Lysozyme as an alternative to antibiotics improves growth performance and small intestinal morphology in nursery pigs.

Lysozyme is a 1,4-ß-N-acetylmuramidase that has antimicrobial properties. The objective of this experiment was to determine if lysozyme in nursery diets improved growth performance and gastrointestinal health of pigs weaned from the sow at 24 d of age. Two replicates of 96 pigs (192 total; 96 males, 96 females) were weaned from the sow at 24 d of age, blocked by BW and gender, and then assigned to 1 of 24 pens (4 pigs/pen). Each block was randomly assigned 1 of 3 dietary treatments for 28 d: control (two 14-d phases), control + antibiotics (carbadox/copper sulfate), or control + lysozyme (100 mg/kg diet). Pigs were weighed and blood sampled on d 0, 14, and 28 of treatment. Blood was analyzed for plasma urea nitrogen (PUN) and IgA. At 28 d, pigs were killed, and samples of jejunum and ileum were collected and fixed for intestinal morphology measurements. An additional jejunum sample was taken from the 12 pigs with the median BW per treatment to determine transepithelial electrical resistance (TER). Pigs consuming antibiotics or lysozyme grew at a faster rate than control pigs (0.433 ± 0.009 and 0.421 ± 0.008 vs. 0.398 ± 0.008 kg/d, respectively; P < 0.03), which resulted in heavier ending BW (20.00 ± 0.31, 19.8 ± 0.29, and 18.83 ± 0.32 kg, respectively; P < 0.03). Feed intake was not different (P > 0.48), but G:F was improved in pigs consuming antibiotics or lysozyme (0.756 ± 0.014, 0.750 ± 0.021, and 0.695 ± 0.019 kg/kg; P < 0.05). Immunoglobulin A (P < 0.03) and PUN (P < 0.01) increased during the experiment, regardless of dietary treatment (P > 0.48). Dietary treatment did not affect TER (P > 0.37), but gilts had lower TER compared with barrows (P < 0.04). No differences in villi height or crypt depth were observed in the ileum (P > 0.53). However, jejunum villi height was increased and crypt depth was decreased in pigs consuming antibiotics or lysozyme (P < 0.001), resulting in an increased villi height:crypt depth of 72% (P < 0.001). Thus, we concluded that lysozyme is a suitable alternative to carbadox/copper sulfate diets fed to pigs weaned from the sow at 24 d of age.

An investigation of the etiology of a mild diarrhea observed in a group of grower/finisher pigs.

An investigation into a mild diarrhea in a group of grower/finisher pigs was carried out in order to determine the etiology. A tiamulin injection and a carbadox-medicated ration were given to pens of pigs in a 2 x 2 factorial experimental design. Pens of pigs were assessed a score, based on the consistency of the feces in the pen, each week. The clinical investigation looked for the intestinal pathogens Brachyspira pilosicoli, B. hyodysenteriae, Lawsonia intracellularis, Salmonella spp., Yersinia spp., transmissible gastroenteritis virus, and rotavirus. Despite a rigorous investigation, the diarrhea was not attributed to any pathogen. A mild colitis was noted among pigs necropsied while affected with diarrhea. Improved diagnostic tools may allow a more effective response to an outbreak of mild disease, while at the same time reducing the amount of antimicrobials used in swine production.

Associations between off-label feed additives and farm size, veterinary consultant use, and animal age.

Data from the United States National Swine Survey collected by the National Animal Health Monitoring System were used to describe the use of feed additives in swine feeds. Data were collected from 710 farms. The concentration of feed additives expressed in grams per ton of complete feed was described by stage of production, and the use of feed additives above the labeled treatment levels (i.e. off-label) was identified. Of the 3328 feeds, about 79% contained feed additives used in the labeled manner. For all classes of pigs, the prevalence of labeled feed additive use was greater than 75%. Penicillin was used according to its label most often, followed by apramycin, bacitracin, tetracyclines, lincomycin, and tylosin. Carbadox had the highest prevalence of off-label use. Of the 699 feeds that included feed additives in an off-label manner, about 57% included additives at greater than the recommended concentrations or were fed to an incorrect class of pig. About 56% of the feeds had off-label combinations of additives. Small farms were more likely to use rations with no feed additives than intermediate or large farms (P < 0.001). Of those farms using feed additives, the odds of a small farm using all feed additives in the labeled manner was 7.7 times that of an intermediate or large farm (P < 0.0001). After controlling for herd size, producers who used a veterinary consultant were 2.1 times more likely to use feeds with feed additives (P < 0.0001).

Quinoxaline-2-carboxylic acid (QCA) in swine liver and muscle.

