Effects of palygorskite composites on growth performance and antioxidant status in broiler chickens.

This work aimed to investigate the effects of the palygorskite (PAL) composites on the growth performance and antioxidant status in broiler chickens. A total of 192 one-day-old Ross 308 broilers were randomly divided into 3 treatment groups. Broilers were fed basal diets supplemented with either 50 mg/kg chlortetracycline (CTC group), 1 g/kg ZnO/PAL (ZnO/PAL group), or 1 g/kg chitooligosaccharides/ZnO/PAL (COS/ZnO/PAL group), respectively. The results showed that PAL composites were found to exhibit similar effects on growth performance as CTC (P > 0.05). ZnO/PAL and COS/ZnO/PAL enhanced the activity of serum glutathione peroxidase (GSH-Px) compared with CTC both at 21 and 42 d (P < 0.05). Compared with the CTC group, COS/ZnO/PAL enhanced serum catalase (CAT) activity at 21 d (P < 0.05), and decreased serum malondialdehyde (MDA) content at 42 d (P < 0.05). Compared with the CTC group, ZnO/PAL decreased duodenal mucous MDA content at 21 d, while ZnO/PAL did not affect activities of superoxide dismutase (SOD) and GSH-Px in the duodenum (P > 0.05). The duodenal mucous activities of SOD and GSH-Px were the highest in the COS/ZnO/PAL group at 42 d (P < 0.05). At 21 d, broilers in the COS/ZnO/PAL group had the lowest MDA content and the highest total antioxidant capacity (T-AOC) in the jejunum (P < 0.05). Palygorskite composites decreased ileum mucous MDA content compared with CTC treated broilers at 21 d (P < 0.05). At 42 d, ileum mucous T-AOC was increased both in the ZnO/PAL and COS/ZnO/PAL groups compared with the CTC group (P < 0.05). The ileum mucous GSH-Px activities both in the ZnO/PAL and COS/ZnO/PAL groups were increased compared with the CTC group (P < 0.05). In conclusion, the broilers given the basal diet supplemented with the PAL composites exhibited similar growth performance to their counterparts in the AGP group. Additionally, the PAL composites improved the antioxidant status of broilers and the beneficial effects of COS/ZnO/PAL on the antioxidant status are more pronounced.

Changes in the diversity and composition of gut microbiota of weaned piglets after oral administration of Lactobacillus or an antibiotic.

The gut microbiota plays important roles in the health and well-being of animals, and high-throughput sequencing facilitates exploration of microbial populations in the animal gut. However, previous studies have focused on fecal samples instead of the gastrointestinal tract. In this study, we compared the microbiota diversity and composition of intestinal contents of weaned piglets treated with Lactobacillus reuteri or chlortetracycline (aureomycin) using high-throughput sequencing. Nine weaned piglets were randomly divided into three groups and supplemented with L. reuteri, chlortetracycline, or saline for 10 days, and then the contents of three intestinal segments (jejunum, colon, and cecum) were obtained and used for sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. The microbiota diversity and composition in the jejunum were different from those in the colon and cecum among the three treatments. In the jejunum, treatment with L. reuteri increased the species richness of the microbiota, as indicated by the ACE and Chao1 indexes, compared with the chlortetracycline group, in which several taxa were eliminated. In the colon and cecum, relative abundances of the phylum Firmicutes and the genus Prevotella were higher in the chlortetracycline group than in the other groups. Distances between clustered samples revealed that the L. reuteri group was closer to the chlortetracycline group than the control group for jejunum samples, while colon and cecum samples of the L. reuteri group were clustered with those of the control group. This study provides fundamental knowledge for future studies such as the development of alternatives to antibiotics.

Impact of medicated feed along with clay mineral supplementation on Escherichia coli resistance to antimicrobial agents in pigs after weaning in field conditions.

