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Within all cattle production systems, veal calves are the most severely affected by abomasal damage, with current prevalence at slaughter ranging from 70 to 93% of all animals affected. Although most damage is found in the pyloric region of the abomasum, fundic lesions are also found. Despite past research into the etiology of abomasal damage and the many risk factors that have been proposed, consensus on the causal factors of abomasal damage in veal calves has not yet been reached. The aim of this review was to integrate and analyze available information on the etiology of, and possible risk factors for, abomasal damage in veal calves. We describe various proposed pathways through which risk factors may contribute to damage formation and conclude that the etiology of abomasal damage is most likely multifactorial, with diet being a main contributor. Pyloric lesions, the most common type of damage in veal calves, are likely the result of large and infrequent milk and solid feed meals, whereas fundic lesions may be caused by stress, although the evidence for this is inconclusive. Providing calves with multiple smaller milk and solid feed meals (or ad libitum provision) may decrease abomasal damage. In future research, ulcers, erosions, and scars as well as fundic and pyloric lesions should be recorded separately, because etiologies of these may differ. Further research is required to understand the exact pathway(s) by which milk replacer causes abomasal damage in veal calves; that is, whether low abomasal pH, overloading, or composition are important. Further research is also required to elucidate whether rapid intake of milk replacer and solid feed, which is influenced by restricted amounts fed, inter-calf competition, and calf breed, increases abomasal damage. Research is also needed into the effect of medication and nutrient deficiencies other than iron. The types of experimental designs that can be used for future research could be enhanced if a means to assess abomasal damage antemortem is developed. We conclude that it is unlikely that abomasal or ruminal hairballs, iron deficiency, water provision, and various infections and diseases are significant contributors to abomasal damage in veal calves.

Weaning of piglets causes stress due to environmental, behavioral, and nutritional stressors and can lead to postweaning diarrhea and impaired gut development. The diet changes experienced during weaning require extensive adaptation of the digestive system. A well-developed piglet that had creep-feed experience before weaning performs better after weaning. In the current study, the effect of providing sow-fed piglets with a supplemental nutrient-dense complex milk replacer (NDM) on gut development and growth performance was studied. Litters of sows with similar parities (3.6 ± 0.8) and similar numbers of live born piglets (13.5 ± 0.3) were assigned to 1 of 2 groups: 1 group of piglets had ad libitum access to NDM from Day 2 through 21 after birth, whereas the other group was used as controls. Nutrient-dense complex milk replacer-fed piglets were shown to be significantly heavier after 21 d of supplementation compared with the control piglets. At Day 21, 3 piglets from each litter were euthanized for morphological and functional analyses of the intestinal tract. The small intestines of NDM-fed piglets had significantly higher weights (g) as well as significantly higher relative weight:length ratios (g//cm) compared with the small intestines of control piglets (0.05). Morphometric analysis demonstrated that villi length and numbers of goblet cells did not differ between groups. However, NDM-fed piglets had deeper crypts (0.001) and an increased expression of the cell-proliferation marker proliferating cell nuclear antigen in crypts (0.05), suggesting higher cell-proliferation rates. The gene encoding IGF-1 showed a tendency to higher gene expression in the jejunum from NDM-fed piglets ( = 0.07) compared with the jejunum from control piglets, suggesting that IGF-1 might be involved in the regulation of cell proliferation and intestinal growth. Finally, as a result of dietary fiber in NDM, piglets showed significantly increased concentrations of metabolic fermentation products. This suggests differences in metabolic activity in the colon between treatment groups. In conclusion, providing sow-fed piglets with NDM before weaning stimulates intestinal proliferation, leading to increased circular growth. Nutrient-dense complex milk replacer supplementation might, therefore, help piglets through the transition period at weaning by increased BW and increased capacity for uptake of nutrients.

Malabsorption syndrome (MAS) is a multifactorial disease that causes intestinal disorders in broilers due to infection of the gastrointestinal tract with different infectious agents. The exact aetiology is unknown, although several viruses are isolated from MAS affected chickens. None of these isolated infectious agents alone inducted the malabsorption syndrome. MAS in broilers is characterised by poor growth and lesions in the Gl-tract, mainly in the small intestine. Experimentally, MAS can be induced in one-day old broilers by oral inoculation of homogenates obtained from digestive tract tissues of MAS affected broilers. Susceptibility to the MAS syndrome differs between broiler lines. The susceptibility to MAS is correlated with the severity of the lesions, apoptosis and heterophil infiltration of the jejunum. Susceptibility to MAS is also related to the frequency of CD4 and CDS positive T-cells in the intestinal villus and the mRNA expression level of different cytokines in control and in MAS induced broilers. With the use of micro-arrays differences in gene expression levels between broiler lines that differ in MAS susceptibility were observed. From these experiments genes that are immune and food absorption related were identified. If some of these genes or the T-cell population in the gut and the other MAS susceptible related parameters could predict or prevent MAS susceptibility in broilers needs to be further investigated but can be interestingly for breeding programmes.

