Recovery of Salmonella enterica from seropositive finishing pig herds

The aim of this study was to assess the probability of detecting Salmonella from pen faecal samples in seropositive classified finishing pig herds. The study involved 77 herds from Denmark (20), The Netherlands (20), Greece (17) and Germany (20). The serological herd status was determined by the blood-sampling of 50 finishing pigs. Bacteriological sampling was performed by 20 pen faecal samples per herd. Over-all, 47% of the blood samples had an OD% larger than 10 and 23% larger than 40. Salmonella was isolated from 135 (9.3%) pen faecal samples in 32 herds (42%). Twenty-eight of these herds (87.5%) had a within-herd seroprevalence larger than 50% at sample cut-off OD% > 10. In our study, there was an increasing probability of recovering Salmonella with increasing within-herd seroprevalence. However, this was only a moderate correlation. A correlation coefficient of 0.62 was found between the proportion of culture positive- and seropositive samples in a herd at cut-off OD%> 10 and of 0.58 at cut-off OD% > 40. Serology is a measure of historical exposure, which may or may not correlate closely to the microbiological burden at the time of sampling. Due to the low sensitivity of culture methods, apparent 'false-positive' serological results may well represent real infections not detected by bacteriological testing. For screening purposes, serological testing provides an indication of exposure to Salmonella, which forms the basis for targeted sampling, intervention and logistic slaughter procedures.     

Differences in polymorphonucleocyte function and local inflammatory response between horses and ponies

REASONS FOR PERFORMING STUDY: Wound healing proceeds faster in ponies than in horses and complications during healing, such as wound infection, occur less frequently in ponies. Earlier studies suggested that this difference might be related to differences in the initial post traumatic inflammatory response. HYPOTHESIS: That polymorphonuclear leucocyte (PMN) function and profiles of humoral factors in local inflammatory processes are different in horses and ponies. METHODS: PMNs were isolated from venous blood of horses and ponies. Chemotaxis and reactive oxygen species (ROS) production was determined. Tissue cages were implanted in limbs and necks of horses and ponies and injected with carrageenan and, 3 weeks later, with LPS. In sequential samples of inflammatory exudate, the numbers of macrophages and PMNs and the production of PGE2, TNFalpha, IL-1, IL-6 and chemoattractants were determined. RESULTS: In vitro ROS production of PMNs was significantly higher in ponies than in horses, whereas in vitro PMN chemotaxis was significantly lower in ponies. In the tissue cages for both stimuli, the production of IL-1 and chemoattractants was significantly higher in ponies than in horses and remained so towards the end of the observation period in ponies. CONCLUSIONS: This study demonstrated a higher production of various inflammatory mediators by pony leucocytes. Despite the lower in vitro chemotaxis of pony PMNs, this higher in vivo production resulted in a stronger initial inflammatory response in ponies, as has been reported in studies on wound healing, through the attraction of leucocytes and triggering of the production of other cytokines. A stronger initial inflammation may promote healing by more rapid elemination of contaminants and earlier transition to repair. POTENTIAL RELEVANCE: Modulation of the initial inflammatory response might therefore be a valid option for therapeutic intervention in cases of problematic wound healing. Further, the intraspecies differences in leucocyte function may have an impact on many fields in equine medicine.     

Effect of administration of Lactobacillus crispatus,Clostridium lactatifermentans and dietary lactose on the development of the normal microflora and volatile fatty acids in the caeca of broiler chicks

1. Lactobacillus crispatus and Clostridium lactatifermentans, both isolated from the caeca of chickens, grown together in an in vitro model system are able to ferment lactose to acetate and propionate. In this study, the capabilities of these organisms were studied in vivo. 2. The effect on concentrations of volatile fatty acids and lactate, together with the development of some bacterial groups in the caeca of chicks, was studied after oral inoculation with L. crispatus and C. lactatifermentans together with dietary lactose. For this purpose, chicks were divided into 4 groups: (i) control group, (ii) dietary lactose, (iii) L. crispatus and C. lactatifermentans, and (iv) dietary lactose together with L. crispitaus and C. lactatifermentans. 3. In general, concentrations of (undissociated) volatile fatty acids in the caeca were not significantly different in broilers receiving both bacteria and dietary lactose compared with control broilers. Concentrations of lactate in the caeca of 14-d-old broilers treated with any of the three treatments were significantly higher than in the caeca of control broilers. 4. This indicates that L. crispatus or other lactate-producing organisms were responsible for the elevated concentrations of lactic acid. Clostridium lactatifermentans has probably not colonised the caeca sufficiently to ferment this lactate further to acetate and propionate. 5. Numbers of Enterobacteriaceae and enterococci in the caeca of broilers receiving both bacteria and dietary lactose were not different from control broilers. 6. We conclude from these results that under the conditions applied in this study a mixture of L. crispatus and C. lactatifermentans with dietary lactose was able to increase lactate concentrations but was unable to increase concentrates of acetate and propionate in the caeca of broiler chicks.     

