Effects of feeding cracked corn to nursery and finishing pigs.

Four experiments were conducted to determine the effects of supplementing cracked corn in nursery and finishing pig diets (PIC TR4 × 1050). In Exp. 1, 144 pigs (7.5 kg BW) were used in a 28-d experiment with 6 pigs per pen and 6 pens per treatment. Treatments were corn-soybean meal based in the form of mash, pellets (PCD), and pellets with 100% of the corn ground (PGr; 618 mm) or cracked (PCr; 3444 mm) and blended into the diet after the rest of the formulation had been pelleted. For d 0 to 28, pigs fed mash had increased (P = 0.042) ADFI compared with those fed the PCD diet. Pigs fed PCD had increased (P < 0.05) ADG and G:F compared with pigs fed PGr and PCr. Pigs fed PCr had decreased (P = 0.004) G:F compared with those fed PGr. For Exp. 2, 224 nursery pigs (7.4 kg BW) were used in a 28-d study with 7 pigs per pen and 8 pens per treatment. Treatments were similar to Exp. 1, with 50% of the corn either ground (445 mm) or cracked (2142 mm). For d 0 to 28, pigs fed mash had greater (P < 0.05) ADFI and G:F than pigs fed the PCD diet. Pigs fed the PCD diet had decreased (P = 0.001) ADFI and increased (P = 0.001) G:F compared to those fed PGr and PCr. For Exp. 3, 208 pigs (62.6 kg BW) were used in a 63-d experiment with 13 pigs per pen and 4 pens per treatment. Treatments were corn-soybean meal based with 0, 10, 20, and 40% cracked corn (3549 µm). All treatments were fed in mash form. For d 0 to 63, increasing cracked corn tended to decrease (linear, P = 0.093) G:F and decreased (linear, P = 0.047) carcass yield. Adding up to 40% of cracked corn to a mash diet decreased (P < 0.05) scores for keratinization and ulcers. For Exp. 4, 252 finishing pigs (40 kg BW) were used with 7 pigs per pen and 9 pens per treatment. The treatments were the same as described in Exp. 2. For the 80-d experiment, pigs fed mash had decreased (P < 0.05) ADG, stomach keratinization, and ulcer scores and increased (P < 0.05) yield and loin depth compared with pigs fed the PCD diet. Pigs fed PCD had increased (P < 0.05) ADG and G:F and decreased (P = 0.026) loin depth compared with pigs fed PGr and PCr diets. Pigs fed PCr had increased (P = 0.023) ADG and decreased (P = 0.001) yield compared with pigs fed PGr. Pigs fed PCr had decreased (P < 0.05) stomach keratinization and ulcer scores compared with pigs fed the PCD and PGr diets. In conclusion, pigs fed PCD had the greatest G:F, and PGr and PCr treatments had negative effects on G:F of pigs. Scores for stomach lesions were lowest for pigs fed PCr.

Comparison of host immune responses to homologous and heterologous type II porcine reproductive and respiratory syndrome virus (PRRSV) challenge in vaccinated and unvaccinated pigs.

Porcine reproductive and respiratory syndrome (PRRS) is a high-consequence animal disease with current vaccines providing limited protection from infection due to the high degree of genetic variation of field PRRS virus. Therefore, understanding host immune responses elicited by different PRRSV strains will facilitate the development of more effective vaccines. Using IngelVac modified live PRRSV vaccine (MLV), its parental strain VR-2332, and the heterologous KS-06-72109 strain (a Kansas isolate of PRRSV), we compared immune responses induced by vaccination and/or PRRSV infection. Our results showed that MLV can provide complete protection from homologous virus (VR-2332) and partial protection from heterologous (KS-06) challenge. The protection was associated with the levels of PRRSV neutralizing antibodies at the time of challenge, with vaccinated pigs having higher titers to VR-2332 compared to KS-06 strain. Challenge strain did not alter the cytokine expression profiles in the serum of vaccinated pigs or subpopulations of T cells. However, higher frequencies of IFN-γ-secreting PBMCs were generated from pigs challenged with heterologous PRRSV in a recall response when PBMCs were re-stimulated with PRRSV. Thus, this study indicates that serum neutralizing antibody titers are associated with PRRSV vaccination-induced protection against homologous and heterologous challenge.

Preliminary findings of a previously unrecognized porcine primary immunodeficiency disorder.