In a case-control study, the role of porcine circovirus 2 (PCV2) and putative co-factors in the development of porcine dermatitis and nephropathy syndrome (PDNS) were investigated. Pigs with and without PDNS were examined for macroscopic lesions and histopathology. In addition, organs and tissues were collected at necropsy and examined for the presence of fibrinous deposits (immune complexes), CD8+ cells, and for the presence of bacterial and viral infections. Results from PDNS cases were compared with those of three control groups comprising pigs without clinical signs of PDNS and selected from; (1) the same compartment as PDNS cases, (2) another compartment but in the same PDNS herd, and (3) a control herd without any history of PDNS or post-weaning multisystemic wasting syndrome. Macroscopic and histopathological lesions found in PDNS cases were comparable to those previously documented for PDNS e.g. skin lesions and renal lesions representing glomerulonephritis associated with fibrinous deposits and to a lesser extent with interstitial nephritis. PCV2 was detected by PCR in 100% of the PDNS cases, mainly in lymph nodes and tonsils, and in 63% of the control pigs from PDNS free herds. Virus isolation did not reveal infectious PCV2 in all cases. In PDNS affected pigs the PCV2 serum antibody titres were consistently extremely high and the mean PCV2 antibody titre in PDNS pigs was significantly higher than the mean PCV2 antibody titres in pigs from all 3 control groups. Immunohistochemical investigation of kidneys from PDNS affected pigs revealed an increased accumulation of IgG1 + IgG2 and IgM, the complement factors C1q and C3, but also an increase of CD8+ cells. The amounts of IgA and the complement factor C5 in kidneys of PDNS pigs were only slightly increased as compared to control pigs. This study demonstrates that PCV2 infections can result in extremely high PCV2 antibody titres and that PCV2 is a candidate as primary agent in the development of PDNS. The causative physiological basis for PDNS may be the excessive levels of PCV2 antibodies.

Paratuberculosis is a chronic and progressive disease of the intestine in ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map). The bacterium is transmitted to young animals, becomes manifest in adulthood and leads to economic losses. The aim of this study is to investigate if cows shedding Map possess oocytes and embryos that are carriers of the bacterium. New genetical material can enter the dairy farm using embryo transfer but the question as to whether this technique is safe with respect to transmission of paratuberculosis has yet to be addressed. We selected and bought 16 cows, all proven to be moderate shedders of the bacterium in the faeces immediately prior to the experiment but none were clinically sick. One sample of uterine content was collected from each animal by flushing the uterus on the day of heat and five samples of homogenised uterine tissue were collected on the eighth day of the same cycle by biopsy. In addition, 217 cumulus-oocyte complexes (COCs), ranging from 3 to 35 COCs per animal, were collected using ultrasound guided transvaginal puncture of the ovarian follicles (OPU). On the seventh day of the subsequent cycle 31 embryos were obtained using the classic technique of super ovulation induction, artificial insemination (AI), followed by flushing of the uterus. These embryos have been washed and trypsinised. Fourteen of the 16 cows were treated again for super ovulation in the subsequent cycle and 19 foetuses were collected by opening of the uterus after euthanasia on Days 35-49 of the cycle. All samples were cultured for presence of Map and checked every 2 months during 1 year for bacterial growth. None of the samples showed growth of Map after 12 months of culture. Pathological examination of the cows revealed different degrees of severity of pathological alterations of the intestinal tract and mesenteric lymph nodes. However, the results suggest that neither in vivo embryo's nor oocytes are carriers of the bacteria and do not form an extra risk at transfer. However, due to the limited size of the experiment (sample size of 16 cows), a certain margin for error remains.

To study the effect of a previous porcine respiratory and reproductive syndrome-infection (PRRS) of the respiratory tract on influenza virus and Actinobacillus pleuropneumoniae (App) infections, 3-week-old specific-pathogen-free (spf) piglets were intranasally infected with PRRS virus. One week later, when the lung alveolar macrophages of PRRSV infected pigs were lowest in number, a second infection was applied by intranasal aerosol of influenza virus H3N2 or by endobronchial instillation of a mildly virulent App. The first experiment consisted of two groups (only influenza infection or dual PRRSV/influenza infection). A second experiment consisted of 4 groups (only influenza infection, only PRRSV infection, dual PRRSV/influenza infection and uninfected controls). At day 2, 4, 14 and 21 after influenza infection, two pigs were killed and sampled for virological and histopathological examination. Influenza H3N2 virus caused only a mild inflammation of the smaller bronchioli. Previous PRRSV infection did not influence clinical signs during influenza infection. Next, we studied in two experiments the effect of dual PRRSV/App infection during the acute stage at two days after App infection. In a third experiment, the influence of PRRSV on more chronic stages of App infection was studied at two weeks after the App infection. At the end of the experiments, the pigs were killed. Lungs were ranked according to size and kind of the lesions. Lesions were cut and measured, samples were taken for virological and histopathological examination. Statistical analysis of the ranked lung-lesions in the first experiment showed a distinct but small effect of previous PRRSV infection on the development of App-lesions. In PRRSV infected pigs, App produced a more severe disease. The second and third experiment however failed to show any influence of the previous PRRSV infection on the App infection. We conclude that previous PRRSV infection of the respiratory tract of spf pigs does not necessarily enhance the severity of secondary infections of the respiratory tract. Author Keywords: Porcine reproductive and respiratory syndrome virus; Swine influenza virus; Actinobacillus pleuropneumoniae; Dual infections; Pigs