Chemiluminescent immunoassay in comparison with the indirect ELISA as reference method for detecting Salmonella antibodies in swine meat juice

The efficiency of chemiluminescent immunoassay (CLIA) in detecting Salmonella antibodies in the meat juice of slaughter swine was compared with the indirect ELISA (BgVV method). Based on the screening test results of 987 meat juice samples obtained from different laboratories in Germany, a good level of agreement between the two systems was obtained with a kappa value of 0.824 at 20% cut-off and 0.798 at 40% cut-off. At 20% and 40% cut-off levels, a sensitivity of 96.2% and 97.3%, respectively, and a specificity of 94.6% and 95.1%, respectively, were demonstrated between CLIA and ELISA. The detecting LPS antigen was tested for specificity and a cross-reaction with two E. coli and Yersinia strains was found when tested with ELISA. This reaction was not observed in CLIA, possibly because of the broader measurement spectrum of this test which allows a more distinctive definition of immunologic reactions. The same explanation can be given for the increased number of meat juice samples which were positively detected only in ELISA but not in CLIA. The positively classified samples in screening were further tested for reciprocal titers in both test systems, and a higher correlation between screening and titration results was obtained for CLIA. Towards the end of the study, a preliminary comparison of CLIA with two available commercial ELISA test kits was conducted and the same tendency was observed, namely, wider detection range of CLIA compared to the other tests. Based on the results of this study, CLIA can be used as a reference method in detecting Salmonella antibodies in the meat juice of slaughter pigs.     

Effects of restricted feeding on physiological stress parameters in growing broiler breeders

1. In previous studies, a lack of agreement in measurements of plasma corticosterone concentrations and heterophil:lymphocyte (H/L) ratio as physiological indices of stress, caused by hunger and frustration in restricted-fed broiler breeders, was observed. It could be suggested that the differences between previous studies were caused by differences in duration of restriction and time of the day of the measurements. Therefore, in the present study the plasma corticosterone concentration and the H/L ratio were again determined in restricted- and ad libitum-fed growing broiler breeders, taking possible causes of disagreement between previous studies into account. In addition, we measured the daily rhythm in body temperature and heart rate, and the corticosterone responses to an acute stressor as physiological indices of stress. 2. Female broiler breeders (64 per treatment, housed in groups of 4 birds) were used in the experiment. Behaviour, baseline plasma corticosterone concentrations and H/L ratio were determined at 21 d of age (immediately after the start of food restriction), and at 42 and 63 d of age. Body temperature, heart rate and activity were measured by radiotelemetry for 36 h at 49 and 70 d of age. In addition, the plasma corticosterone response to acute stress (5 min manual restraint) was measured at 77 or 78 d of age. 3. Restricted broiler breeders had higher plasma corticosterone concentrations at 42 and 63 d of age, but no differences in H/L. ratio were found between restricted birds and unrestricted control birds. Restricted broiler breeders had a higher corticosterone response to 5 min manual restraint than unrestricted birds. Restricted birds displayed a clear day-night rhythm in body temperature, heart rate and activity whereas such a rhythm was blunted in ad libitum-fed birds. 4. It is discussed that some physiological differences (plasma corticosterone concentrations, body temperature and heart rate) between ad libitum-fed and restricted broiler breeders may have been caused by differences in metabolic rate as well as by differences in the level of stress. It is concluded that a combination of behavioural measurements and a wide range of physiological parameters should be used for the assessment of stress in growing broiler breeders.     

Experimental reproduction of malabsorption syndrome with different combinations of reovirus, Escherichia coli, and treated homogenates obtained from broilers

Attempts to reproduce malabsorption syndrome (MAS) by oral inoculation with several different combinations including intestinal homogenate, reovirus, and hemolytic Escherichia coli obtained from MAS-affected chickens and intestinal homogenate from healthy chickens (healthy homogenate) were performed in 1-day-old specific-pathogen-free (SPF) broilers. The MAS homogenate, serving as a positive control, induced weight gain depression and intestinal lesions such as cystic crypts of Lieberkuhn, villus atrophy, and lymphoid and/or granulocytic infiltration. The healthy homogenate, the formalin-treated MAS homogenate, the formalin-treated healthy homogenate, and phosphate-buffered saline caused neither weight gain depression nor intestinal lesions. We were able to reproduce both weight gain depression and intestinal lesions by inoculation of reovirus either combined with the formalin-treated MAS homogenate or combined with healthy homogenate. Surprisingly, when hemolytic E. coli was added to the combination of reovirus with formalin-treated MAS homogenate, this did not cause weight gain depression although this combination caused the described intestinal lesions. Identical results were obtained with the combination of formalin-treated MAS homogenate with hemolytic E coli or the combination of reovirus with hemolytic E. coli. The intestinal lesions were more severe and developed faster by combinations including reovirus and formalin-treated MAS homogenate. This study indicates that a combination of enteropathogenic reovirus with other agents or substances that are present in an intestinal homogenate from MAS-affected and healthy chickens can induce MAS in SPF broilers. Escherichia coli is not essential for induction of weight gain depression but can play a role in development of intestinal lesions. Furthermore, intestinal lesions alone will not always result in weight gain depression.     