Weaned pigs from a line bred for increased feed efficiency were enrolled in a study of the role of host genes in the response to infection with Porcine Reproductive and Respiratory Syndrome Virus (PRRSV). Four of the pigs were euthanatized early in the study due to weight loss with illness and poor body condition; 2 pigs before PRRSV infection and the other 2 pigs approximately 2 weeks after virus inoculation. The 2 inoculated pigs failed to produce PRRSV-specific antibodies. Gross findings included pneumonia, absence of a detectable thymus, and small secondary lymphoid tissues. Histologically, lymph nodes, spleen, tonsils, and Peyer's patches were sparsely cellular with decreased to absent T and B lymphocytes.

Effect of dietary mannanoligosaccharide and sodium chlorate on the growth performance, acute-phase response, and bacterial shedding of weaned pigs challenged with Salmonella enterica serotype Typhimurium.

A 28-d experiment evaluated the growth, acute-phase response, and bacterial shedding patterns in pigs (n = 96; initially 6.8 +/- 1.3 kg) fed mannanoligosaccharides (MANNAN) and sodium chlorate (CHLORATE) before and after oral challenge with Salmonella enterica serotype Typhimurium (ST). The negative control diet contained no antimicrobial (CON), and the positive control contained carbadox (CARB; 55 ppm). Test diets contained (as-fed basis) MANNAN (1,500 ppm) or CHLORATE (800 ppm). Pigs were fed diets for 14 d and then given ST orally. Pigs fed CARB had greater ADG over the entire study than pigs from other treatments (P < 0.05). During wk 1 to 2, before ST challenge, feed intake (as-fed basis) was lower for pigs fed MANNAN and CHLORATE than pigs fed CARB (P < 0.05). During the final 2 wk, pigs fed CARB had greater feed intake than pigs on other treatments (P < 0.05). Gain/feed was greater for pigs fed CARB in the 2 wk before ST (P < 0.05); however, in wk 3 to 4 after ST, gain/feed was reduced for CON pigs compared to pigs on other treatments (P < 0.05). Serum IGF-I was decreased at 2 and 4 d after ST (P < 0.001), and, overall, IGF-I was greater in pigs fed CARB than CON or CHLORATE (P < 0.05). Serum haptoglobin concentrations were greater (P < 0.001) for all treatments at d 6 compared with d 13 after ST. Overall, haptoglobin was greater for MANNAN than for CARB and CHLORATE (P < 0.05) and tended to be increased (P < 0.06) relative to CON. Interleukin-6 was not affected by treatment or day post-ST challenge. Fecal shedding of salmonellae organisms was less for CHLORATE (P < 0.05) than all other treatments at 7 d after ST. Shedding scores decreased from d 7 to 14 after ST (P < 0.05) for the CON, CARB, and MANNAN treatments. We conclude that feeding MANNAN and CHLORATE before acute enteric disease challenge may support improved gut function as evidenced by improved gain/feed, and that CHLORATE may decrease bacterial shedding. But neither MANNAN nor CHLORATE enhanced growth relative to the absence of dietary antimicrobials, nor was either treatment as effective as CARB following ST challenge.

Severe complication after administration of formalin for treatment of progressive ethmoidal hematoma in a horse.

Formalin was injected into an ethmoidal hematoma in an 18-year-old Arabian gelding. Abnormal neurologic signs were observed within minutes of the injection. The horse did not respond favorably to medical treatment of the neurologic signs and was euthanatized. Postmortem examination revealed erosion and necrosis of the ventral cribriform plate, which appeared to have allowed the injected formalin to reach the rostral portion of the frontal lobe of the brain. Endoscopy and radiography had been performed prior to euthanasia, but neither delineated the cribriform lesion. Before treating large progressive ethmoidal hematomas with formalin, it may be beneficial to perform computed tomography to assess the extent of damage caused by the lesion.

Chlamydial infections in small ruminants.

Chlamydophila abortus (formerly Chlamydia psittaci) is one of the most important causes of reproductive failure in sheep and goats, especially in intensively managed flocks. The disease is usually manifested as abortion in the last 2 to 3 weeks of gestation, regardless of when the animal was infected. Ewes that abort are resistant to future reproductive failure due to C. abortus, but they become inapparent carriers and persistently shed the organism from their reproductive tracts during estrus. Chlamydophila pecorum is the other member of the genus that affects small ruminants, and it is recognized as a primary cause of keratoconjunctivitis in sheep and goats and of polyarthritis in sheep.

Comparison of cultivation and PCR-hybridization for detection of Salmonella in porcine fecal and water samples.