The study aimed at assessing the prevalence of poor rumen development, presence of rumen plaques, rumen papillae hyperkeratinization, and abomasal lesions in veal calves and to investigate risk factors for their occurrence at the farm level. Within a wide cross-sectional study, a sample of 170 veal farms representative of the European veal meat production systems was considered in the 3 major producing countries (99 in the Netherlands, 47 in France, and 24 in Italy). An average of 59±10 (SD) rumens and abomasa belonging to calves from a single batch per farm were inspected at the abattoir by trained observers to assess the incidence of these gastrointestinal disorders. Potential risk factors for their occurrence related to farm management, housing, and to the feeding plan were obtained by a questionnaire submitted to the stockperson. Prevalence of poor rumen development (almost no papillae present), rumen plaques, and hyperkeratinization were 60.4, 31.4, and 6.1% of rumens, respectively, whereas abomasal lesions in the pyloric area were recorded in 74.1% of abomasa. Independent variables related to the feeding system confirmed to be the main risk factors for the occurrence of gastrointestinal disorders in veal calves. However, additional risk sources for each given problem were identified among housing and management variables. The provision of a low amount of solid feed (≤50kg of dry matter/head per cycle) was a relevant risk for rumen underdevelopment. Rumen wall alterations (plaques and hyperkeratinization) and abomasal lesions were instead associated with the administration of large quantities of solids (151–300kg of dry matter/head per cycle) in calves receiving milk replacer during the entire fattening cycle. Among the types of solid feed, cereal grain acted as a preventive measure for low rumen development, whereas it was a risk factor for the occurrence of rumen plaques, papillae hyperkeratinization, and abomasal lesions. Some housing and management options adopted to improve veal calf welfare (i.e., higher space allowance and use of heating) were associated with lower risk for gastrointestinal disorders.

Sixty-four male Holstein-Friesian x Dutch Friesian veal calves (46 +/- 3.0 kg) were used to evaluate the effect of the inclusion of different levels and sources of dietary roughage on animal performance and rumen development. Treatments consisted of 1) C100 = concentrate only; 2) C70-S30 = concentrate (70%) with straw (30%), 3) C70-G30 = concentrate (70%) with dried grass (30%), 4) C70-G15-S15 = concentrate (70%) with dried grass (15%) and straw (15%), 5) C70-CS30 = concentrate (70%) with corn silage (30%), 6) C40-CS60 = concentrate (40%) with corn silage (60%), 7) C70-CS30-AL = concentrate (70%) with corn silage (30%) ad libitum, 8) C70-G15-S15-AL = concentrate (70%) with dried grass (15%) and straw (15%) ad libitum. All dietary treatments were provided in addition to a commercial milk replacer. Concentrate was provided as pellets and roughage was chopped. The dietary treatments 1 to 6 were supplied restrictedly to a maximum of 750 g of dry matter (DM) per day, whereas treatments 7 and 8 were offered ad libitum in combination with a reduced amount of milk replacer. Calves were euthanized after 10 wk. Straw supplementation (C70-S30 vs. C70-G30 and C70-CS30) reduced DM intake, and ad libitum supply of concentrate and roughage increased DM intake. Roughage addition did not affect growth performance. Rumen fermentation was characterized by low pH and high total volatile fatty acids and reducing sugar concentrations. Calves fed ad libitum showed lower ruminal lactate concentrations than calves fed restrictedly. Ammonia concentrations were highest in calves fed C-100 and lowest in calves fed ad libitum. The recovery of CoEDTA (added to milk replacer) varied between 20.5 and 34.9%, indicating that significant amounts of milk entered the rumen. Roughage addition decreased the incidence of plaque formation (rumen mucosa containing focal or multifocal patches with coalescing and adhering papillae covered by a sticky mass of feed, hair and cell debris) and the incidence of calves with poorly developed rumen mucosa. However, morphometric parameters of the rumen wall were hardly influenced by the type and level of roughage. Ruminal polysaccharide-degrading enzyme activities reflected the adaptation of the microorganisms to the dietary concentrate and roughage source. Results indicated that in veal calves, the addition of roughage to concentrate diets did not affect growth performance and positively influenced the macroscopic appearance of the rumen wall.

In this study, 60 pigs with clinical signs of post-weaning multisystemic wasting syndrome (PMWS) from 20 different pig herds and 180 control pigs (without clinical signs of PMWS) were examined to get more insights into the frequencies of porcine circovirus 2 infections and the presence of co-infections in pigs with and without clinical signs of PMWS in the Netherlands. Porcine circovirus type 2 was detected in 100% of the pigs with clinical signs of PMWS by virus isolation and/or PCR and in 50% of the pigs from PMWS-free herds. There was an association between the levels of infectious PCV2 and/or PCV2 DNA load and the severity of clinical signs as described for PMWS. A high variation in PCV2 antibody titres was found in the clinically affected pigs, and 27% of these pigs did not mount PCV2 antibody titres higher than 1:200. A concurrent infection of PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV) was found in at least 83% of the pigs with clinical signs of PMWS and in 35% of the pigs from PMWS-free herds. Co-infections of European- and American-type PRRSV were detected only in PMWS herds and in one control herd with a history of PMWS clinical signs.

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. (C) 2003 Elsevier Science B.V. All rights reserved.