The aim of this study was to examine changes in antimicrobial resistance (AMR) phenotype and virulence and AMR gene profiles in Escherichia coli from pigs receiving in-feed antimicrobial medication following weaning and the effect of feed supplementation with a clay mineral, clinoptilolite, on this dynamic. Eighty E. coli strains isolated from fecal samples of pigs receiving a diet containing chlortetracycline and penicillin, with or without 2% clinoptilolite, were examined for antimicrobial resistance to 15 antimicrobial agents. Overall, an increased resistance to 10 antimicrobials was observed with time. Supplementation with clinoptilolite was associated with an early increase but later decrease in blaCMY-2, in isolates, as shown by DNA probe. Concurrently, a later increase in the frequency of blaCMY-2 and the virulence genes iucD and tsh was observed in the control pig isolates, being significantly greater than in the supplemented pigs at day 28. Our results suggest that, in the long term, supplementation with clinoptilolite could decrease the prevalence of E. coli carrying certain antimicrobial resistance and virulence genes.

Comparison of feed additive technologies for preconditioning of weaned beef calves.

Our objective was to evaluate the response of weaned calves to different supplemental feed additives in a supplement to affect calf performance and mitigate stress response observed during weaning and preconditioning. At weaning in each of 2 yr, 160 Angus and Brangus calves (203 and 227 ± 2.3 and 2.5 kg) were stratified by BW, sex, and breed and were randomly allotted to 1 of 4 treatments ( = 40 calves/treatment): 1) supplement without feed additives (control, CON), 2) supplemented with chlortetracycline, 350 mg/d (CTC), 3) supplemented with monensin, 175 mg/d (RUM), and 4) supplemented with rumen modifier, 5 g/d (ACT). Calves were held by treatment in 1 of 4 drylot pens for 7 d after weaning and were offered ad libitum access to hay and 2.27 kg/d of supplement before placement in one of thirty-two 0.8-ha pastures (5 calves/pasture). On pasture calves were supplemented with 2.27 kg/d (yr 1) or supplemented at 1.0% BW (yr 2). Calf BW and blood samples were collected following weaning (d 0, 1, 4, 7, 11 in yr 1; d 0, 1, 3, 7, 14 in yr 2), at the conclusion of the preconditioning period (d 50, 51 in yr 2), and after transportation (d 52, 55, 59, 65 in yr 2) for analysis of acute phase protein (APP) concentrations. In yr 2, after 44 d on pasture, calves were loaded on 2 semitrucks and transported for 24 h. On return, calves were placed in 4 pastures with hay and fed their respective supplements for 14 d. For each year, data were analyzed with the MIXED procedure of SAS. The model included the main effect of treatment, and pasture was the experimental unit. All variables quantified by day were analyzed using repeated measures. In yr 1, ACT and CTC had greater (P <0.05) 52-d ADG than RUM, whereas CON was intermediate. However, in yr 2, over the 50-d postweaning period there was no difference (P = 0.20; 0.52 kg/d) in ADG response among treatments. After transportation, 7- and 14-d ADG were improved (P < 0.05) for ACT and CTC compared with CON and RUM. In both years, postweaning plasma concentrations of haptoglobin were similar (P > 0.05) among treatments; however an effect of day after transport (P < 0.001) was observed. Feed cost of gain and income over production cost (P ≥ 0.15; mean = $0.51/kg and $73.51, respectively) were not different among treatments. Use of supplemental additives may improve calf performance during a preconditioning period of this duration, but no additive was effective at mitigating stress postweaning. Additives were equally effective in supporting calf growth performance during a posttransportation period.

Effects of chlortetracycline and copper supplementation on the prevalence, distribution, and quantity of antimicrobial resistance genes in the fecal metagenome of weaned pigs.

Use of in-feed antibiotics such as chlortetracycline (CTC) in food animals is fiercely debated as a cause of antimicrobial resistance in human pathogens; as a result, alternatives to antibiotics such as heavy metals have been proposed. We used a total community DNA approach to experimentally investigate the effects of CTC and copper supplementation on the presence and quantity of antimicrobial resistance elements in the gut microbial ecology of pigs. Total community DNA was extracted from 569 fecal samples collected weekly over a 6-week period from groups of 5 pigs housed in 32 pens that were randomized to receive either control, CTC, copper, or copper plus CTC regimens. Qualitative and quantitative PCR were used to detect the presence of 14 tetracycline resistance (tet) genes and to quantify gene copies of tetA, tetB, blaCMY-2 (a 3rd generation cephalosporin resistance gene), and pcoD (a copper resistance gene), respectively. The detection of tetA and tetB decreased over the subsequent sampling periods, whereas the prevalence of tetC and tetP increased. CTC and copper plus CTC supplementation increased both the prevalence and gene copy numbers of tetA, while decreasing both the prevalence and gene copies of tetB. In summary, tet gene presence was initially very diverse in the gut bacterial community of weaned pigs; thereafter, copper and CTC supplementation differentially impacted the prevalence and quantity of the various tetracycline, ceftiofur and copper resistance genes resulting in a less diverse gene population.

