for 12 h/d, beginning at d 14 and lasting until weaning (d 43 +/- 1 d). In IS6, litters (n = 14) and sows were separated from 0800 to 1400 and from 2000 to 0200; in IS12 litters (n = 14) and sows were separated between 0800 and 2000. In IS litters, the activity pattern over the 24-h cycle was markedly changed by IS; litter activity was lower (P < 0.001) during sow absence and greater (P < 0.001) during sow presence compared with the unweaned CT litters. Moreover, both total nursing frequency (P < 0.001) and the percentage (P < 0.002) of successful nursings were reduced by IS. Although total nursing frequency was greater in IS6 compared with IS12 (on d 21 and 28), no differences in the frequency of successful nursings existed between IS6 and IS12 from d 14 onward. Eating behavior was increased shortly after the onset of IS (d 17) in both IS6 (P = 0.059) and IS12 (P < 0.001) compared with the unweaned CT litters. The IS12 litters showed more eating behavior compared with IS6 and their exploratory behavior increased in time (P < 0.001), whereas IS6 showed more nursing behavior. Aggressive or manipulative behavior of both IS treatments was similar compared with the unweaned CT, and remained relatively unaltered with time in IS12 and IS6. Weaning in the CT resulted in more manipulative (P < 0.001) and aggressive (P = 0.004) behavior compared with pre-weaning values. Intermittent suckling may contribute to adaptation to the postweaning state by stimulating eating behavior, without causing obvious behavioral distress.
    Journal of Animal Science 01/2008; 85(12):3415-24. · 2.09 Impact Factor
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    ABSTRACT: In this study, the contribution of management practices, herd characteristics, and seasonal variables to the herd somatic cell count (SCC) was quantified in herds with low (<150,000 cells/mL), medium (150,000-200,000 cells/mL), and high (>200,000 cells/mL) herd SCC (HSCC). Selection of the variables was performed using a linear mixed effect model; HSCC was calculated as the arithmetic mean of the individual cow's SCC. The data concerning management practices were derived from 3 questionnaires on mastitis prevention and management practices on 246 Dutch dairy farms. The monthly Dairy Herd Improvement test data of these 246 farms were used to calculate the herd characteristics and seasonal effects. None of the management practices were associated with HSCC in all 3 HSCC categories. Some variables only had a significant association with HSCC in one HSCC category, such as dry premilking treatment (-9,100 cells/mL in the low HSCC category) or feeding calves with high SCC milk (11,100 cells/ mL in the medium HSCC category). Others had an opposite effect on HSCC in different HSCC categories, such as average parity (-6,400 and 11,000 cells/mL in the low and medium HSCC category, respectively) and feeding calves with fresh milk (10,300 and -9,700 cells/ mL in the low and high HSCC category, respectively). We conclude that, given the individual Dairy Herd Improvement data and information on management practices of an individual farm, it is possible to provide quantitative insight into the contribution of these different variables to the HSCC of an individual farm. Being able to provide such insight is a prerequisite for interpretation, prediction, and control of HSCC on individual dairy farms.
    Journal of Dairy Science 09/2007; 90(9):4137-44. · 2.57 Impact Factor
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    ABSTRACT: To determine whether the addition of chromic oxide (Cr(2)O(3)) to creep feed could be used as a visual marker in feces for selection of creep feed-eating suckling pigs. 20 suckling pigs. Via syringe, 5 pigs (2 to 3 days old on day 0; 1 pig/treatment) from each of 4 litters received oral administrations of 10, 20, 30, or 40 g of creep feed containing 10 g of Cr(2)O(3)*kg(1) on each of 2 consecutive days (days 20 and 21) or 30 g of creep feed containing 10 g of Cr(2)O(3)*kg(1) on day 20 and 30 g of Cr(2)O(3)-free creep feed on day 21. On days 21 through 24, 6 fecal samples were collected from each pig at regular intervals between 8:00 AM and 6:00 PM. Green-colored feces were considered indicative of creep feed consumption (eaters). Data analyses were based on single and multiple fecal samples. On day 22, evaluation of 1 fecal sample/pig and multiple fecal samples per pig resulted in identification of as many as 40% and only 15% of the feed-treated pigs wrongly as noneaters, respectively. Repeated sampling over multiple days would identify 99% of eaters accurately. Pigs erroneously identified as noneaters were those administered either low amounts of Cr(2)O(3)-supplemented creep feed for 2 days or Cr(2)O(3)-supplemented creep feed on only 1 day. Data suggest that addition of Cr(2)O(3) to creep feed enables selection of individual creep feed-eating suckling pigs via examination of feces, provided that repeated fecal samples are evaluated.