A 2 year-old cow with abnormal behaviour was observed during a farm visit. Rectal palpation of the cow revealed the presence of a mass of at least 12 cm in diameter. After further examination, it appeared that 'ovarian tumour' was the most likely differential diagnosis. In order to confirm this diagnosis, blood samples were drawn and analysed for plasma progesterone and plasma oestradiol-17 beta concentrations. Also, the gross pathology and histology of the mass were evaluated. The combination of the clinical presentation of the cow, the hormone concentrations, and the histological appearance of the mass confirmed the diagnosis ovarian tumour. The tumour was classified as granulosa-theca cell tumour.

Four pigs, each of about 8 weeks of age were submitted for pathological examination because of severe cachexia, combined with an enormous distension of the abdomen. In the herd, where these pigs originated from, these clinical signs were observed frequently for some period of time and stricture of the rectum was suspected. All pigs showed a severe cachexia, and most prominent in all pigs was a megacolon with large and distended colon and caecum and stenosis about 30 to 60 cm cranial of the anus. Tissue specimens were taken from the rectum, from the colon cranial and caudal of the stenosis and from the jejunum and examined histologically. Ganglia in the intestinal wall were examined immunohistochemically by using antibodies recognising neurofilament protein (kD 200). In all pigs submucosal and myenteric ganglia were absent in the post stenotic colon and rectum and in transverse section of the stenosis, whereas in the prestenotic colon of all pigs and also in the jejunum ganglia were present. Segmental aganglionosis of the colon is also known in humans (Hirschsprung disease) and other animal species and is considered as a congenital disorder. We also suggest a familiar background of the disease in these pigs.

To determine a possible relationship between the compulsory vaccination against bovine herpesvirus 1 (BHV1) and cattle wasting disease, the effects of BHV1 vaccination on heifers were investigated. Twenty heifers in the third trimester of pregnancy were randomly allotted to a vaccine and a control group. The vaccine group was vaccinated twice with a 50-fold dose of BHV1 vaccine and the control group was inoculated with the diluent. The experiment was performed double blind. After vaccination, the cows were examined daily and condition scores were determined weekly. Blood, milk, and faeces samples were collected weekly for virological, bacteriological, and immunological investigation. The heifers were euthanized either 9 or 13 weeks after the first inoculation and pathological, virological, and bacteriological examination was performed. No differences were detected between the vaccine group and the control group. No concurrent infections were detected and there were no indications of immunosuppression after vaccination. No relationship between the BHV1 vaccination and wasting disease in cattle was detected.

In forty-five Holstein Frisian dairy cows (1-6 weeks post partum; mean age: 5.1 +/- 1.2 years) the serum total bile acid concentrations (SBA) were measured enzymatically. In all cows a left sided abomasal displacement was corrected surgically by right side laparotomy and omentopexy three days before investigation. The liver fat content was determined in all cows histologically. Liver failure was assumed if typical clinical signs (ataxia, general depression, recumbency or coma), an increased venous plasma ammonia level (35 mumol/l) and a decreased plasma amino acid index (4.0) were found. Cows without liver failure (N = 29) were grouped according to the liver fat content as cows with mild (N = 5), moderate (N = 19) or severe hepatosteatosis (N = 5). Histological examination of liver biopsies in cows with liver failure (N = 16) revealed in twelve cases a severe fatty liver and in four cases a hydropic degeneration of the liver tissue. Although in cows without liver failure mean SBA concentrations were higher in the group with moderate (47.3 +/- 30.9 mumol/l) or severe fatty liver (32.9 +/- 21.7 mumol/l) than in that with mild lipidosis (18.0 (16.8 mumol/l), differences were not significant. The mean SBA concentration in cows with liver failure (70.5 +/- 49.5 mumol/l) was only significantly (p0.05) increased compared to cows with uncomplicated mild hepatic lipidosis. In conclusion, the determination of SBA concentrations is of little value in the recognition of fatty liver or even liver failure due to the considerable variance of SBA concentrations in dairy cows.

On a pig farm with about 2000 pigs, respiratory problems regularly developed in fattening pigs 3 to 4 weeks after the start of the fattening period. A postmortem examination was carried out on four pigs during the acute phase of their illness. The animals showed signs of viral pneumonia. In two animals porcine respiratory virus (PRCV) was discovered and in the other two animals porcine reproductive and respiratory syndrome virus (PRRSV). The possible role of these two viruses in the aetiology of the health problems on this farm is discussed in the context of the results of a longitudinal serological study.

Blood parameters, feed intake and milk yield were determined in 53 cows with a left displacement of the abomasum (LDA) on the day of surgery (ds; laparotomy and omentopexy) and during the following four days (d1-d4). Using histological methods severe (group SF), moderate (group MF) or no/mild (group NF) fatty liver was found in 32%, 40% and 28% of the patients, respectively. Moderate and severe fatty liver were found almost exclusively in cows in the first three weeks post partum. Post surgery, feed intake and daily milk yield increased steadily in cows of the NF- and MF-group; in cows suffering from severe fatty liver feed intake remained low (p0.05). On ds, mean serum levels of nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), total bilirubin, aspartate aminotransferase (ASAT), gammaglutamyl transpeptidase (GGT) and glutamic dehydrogenase (GLDH) in SF-cows were significantly (p0.05) higher and values of cholesterol significantly lower (p0.05) as compared to the NF- and MF-group; no significant differences were found between the groups in mean serum glucose concentrations. In the four day period following surgery, in all groups mean serum levels of ASAT, GGT, GLDH and cholesterol remained nearly unchanged, whereas total bilirubin, NEFA, BHB and glucose decreased significantly (p0.05). Apart from LDA, 55% of the patients were suffering from mastitis, endometritis or lameness. Within three weeks post surgery, 3 cows of the SF-group and 1 cow of the MF-group developed recumbency and liver coma, and were culled for that reason. In conclusion, post surgical convalescence of cows with LDA is clearly related to disturbances of energy metabolism and fatty liver. Therefore, successful treatment of cows suffering from LDA requires the effective treatment of excessive lipomobilization, ketosis and fatty liver along with the immediate surgical correction of LDA.