The effects of potassium diformate and its molecular constituents on the apparent ileal and fecal digestibility and retention of nutrients in growing-finishing pigs

Five 43-kg barrows [(Dutch Landrace x Yorkshire) x Yorkshire] were fitted with steered ileocecal valve cannulas to compare the effects of K-diformate (KDF), a specifically conjugated salt vs its molecular constituents, namely, formic acid and K-formate, as acidifiers in lysine-deficient diets on the apparent ileal (ID) and fecal digestibility, retention of nutrients, and manure production. The animals were randomly assigned to five dietary treatments according to a 5 x 5 Latin square design as follows: 1) control-no acidifier; 2) 1% KDF (= 0.65% K-formate + 0.35% formic acid, or 0.7% [HCOO-] + 0.3% [K+]); 3) 0.65% K-formate (= 0.35% [HCOO-] + 0.3% [K+]); 4) 0.35% formic acid (= 0.35% [HCOO-]); and 5) 1.3% K-formate (= 0.7% [HCOO-] + 0.6% [K+]). Diets were formulated with barley, wheat, soybean meal, and canola meal as major ingredients, and provided all nutrients at adequate levels, except for lysine (24% less than estimated requirement). Feeding level was equal to 2.5 x maintenance requirement (MR) for ME (MR = 418 kJ ME x BW(-0.75)), and daily rations were given in two portions after mixing with water in a ratio of 1:2.5. Chromic oxide was used as an indigestible marker. No clinical health problems due to the dietary treatments were observed. Irrespective of the additive, there were no differences (P < or = 0.10) in the ID of DM, OM, CP, or essential amino acids compared to the control, except for phenylalanine (P < or = 0.05). Among nonessential AA, only the ID of tyrosine tended (P = 0.092) to increase (up to 3.9 percentage units). The fecal digestibility of ash and K were greater (P < or = 0.001) in pigs fed supplemental K, irrespective of its source. The greater intake and fecal digestibility of K corresponded with greater (P < or = 0.05) losses of K in urine. Body retention of N, Ca, total P, and K was similar (P > or = 0.10) among treatments. As estimated from a separate nonorthogonal analysis, supplemental K improved (P < or = 0.05) body N by 3.7 percentage units compared to the control. The results of this study do not provide a clear explanation for the improved growth performance reported previously with KDF and its molecular constituents, and further research on their in vivo mode of action will require methodological refinement, especially with regard to the efficiency of AA utilization.     

Assessment of chromium tripicolinate supplementation and dietary energy level and source on growth, carcass, and blood criteria in growing pigs

Two experiments were conducted to evaluate potential interactive effects of supplemental Cr and dietary energy supply in growing pigs. Experiment 1 used 36 individually penned barrows, 25 to 65 kg, in a 2 x 3 factorial arrangement of supplemental Cr (0 or 200 ppb) and energy level (70, 80, or 90% of ME requirement). A corn-soybean meal basal diet was designed to supply all protein, mineral, and vitamin needs and 70% of the estimated ME need at 70% of ad libitum feed intake. Additional energy to 80% or 90% of the ME requirement was provided by a cornstarch/corn oil blend. In Exp. 2, 30 individually penned barrows, 23 to 68 kg, were used in a 2 x 4 factorial arrangement of supplemental Cr (0 or 200 ppb) and added energy source (none, cornstarch, corn oil, or choice white grease) with basal diets identical to Exp. 1. The various energy sources were added to 90% of the ME requirement. In both experiments, growth data were collected over a 50-d period and pigs were killed at 70.1 kg. Increasing energy levels increased (linear, P < 0.01) ADG, average backfat thickness, 10th rib backfat thickness, and cooler shrink and decreased (linear, P < 0.01) longissimus muscle area in Exp. 1. Carcass composition increased (linear, P < 0.01) in lipid and decreased in protein, water, and protein:lipid ratio in response to increasing ME levels. Similar results were observed in Exp. 2 in response to added energy, regardless of the energy source used. In response to ME, linear increases (P < 0.05) in plasma insulin concentration before feeding and after feeding were observed in Exp. 1. In Exp. 2, plasma insulin concentration was lower for the basal diet before feeding (P < 0.05) and higher for the starch diet after feeding (P < 0.01); insulin:glucose ratio increased (P < 0.01) after feeding for starch compared to oil and fat. No consistent effect of Cr or Cr x ME level on performance or carcass was observed (P > 0.10) in these experiments. Similarly, no Cr effect or Cr x ME interaction (P > 0.10) was observed in plasma glucose or insulin levels. Dietary energy levels markedly affected growth criteria in growing pigs (23 to 68 kg) in these experiments, as anticipated, but supplemental Cr was without effect on performance or carcass responses.     

