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1.
Protection of pregnant swine by vaccination against leptospira infection   总被引：2，自引：0，他引：2  
SUMMARY The protection conferred on pregnant gilts by 2 commercially available Leptospira interrogans serovars pomona and tarassovi bacterins was evaluated. Gilts vaccinated either 3, 6 or 12 months prior to natural challenge with L. interrogans serovar pomona had significantly lower abortion rates (2% vs 69%) and foetal mortality rates (14% vs 57%) than unvaccinated controls. One vaccine was significantly superior to the other and contained approximately twice the number of L. interrogans serovar pomona organisms per vaccine dose. Neither vaccine protected against renal colonisation but vaccination reduced urinary excretion of leptospires. Both vaccines reduced agglutinating antibody response to infection, as measured by the microscopic agglutination (MA) test. This may prevent the detection of a carrier animal by serology. Foetal pigs did not develop specific MA titres. Cultural methods were not reliable in making a diagnosis of foetal infection. Histopathology of foetal liver and kidneys helped in making a diagnosis of foetal infection.  相似文献   

2.
Renal dysfunction due to leptospirosis has been reported infrequently in the horse. The animals in this case presentation developed an acute and persistent febrile illness that could have been attributed to a number of infectious diseases. Upon numerous subsequent clinical evaluations, detection of renal dysfunction narrowed the list of differential diagnoses. This Case Report describes 3 horses with acute renal disease from Leptospira interrogans. Pyrexia was the initial clinical sign and was refractory to antimicrobial therapy. Once azotaemia developed, leptospirosis was diagnosed as the origin of the renal dysfunction. Treatment included i.v. crystalloid fluids, diuretics, anti‐inflammatory medication, antibiotics, pentoxifylline and polysulphated glucosaminoglycan. Additionally, one of these 3 horses required a continuous infusion of vasopressors to resolve the azotaemia. Pyrexia resolved within 48 h of treatment initiation for leptospirosis. The azotaemia resolved completely after 3 months (Case 1), 3 weeks (Case 2) and 5 days (Case 3).  相似文献   

3.
A commercially manufactured leptospirosis vaccine containing serovars pomona and hardjo and licensed for use in cattle and sheep was investigated to determine if it would prevent leptospiruria in pigs exposed to serovar pomona. Twenty piglets were each vaccinated twice at an interval of three weeks. Twenty other piglets were unvaccinated and served as controls. Three weeks after the second dose of vaccine all animals were exposed for 64 to 89 days to a natural infection with pomona. During the investigation blood samples were examined serologically and urine samples were examined by dark ground microscopy and cultured for the presence of leptospirae. Attempts were made to culture leptospirae from kidneys at slaughter. Kidneys were also examined histologically for evidence of leptospira infection. One vaccinated animal developed a respiratory disease. It was treated with antibiotics and removed from the trial. Leptosphuria was demonstrated in six of the remaining 19 vaccinated pigs and leptospirae were found in nine of 578 (1.5%) urine samples examined from these animals during the period of exposure. In contrast leptospiruria occurred in 19 of 20 unvaccinated pigs and leptospirae were found in 253 of 642 (39.4%) urine samples examined from these animals. Histopathological lesions consistent with leptospirosis were found in kidneys examined from two of 16 vaccinates and 17 of 18 non-vaccinates. Antibodies to serovar pomona were detected in 12 of 19 vaccinated pigs examined three weeks after the second dose of vaccine and before exposure to infection, and in all of 18 unvaccinated pigs examined after exposure to infection. It was concluded that use of this vaccine in pigs resulted in a significant degree of protection against leptospiruria.  相似文献   

4.
Resistance to renal leptospirosis was demonstrated in cattle vaccinated with Leptospira interrogans serotype pomona bacterin. Fewer vaccinated cattle given challenge inoculum of virulent serotype pomona leptospires 12 months after vaccination had kidneys with gross focal lesions in the cortex than did nonvaccinated controls. Histopathologic changes characteristically associated with renal leptospirosis occurred less frequently and renal tissue damage was less severe in vaccinated cattle than in nonvaccinated controls. The isolation of serotype pomona from only 1 of 29 vaccinated cattle, compared to 7 isolations from 11 nonvaccinated cattle, at 26 days after challenge inoculum was given, indicated that mild renal infection occurred only infrequently in vaccinated cattle. It appeared that challenge inoculation of vaccinated cattle with virulent serotype pomona leptospires stimulated an accelerated secondary immune response in which immunity limited the multiplication of leptospires in the kidney.  相似文献   