Effects of Clostridium butyricum on growth performance, antioxidation, and immune function of broilers.

To investigate the effects of Clostridium butyricum on growth performance, antioxidation, and immune function of broilers, 320 one-day-old Arbor Acres commercial male chicks were assigned to one of 5 treatments with 8 replicates in a completely randomized design for 42 d. The 5 treatments were basal diet (control), basal diet supplemented with 2.5×10(8) cfu C. butyricum/kg (CB1), basal diet supplemented with 5×10(8) cfu C. butyricum/kg (CB2), basal diet supplemented with 1×10(9) cfu C. butyricum/kg (CB3), and basal diet supplemented with 150 mg aureomycin/kg (antibiotic). The results showed that all C. butyricum-supplemented groups during d 1 to 21 and the CB2 group during d 22 to 42 had higher ADG compared with the control (P<0.05). Chicks fed the CB3 diet had higher glutathione S-transferase (GST) activity (P<0.05), and chicks fed the CB2 diet had a higher glutathione (GSH) concentration in duodenal and ileal mucosa at 21 d of age than those in the control group (P<0.05). Chicks fed the CB3 diet had a lower malondialdehyde (MDA) concentration in duodenal mucosa than those in the control and CB1 groups (P<0.05). Chicks fed the CB2, CB3, and antibiotic diets had a lower MDA concentration in ileal mucosa than those in the control and CB1 groups (P<0.05). Broilers fed the CB3 diet had greater superoxide dismutase (SOD) activity in the ileal mucosa on d 21 and in jejunal mucosa on d 42 than those in the other groups (P<0.05). Chicks fed the CB2, CB3, and antibiotic diets had a higher GSH concentration in duodenal and jejunal mucosa on d 42 than those in the control group (P<0.05). Broilers fed the CB2 and CB3 diets had a lower MDA concentration in the jejunal mucosa on d 42 than those in the control and CB1 groups. Chicks fed diets supplemented with C. butyricum had a higher IgM concentration than those in the control group at 21 and 42 d of age (P<0.05). The results indicate that C. butyricum improves broilers' growth performance, antioxidation, and immune function.

Effects of chlortetracycline and copper supplementation on antimicrobial resistance of fecal Escherichia coli from weaned pigs.

Feed-grade chlortetracycline (CTC) and copper are both widely utilized in U.S. pig production. Cluster randomized experiment was conducted to evaluate the effects of CTC and copper supplementation in weaned pigs on antimicrobial resistance (AMR) among fecal Escherichia coli. Four treatment groups: control, copper, CTC, or copper plus CTC were randomly allocated to 32 pens with five pigs per pen. Fecal samples were collected weekly from three pigs per pen for six weeks. Two E. coli isolates per fecal sample were tested for phenotypic and genotypic resistance against antibiotics and copper. Data were analyzed with multilevel mixed effects logistic regression, multivariate probit analysis and discrete time survival analysis. CTC-supplementation was significantly (99% [95% CI=98-100%]) associated with increased tetracycline resistance compared to the control group (95% [95% CI=94-97%]). Copper supplementation was associated with decreased resistance to most of the antibiotics tested, including cephalosporins, over the treatment period. Overall, 91% of the E. coli isolates were multidrug resistant (MDR) (resistant to ≥3 antimicrobial classes). tetA and blaCMY-2 genes were positively associated (P<0.05) with MDR categorization, while tetB and pcoD were negatively associated with MDR. tetA and blaCMY-2 were positively associated with each other and in turn, these were negatively associated with both tetB and pcoD genes; which were also positively associated with one another. Copper minimum inhibitory concentration was not affected by copper supplementation or by pcoD gene carriage. CTC supplementation was significantly associated with increased susceptibilities of E. coli to copper (HR=7 [95% CI=2.5-19.5]) during treatment period. In conclusion, E. coli isolates from the nursery pigs exhibited high levels of antibiotic resistance, with diverse multi-resistant phenotypic profiles. The roles of copper supplementation in pig production, and pco-mediated copper resistance among E. coli in particular, need to be further explored since a strong negative association of pco with both tetA and blaCMY-2 points to opportunities for selecting a more innocuous resistance profile.