OBJECTIVE--To evaluate the functional importance of impaired reticular contractions attributable to inflammatory adhesions in the pathogenesis of vagus indigestion in cows with traumatic reticuloperitonitis (TRP). DESIGN--Case control study. ANIMALS--42 dairy cows with TRP were compared with 10 healthy control cows. Cows with TRP were assigned to 3 groups: cows with uncomplicated TRP (n = 15), cows with TRP and a disturbance of digesta passage through the reticular-omasal orifice (TRP-AD; n = 17), and cows with TRP and a disturbance of digesta passage through the pylorus (TRP-PD; n = 10). PROCEDURE--Cows were evaluated, using routine clinical methods, biochemical analysis of blood and ruminal fluid samples, exploratory rumenotomy, and postmortem examination. RESULTS--Damage of thoracic and abdominal parts of the main vagal branches were not evident in cows with TRP. Parareticular inflammatory adhesions were more extensive in cows with TRP-AD and in cows with TRP-PD than in cows with uncomplicated TRP. Reticular motility was decreased in cows with TRP-AD and TRP-PD, compared with cows with uncomplicated TRP and control cows. In contrast to cows with uncomplicated TRP and cows with TRP-AD, the abomasum was impacted with large amounts of long fibrous material in most of the cows with TRP-PD. CLINICAL IMPLICATIONS--We believe that disturbances of digesta passage in cows with TRP represent distinct stages of a common pathogenetic course. The primary disease mechanism was a disturbance in particle-separating processes in the reticulum/rumen attributable to mechanical inhibition of reticular motility that was the result of extensive inflammatory parareticular adhesions.

A dose-defined aerosol infection of pigs was used to study the immunogenic and protective potentials of oral immunization with dead or live Actinobacillus pleuropneumoniae serotype 9 reference strain CVI 13261 against an aerogenic challenge. Pigs were vaccinated with a single dose of 10(11) CFU of viable (n = 8) or inactivated (n = 8) A. pleuropneumoniae given orally in a gelatin capsule. After 3 weeks, vaccinated pigs and nonvaccinated controls were challenged aerogenically with a dose of 10(8) CFU of A. pleuropneumoniae CVI 13261. The protective efficacy of oral immunization was evaluated by clinical and postmortem examinations. Bronchoalveolar lavage in pigs was performed during the experiment to obtain lavage samples for assessment of local antibodies. Isotype-specific antibody responses in sera and in bronchoalveolar lavage fluids were determined by enzyme-linked immunosorbent assays based on whole-cell antigen. Oral immunization did not induce clinical side effects. After aerosol challenge, two animals of both vaccinated groups (25% in each case) showed a moderate fever for 2 days, whereas all four pigs (100%) of the nonvaccinated control group developed severe fever. In contrast to the controls, which developed severe pleuropneumonia, the vaccinated pigs had only mild pulmonary lesions. Three weeks after challenge, 13 of 16 vaccinated pigs (81%) were found to be free of pathomorphological changes of the lungs. From two of these pigs immunized with live bacteria we were able to reisolate A. pleuropneumoniae. A significant systemic and pulmonary increase in the concentrations of immunoglobulin A (IgA), IgM, and IgG antibodies reactive with A. pleuropneumoniae was detectable after aerosol challenge in both vaccinated groups. Immunization with viable bacteria was found to induce significantly higher concentrations of each Ig isotype in bronchoalveolar lavage fluids and sera than immunization with inactivated A. pleuropneumoniae. These serological findings were not reflected in the reduction in clinical disease after challenge in comparison to the case for the pigs vaccinated with inactivated bacteria. We concluded that a single oral administration of A. pleuropneumoniae provides partial clinical protection against aerosol challenge infection in the respiratory tract.

Tyzzer's disease, caused by Bacillus piliformis and characterized by a multifocal, necrotizing hepatitis was diagnosed in a 25 days old, male, German warmblood foal. The animal was submitted to the clinic of horses because of colic symptoms and a severe depression. Upon arrival it was comatose, recumbent and showed opisthotonos. Due to a severe, metabolic acidosis and a rapid progression of the disease, the foal was euthanatized. In immediately formalin-fixed tissue samples Bacillus piliformis was detected in the cytoplasma of hepatocytes by different histological techniques (Giemsa stain, silver impregnation technique by Warthin-Starry, immunohistology). This case is discussed within a literature review.