5.
The efficacy of two bacterins containing an Actinobacillus pleuropneumoniae serotype 10 strain was evaluated. The bacterial cells constituting bacterin 1 and 2 were grown under nicotinamide adenine dinucleotide (NAD)‐rich (low‐adherence capacity to alveolar epithelial cell cultures) and NAD‐restricted (high‐adherence capacity to alveolar epithelial cell cultures) conditions, respectively. Ten pigs were vaccinated twice with the bacterin 1 and nine pigs with the bacterin 2. Ten control animals were injected twice with a saline solution. Three weeks after the second vaccination, all pigs were endobronchially inoculated with 106.5 colony‐forming units (CFU) of an A. pleuropneumoniae serotype 10 strain. In the bacterin 1 and 2 group, three and two pigs died after inoculation, respectively. Only two pigs of the control group survived challenge. Surviving pigs were killed at 7 days after challenge. The percentage of pigs with severe lung lesions (>10% of the lung affected) was 100% in the control group, 70% in the bacterin 1 group and 22% in the bacterin 2 group. Actinobacillus pleuropneumoniae was isolated from the lungs of all animals. The mean bacterial titres of the caudal lung lobes were 7.0 × 106 CFU/g in the control group, 6.3 × 105 CFU/g in the bacterin 1 group and 1.3 × 106 CFU/g in the bacterin 2 group. It was concluded that both bacterins induced partial protection against severe challenge. Furthermore, there are indications that the bacterin 2, containing A. pleuropneumoniae bacteria grown under conditions resulting in high in vitro adhesin, induced better protection than the bacterin 1.  相似文献   

6.
The efficacy of a subunit vaccine containing the Apx toxins of Actinobacillus pleuropneumoniae and transferrin‐binding proteins was determined. Ten pigs were vaccinated twice with the vaccine. Eight control animals were injected twice with a saline solution. Three weeks after the second vaccination, all pigs were endobronchially inoculated with 106.5 colony‐forming units (CFU) of an A. pleuropneumoniae serotype 9 strain. In the vaccine group, none of the pigs died after inoculation. Only one pig of the control group survived challenge. Surviving pigs were killed at 7 days after challenge. The mean percentage of affected lung tissue was 64% in the control group and 17% in the vaccine group. Actinobacillus pleuroípneumoniae was isolated from the lungs of all animals. The mean bacterial titres of the caudal lung lobes were 5.0 × 108 CFU/g in the control group and 3.0 × 106 CFU/g in the vaccine group. It was concluded that the vaccine induced partial protection against severe challenge.  相似文献   

7.
AIMS: To evaluate a multivalent leptospiral and clostridial vaccine for prevention of renal colonisation and urinary shedding in sheep, following experimental challenge with New Zealand strains of Leptospira borgpetersenii serovar Hardjo type Hardjobovis and L. interrogans serovar Pomona.

METHODS: Two separate but similarly designed studies were conducted. In both studies, Romney-cross lambs, aged 9–11 weeks, were randomly allocated to a vaccinated group and a control group. Vaccinated lambs each received two 1.5-mL S/C doses of a multivalent leptospiral and clostridial vaccine, 4 weeks apart, and animals in the control groups received the same dose of saline. Groups of 12 vaccinated and 12 control lambs were randomly selected in each study for challenge with serovars Hardjo or Pomona. Challenge was initiated 16 weeks following the second vaccination with three daily doses of live leptospires by intranasal and conjunctival routes. Following challenge, urine samples were collected weekly for 6 weeks, for dark field microscopy and leptospiral culture; 6 weeks after challenge the lambs were slaughtered and kidneys collected for leptospiral culture.

RESULTS: In lambs challenged with serovar Hardjo, 8/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive for leptospires following culture, compared with 0/12 lambs in the vaccinated group (p=0.001). In lambs challenged with serovar Pomona, 9/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive following culture, compared with 0/12 lambs in the vaccinated group (p<0.001). Prevention of renal colonisation and urinary shedding, expressed as the prevented fraction, was 100 (95% CI=61.7–100)% and 100 (95% CI=68.3–100)% against challenge with serovars Hardjo and Pomona, respectively, at 4 months after vaccination.