Effects of ceftiofur and chlortetracycline treatment strategies on antimicrobial susceptibility and on tet(A), tet(B), and bla CMY-2 resistance genes among E. coli isolated from the feces of feedlot cattle.

A randomized controlled field trial was conducted to evaluate the effects of two sets of treatment strategies on ceftiofur and tetracycline resistance in feedlot cattle. The strategies consisted of ceftiofur crystalline-free acid (CCFA) administered to either one or all of the steers within a pen, followed by feeding or not feeding a therapeutic dose of chlortetracycline (CTC). Eighty-eight steers were randomly allocated to eight pens of 11 steers each. Both treatment regimens were randomly assigned to the pens in a two-way full factorial design. Non-type-specific (NTS) E. coli (n = 1,050) were isolated from fecal samples gathered on Days 0, 4, 12, and 26. Antimicrobial susceptibility profiles were determined using a microbroth dilution technique. PCR was used to detect tet(A), tet(B), and bla CMY-2 genes within each isolate. Chlortetracycline administration greatly exacerbated the already increased levels of both phenotypic and genotypic ceftiofur resistance conferred by prior CCFA treatment (P<0.05). The four treatment regimens also influenced the phenotypic multidrug resistance count of NTS E. coli populations. Chlortetracycline treatment alone was associated with an increased probability of selecting isolates that harbored tet(B) versus tet(A) (P<0.05); meanwhile, there was an inverse association between finding tet(A) versus tet(B) genes for any given regimen (P<0.05). The presence of a tet(A) gene was associated with an isolate exhibiting reduced phenotypic susceptibility to a higher median number of antimicrobials (n = 289, median = 6; 95% CI = 4-8) compared with the tet(B) gene (n = 208, median = 3; 95% CI = 3-4). Results indicate that CTC can exacerbate ceftiofur resistance following CCFA therapy and therefore should be avoided, especially when considering their use in sequence. Further studies are required to establish the animal-level effects of co-housing antimicrobial-treated and non-treated animals together.

Chronic exposure to the mycotoxin T-2 promotes oral absorption of chlortetracycline in pigs.

The aim of this study was to investigate whether T-2 toxin, a potent Fusarium mycotoxin, affects the oral absorption of the antibiotic chlortetracycline in pigs. Animals were allocated to blank feed without T-2 toxin (controls), feed containing 111 µg T-2/kg feed, T-2-contaminated feed supplemented with a yeast-derived feed additive, or blank feed supplemented solely with the feed additive, respectively. After 21 days, an intragastric bolus of chlortetracycline was given to assess potential alterations in the pharmacokinetics of this commonly used antibiotic. A significantly higher area under the plasma concentration-time curve and maximal plasma concentration of chlortetracycline was observed after intake of T-2-contaminated feed compared with control. Thus, exposure to T-2-contaminated feed can influence the oral bioavailability of chlortetracycline. This effect could have consequences for the withdrawal time of the drug and the occurrence of undesirable residues in edible tissues.

Effects of lasalocid and intermittent feeding of chlortetracycline on the growth of prepubertal dairy heifers.