The concentration of quinoxaline-2-carboxylic acid (QCA) determined by HPLC after alkaline hydrolysis of liver and muscle of swine, ranged from < 3 ng/g to 45.3 ng/g in liver, and from < 3 ng/g to 10.8 ng/g in muscle samples. After the 77th day of therapy QCA was found in samples of liver (9.7 ng/g). Recoveries obtained for both liver and muscle were 70% at 5 ng/g, 77% and 75% respectively at 10 ng/g, and 90% for both liver and muscle at 30 ng/g. This experiment was performed within the frame of the National Monitoring Programme of Residues in Animal Tissues in the Republic of Croatia.

Sensitivity of strains of Serpulina hyodysenteriae isolated in Hungary to chemotherapeutic drugs.

The sensitivity of 332 strains of Serpulina hyodysenteriae isolated in Hungary between 1978 and 1992 was tested against seven chemotherapeutic drugs frequently used for the treatment of swine dysentery, and the changes in the patterns of resistance were also monitored. All the strains remained sensitive to carbadox, with minimum inhibitory concentrations (MIC) of only 0.05 to 0.40 microgram/ml at present. The susceptibility of the strains to dimetridazole has gradually decreased, but about half of the strains are still sensitive, with large numbers of "moderately sensitive' strains; the MIC values varied within wide limits (0.1 to 50 micrograms/ml). Most of the strains were resistant to tylosin, with MIC values from 0.1 to 100 micrograms/ml. The number of strains resistant to lincomycin has gradually increased, but about half of the strains remain sensitive; the MIC values ranged from 0.2 to 100 micrograms/ml. Recently, tiamulin has proved the most effective antibiotic, but some resistant strains have already emerged (MIC values 0.05 to 50 micrograms/ml). Monensin was good for the prevention of swine dysentery, but resistance may evolve quickly; the MIC values ranged from 0.4 to 25 micrograms/ml. For sedecamycin, the MIC values (6.25 to 100 micrograms/ml) were much higher than expected.

Prevention and treatment of atrophic rhinitis in pigs with Getroxel, chlorquinaldol and oxytetracycline.

The sensitivity of ten Bordetella bronchiseptica and ten Pasteurella multocida strains, each isolated from cases of atrophic rhinitis (AR), was examined in tube dilution test. Getroxel, chlorquinaldol and oxytetracycline and the former two ones combined with trimethoprim inhibited the growth of both species in vitro. The minimum inhibitory and the minimum bactericidal concentration was less than 0.5 microgram/ml. When efficacy was tested in SPF in the group fed a combination of Getroxel, chlorquinaldol and oxytetracycline (60 mg, 240 mg and 360 mg/kg of feed, respectively), P. multocida disappeared from the nasal cavity by the end of a 30-day treatment. B. bronchiseptica was reisolated in low numbers from 2 out of 9 piglets. The daily body mass gain was by 7.9% higher and the feed conversion rate was by 19% better than in the control group. After slaughter, only mild signs of AR were seen in 3 out of 9 piglets treated with the above-mentioned drug combination, while in the control group severe lesions were observed in 8 out of 9 pigs. In treated commercial herds P. multocida disappeared from the nasal cavity of the piglets by the end of the treatment (42nd day of life), but the B. bronchiseptica strains could not be completely eliminated. Due to the treatment, mortality between 2 and 6 weeks of age decreased by 0.8-7.6%. Daily body mass gain was, on the average, 16.4% higher, the amount of feed needed for 1 kg body mass gain was by 15.3% lower and the duration of fattening was by 30.8 days shorter than in the control groups.

In vitro and in vivo activities of sedecamycin against Treponema hyodysenteriae.

Sedecamycin (lankacidin A), one of the lankacidin-group antibiotics, showed potent activity against Treponema hyodysenteriae. The MICs of sedecamycin against 79 field isolates of T. hyodysenteriae ranged from 0.78 to 12.5 micrograms/ml, the MIC for 90% of the strains tested (MIC90) being 3.13 micrograms/ml. The protective and therapeutic effects of sedecamycin were compared with those of carbadox, tiamulin, and lincomycin against experimental infection with T. hyodysenteriae in mice. The protective effect of sedecamycin was similar to that of carbadox, two times more potent than that of tiamulin, and three times greater than that of lincomycin. In the therapeutic test, sedecamycin showed activity similar to that of carbadox and was two times more active than both tiamulin and lincomycin. At doses of 10 mg or more of sedecamycin per kg, the recurrence of shedding of T. hyodysenteriae into the feces of mice was not detected for at least 8 weeks postmedication.