The nutritional value of degermed,dehulled corn for pigs and its impact on the gastrointestinal tract and nutrient excretion

Three experiments were designed to assess the feeding value and potential environmental benefits of feeding degermed, dehulled corn, a low fiber by-product originating from the corn dry milling process, to pigs. Twelve 27-kg (SE = 0.8) barrows were used in Exp. 1 to measure the apparent fecal digestibility of DM, GE and N of degermed, dehulled corn compared with corn grain. Two diets were formulated to contain either 96.4% of degermed, dehulled corn or corn grain plus supplemental vitamins and minerals. Digestibilities of DM, GE, and N were greater in degermed, dehulled corn (96.2, 96.0, and 93.6%, respectively) compared with corn grain (89.0, 89.0, and 78.4%, respectively) (P < 0.01). Overall, a 67 and 29% reduction in DM and N excretion, respectively, was observed. In Exp. 2, eight 70-kg (SE =1.8) barrows were surgically fitted with ileal cannulae and fed the same diets as in Exp. 1, to measure the ileal digestibility of nutrients in degermed, dehulled corn. Ileal digestibility of DM, energy, and N was 13, 15, and 7% greater in degermed, dehulled corn (P < 0.05). Apparent ileal digestibility coefficients of leucine, methionine, and phenylalanine were greater in degermed, dehulled corn compared with corn grain (P < 0.05) while a trend for a lower tryptophan digestibility in degermed, dehulled corn was observed (P = 0.067). In Experiment 3, 96 nursery pigs with an initial average BW of 8.8 kg (SE = 0.08), fed a starter diet formulated with degermed, dehulled corn or corn grain as the major grain source, were used in a 28-d growth performance study. At the end of the study, 24 pigs (1 pig per pen) were sacrificed and gastrointestinal tract measurements were taken. Daily growth rates of pigs were the same between diets (0.64 kg/d). A trend for reduced feed intake (P = 0.073) in pigs fed degermed, dehulled corn led to a 4% improvement in gain to feed (P < 0.05). Feeding degermed, dehulled corn had no effect on gut fill, gastrointestinal tract weight, or liver weight (P > 0.05). Ileal villus lengths and crypt depths were not affected by feeding degermed, dehulled corn although ileal villus widths were greater in pigs fed corn grain. Results from these trials suggest that corn processed to remove poorly digestible fiber fractions provides more digestible nutrients than corn grain. As a result, degermed, dehulled corn reduces fecal and N excretion, thus providing a means to reduce nutrient excretion.     

A prolonged photoperiod improves feed intake and energy metabolism of weanling pigs

In a 2-wk experiment, the effect of photoperiod on performance and energy metabolism of newly weaned pigs was studied. Forty 4-wk-old crossbred weanling barrows weighing 8.0 kg (SE = 0.13) were assigned to one of eight groups (five pigs per group) based on BW and litter. Groups were allotted to one of two lighting schedules: 8 h light:16 h darkness or 23 h light:1 h darkness. Each group was housed in a climate respiration chamber. Piglets had ad libitum access to feed and water. Energy and nitrogen balances, heat production, ADFI, and ADG were measured weekly. Heat production, energy metabolism, and performance were unaffected (P > 0.10) by photoperiod during wk 1. However, in the 2nd wk ADFI (418 vs 302 g/d) and ADG (381 vs 240 g/d) were higher (P < 0.05 and P = 0.05, respectively) for pigs on the 23:1 h lighting schedule than for those on the 8:16 h schedule. Furthermore, heat production (P < 0.10), total energy retention, and energy retained as protein and as fat were higher (P < 0.05) during wk 2 in pigs on the 23:1 h lighting schedule (8, 125, 41, and 350%, respectively) than in those on the 8:16 h schedule. Moreover, metabolizability of energy tended to be higher (P < 0.10) and energy requirements for maintenance were lower (P < 0.05) during wk 2 for pigs on the 23:1 h schedule compared with those on the 8:16 h schedule (P < 0.10). In conclusion, exposing pigs to a longer period of light after weaning stimulated ADFI and ADG. In addition to the feed intake, the high ADG is due to an improved metabolizability of energy and a reduced energy requirement for maintenance. This study suggests that lighting schedule can be used as a tool to stimulate feed intake after weaning.