CONCLUSIONS AND CLINICAL RELEVANCE: Use of a multivalent leptospiral and clostridial vaccine demonstrated protection against challenge from New Zealand strains of serovars of Hardjo and Pomona 4 months after vaccination in lambs first vaccinated at 9–11 weeks of age. Further studies are required to assess the duration of immunity against challenge in sheep.  相似文献   


8.
The objectives of this study were to elucidate at which age tonsillar colonisation by Actinobacillus pleuropneumoniae occurs in pigs and relate this occurrence to the presence of colostral antibodies to A. pleuropneumoniae. The infection patterns were studied in an isolated cohort of pigs, which consisted of the offspring from five sows originating from a conventional pig herd. The sows were transferred to isolated research facilities before farrowing. A. pleuropneumoniae was detected on the tonsils of all sows. After a nursing period of 3 weeks, the pigs were weaned and reared isolated from other pigs until slaughter. The pigs were examined repeatedly for the presence of A. pleuropneumoniae on the tonsils and for antibodies to A. pleuropneumoniae using bacteriological and serological techniques, respectively.A. pleuropneumoniae was detected in the tonsils of one pig as early as 11 days after birth, showing that A. pleuropneumoniae can be transmitted from sow to offspring during a 3-week nursing period. The cumulative proportion of pigs carrying A. pleuropneumoniae in their tonsils increased significantly between the age of 4-12 weeks. This age period corresponded to the age at which the proportion of pigs with detectable levels of colostral antibodies to the different serotypes of A. pleuropneumoniae was declining. Since these two events take place in the same age period, we expect a possible biological association between the level of the passive immunity and the degree of tonsillar colonisation. The median duration of tonsillar colonisation was estimated to approximately 7-8 weeks.  相似文献   

9.
North American horses are commonly exposed to Leptospira organisms. Leptospira Bratislava is the most common infecting serovar but this serovar has not been confirmed to cause clinical disease in North American horses. Leptospira Pomona type kennewicki is responsible for most of the clinical diseases (leptospirosis) in North American horses. Leptospirosis is most commonly associated with diseases of the placenta and fetus, the kidneys and the eyes in horses. In-utero infections in pregnant mares may result in abortion, neonatal illness or birth of an antibody positive healthy foal. Acute renal failure in younger horses and recurrent uveitis in adult horses are other well documented clinical syndromes of leptospirosis. Abortions, neonatal disease and acute renal failure are caused by a subacute infection, while horses with Leptospira associated recurrent uveitis develop ocular disease months or years after the initial Leptospira infection. Diagnosis of Leptospirosis is made by a combination of antigen or antibody testing methods. Mares that abort following Leptospira infection have no additional clinical signs at the time of abortion but may shed the offending Leptospira spp. in the urine for several weeks. Antibiotic treatments are sometimes used in hopes of decreasing Leptospira shedding in infected horses or prophylactically in exposed pregnant mares but documentation of efficacy is lacking. Horses with Leptospira - associated acute renal failure can be successfully treated with antibiotics and supportive care. Recurrent uveitis is commonly associated with leptospirosis in North American horses and although horses may have chronic intraocular infection triggering an immune disease, systemic antimicrobial therapy has not been effective in eliminating the organism from the eye. An equine approved Leptospira Pomona type kennewicki vaccine is now available in North America.  相似文献   

10.
Serum samples were collected from 30 piglets, derived from 17 litters, whose dams had been vaccinated against leptospirosis. Microscopic agglutination test (MAT) titres against Leptospira interrogans serovar pomona varied greatly from pig to pig; there was less variation among littermates. Titres declined between 4 and 10 weeks of age, with an uncorrected half-life of 15.5 days, consistent with IgG being the main antibody class involved. Twelve pigs, 4 derived from unvaccinated sows and 8 from sows vaccinated against leptospirosis, were challenged intravenously at 8 weeks of age with leptospires of serovar pomona. Colostrum-derived antibody protected 4 out of 8 pigs, and in 1 of the remaining 4 the serological response was reduced. Three of the protected pigs showed reduced serological responses and in the fourth the response was strong, but delayed. All of the pigs derived from unvaccinated sows developed leptospiraemia and leptospiruria and showed strong serological responses. Protection by colostrum-derived antibody bore an inexact relationship to MAT titre, but a titre of 16 appeared to be sufficient for protection.  相似文献   