A total of 150 fecal and water samples from four swine farms were tested for the presence of Salmonella enterica using different enrichment techniques as follows: (i) 92 fecal samples from nursery and farrowing barns at three swine farms were preenriched overnight in tryptic soy broth (TSB) at 37 degrees C followed by overnight enrichment in Rappaport-Vassiliadis 10 broth (RV10) at 42 degrees C; (ii) 24 water samples from the third farm were preenriched overnight in 3MC broth at 37 degrees C followed by overnight enrichment in RV10 at 42 degrees C; and (iii) 34 fecal samples from a fourth farm, a finishing farm, were enriched overnight in RV10 at 42 degrees C with no additional enrichment. Following each of the enrichment techniques, samples were subcultured onto modified semisolid Rappaport-Vassiliadis (MSRV) agar prior to transfer to Hektoen Enteric agar plates for the recovery of viable Salmonella bacteria. Presumptive Salmonella isolates were biochemically and serologically confirmed. For the PCR detection of Salmonella, a 1-ml portion was removed from each sample after the first overnight enrichment and the DNA was extracted using a Sepharose CL-6B spin column. Amplicons (457 bp) derived from primers to the invA and invE genes were confirmed as Salmonella specific on ethidium bromide-stained agarose gels by Southern hybridization with a 20-mer oligonucleotide probe specific for the Salmonella invA gene. Neither the standard microbiological method nor the molecular method detected all of the 65 samples that tested positive by both methods or either method alone. Salmonella bacteria were detected by both cultivation and PCR-hybridization in 68% (17 of 25) of the positive samples that were preenriched in TSB, in 73% (11 of 15) of the positive samples preenriched in 3MC broth, and in 24% (6 of 25) of the positive samples enriched in RV10. Agreement between Salmonella detection using cultivation with preenrichment and detection by PCR was 76% using the kappa statistic. However, agreement between Salmonella detection using cultivation without preenrichment and detection by PCR was about 6%; the PCR assay detected 80% (20 of 25) of the 25 positive samples, while Salmonella bacteria were recovered from only 44% (11 of 25) by cultivation. Our results indicate that the PCR-hybridization approach is equivalent to or better than cultivation for detecting Salmonella in swine feces or water samples from swine farms when using the medium combinations evaluated in this study.

Prevalence and reproductive effects of Ureaplasma diversum in beef replacement heifers and the relationship to blood urea nitrogen level.

A systematic sample of replacement heifers from 5 herds underwent prebreeding vaginal swab cultures for Ureaplasma diversum. Heifers from three of the herds were subsequently sampled at pregnancy examination. Sampled heifers were given a vaginal lesion score (VLS), reproductive tract score (RTS) and body condition score (BCS), and peripheral blood was collected for serum blood urea nitrogen (BUN) estimation. Culture results revealed an overall prevalence of Ureaplasma diversum of 51% (87/171) at prebreeding and 65% (64/98) at pregnancy examination. Within herd prevalence ranged from 36% to 64% at prebreeding and 54% to 76% at pregnancy examination. Prevalence tended to differ between herds (P=0.08). At the prebreeding examination, heifers with a BCS of 5.5 or less were more likely to be culture positive than heifers with a BCS greater than 5.5 (p<0.05). No relationship was noted between BUN, VLS, RTS, or pregnancy status and prebreeding culture status. There was little variability among the heifers for any of these variables, with vaginal lesion scores generally being mild, RTS scores being high and BCS scores being moderate. At pregnancy examination, heifers that were culture negative tended to be more likely to be pregnant (odds 3.7, p=0.10) than culture positive heifers.

Isolation of cilia-associated respiratory (CAR) bacillus from pigs and calves and experimental infection of gnotobiotic pigs and rodents.

