Isolation of Actinobacillus seminis from rams in the United Kingdom.

Actinobacillus seminis was isolated from the semen of five rams on four farms. Four of the rams had abnormal semen and three were also infertile. The isolates of A seminis showed similar phenotypic profiles and electrophoretic protein patterns to the type strain of A seminis but were distinct from Histophilus ovis previously isolated from rams with epididymitis in Scotland. The infection appeared to be subclinical but two of the five rams had palpable abnormalities of their testes. Three rams were treated with antibiotics but the infection persisted. No gross lesions were found in the genitalia of two of three rams examined post mortem but one had necrotic abscesses in the testes and epididymis. A seminis was isolated from the seminal vesicles and epididymis of one ram without gross lesions but not from the genitalia of the other two. On one farm the infection in a recently purchased ram led to the detection of another case as a result of the bacteriological screening of 11 stock rams not in contact with the initial case. These five subclinical cases, which included a supposedly healthy stock ram, suggest that A seminis infection may be widespread and should be considered in cases of infertility.     

CLINICAL AND PATHOLOGICAL STUDIES OF BORDER LEICESTER RAMS NATURALLY INFECTED WITH ACTINOBACILLVS SEMINIS

Clinical examination of 31 rams with evidence of Actinobacillus seminis infection revealed 15 cases with marked lesions of the scrotal contents, two cases with very mild lesions, one with testicular atrophy but no abnormality of the epididymides, and another 13 without any palpable abnormalities of the genitalia. The rams were from a Border Leicester flock and included 27 un-mated rams from 6 to 12 months old. Histological examinations of affected epididymides showed a mixed purulent and non-purulent inflammation, with cystic hyperplasia of the ductus epididymis. Interstitial fibrosis and spermatic granulomas were seen in chronic lesions. Bilateral testicular atrophy and seminal degeneration were found in the nine rams that were autopsied. The clinical and pathological features of the disease are similar to those of ovine brucellosis. A pyelonephritis of unknown significance was found in four of the nine rams examined.     

Serological survey of the prevalence of Toxoplasma gondii antibodies in rams in sheep flocks in New South Wales

SUMMARY Serum samples from 5724 rams on 534 farms in New South Wales were tested in the indirect fluorescent antibody test for toxoplasmosis. Nine per cent of rams had titres of 64 or higher and 41% of flocks had either one or more rams with a titre of 64 or higher. There were significant differences in the geographical distribution of infected flocks, ranging from 57.8% of flocks infected on the tablelands to 41% on the slopes and 22.4% on the plains. There were significantly more infected commercial flocks (47.5%) than stud flocks (32.9%). The results indicated that the prevalence of infection was influenced by management, with a higher prevalence of infection in flocks kept under an intensive or semi-intensive system of management.     

Serology and semen culture for the diagnosis of Brucella ovis infection in chronically infected rams

The serological response to Brucella ovis and the shedding of the organism in semen was followed for a period of 13-14 months in 42 naturally infected rams. Most rams remained chronically infected and excreted the organism in their semen throughout the investigation. B. ovis was isolated from 87.9% of the semen samples from the infected rams. The most common sites from which B. ovis could be isolated at necropsy were the epididymides and accessory sexual glands. In one ram the organism was isolated from lung, spleen, kidney and iliac lymph nodes. Three rams ceased to shed B. ovis in their semen during the course of the investigation. Seventy-five (11%) of 686 sera from infected rams were negative in the complement fixation test (CFT) although 76% and 77% of CFT-negative sera were positive in the gel diffusion precipitin test (GDT) and enzyme labelled immunosorbent assay (ELISA) respectively. The high incidence of CFT-negative infected rams was due to the selection for the investigation of many rams with histories of negative or vacillating CFT titres. Sera from five rams which never shed B. ovis in their semen reacted erratically in the three serological tests. The five rams were from heavily infected flocks and were kept in contact with infected rams throughout the investigation.     

Serology and semen culture for the diagnosis of Brucella ovis infection in chronically infected rams

The serological response to Brucella ovis and the shedding of the organism in semen was followed for a period of 13–14 months in 42 naturally infected rams. Most rams remained chronically infected and excreted the organism in their semen throughout the investigation B. ovis was isolated from 87.9% of the semen samples from the infected rams. The most common sites from which B. ovis could be isolated at necropsy were the epididymides and accessory sexual glands. In one ram the organism was isolated from lung, spleen, kidney and iliac lymphnodes. Three rams ceased to shed B. ovis in their semen during the course of the investigation. Seventy-five (11%) of 686 sera from infected rams were negative in the complement fixation test (CFT) although 76% and 77% of CFT-negative sera were positive in the gel diffusion precipitin test (GDT) and enzyme labelled immunosorbent assay (ELISA) respectively. The high incidence of CFT-negative infected rams was due to the selection for the investigation of many rams with histories of negative or vacillating CFT titres. Sera from five rams which never shed B. ovisin their semen reacted erratically in the three serological tests. The five rams were from heavily infected flocks and were kept in contact with infected rams throughout the investigation.     

Actinobacillus seminis infection in sheep in the Republic of South Africa. I. Identification of the problem

A clinical palpation and semen smear examination of 647 rams submitted to the Regional Veterinary Laboratory during 1967 revealed that 42 (6,5%) of these animals had clinical epididymitis or orchitis, 6 (0,9%) showed other types of genital lesions and 98 (15,1%) suffered from subclinical genital infection. A. seminis and A. seminis-like organisms were isolated from semen specimens of 18 out of 35 rams with clinical epididymitis or orchitis, 25 out of 33 rams with subclinical infection and none out of 13 rams which showed no neutrophils in their semen. On 4 stud farms where Elberg Rev. 1 vaccine was meticulously applied and the complete absence of Brucella ovis infection was established, of a total of 327 rams examined, 10 (3,6%) were found to be clinically and 72 (22,0%) subclinically affected. A. seminis was isolated from 5 out of 6 of these rams with clinical lesions and 10 out of 15 of those which showed evidence of subclinical infection.     