    American Journal of Veterinary Research 08/2007; 68(7):748-52. · 1.35 Impact Factor
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    ABSTRACT: The effect of vaccination with a killed whole-cell vaccine of extracellular factor-positive Streptococcus suis serotype 2 (S suis 2 EF(+)) combined with medication with amoxicillin on the presence of virulent S suis 2 EF(+) strains on the tonsils of sows and their offspring was evaluated. In two herds, 14 pregnant sows that carried these virulent strains, as detected by PCR in three consecutive tonsillar brush samples, were selected and randomly assigned to be treated or left untreated as controls. The treated sows were vaccinated at six and three weeks before the expected farrowing date and medicated from one week before expected farrowing until the end of the experiment. Two weeks before parturition, the sows were housed in individual isolation farrowing rooms, and the sow and its litter were sampled by using tonsil brushes and tonsil swabs, respectively. Approximately 27 days postpartum, the sows and their piglets were euthanased and their tonsils were collected and analysed by pcr. No S suis 2 EF(+) could be detected in the tonsils of the seven treated sows, but the tonsils of the seven untreated sows remained positive. Only one of the litters of the untreated sows became infected, five days after birth, and none of the litters of the treated sows became infected.
    The Veterinary record 06/2007; 160(18):619-21. · 1.80 Impact Factor
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    ABSTRACT: An experiment was conducted to determine if the improved creep feed intake observed during intermittent suckling (IS) is important for postweaning performance. Therefore, creep feed intake of litters was assessed, and within litters, eaters and noneaters were distinguished using chromic oxide as an indigestible marker. Batches of sows were suckled intermittently (IS, 7 batches; n = 31) or continuously (control, 7 batches; n = 31). In the IS group, litters were separated from the sow for a period of 12 h/d (0930 to 2130), beginning 11 d before weaning. Litters were weaned at 4 wk of age. Litters had free access to creep feed from 1 wk of age onward. Five days after weaning, the piglets were moved as a litter to weanling pens. At 8 wk of age, 2 barrows and 2 gilts were randomly chosen from each litter and moved to a finishing facility. Feed intake was improved by IS during the last 11 d of lactation (IS, 284 +/- 27 vs. control, 83 +/- 28 g/piglet; P < 0.001) and after weaning during the first (IS, 201 +/- 24 vs. control, 157 +/- 25 g x piglet(-1) x d(-1); P < 0.05) and second (IS, 667 +/- 33 vs. control, 570 +/- 35 g x piglet(-1) x d(-1); P < 0.05) wk. Thereafter, no differences were found to slaughter. Weaning BW was lower in IS litters (IS, 7.1 +/- 0.01 vs. control, 8.1 +/- 0.01 kg/piglet; P < 0.05), but 7 d after weaning BW was similar (IS, 8.5 +/- 0.2 vs. control, 8.7 +/- 0.2 kg/piglet; P = 0.18), and no differences were found to slaughter. The percentage of eaters within a litter was not increased by IS during lactation (IS, 23 +/- 4.5% vs. control, 19 +/- 4.1%; P = 0.15). Weaning BW did not differ between eaters and noneaters (eater, 7.7 +/- 0.1 vs. noneater, 7.5 +/- 0.08 kg/piglet; P = 0.63). From 1 until 4 wk after weaning, piglets that were eaters during lactation had heavier BW than noneaters (eater, 20.3 +/- 0.3 kg vs. noneater, 18.2 +/- 0.2 kg; P < 0.05). The influence of eating creep feed during lactation on BW and ADG and the influence of suckling treatment never showed an interaction. We conclude that IS increases ADFI during lactation on a litter level and improves ADG in the first week and ADFI in the first and second weeks after weaning. No long-term effects on ADFI or ADG were observed throughout the finishing period. In the current experiment, in which creep feed intake was low, the percentage of eaters within a litter was not increased, suggesting that creep feed intake of piglets that were already eating was stimulated by IS. Further, piglets that were eaters during lactation had heavier BW up to 4 wk after weaning.