11.
OBJECTIVE: To determine kinetics of antibody absorption, persistence of antibody concentrations, and influence of titers on vaccination of baby pigs with a vaccine against classical swine fever (CSF). ANIMALS: 15 sows and their litters. PROCEDURE: Farrowings were supervised. Initial time of suckling was recorded. In the first experiment, blood samples were collected at farrowing, 2 and 4 hours after suckling, and hourly until 10 hours after initial suckling. Samples were assayed for CSF antibodies, using a serum neutralizing (SN) test. A second experiment included 33 baby pigs vaccinated as follows: 10 prior to ingestion of colostrum, 18 between 1 and 4 hours after ingestion of colostrum, and 5 at 12 hours after ingestion of colostrum. Fourteen pigs were vaccinated when 7 weeks old, and 15 pigs were not vaccinated. At 10 weeks of age, pigs were challenge-exposed with virulent CSF virus. Blood samples were collected and assayed for CSF antibodies and p125 antigen and p125 antibodies. RESULTS: CSF antibodies were detected in pigs beginning 2 hours after suckling. Colostral antibodies persisted for > 7 weeks (half-life, 79 days). Vaccination of pigs before suckling provided effective protection from severe disease after challenge-exposure. However, vaccination of neonates with antibody titers was not effective, because 19 of 23 (82%) pigs succumbed after challenge-exposure. All pigs vaccinated when 7 weeks old resisted challenge-exposure, whereas all unvaccinated control pigs succumbed. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination before ingestion of colostrum conferred good protection against CSF in baby pigs. Vaccination of 7-week-old pigs that had decreasing concentrations of passively acquired antibodies was efficacious.  相似文献   

12.
Eight conventionally reared, 1- to 11-week old Ayrshire calves were naturally infected by a strain of Mycoplasma dispar (M. dispar). The colonisation was quantitatively followed by nasal swab samples, transtracheal aspiration samples and by the examination of the whole of the respiratory tract for mycoplasmas at slaughter after a follow-up period of 7–10 months.The fairly uniform pattern of the colonisation by M. dispar was revealed: A high degree of colonisation, measuring 105–108 colour change units (ccu) per nasal sample, lasted for a period of 2–5 months and was followed by a slow decrease in titres. Seven of the calves still harboured M. dispar in their respiratory tracts at slaughter. Intermittently obtained transtracheal aspiration samples were all positive for M. dispar and the titres were regularly higher than those for the simultaneously taken nasal samples indicating a high ability of M. dispar to continuously colonize the more distal parts of the respiratory tract. It was demonstrated that the sensitivity of nasal swabbing in the detection of M. dispar infection largely depended on the phase of colonisation : The method was good for the detection of a fairly recent infection of M. dispar, but inadequate for detection of low grade carriers.In various phases, the calves also became infected by Mycoplasma bovirhinis and Acholeplasma laidlawii. Their ability to colonize the whole respiratory tract was lower than that of M. dispar.  相似文献   

13.
The hardjo component of a bivalent hardjo/pomona vaccine prepared from cultures grown in a protein-free medium was tested in calves which experienced a natural challenge about 7 months after vaccination. A significant degree of protection was obtained using either seroconversion or positive urine cultures as in-dicators of infection. Seroconversion occurred in 10/10 non-vaccinates and 2/9 vaccinates (p <0.01), Leptospires of serovar hardjo were isolated from the urine of 6/10 non-vaccinated calves and 0/9 vaccinated animals (p <0.05).  相似文献   

14.
Differentially extended specific protection by two commercial vaccines against Yersinia ruckeri serotype O1 biotype 2 was studied following 30 s immersion exposure. Rainbow trout were challenged intra-peritoneally (i.p.) with Y. ruckeri serotype O1, biotype 2 (≈106 to 107 CFU/fish) at 4, 6 and 8 months after vaccination with vaccines containing either biotype 1 (AquaVac® ERM) or both biotypes 1 and 2 (AquaVac® RELERA?). The specific pattern of vaccine-mediated protection was evaluated by relative percentage survival (RPS) analysis at 4 and 6 months post-vaccination and by obtaining gross pathological observations at 4 and 8 months respectively. We determined specific significant and superior protection in terms of increased survivability in AquaVac® RELERA? vaccinated fish and observed correspondingly fewer pathological changes. The challenge trials indicated a longer protection for at least 6 months without any booster vaccination. A specific and adaptive response induced by AquaVac® RELERA? vaccine against Y. ruckeri biotype 2 was clearly indicated. In addition, some degree of cross protection rendered by AquaVac® ERM containing biotype 1 during infection with Y. ruckeri biotype 2 was also noted.  相似文献   