This article briefly describes the PRRS (Porcine Reproductive and Respiratory Syndrome), which arose in the winter of 1990 in Germany and other European countries. The data are accumulated from the literature and own experiences. The clinical picture of this new disease, which led to important economical losses is dominated by 1. an increased rate of reduced length of pregnancy with late abortion before day 110 or an increased length of pregnancy; 2. an increase of stillborn piglets; 3. a larger scale of preweaning mortality combined with a higher frequency of secondary infections. Pathological findings in piglets are subcutaneous edema, accumulation of fluids in the body cavities and sometimes interstitial pneumonia is observed. In sows originating from affected farms examined before partus a mononuclear placentitis is present. At present a non-classified virus, isolated by Dutch researchers is proposed to be the causative agent and named Lelystad virus.

Acute to subacute vitamin D toxicosis is described in two different fattening pig herds. A few days after admixing a new batch of vitamin/mineral-premix most of the fattening hogs developed anorexia, polydipsia and polyuria. Emesis was seen in some of the animals. About two weeks after consumption of the suspected feed two thirds of the pigs had a rough hair coat and a very poor weight gain. Because of the results of haematological and metabolic findings from blood and urine samples of diseased pigs a calcinosis and tubular nephrosis was diagnosed. Patho-histological findings of the euthanatized morbid pigs included severe chronic interstitial nephritis, glomerulonephritis and mineralisation of a number of organs. Some of the animals showed degeneration of the myocardium. Feeding two healthy pigs with the incriminated feed the disease was reproduced.

In a flock of sheep to which food with excess copper (= Cu) had been fed for some months 39 animals died of chronic copper toxicosis. In 5 sheep of this flock the plasma concentrations of the enzymes glutamate dehydrogenase (GLDH), sorbitol dehydrogenase (SDH), aspartate-amino-transferase (ASAT) and copper were measured several times over a period of 100 days. At day 23, 58 and 97 needle biopsies of the liver were taken. The biopsies were used for histological examination and Cu-analysis. After 100 days the sheep were slaughtered and chronic copper poisoning was diagnosed by raised Cu concentration and typical histological alterations in the liver. The activities of GLDH and SDH in the plasma of the 5 sheep were consistently above normal, ASAT activity and the plasma Cu level were raised only occasionally. The results of Cu determination in biopsy samples were of little predictive value compared with post mortem Cu analysis of the liver.

In an investigation over five months the adrenal toxic effect of the quinoxaline derivate olaquindox in pigs of different ages (10 and 16 weeks) after accidental feeding of a 15-fold overdosage of olaquindox is demonstrated. The substance induced clinical and hematological changes comparable with Addison's disease. A reduced gain of body weight was observed, predominant hematological findings were a hyperkalemia and a hyponatremia, which reversed to normal values after 17 weeks in the younger group and after 14 weeks in the older group. Whereas five weeks after the first intake of the feed, degenerative changes of the zona arcuata were most prominent, a destructive fibrosis and a reduction of the adrenal cortex were more marked 12 and 13 weeks later. Due to the loss of aldosterone the electrolyte imbalances led to degenerative changes in the skeletal muscles and in the myocardium. Pigs of younger age were more affected than elder ones. Subcapsular cells with basophilic nuclei resembling normal cells of the zona arcuata appear 18 to 22 weeks after the first overdosage of olaquindox and are suggestive in combination with normal electrolyte values of a regeneration of the zona arcuata.

An acute outbreak of encephalomyelitis in lions from a safari-park was investigated. Three moribund lions were euthanatized and a post mortem examination was performed. A disseminated non-suppurative polioencephalomyelitis with demyelination in the spinal cord was the only pathological finding. From tonsil material of one lion feline herpesvirus type 1 was isolated. Canine distemper virus, pseudorabies virus, feline infectious peritonitis virus and rabies were excluded as cause of the disease. The possible role of FHV-1 in etiology of the disease is discussed.

A method has been developed for the isolation of bovine type II pneumocytes by enzymatic tissue dissociation and subsequent density gradient centrifugation. After mechanical defibrination, the crude cell suspension contains 71.9 +/- 26.6 X 10(7) cells (viability greater than 95%) with a type II cell purity of 39.4 +/- 10.9%. Due to their low buoyant density, bovine type II pneumocytes can be purified in a single step to 95.7 +/- 1.7% by discontinuous density gradient centrifugation on a 1.040 g/ml Percoll gradient. Isolated cells are identified by light and fluorescence microscopy that show their characteristic intracytoplasmatic surfactant granules. The fine structure of the surfactant lamellar bodies is examined in ultra thin sectioned and freeze-fractured type II pneumocytes. Isolation of bovine type II pneumocytes for the in vitro study of the surfactant system offers an alternative to the use of laboratory animals and provides an ideal system for the isolation of any desired cell number from one animal by simply increasing the size of the lung segment to be trypsinized.

A pig grower ration containing olaquindox at a concentration of 778 mg/kg was accidentally fed to 10 respectively 16 weeks old weaner pigs. The subsequent intoxication was characterized by poor growth and long-term disturbances of renal function and electrolyte metabolism. A deficiency of aldosterone, produced by a selective degeneration of the arcuate zone of the adrenal cortex, is probably the cause of the hyponatremia, hyperkalemia and hemoconcentration observed. Simultaneously plasma levels of urea and creatinine were elevated five- to eightfold. Due to hyperkalemia episodes with collapse, paralysis and severe electrocardiographic changes occurred several times. Two pigs died in the course of such attacks. Individuals, which transiently showed distinct clinical symptoms of intoxication, did not show any signs of disease 15 or 18 weeks later. Therefore it may be assumed, that the lesions of the adrenals, heart and skeletal muscle caused by olaquindox intoxication are reversible in some cases.