    Journal of Animal Science 05/2007; 85(5):1295-301. · 2.09 Impact Factor
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    ABSTRACT: The objective of this study was to determine whether intestinal blood flow can be measured adequately in group-housed animals using the recently developed Physiogear™ I wireless flowmeter. We used the weaner pig as one of many possible animal models. Four 7-kg piglets were instrumented with a 3-mm flowprobe around the superior mesenteric artery (SMA) and SMA flow was measured pre- and post-weaning. During measurements, behavior was recorded. The piglets did not show any abnormal behavior and were not restrained by the flowmeter. Severe reductions (> 75%) in SMA flow coincided with nursing (pre-weaning) and aggressive behavior (post-weaning) and were only short-lived. Our results demonstrate that the Physiogear™ I flowmeter can be used to measure flow in group-housed animals without any human contact, providing the opportunity to relate flow measurements to undisturbed animal behavior.
    05/2007;
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    ABSTRACT: The aim of the study was to measure the effect of creep feeding during lactation on net absorption in the small intestine at 4 days after weaning. Intermittent suckling was used to increase creep feed intake during lactation. Creep feed containing chromic oxide was provided. Based on the colour of the faeces, piglets were classified as `eaters¿ or `non-eaters¿, respectively. At day 4 after weaning, an in vivo small intestine segment perfusion test was performed at 5 sites along the small intestine in 24 piglets (12 eaters and 12 non-eaters). At both sides of each intestinal segment a tube was fitted to perfuse and drain fluid in order to assess net absorption. Net absorption was higher in eaters than in non-eaters (P < 0.001). Net absorption varied greatly between and within piglets and was highest in the caudal segments of the small intestine (P < 0.001). These data suggest that creep feeding could be a useful tool in the prevention of post-weaning diarrhoea.
    Livestock Science 05/2007; · 1.25 Impact Factor
  • 01/2007;
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    ABSTRACT: The objective of this study was to determine whether intermittent suckling (IS) combined with an extended lactation can reduce postweaning growth check in pigs. Three weaning regimens [conventional weaning (CW), IS with 6-h separation intervals (IS6), and IS with 12-h separation intervals (IS12)] were compared. In CW (n = 17 litters), litters had continuous access to the sow until weaning (d 21, d 0 = farrowing). In IS6 and IS12, litters were separated from the sow for 12 h/d, beginning at d 14 and lasting until weaning (d 41 to 45). Litters were with the sow from 1400 to 2000 and from 0200 to 0800 (IS6, n = 14) or between 2000 and 0800 (IS12, n = 14). Litter size was standardized within 2 d after farrowing by crossfostering, resulting in an average litter size of 10.9 +/- 1.8 piglets. Piglets had ad libitum access to creep feed from d 7 onward. One week after the onset of IS (d 20), creep feed intake was increased in litters from both IS groups compared with CW litters (P < 0.05). Both IS groups consumed considerable amounts of creep feed before weaning (d 41 to 45). Total feed intake before weaning was greater (P = 0.004) in IS12 (3,808 +/- 469 g/piglet) than in IS6 (2,717 +/- 404 g/piglet). In comparison, CW litters consumed 18 +/- 9 g/piglet before weaning (d 21). Irrespective of weaning regimen, total feed intake of litters before weaning was highly correlated with post-weaning feed intake (P < 0.001). Furthermore, in all treatment groups, total preweaning feed intake was correlated with postweaning growth (P < 0.10). Irrespective of treatment, piglets suckling anterior teats grew faster than piglets suckling middle or posterior teats during the first 2 wk of lactation. Body weights at the end of the experiment (d 55) were similar among weaning regimens. Onset of IS induced a growth check in both IS groups (34% for IS12 and 22% for IS6). Only a mild growth check was observed after weaning of IS litters (14% for both IS groups). However, a serious growth check (98%) was observed after weaning of CW litters. Results of the current study indicate that IS stimulated feed intake during lactation, providing a more gradual transition to weaning. Because the IS6 regimen did not prevent the growth check after the onset of IS and is rather laborious, we suggest that IS12 might be preferable for a practical implementation of IS.