15.
A study was conducted to determine the seroprevalence of leptospirosis and infecting serovars across livestock (cattle, sheep, goats, and pigs) in Trinidad using the microscopic agglutination test with an international panel of 23 serovars. Of a total of 590 cattle tested, 21.5% were seropositive with agglutinations to 13 of the 23 antigens used in the panel. Icterohaemorrhagiae (9.3%), Sejroe (4.1%), Ballum (4.1%), and Autumnalis (1.9%) were the predominant serogroups detected in the cattle sampled (n = 590). Of 222 sheep tested, 5.0% were seropositive with agglutinations to five serovars belonging to two serogroups. These serogroups were Autumnalis at 2.7%, and Icterohaemorrhagiae at 2.3% of all sheep tested (n = 222). Of a total of 180 goats tested, 3.3% were seropositive, all agglutinating to the Icterohaemorrhagiae serogroup, 1.7% to serovar Copenhageni, 1.1% to serovar Mankarso, and 0.6% to serovar Icterohaemorrhagiae. Among pigs (n = 200), 5.0% were seropositive for five serovars belonging to three serogroups. These serogroups were Icterohaemorrhagiae at 2.5%, Australis at 2%, and Ballum at 0.5%. Overall, age and sex of animals were not significantly associated with leptospirosis with the exception of cattle where age was a significant factor for seropositivity. It was concluded that for livestock, leptospirosis may be an important zoonotic and economic disease, particularly in the case of cattle. It is imperative that the impact of leptospirosis on abortion, stillbirths, and decreased milk production in livestock in the country be assessed.  相似文献   

16.
Summary

A field trial was carried out with Nobi‐Vac AR vaccine in 11 swine breeding herds. One herd suffered from severe B. bronchiseptica (BB+) rhinitis in piglets, while no clinical Atrophic Rhinitis (AR) was observed. Ten herds were described as AR problem herds, because clinical AR was observed for at least 1 year in spite of the fact that medication of sows and piglets was carried out and adequate housing and management systems were available in most herds. BB+ was isolated in 9 of these 10 farms and the AR pathogenic P. multocida (PM+) in all these farms.

The trial started when piglets were born of sows which had been vaccinated 3 times. All piglets between 7 and 10 weeks old were examined clinically for AR. Nasal swabs from 20 pigs on each farm were screened bacteriologically for BB+ and PM+ every other month.

A severe reoccurrence of AR was found in 2 of the 10 AR problem farms. In these 2 herds the ‘all in‐all out’ system was not applied in farrowing and weaning houses. In the 8 other AR problem herds the percentage of pigs with AR decreased significantly below the average level of 1% per year. The percentage of pigs infected with BB+ and PM+ also decreased significantly. PM+ was significantly related to the percentage of clinical AR piglets. Seasonal effects contributed to a minor extent to the percentage of AR piglets.

After 2.5 years of this trial PM+ could not be isolated during the last 12 months in six of the remaining AR problems herds.

The conclusion is that Nobi‐Vac AR vaccination of the sow gave protection against clinical AR in piglets on those farms (80%) which provided adequate housing and management systems.  相似文献   

17.
In this study, an intranasal immunization strategy was set up in maternally immune pigs in order to protect them not only clinically but also virologically. Two genetically engineered Aujeszky’s disease virus (ADV) strains, Kaplan gE?gI? and Kaplan gE?gC?, were used for intranasal immunization. Both strains were safe for 4-week-old pigs. A single intranasal inoculation of 106.0 TCID50 of Kaplan gE?gI? and Kaplan gE?gC? at 4 weeks of age in the presence of moderate titres of maternally derived antibodies (SN titres: 12–16) reduced the amount of weight loss, fever and virus excretion upon challenge 6 weeks later. In a second experiment, the effect of an additional intramuscular booster with three different commercial vaccines (containing attenuated Bartha or NIA3-783 or inactivated Phylaxia; all suspended in an oil-in-water emulsion) at 10 weeks of age was evaluated. One month after the last intramuscular booster, between five and seven pigs from each group were selected for challenge. All intranasally/intramuscularly immunized pigs showed a significantly better clinical and virological protection after challenge than the single intranasally immunized pigs. In the double immunized group, the protection was better when Kaplan gE?gC? was used for the intranasal priming (only two of 14 pigs excreted virus with a duration of 4 days) than when Kaplan gE?gI? was used (13 of 18 pigs excreted virus with a duration ranging from 1 to 4 days). The virological protection was not influenced by the type of vaccine used for booster vaccination. Because the intranasal/intramuscular immunization approach is very compatible with current pig movements on farms and pigs with moderate levels of maternally derived antibodies can effectively be immunized, it can be considered as a good alternative to intramuscular/intramuscular vaccinations especially in regions with a high ADV prevalence.  相似文献   

18.
A trial was conducted to assess the efficacy of a single intra-muscular injection of 25mg per kg of streptomycin in stopping leptospiruria in growing pigs exposed to a natural infection.