Forty Holstein heifers entered the 12-wk study at approximately 12 wk of age. At enrollment, heifers were blocked by birth date and assigned to 1 of 4 treatments: (1) carrier (30 g; control); (2) lasalocid + carrier (1 mg/kg of body weight; L); (3) chlortetracycline + carrier (22 mg/kg of body weight; CTC); (4) L + CTC + carrier (CTCL). Heifers on CTC and CTCL were provided treatment Monday through Friday and carrier only on Saturday and Sunday. These heifers were provided their respective treatment during wk 1 to 4, 6, and 10; wk 5, 7 to 9, and 11 to 12 heifers were provided the nonmedicated carrier. Heifers were individually fed a total mixed ration with treatments top-dressed at 1200 h daily. Dry matter intake was monitored for each heifer and feed provided was adjusted according to individual intakes. Skeletal measurements were taken weekly and blood samples were obtained every Monday, Wednesday, and Friday. Blood samples were analyzed for thyroxine concentration via radial immunoassay. Heifers supplemented with L had lower average daily gain , overall body weight gain, and trends for lower daily body length gain and overall girth gain compared with CTC heifers, but similar to control and CTCL heifers. Heifers fed L had lower hip height gain and overall hip height gain compared with CTCL heifers, but similar to control and CTC heifers. Heifers fed L had lower overall withers height gain compared with control heifers, but similar to CTC and CTCL heifers. No treatment effect on thyroxine concentrations was observed. These data indicate that L did not increase growth. Results from this experiment indicate that supplementing heifers with L was not beneficial and no benefits to supplementing heifers with CTC or the combination of CTC and L were evident compared with control heifers. Heifers in this study experienced minimal health problems and were regarded to be under low stress levels. Supplementing CTC and L may be beneficial to growing heifers under conditions where disease exposure and stressors are greater.

Impact of subtherapeutic administration of tylosin and chlortetracycline on antimicrobial resistance in farrow-to-finish swine.

The use of antimicrobial agents in swine production at subtherapeutic concentrations for the purpose of growth promotion remains controversial due to the potential impact on public health. Beginning at weaning (3 weeks), pigs received either nonmedicated feed or feed supplemented with subtherapeutic levels of either tylosin (11-44 ppm) or chlortetracycline (5.5 ppm). After only 3 weeks, pigs given feed supplemented with tylosin had significantly higher levels of tylosin-resistant anaerobes (P < 0.0001) compared with the control group, increasing from 11.8% to 89.6%, a level which was stable for the duration of the study, even after a 2-week withdrawal prior to slaughter. Tylosin-fed pigs had a higher incidence of detection for erm(A), erm(F), and erm(G), as well as significantly (P < 0.001) higher concentrations of erm(B) in their feces. The continuous administration of chlortetracycline-supplemented feed, however, had no significant effect on the population of chlortetracycline-resistant anaerobes in comparison with nontreated pigs (P > 0.05). The resistance genes tet(O), tet(Q), and erm(B) were detected in all pigs at each sampling time, while tet(G), tet(L), and tet(M) were also frequently detected. Neither chlortetracycline nor tylosin increased the growth rate of pigs.

Dietary chlortetracycline induces differential effects on the accuracy of quantitative computed tomography and dual energy X-ray absorptiometry in assessing vertebral bone mineral density in growing pigs.

The effect of dietary chlortetracycline (CTC) on the bone mineral density (BMD) of growing pigs was assessed using quantitative computed tomography (qCT) and dual energy X-ray absorptiometry (DXA). Pigs of 28 and 84 days old were given either drug-free (n=48) or CTC-fortified (800 ppm) diets for 56 days. At day 28, eight control pigs were selected for qCT and DXA, and their second lumbar vertebrae were removed. Eight control and eight CTC-treated animals were selected at days 84 and 140, respectively, and six pigs from each of these groups were assessed at day 168. Several CTC-exposure variables had significant effects (P<0.05) on the relationships between qCT-, trabecular- and vertebral body-BMD (R2 increments of 0.03 and 0.01, respectively) and between DXA-, trabecular- and vertebral body-BMD (R2 increments of 0.40 and 0.10, respectively). The findings of this study demonstrate that the qCT method is more reliable than the DXA technique in monitoring tetracycline-induced changes in porcine vertebral BMD. The magnitude of the effect of the drug treatment on the DXA-BMD estimation was surprisingly high, suggesting that DXA should not be used to monitor such changes in growing pigs. In contrast, the marginal influence of drug treatment on the qCT-BMD assessment suggests that this methodology is useful in this context. Furthermore, the qCT method may also have applications in the investigation of the effect of other osteotropic substances or bone metabolism modulators on BMD.