    Journal of Animal Science 01/2007; 85(1):258-66. · 2.09 Impact Factor
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    ABSTRACT: In this study, the sensitivity (Se) and specificity (Sp) of a PCR for the detection of EF-positive Streptococcus suis serotype 2 strains in tonsillar swabs of live sows were assessed. We sampled 471 sows originating from four farrow-to-finish farms by tonsillar swabbing and collected their tonsils after slaughter. On these specimens, a PCR, a bacterial examination (BE) or both were performed for the detection of EF-positive S. suis serotype 2 strains. Swab-PCR, Tonsil-PCR and Tonsil-BE were regarded as three integral tests. A Bayesian approach was used to calculate the Se and Sp of the tests. Se and Sp for Swab-PCR were 0.63 (95% credibility interval <0.52, 0.74>) and 0.96 (<0.92, 0.99>), respectively. Values for Se and Sp of Tonsil-PCR amounted to 0.88 (<0.75, 0.96>) and 0.94 (<0.87, 0.99>), respectively. For Tonsil-BE, Se was 0.65 (<0.51, 0.76>) and Sp was 0.97 (<0.91, 0.99>). Repetition of the swabbing procedure after 10 min resulted in a higher Se 0.85 (<0.67, 0.96>) than the Se of the first-Swab-PCR. Repetition of the PCR on the same sample did not result in any significant changes in the outcome of the analysis.
    Veterinary Microbiology 08/2005; 109(3-4):223-8. · 3.13 Impact Factor
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    ABSTRACT: The absorption enhancing effects of chitosan and its derivatives have been intensively studied in recent years. It has been shown that these compounds are potent absorption enhancers. Chitosan is only soluble in acidic environments and is therefore incapable of enhancing absorption in the small intestine, the main absorption area in the gastrointestinal tract. Special emphasis has been placed on the absorption enhancing properties of N-trimethyl chitosan chloride (TMC), a partially quaternised derivative of chitosan, due to its solubility in neutral and basic environments. TMC is prepared by the reductive methylation of chitosan. The degree of quaternisation can be altered by increasing the number of reaction steps or by increasing the reaction time. Although the molecular weight of the polymer increases with addition of the methyl groups, a net decrease in the molecular weight is observed due to a decrease in the chain length of the polymer. TMC, like chitosan, possesses mucoadhesive properties. In vitro studies performed on Caco-2 cell monolayers showed a pronounced reduction in the transepithelial electrical resistance (TEER). TMC is also able to increase the permeation of hydrophilic compounds such as [14C]-mannitol and [14C] polyethylene glycol 4000 ([14C] PEG 4000, MW4000) across the cell monolayers. It was also shown that the degree of quaternisation of the polymer plays an important role on its absorption enhancing properties, especially in neutral environments where chitosan is ineffective as an absorption enhancer. The reduction in TEER is an indication of the opening of the tight junctions located between epithelial cells. Opening of the tight junctions will result in enhancement of absorption via the paracellular route. Confocal laser scanning microscopy confirmed transport of large hydrophilic compounds via the paracellular route as well as the mechanism of action of the polymer in which redistribution of the cytoskeletal F-actin is provoked, which leads to the opening of the tight junctions. Various in vivo studies in different animal models confirmed the ability of TMC to increase the absorption of the peptide drugs buserelin and octreotide after intraduodenal or -jejunal administration. However, TMC has always been administered as a solution in these studies. The impracticality of administering a solution, as well as the fact that most peptides are unstable in the presence of water, have led to the need for a solid oral dosage form with which TMC can be administered together with peptide drugs. Recent studies have focused on the development and in vivo evaluation of solid oral dosage forms.