Filamentous, gram-negative bacteria morphologically similar to cilia-associated respiratory (CAR) bacillus of rodents and rabbits were isolated from the tracheas of 5 pigs and 4 calves. All pigs but none of the calves had histologic lesions of chronic tracheitis. In silver-stained histologic sections, CAR bacilli were adhered to the tracheal epithelium of each pig but were not found in the calves. Like CAR bacillus of rats, the bacteria displayed gliding motility and grew only in cell culture or cell culture medium supplemented with fetal serum. Initially, all isolates were contaminated by Mycoplasma spp. This contamination was eliminated from 4 pig isolates by limiting dilutions, and mycoplasma-free isolates were used to intranasally inoculate gnotobiotic pigs and CAR bacillus-free mice and rats and to immunize guinea pigs. The gnotobiotic pigs remained healthy, and when they were necropsied 4 and 7 weeks after infection no macroscopic or microscopic lesions were found in the respiratory tract. However, CAR bacillus was isolated at both times from the nasal cavities and tracheas of inoculated pigs, and the ciliated tracheal epithelium of infected pigs necropsied 7 weeks after infection was colonized by low numbers of CAR bacillus-like bacteria. The rats and mice remained healthy through week 12 postinoculation, and evidence of short- or long-term colonization was not detected by histologic examination or culture. When used as primary antibody for immunohistochemical staining, sera from guinea pigs immunized with pig CAR bacillus specifically stained CAR bacilli colonizing the respiratory epithelium of naturally infected pigs, whereas sera collected prior to immunization failed to react with the bacteria. These results indicate that CAR bacilli are unlikely to be primary pathogens of pigs or cattle and that rodents do not act as reservoirs.

Demodicosis in an American bison.

An 18-month-old, male American bison (Bison bison) was presented with 7- to 9-mm size nodules periorbital, perineal, and on the ventral surface of the tail. Demodex spp. were identified from the exudate by microscopic examination. Examination 6 mo later revealed that the infestation had nearly cleared without treatment.

Norepinephrine stimulates in vitro growth but does not increase pathogenicity of Salmonella choleraesuis in an in vivo model.

Norepinephrine stimulates growth of Escherichia coli, Yersinia enterocolitica, and Pseudomonas aeruginosa in serum-supplemented media, and in vivo increases in norepinephrine may be important in the pathogenesis of sepsis by gram-negative bacteria. Because salmonellosis often is associated with stress, the effects of norepinephrine on in vitro growth, and in vivo pathogenicity of the swine pathogen Salmonella choleraesuis were investigated. When RPMI 1640 with and without pig serum was inoculated with fewer than 100 S. choleraesuis/ml and incubated overnight, bacterial numbers were 10(4) to 10(6) lower in RPMI containing serum. Norepinephrine restored bacterial growth in RPMI with serum to normal levels, but it did not increase growth in serum-free RPMI. Similar results were obtained with SAPI, a nutrient-poor medium previously used to study the effect of norepinephrine on growth of gram-negative bacteria. Conditioned media were produced by growing S. choleraesuis in RPMI containing serum with and without norepinephrine and filter sterilizing. Conditioned medium produced with norepinephrine stimulated growth of S. choleraesuis but not E. coli, whereas conditioned medium produced without norepinephrine stimulated growth of both bacteria. To determine the in vivo effects of norepinephrine, rats were implanted with tablets that secrete norepinephrine for 20 to 24 hours or with identical tablets without norepinephrine and infected intraperitoneally with graded doses of S. choleraesuis. The LD-50 of S. choleraesuis was the same in both groups, and norepinephrine did not affect the carrier rate at 30 days after infection. We concluded that although norepinephrine stimulates in vitro growth of S. choleraesuis in serum-based media, the increase in norepinephrine levels in the present in vivo system was probably not sufficient to influence the pathogenesis of S. choleraesuis infection.

Prevalence of intestinal chlamydial infection in pigs in the midwest, as determined by immunoperoxidase staining.

OBJECTIVE: To determine prevalence of intestinal chlamydial infection in pigs and to compare prevalence of diarrhea in infected pigs with that in noninfected pigs to evaluate the importance of Chlamydia sp as causes of diarrhea in pigs. ANIMALS AND PROCEDURES: Intestines from 351 sick pigs submitted to 2 veterinary diagnostic laboratories and from 96 healthy pigs that were part of an Escherichia coli susceptibility study were examined by immunoperoxidase staining for chlamydial antigen. The proportion of Chlamydia-infected pigs in each group was calculated and compared. The proportion of Chlamydia-infected pigs with diarrhea was compared with the proportion of noninfected pigs with diarrhea. RESULTS: 15% of the sick and healthy pigs were infected with Chlamydia sp. Prevalence of diarrhea was equal between infected and noninfected pigs. Chlamydia sp were the third most common pathogens identified, and prevalence of chlamydial infection increased after 3 weeks of age. CONCLUSIONS AND CLINICAL RELEVANCE: Intestinal chlamydiosis is common in commercial pigs, but most, if not all, infections are subclinical Without collaborative evidence, simply identifying Chlamydia sp in feces or the intestinal tract of pigs with enteritis or diseases of other organ systems should not be considered proof that the organism caused the clinical signs of disease.