Effect of lactoferrin on the growth performance, intestinal morphology, and expression of PR-39 and protegrin-1 genes in weaned piglets.

A total of 90 weaned female pigs (Duroc x Landrace x Yorkshire) were used in a 15-d growth experiment to investigate the effect of lactoferrin on growth performance, intestinal morphology, and expression of PR-39 and protegrin-1 genes. The pigs were allocated on the basis of BW and litter to 3 dietary treatments in a randomized complete block design. There were 3 replicate pens per treatment, and the pigs were grouped with 10 pigs per pen. The dietary treatments were (1) basal diet; (2) basal diet + 20 mg of flavomycin/kg + 110 mg of aureomycin/kg; (3) basal diet + 1.0 g of lactoferrin/kg. Six pigs, randomly selected from each treatment (2 piglets/pen) were slaughtered for intestinal morphology and expression of PR-39 and protegrin-1 genes at the end of the experiment. Supplementation with lactoferrin improved growth performance; it increased ADG by 41.80% (P < 0.01) and efficiency of gain (G:F) by 17.20% (P < 0.05). Intestinal villus height was increased by 15.30% (P < 0.05), and crypt depth was decreased by 9.60% (P < 0.05). Supplemental lactoferrin increased the relative abundance of mRNA for PR-39 and protegrin-1 by 143% (P < 0.01) and 217% (P < 0.01), respectively. The use of lactoferrin as an additive to improve nonspecific immunity and strengthen host defenses would be good a method of defending weaned pigs from infections and weanling stress.

Verotoxins in commensal Escherichia coli in cattle: the effect of injectable subcutaneous oxytetracycline in addition to in-feed chlortetracycline on prevalence.

Using a self-paired observational study, the association between therapeutic oxytetracycline use and the prevalence of virulence genes in commensal Escherichia coli (E. coli) from cattle was examined. Faeces were collected from 39 yearling bulls prior to and after treatment with oxytetracycline and from 44 untreated animals. Between samplings all animals received in-feed chlortetracycline for 16 days. Five E. coli were isolated from each sample and tested by a polymerase chain reaction (PCR) capable of detecting all verotoxin (vt) genes. Positive isolates were further tested with a multiplex PCR to detect vt1, vt2, eaeA and hlyA. For vt, 23 animals were positive at both samplings, 26 negative at both samplings, 22 negative animals became positive and 12 positive animals became negative. Sixty-eight per cent of the discordant pairs changed from vt-negative to vt-positive (95% CI 48-80) suggesting pressure toward becoming vt-positive perhaps due to the transfer of genes due to mixing of cattle in the months between samplings or an effect of chlortetracycline.

[The excipient properties of shea butter compared with vaseline and lanolin]. / Les propriétés d'excipient du beurre de Karité comparées à celles de la vaseline et de la lanoline.

A shea butter ointment containing 3% aureomycin (clortetracyclin hydrocloride) was prepared and some of its macroscopic and microscopic characteristics were evaluated. Then, the release of the active ingredient was compared by UV spectrophotometry with those obtained when excipients such as petroleum jelly and lanoline were used. Results had shown that the shea butter ointment had satisfactory characteristics. In the other hand, it was found that shea butter released the aureomycin easily and at a faster rate than the other excipients.

Effects of antimicrobials and weaning on porcine serum insulin-like growth factor binding protein levels.