Hexane-extracted calendula meal was tested in an acceptance trial with eighty 8–13 weeks old crossbred pigs to determine their response to diets containing 0, 2, 6, 10 or 20% calendula meal. Performance parameters included feed intake, daily growth and post mortem histopathological examination of vital organs. Pigs fed a diet containing 2% calendula meal consumed significantly more feed than the ones fed a calendula-free diet. As the calendula meal content of the diet increased, feed intake tended to decrease.Post mortem examination of vital organs showed statistically significant (P < 0.10) between-treatment differences in heart, kidney, thyroid and pancreas size expressed as percentage of bodyweight.The results of blood and blood serum analyses for haematocrit, haemoglobin, oxygenated haemoglobin, aspartate-aminotransferase, alanine-aminotransferase, lactate dehydrogenase, creatinine and zinc remained within the reference values for young pigs.Although calendula meal showed potential as a ration ingredient for young pigs it is advised not to include more than 10% of it in the diet.

A pig grower ration containing olaquindox at a concentration of 778 mg/kg was accidentally fed to 10 respectively 16 weeks old weaner pigs. The subsequent intoxication was characterized by poor growth and long-term disturbances of renal function and electrolyte metabolism. A deficiency of aldosterone, produced by a selective degeneration of the arcuate zone of the adrenal cortex, is probably the cause of the hyponatremia, hyperkalemia and hemoconcentration observed. Simultaneously plasma levels of urea and creatinine were elevated five- to eightfold. Due to hyperkalemia episodes with collapse, paralysis and severe electrocardiographic changes occurred several times. Two pigs died in the course of such attacks. Individuals, which transiently showed distinct clinical symptoms of intoxication, did not show any signs of disease 15 or 18 weeks later. Therefore it may be assumed, that the lesions of the adrenals, heart and skeletal muscle caused by olaquindox intoxication are reversible in some cases.

The objective of this experiment was to examine the effects of concentrates in feed, differing in carbohydrate source, on the rumen development of veal calves. For this purpose, 160 male Holstein Friesian x Dutch Friesian crossbred calves were used in a complete randomized block design with a 5 x 2 factorial arrangement. Dietary treatments consisted of 1) a milk replacer control, 2) a pectin-based concentrate, 3) a neutral detergent fiber-based concentrate, 4) a starch-based concentrate, and 5) a mixed concentrate (equal amounts of the concentrates in treatments 2, 3, and 4). Concentrate diets were provided as pellets in addition to a commercial milk replacer. Calves were euthanized at either 8 or 12 wk of age. Plasma acetate and beta-hydroxybutyrate (BHBA) were measured as indicators of rumen development. Empty rumen weight was determined, and wall samples were taken at slaughter. In most calves, a poorly developed rumen mucosa was observed. Coalescing rumen papillae with embedded hair, feed particles, and cell debris were found in all calves fed the concentrate diets. Calves fed concentrates had significantly heavier rumens than calves fed the control diet. In the dorsal location of the rumen, calves fed concentrate diets showed an increased ratio of mucosa to serosa length compared with calves fed the control diet, whereas in the ventral location only, calves fed the pectin and mixed diets showed larger ratios of mucosa to serosa length. Mucosa thickness and muscle thickness were greater in the ventral and dorsal locations of the rumen, respectively. In both locations, the NDF diet resulted numerically in the lowest mucosa thickness and highest muscle thickness among the concentrate treatments. At 8 wk, calves fed the concentrate diets had higher plasma acetate concentrations than calves on the control treatment. However, at 12 wk, only NDF-fed calves showed significantly higher plasma acetate concentrations. The plasma BHBA concentrations of calves at 8 wk of age fed the pectin and mixed diets were higher than those of the control diet-fed calves. At 12 wk, no differences in BHBA concentrations were observed among treatments. Results of a principal component analysis indicated that, in addition to rumen volatile fatty acid concentrations, other factors were likely to affect rumen development, and that the relationships between rumen development and individual types of volatile fatty acids present in the rumen liquor were similar. Also, variations in rumen development coincided with variations in plasma acetate and BHBA concentrations.