    European Journal of Pharmaceutics and Biopharmaceutics 10/2004; 58(2):225-35. · 3.83 Impact Factor
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    ABSTRACT: An experiment was conducted to study effects of intermittent suckling on creep feed intake and weight gain of litters. Loss of weight and backfat during lactation, as well as reproductive performance, were also measured. Batches of multiparous sows (Parity 1 to 12, 4.1 on average) were either suckled intermittently (IS, eight batches; n = 50) or continuously (control, eight batches; n = 62). Litters were weaned at 27 +/- 2 d of age, on average. Litter size (11.1 +/- 0.2 piglets, on average) was standardized within a batch within 3 d of birth. All litters had free access to creep feed and water from 1 wk of age onward. In the IS group, litters were separated from the sow for a period of 12 h/d (0930 to 2130), starting 11 d before weaning. Rectal ultrasonography was applied at d 3 after weaning to check the ovaries for follicle development or presence of corpora lutea. Creep feed intake by the litters during lactation was higher in IS litters than in control litters (686 +/- 57 vs. 314 +/- 42 g/piglet, P < 0.01). The distribution of creep feed intake shifted from a skewed one, with a majority of litters consuming less than 250 g/piglet in control litters, to a normal distribution, with an average creep feed intake of 500 to 750 g/piglet in IS litters. During the 7 d after weaning, creep feed intake in IS litters was also higher (281 +/- 15 vs. 204 +/- 9 g-piglet(-1) x d(-1), P < 0.01). The ADG of piglets during lactation was negatively affected by IS, resulting in lower weight at weaning (7,229 +/- 140 vs. 7,893 +/- 145 g/piglet, P < 0.05). During the 7 d after weaning, however, ADG was higher in IS litters (255 +/- 10 vs. 177 +/- 8 g-piglet-1 x d(-1), P < 0.01), and 7 d after weaning, the weights of the litters were similar (9,011 +/- 167 vs. 9,132 +/- 164 g/ piglet, P = 0.81). The IS litters that consumed little or no feed during lactation had an ADG after lactation that was higher than in control litters, with comparable creep feed intake during lactation: 204 vs. 136 g/d. Body weight loss by the sows during lactation was lower in IS sows (-10 +/- 2 vs. -16 +/- 1 kg, P < 0.05). A higher percentage of IS sows ovulated during lactation (22 vs. 3%, P < 0.01), and weaning-to-ovulation interval (excluding sows with lactational ovulation) was shorter in IS sows (4.7 +/- 0.2 vs. 5.3 +/- 0.2 d, P < 0.05). We conclude that IS increased creep feed intake during lactation, and that IS increased ADG after weaning, despite lower weaning weights. Ovulation during lactation was induced in 22% of the IS sows.
    Journal of Animal Science 02/2004; 82(2):405-13. · 2.09 Impact Factor
  • 01/2004;
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    ABSTRACT: This paper describes a methodology to quantify the transmission of Actinobacillus (A.) pleuropneumoniae from subclinically infected carrier pigs to susceptible contact pigs, and to test the effect of possible interventions on the transmission. The methodology includes the design of a transmission experiment, and a method with which A. pleuropneumoniae transmission can be quantified and with which the effect of an intervention on the transmission can be tested. The experimental design consists of two parts. First, subclinically infected carrier pigs are created by contact exposure of specific-pathogen-free pigs to endobronchially inoculated pigs. Second, transmission is observed from the group of carrier pigs to a second group of susceptible contact pigs after replacing the inoculated pigs by new contact pigs. The presented analytical method is a generalised linear model (GLM) with which the effect of an intervention on the susceptibility and infectivity can be tested separately, if the transmission is observed in heterogeneous populations. The concept of the experimental transmission model is illustrated by describing an A. pleuropneumoniae transmission experiment in which the effect of vaccination on the susceptibility is quantified. Although it could not be demonstrated that vaccination has an effect on the susceptibility of pigs, it was demonstrated that nasal excretion of A. pleuropneumoniae is related to the infectivity of pigs.
    Preventive Veterinary Medicine 08/2003; 60(1):53-68. · 2.39 Impact Factor
  • G Nodelijk, M Nielen, M C M De Jong, J H M Verheijden
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    ABSTRACT: Understanding the spread of porcine reproductive and respiratory syndrome virus (PRRSV) in pig populations is essential to the development of effective PRRS prevention and control strategies. Moreover, knowledge of the field dynamics of PRRSV in pigs will provide insights into the clinical relevance of PRRS, and will enable the targeting of interventions. This review of PRRSV includes discussion on the occurrence of outbreaks, the persistence of infection and the fade-out of infection in Dutch breeding herds. The dynamic character of PRRSV infections in endemically infected herds and the relevance of the disease under Dutch field conditions are also highlighted. Furthermore, several strategies aimed at controlling the spread of PRRSV are discussed.
    Preventive Veterinary Medicine 08/2003; 60(1):37-52. · 2.39 Impact Factor

Publication Stats

546 Citations
88.52 Total Impact Points

Institutions

  • 2003–2009
    • Wageningen University
      • Department of Quantitative Veterinary Epidemiology
      Wageningen, Gelderland, Netherlands
  • 1989–2008
    • Universiteit Utrecht
      • • Department of Farm Animal Health
      • • Faculty of Veterinary Medicine
      Utrecht, Provincie Utrecht, Netherlands