Pathological effects of carbadox in pigs with special emphasis on the adrenal.

Weaned pigs, 4-weeks-old, were divided into 6 groups of 13 animals each, which received 0, 25, 50, 100, 150 and 200 ppm (mg per kg) of carbadox medicated feed, respectively. After 5 and 10 weeks of carbadox administration, three and two pigs, respectively, of each group were necropsied. After 5 weeks treatment, gross lesions were seen in pigs receiving 50 ppm or more. The main features were retarded growth, dehydration with dry contents in the intestine, especially in the colon and findings suggestive of pica. The severity of lesions increased with higher dosages. After 10 weeks, the same changes, though much more pronounced, were observed at 100 ppm or higher dosages. After 5 weeks histological changes in the adrenals were found at 50 ppm treatment and upwards. The common feature was a hydropic appearance of the glomerular zone. In the 50 ppm group one out of three and, in the higher dosed groups, all pigs showed these changes. There was a dose-response effect. At 100 ppm or more an enlargement of the glomerular zone was observed, resulting in narrowing of the fascicular layer. The adrenal capsule was slightly thickened and contained cells with PAS-positive granules. After 10 weeks, changes were found at 25 ppm dosage and higher. In the 25 and 50 ppm group half of the pigs had hydropic changes of the glomerular zone. In the higher dosed groups there were also chronic lesions. The outer part of the glomerular zone had become fibrotic. With 150 ppm or more the hydropic changes had extended into the fascicular layer, with development of hyperplastic nodules. This led to disappearance of zonal differentiation. From 100 ppm dosage, many richly granulated PAS-positive cells were present in the thickened capsule, more numerous and more granulated than after 5 weeks treatment. From this study, it can be concluded that carbadox may induce adverse effects on the adrenal in growing pigs at therapeutic (100 to 150 ppm) and feed-additive doses (50 ppm). Even at lower doses (25 ppm), mild lesions were found. The grade of lesions was positively correlated with the duration of exposure to this growth promoter.

Hygromycin A, an antitreponemal substance. II. Therapeutic effect for swine dysentery.

This study was conducted to evaluate hygromycin A fed to growing swine at 1, 5, 10 or 20 g/ton feed for the control of Treponema hyodysenteriae-caused dysentery. Pigs provided carbadox at 50 g/ton feed served as an infected treatment control group. All pigs were orally, via stomach intubation, administered 100 ml of a T. hyodysenteriae broth culture. During the in vivo test, rectal swabs were taken for T. hyodysenteriae isolation, body weights of all pigs and the feed consumption was determined. All pigs were euthanized and necropsied at study end; the large intestine was cultured for T. hyodysenteriae and gross intestinal lesions were noted. T. hyodysenteriae-caused swine dysentery was successfully controlled by feeding hygromycin A at 5 g/ton. Hygromycin A medicated pigs performed as well as or better than carbadox-medicated pigs.

3-Acetyl-4''-isovaleryl tylosin for prevention of swine dysentery.

The 21 field isolates of Treponema hyodysenteriae which were tested were sensitive to 3-acetyl-4''-isovaleryl tylosin (AIV); the minimal inhibitory concentration was 0.25 to 16 micrograms/ml. 3-Acetyl-4''-isovaleryl tylosin administered prophylactically to pigs at concentrations of 5 to 100 mg/kg of feed and tylosin at 110 mg/kg of feed for 28 or 31 days prevented swine dysentery induced by tylosin-sensitive T hyodysenteriae strain SQ2; 15 nonmedicated, inoculated control pigs had bloody diarrhea, and 9 pigs died. In 2 additional trials, AIV administered prophylactically for 28 days at 55 or 110 mg/kg of feed prevented swine dysentery induced by tylosin-insensitive T hyodysenteriae strain B204. All of the inoculated principal pigs medicated with AIV at 55 or 110 mg/kg of feed or carbadox at 55 mg/kg of feed and the noninoculated sentinel pigs for each group had solid feces throughout the 56-day trial. In the nonmedicated, inoculated control groups, bloody diarrhea began at 4 to 5 days after inoculation was done, and 9 of 10 principal pigs and 6 of 9 sentinel pigs had dysentery; 2 pigs died. In the groups medicated with AIV at 27.5 or 5.5 mg/kg of feed, all 5 principal pigs and 3 or 4 sentinel pigs in each group had dysentery; 3 or 4 pigs in each group died. In the group medicated with tylosin at 110 mg/kg of feed, 7 of 10 principal pigs and all 9 sentinel pigs had dysentery; 1 pig died.(ABSTRACT TRUNCATED AT 250 WORDS)

Probable elimination of swine dysentery after feeding ronidazole, carbadox or lincomycin and verification by feeding sodium arsanilate.