Young piglets are very susceptible to infections and therefore vaccination early after birth can help to decrease the disease incidence on swine farms. However, vaccination during the neonatal period is a challenge, because vaccination of newborn pigs is in general less successful compared to adult pigs. The innate and adaptive immune system are still developing during early-life and this results in qualitative and quantitative differences between the immune responses of newborn or neonatal pigs (< 1-week-old) and adult or immunocompetent (> 8-week-old) pigs after vaccination. Research has indicated that effective immuno-stimulators (adjuvants) in adult vaccines may not fulfil the requirements to stimulate the neonatal immune system effectively. Therefore, age-group-adapted vaccine formulations may be necessary to enhance the success of vaccination at an early age. The aim of this thesis was to investigate immune responses in neonatal and adult pigs after Toll-like receptor (TLR) stimulation to increase our understanding of the porcine (neonatal) immune system and the immune responses after vaccination in pigs of different age-groups. In addition to conventional intramuscular (i.m.) vaccination, skin vaccination was used as a delivery route, because skin has the potential to increase vaccine efficacy due to its abundance of antigen presenting cells (APCs). Porcine reproductive and respiratory syndrome virus (PRRSV) was selected as vaccine-antigen, because this is an endemic and important disease in the swine farming. In addition, to date no effective inactivated PRRSV-vaccine has been developed yet.In chapter 2, we studied dendritic cells (DCs) and showed that neonatal porcine DCs derived from blood were composed of the same DC subsets and DC proportions as their adult counterparts, namely: plasmacytoid DCs (pDC), and two types of conventional DCs (cDC1 and cDC2). After TLR1/2 or TLR9 stimulation peripheral blood mononuclear cells (PBMCs) and DCs were activated in both neonatal and adult pigs in an age-dependent way. The results of chapter 2 indicated that TLR1/2 agonists (TLR1/2a) and TLR9a could be promising adjuvant candidates in porcine vaccines for both age-classes.In chapter 3, neonatal and adult pigs were vaccinated in the skin using dissolving microneedle (DMN)-patches as the delivery system. The DMN-patches contained three different individual TLRa-vaccine formulations in combination with inactivated PRRSV (iPRRSV)-antigen. In this study, we investigated the early immune responses in skin and draining lymph nodes 24h after skin vaccination. The DMN-patches containing TLR7/8a induced the most pronounced immune and/or inflammatory response in both age-groups. In neonatal pigs a higher number of genes related to early immune responses were upregulated after TLR7/8a vaccination compared to the adult pigs in both the skin and draining LN, while no age-dependent difference for the local influx of immune cells and the number of APCs in the skin after TLR7/8a vaccination was found. Less striking local vaccine immune responses were noticed also after TLR1/2a and TLR9a application. These results suggested that neonatal and adult pigs could be effectively vaccinated in the skin, especially with TLR7/8a containing vaccines. However, age-dependent immune responses after skin vaccination could be expected.In the adult PRRSV vaccine-study (chapter 4) we investigated if the specific individual TLRa, which have shown in vitro potential (chapter 2) and induced early immune responses after skin vaccination (chapter 3), generated a protective immune response after vaccination in combination with iPRRSV-antigen. To study this, we administered the TLRa containing vaccines both i.m. and into the skin with the same DMN-patches as used in chapter 3. Pigs received a prime vaccination followed by a booster vaccination four weeks later. To measure vaccine efficacy the pigs were infected with PRRSV three weeks after the booster vaccination. In adult pigs TLR1/2a, TLR7/8a or TLR9a containing PRRSV-vaccines did not induce a detectable PRRSV-specific immune response, independent of the administration route. However, the i.m. administered TLR9a vaccine showed reduction of PRRSV shedding after infection compared to the non-vaccinated animals without detectable specific immune responses. In contrast, iPRRSV-antigen combined with the reference oil-in water (O/W) emulsion Montanide™ ISA28 (ISA28) induced an antigen-specific humoral immune response after booster vaccination combined with reduced shedding of PRRSV. A local skin immune response was observed after skin application of TLR7/8a. This skin reaction was comparable to that observed in adult pigs in chapter and was not observed in the other TLRa skin vaccines. These results indicated that the individual TLRa were less effective than the O/W reference adjuvant ISA28 .We considered it unlikely that the same TLRa containing vaccine would be more effective when administered in neonatal pigs. Therefore, in chapter 5 we decided to use different adjuvant formulations for the neonatal PRRSV-vaccine-study. In this study a mixture of the previously used TLRa (TLR1/2a+TLR7/8a+TLR9a) was combined with a squalene based O/W emulsion (SWE) and this vaccine formulation (SWE+TLRa) was administered i.m and into the skin with DMN-patches using a study design comparable to the adult PRRSV-study. The reference O/W adjuvant ISA28 was used in both the neonatal and adult PRRSV-vaccine study. In this neonatal study, only ISA28 induced a specific humoral immune response, while a specific cellular immune response was generated in the SWE group. This suggests that prime vaccination in neonates induced a specific immune response after booster vaccination, dependent on the O/W emulsion formulation, but not dependent on the presence of the TLRa or delivery route. In contrast to the adult pigs none of the vaccines in neonatal pigs with or without TLRa were able to reduce the viral shedding after PRRSV challenge. This study demonstrated that the O/W adjuvant ISA28 was less effective in neonatal pigs compared to adult pigs and that the TLRa in an adjuvant-mixture did not enhance the immune response in a PRRSV vaccineThis thesis showed age-dependent differential immune responses after in vitro and in vivo TLR stimulation and also with O/W adjuvanted PRRSV vaccination. This suggests that neonatal vaccines require a specific adjuvant choice. Further, I conclude that traditional O/W formulations induced a better detectable immune response than when the TLRa were used as adjuvant in combination with the iPRRSV-antigen. Also, we showed that skin vaccination with TLRa did not overcome the weak immunogenic potential of the iPRRSV-antigen. Therefore, the administered vaccine formulations with TLRa were less successful as expected and it can be anticipated that formulating an effective iPRRSV vaccine for (newborn) pigs will continue to be a challenge.

[This corrects the article DOI: 10.3389/fvets.2021.742877.]., (Copyright © 2024 van Dixhoorn, te Beest, Bolhuis, Parmentier, Kemp, van Mourik, Stockhofe-Zurwieden, van Reenen and Rebel.)