The investigation involved 54 pigs, 10–12 weeks old, that were free of serological evidence of infection with serotypes pomona or tarassovi at the start of the trial. The animals were kept in pens in a finishing house through which flowed effluent from other pens containing infected pigs. Urine samples were collected from each pig three times weekly until it was slaughtered for bacon at 20–24 weeks old.

Leptospiruria was first detected between 16 and 74 days after exposure. Twenty-one of 37 pigs which showed leptospiruria were injected with streptomycin. Leptospirae were detected in 11 of 185 (5.9%) subsequent urine samples from these 21 treated animals and serotype pomona was cultured from the kidney of 1 of the 10 animals that were examined from this group at slaughter.

Following the initial detection of leptospiruria in the 16 un-treated pigs, 179 of 211 (84.8%) subsequent urine samples con-tained leptospirae, which were also cultured from the kidneys of 4 out of 11 of these animals.  相似文献   

19.
Isolation of Shiga-toxin (Stx) positive Escherichia coli O157:H7 from commercially grown pigs has been reported. Furthermore, experimental infection studies have demonstrated that Stx-positive E. coli O157:H7 can persist in 12-week-old experimentally orally inoculated conventional pigs for up to 2 months and that persistence was not dependent upon intimin. We have shown that the flagellum of Stx-negative E. coli O157:H7 does not have a role to play in pathogenesis in ruminant models whereas, in poultry, the flagellum of E. coli O157:H7 was important for long-term persistent infection. The contribution of the flagellum of Stx-negative E. coli O157 in the colonisation of pigs was investigated by adherence assays on a porcine (IPI-21) cell line, porcine in vitro organ culture (IVOC) and experimental oral inoculation of conventional 14-week-old pigs. E. coli O157:H7 NCTC12900nal(r) and isogenic aflagellate and intimin deficient mutants adhered equally well to IPI-21 cells. In porcine IVOC association assays, E. coli O157:H7 NCTC12900nal(r) was associated in significantly higher numbers to tissues from the caecum and the terminal rectum than other sites. The aflagellate and intimin deficient mutants significantly adhered in greater numbers to more IVOC gastrointestinal tissues than the parent. Groups of 14-week-old pigs were dosed orally with 10(10)CFU/10ml of either E. coli O157:H7 NCTC12900nal(r) or isogenic aflagellate and intimin deficient mutants and recovery of each test strain was similar. Histological analysis of pig tissues at post mortem examination revealed that E. coli O157 specifically stained bacteria were associated with the mucosa of the ascending and spiral colon. These data suggest that colonisation and persistence of Stx-negative E. coli O157:H7 in pigs, involves mechanisms that do not require the flagellum or intimin.  相似文献   

20.
The objective of this study was to determine if selection response for increased litter size in pigs could be partially attributed to three type 1 marker loci coding for genes known to affect litter size: oestrogen receptor (ESR), retinol‐binding protein 4 (RBP4) and follistatin (FS). In the high litter size line (LS), pigs from the largest litters, based on number of pigs born alive (NBA), were retained to parent the next generation. A randomly selected control line (LC) was maintained. Gilts were reared in litters of 10 pigs or less to minimize maternal effects. Pigs were measured at generations 10–12. Additional traits scored were number of fully formed pigs (NFF) and number of mummified fetuses (MUM). Breeding values for NFF and NBA were greater (p < 0.05) in LS than LC in generations 11 and 12, but no significant line differences were found for MUM. The A allele of the ESR locus was fixed in both lines. After adjustment for effects of genetic drift, frequency of the two alleles segregating for the FS and RBP4 loci did not differ significantly between lines. No significant additive or dominance effects of the FS markers were detected for NFF, NBA and MUM in either LS or LC. Response to selection for increased litter size could not be attributed to effects at the ESR, RBP4 or FS loci.  相似文献   

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