Swine dysentery did not recur during a nine week period after withdrawal of medication in swine fed ronidazole at a level of 60 parts per million of feed for ten weeks or fed either carbadox at 55 ppm or lincomycin at 110 ppm of feed for six weeks. During this period swine dysentery was neither transmitted to accompanying sentinels after the withdrawal of the above medication or was Treponema hyodysenteriae isolated and cultured or observed in stained smears from rectal swabs and feces or from colonic scrapings at necropsy. Beginning three weeks after the withdrawal of medication, all swine were fed sodium arsanilate at a concentration of 220 ppm of feed for three weeks in an attempt to excite the carrier of swine dysentery into developing a swine dysentery diarrhea. A swine dysentery diarrhea did recur during the feeding of sodium arsanilate in swine previously fed ronidazole at a level of 60 ppm of feed for only six weeks. It was concluded: that swine dysentery was probably eliminated with the feeding of ronidazole for the longer duration and with the feeding of carbadox and lincomycin and that sodium arsanilate was of value in identifying the carrier state.

Eliminating swine dysentery from selected herds.

In attempts to eliminate swine dysentery from a herd, the total cost of nitroimidazole medication in the water can be estimated at 16/gal over 3-4 weeks and for carbadox in the feed at 70/100 lb over 6-8 weeks. Use of dimetridazole or ipronidazole in the water for 3-4 weeks or carbadox in the feed for 6-8 weeks eliminates Treponema hyodysenteriae from the porcine gut. A 30-day (10 weeks with carbadox) preslaughter withdrawal time should be provided. Impervious surfaces should be thoroughly sanitized, while permeable surfaces and lots should be cleaned, dried and aired well for 2-3 weeks in warm, dry weather and for at least 60 days in cool, damp weather. Animal vectors and fomites must be controlled. Isolation of new breeding stock for 3-4 weeks helps prevent recontamination. While elimination of swine dysentery is not practical in many herds because of poor facilities or lack of producer commitment, a properly designed program can result in economic benefits.

A swine dysentery model for evaluation of drug prophylaxis: efficacy of various drugs in the control of swine dysentery.

A swine dysentery (SD) model that produces consistent, homogeneous, and severe SD was used in 2 experiments to compare the prophylactic effectiveness of 5 commercially available swine feed additive products. Under the conditions of these studies, carbadox and carbadox + sulfamethazine proved to be the most effective agents in preventing SD during the infection + medication and postmedication periods. Olaquindox was effective in preventing SD in the infection + medication period; however, SD recurrence was high during the postmedication period. Nithiamide and chlortetracycline + sulfamethazine + penicillin were least effective in preventing SD during the infection + medication and postmedication periods.

Effect of pyrantel tartrate and carbadox on acquisition of the swine kidneyworm (Stephanurus dentatus) and other parasites by pigs on contaminated lots.

A combination of pyrantel tartrate (106 mg/kg of body weight) and carbadox (55 mg/kg of body weight) in ground feed was fed to 20 weaned pigs (av wt, 14.4 kg) for 42 days. Another group of 20 pigs included nontreated controls. The pigs were farrowed and suckled in a slat-floored farrowing house and had minimal exposure to the small intestinal threadworm (Stronglyoides ransomi) until they were placed on severely contaminated dirt lots at the start of the experiment. Five pigs from each of the two groups were necropsied on day 42. Carbadox was withheld from the feed for the 15 remaining treated pigs. All other pigs were necropsied when they attained market weight, 72 to 83 days layer. Treated pigs killed at market weight had 44% fewer (P less than 0.10) kidneyworms (Stephanurus dentatus) than did control pigs. A 17% increase (P less than 0.01) in the weights of livers of control pigs when compared with treated market-weight pigs was associated with an increase of fibrotic hepatic tissue of control pigs. Worm infections were reduced in the treated market-weight pigs: by 96% (P less than 0.05) for the large roundworm (Ascaris suum), 77% (P less than 0.01) for nodular worms (Oesophagostomum spp), and 64% (P less than 0.01) for the intestinal threadworm. There was some evidence for prophylaxis in market-weight pigs (P less than 0.10) against lungworms (Metastrongylus spp), but none against the whipworm (Trichuris suis) or thick stomach worms (Ascarops strongylina and Physocephalus sexalatus). Pigs given the pyrantel tartrate in feed until attaining market weight maintained a feed-to-gain ratio superior (7.1%) to that of nontreated pigs.