The effects of subtherapeutic antimicrobial supplementation and weaning on serum levels of IGF-I and insulin-like growth factor binding proteins (IGFBP)-2, -3 and -4 were determined in crossbred weanling pigs. At weaning, pigs were allotted to a diet containing 21.8% crude protein and 1.15% lysine with or without Aureozol (110 mg/kg of Aureomycin chlortetracycline, 110 mg/kg of sulfathiazole, and 55 mg/kg of penicillin) for 4 wk. Insulin-like growth factor-binding proteins and IGF-I analyses were performed on blood samples that were drawn weekly. Weaning decreased serum IGFBP-3 levels in both control and Aureozol-treated groups on d 6 and d 14 (P < 0.05) relative to preweaning levels. The IGFBP-3 values returned to preweaning levels by d 21. Although the circulating levels of both the 43-kDa and the 39-kDa glycosylation variants of IGFBP-3 were affected by weaning, the level of the 39-kDa IGFBP-3 was affected relatively more than that of the 43-kDa IGFBP-3 (P < 0.05). Compared with circulating IGFBP-3 levels in control pigs, Aureozol-treated pigs had higher circulating IGFBP-3 levels on d 21 (43%, P < 0.05) and d 27 (46%, P < 0.05). In direct contrast to the effect of weaning on serum IGFBP-3 level, serum IGFBP-2 levels increased on d 6 and d 14 after weaning (P < 0.05) and decreased to preweaning levels by d 21. The IGFBP-2 levels continued to decline and were less than preweaning levels by d 27 (P < 0.05). Aureozol treatment had no effect on serum IGFBP-2 levels at any time. Serum levels of nonglycosylated IGFBP-4 were not affected by either weaning or Aureozol supplementation. Weaning decreased circulating IGF-I concentration on d 6 in both control and Aureozol-treated pigs (76 and 73%, respectively, P < 0.05) and on d 14 (62%, P < 0.05) and d 21 (32%, P < 0.05) in control pigs. Aureozol-supplemented pigs had higher serum IGF-I concentrations than control pigs on d 14 (82%, P < 0.05), d 21 (55%, P < 0.05), and d 27 (36%, P < 0.05). The Aureozol-fed pigs had a 14.2% increase in BW gain (P < 0.05) and a 59.6% increase in ADG (P < 0.05) compared with pigs fed the control diet. Both Aureozol-supplementation and weaning cause changes in serum IGFBP levels and IGF-I concentrations that might be involved in regulating rate and efficiency of growth.

The effects of the periodical use of in-feed chlortetracycline on the reproductive performance of gilts and sows of a commercial pig farm with a history of clinical and subclinical viral and bacterial infections.

The objective of this study was to assess the effects of in-feed chlortetracycline (CTC) as a measure of preventing or minimizing infectious problems of reproductive failure in gilts and sows. In a farm of 400 Large White x Landrace gilts and sows with a clinical history of porcine respiratory and reproductive syndrome (PRRS) virus, the animals were treated with CTC. Treatment consisted of 10 g CTC sow/day for 15 days every 3 months. It improved the health status of sows by decreasing post-farrowing clinical mastitis and vaginal discharges, abortions, return-to-oestrus and irregular return-to-oestrus rates. These beneficial effects had a positive impact on the performance of the litter. More piglets were born live and weaned. These positive effects improved with repeated use of CTC. The serological evidence of PRRS virus, Leptospira spp. and Chlamydia spp. and the subsequent beneficial use of the antimicrobial agent indicate that reproductive failure, possibly resulting from the bacterial agents can be controlled with in-feed use of broad spectrum antimicrobials.

A field study on the effect of in-feed inclusion of a natural zeolite (clinoptilolite) on health status and performance of sows/gilts and their litters.

The study was conducted to evaluate the effect of the long-term dietary use of a natural zeolite (clinoptilolite, NZ) on health status and reproductive performance of sows/gilts and performance of their litters, along with its compatibility with antibacterials (chlortetracycline, CTC) periodically used in medication programmes. Two hundred and forty sows/gilts and their litters were assigned to two main experimental groups and four subgroups, depending on the inclusion of NZ and CTC in their feed. During the trial, frequent sampling of pregnancy feed for mycotoxicological analysis revealed a high contamination level with zearalenone. No adverse or side effects attributed to NZ were noticed. Furthermore, the combined use of NZ and CTC revealed no clinically apparent interactive effect on the availability of the latter. Reproductive performance was significantly improved by the dietary inclusion of both NZ and CTC. The results also suggested that the beneficial effect of NZ could be additionally considered as an indicator of the amelioration of zearalenone exposure consequences.