Salmonella infection increases porcine antibacterial peptide concentrations in serum.

PR-39 is a multifunctional neutrophil peptide involved in host defense and inflammation. To investigate the involvement of PR-39 in a Salmonella choleraesuis infection, a PR-39 enzyme immunoassay was developed. The concentrations of PR-39 in serum were 13.6 +/- 1.9 ng/ml before challenge and increased (P < 0.01) threefold by 10 to 14 days postinfection. Peripheral blood neutrophil counts paralleled the changes in the concentrations of PR-39 in serum, both returned to basal values by 4 weeks postinfection. These findings suggest that the concentrations of serum PR-39 reflect the involvement of this antibacterial peptide in the host's response to an S. choleraesuis infection.

Growth and microbial flora of nonmedicated, segregated, early weaned pigs from a commercial swine operation.

OBJECTIVE: To determine whether segregated, early weaned pigs have better growth performance and different microbial flora than those pigs raised on-site. DESIGN: Prospective, observational study. ANIMALS: Pigs from a commercial operation that were known to be infected with several common swine pathogens. PROCEDURE: Pigs (7 to 10 days old) were weaned and segregated from the farm of origin and compared with littermate control pigs (14 to 17 days old) that were weaned and raised on-site. Pig weight was measured and microbial flora were isolated at 14-day intervals for 84 days, beginning when the pigs were 7 to 10 days old. RESULTS: At 50 days of age, the segregated, early weaned pigs had a mean weight of 23.7 kg, compared with a mean weight of 12.5 kg for control pigs. Pasteurella multocida was isolated from fewer segregated, early weaned pigs than from controls. Signs of Mycoplasma hyopneumoniae infection were detected in control pigs but not in segregated early weaned pigs. Clinical, serologic, or bacteriologic signs of early postnatal vertical transmission of Actinobacillus pleuropneumoniae were not detected in either group. CLINICAL IMPLICATION: Vertical transmission of M hyopneumoniae was prevented by weaning pigs at 7 to 10 days of age and segregating them off-site, without the use of medication. Although medicated controls were not compared, results from this herd revealed that use of antibiotics is not the most important factor for disease control in segregated, early weaning programs. Minimizing antibiotic use in disease-control protocols reduces costs as well as removes the need for extra-label drugs.

Colonization of the tracheal epithelium of pigs by filamentous bacteria resembling cilia-associated respiratory bacillus.

Warthin Starry staining revealed filamentous bacteria colonizing the tracheal epithelium of 41 of 88 (46.6%) pigs submitted for necropsy at 2 midwestern veterinary diagnostic laboratories. The bacteria were interspersed between and oriented parallel to the cilia. In 4 of 4 colonized pig tracheas, filamentous bacteria were demonstrated by transmission electron microscopy. The bacteria were approximately the same length and diameter as cilia, and in areas of heavy colonization the bacteria outnumbered cilia. The filamentous bacteria were similar in location and morphologic characteristics to cilia-associated respiratory (CAR) bacilli of rats, mice, rabbits, and cattle. Results of immunoperoxidase staining and polymerase chain reaction analysis indicated that the pig CAR bacillus is a different bacterium than the rat CAR bacillus. Rat CAR bacillus causes chronic respiratory disease in rats and mice. The association, if any, between pig CAR bacillus and swine respiratory disease is unknown.

Invasion of enterocytes in cultured porcine small intestinal mucosal explants by Salmonella choleraesuis.

Porcine small intestinal explants maintained in vitro were inoculated with Salmonella choleraesuis to study the characteristics of its invasion of enterocytes. The explants were fixed at selected intervals for up to 12 hours after inoculation and examined by conventional light microscopy, immunoperoxidase staining, and transmission electron microscopy. Although there was diffuse loss of villous enterocytes during the first hour of incubation, the villi were reepithelialized by the end of 2 hours of culture, and the mucosal epithelium remained intact and appeared to be viable through 12 hours of culture. Intraepithelial S choleraesuis were not detected before 6 hours after inoculation, but after 12 hours of incubation, bacteria were numerous within enterocytes. Ultrastructurally, penetration of the brush border by S choleraesuis resulted in focal loss of microvilli. Bacteria were endocytosed into membrane-bound vacuoles where most remained, but a few were free within the cytoplasm of enterocytes. Invasion of the explants closely resembled that described for live animal and cell culture models of Salmonella spp invasion.