Assessment of ram fertility in hill flocks in Argyll

Examination of 1260 rams, involving 1540 semen examinations, revealed that 9 per cent of rams in hill flocks in Argyll were subfertile as assessed by semen evaluation. Although 34 lesions of the genitalia were identified, only 13 were associated with poor semen quality. A five year survey of one blackface flock resulted in the elimination, after three years, of a 17 per cent level of infertility following routine examination of all rams, with an increase of 2.27 per cent in the lamb crop. Based on the 1981 lamb prices for this flock an increased income of 1085 pounds was achieved.     

Early sequential findings in the genitalia of rams experimentally infected with Actinobacillus seminis

AIM: To investigate and assess the sequential pathological changes in the epididymis and testis of young rams injected intra-epididymally with Actinobacillus seminis. METHODS: Twenty yearling Suffolk and Suffolk-cross rams were randomly divided into two groups comprising 16 test and four control animals. Each test ram received 2.3 x 109 cfu/ml of A. seminis injected intra-epididymally. Every 24 h post-inoculation (p.i.), two test rams were randomly selected, euthanised, and necropsied, until the end of the experiment at 192 h p.i. One control animal was euthanised at 24 h, 48 h, 96 h and 144 h p.i., respectively. The reproductive tract of each ram was carefully examined, lesions photographed, and tissues cultured. Thin sections of tissue samples were fixed and examined by light microscopy; additionally, epididymal tissues were examined by scanning electron microscopy (ScEM). RESULTS: Gross lesions were observed in the cauda epididymis of all test rams, and ranged from swelling at 24 h p.i. through enlargement and granuloma formation from 72 h p.i., to gradual enlargement and increasing firmness by 192 h p.i. Gross testicular atrophy was observed in three rams. Histologically, spermatic granulomas were evident in the epididymis and the tunica vaginalis of 10 and four rams, respectively. Cauda epididymitis was present in all rams, and caput and corpus epididymitis in eight and four rams, respectively. Interstitial orchitis was observed in seven, testicular degeneration in 14, and localised and diffuse tunica vaginalitis in 12 rams. Epididymal vasculitis and infiltration of eosinophils were observed as early as 24 h p.i. Moderate disruption of the epididymal duct from 72 h p.i., with subsequent release of spermatozoa into the interstitium, was revealed by ScEM. Actinobacillus seminis was cultured from the granuloma of six test rams from 72 h p.i. CONCLUSIONS: Actinobacillus seminis has the ability to persist in the genitalia of young rams following experimental infection. Suppurative epididymitis is observed as early as 24 h p.i., and spermatic granuloma within 72 h p.i. Infiltration of eosinophils appears to be an early host response to the bacterium, and may play a role in the pathogenesis of the epididymitis.     

The response of vaccinated rams to experimental challenge using Brucella ovis

One hundred and thirty eight rams were allocated to four experimental groups. An inactivated Br. ovis vaccine was administered either once by the intraperitoneal route (1 i/p), twice by the intraperitoneal route (2 i/p), or twice by the subcutaneous route (2 s/c), and the last group was left unvaccinated. They were then challenged by the intravenous inoculation of between 123 and 1.23 x 108 live Br. ovis bacteria. The number of rams that succumbed to infection within the four groups was 4135 (11%) for the 2 s/c, 7133 (21%) for the 2 i/p, 9135 (26%) for the 1 i/p and 18135 (51%) for the unvaccinated rams. Vaccination reduced the number of rams that succumbed to experimental challenge and although there were differences between the vaccinated groups, these were not statistically significant. Following challenge, unvaccinated rams were the first to excrete Br. ovis in their semen three weeks following inoculation. Next, those vaccinated by either one or two doses by the intraperitoneal technique began to excrete the organism (five weeks) and then finally those rams vaccinated twice by the subcutaneous route (seven weeks).     

Observations on the eradication of Brucella ovis infection from a ram flock

The measures taken to eradicate Brucella ovis infection from a naturally infected flock of 64 rams are described. Lesions of epididymitis were detected in 18 rams, all of which gave either positive or suspicious reactions in the complement fixation test. A further 20 rams gave serological reactions in the complement fixation test. Subsequently, semen was collected from 14 of these 20 rams and B. ovis was cultured from the semen of all 14 rams. Serum samples from two rams failed to react in the complement fixation test. However, they were identified as infected with the aid of an enzyme-linked immunosorbent assay and the subsequent culture of semen samples. It is suggested that, when eradicating B. ovis infection from ram flocks, the enzyme-linked immunosorbent assay be used in addition to both the complement fixation test and the physical examination. Using a combination of tests as described can increase the likehood of an earlier eradication of B. ovis infection.     

Toxoplasmosis in rams: possible significance of venereal transmission

Three rams were infected with tick-borne fever eight months after infection with toxoplasma. There was no clinical evidence of reactivation of the latent toxoplasma infection and semen samples from the rams were not infective to mice. Semen samples from 77 apparently normal rams were tested for toxoplasma infection by passage through mice; none of the samples produced patent infections in mice. Two rams with chronic toxoplasma infection were repeatedly mated with seronegative ewes. None of the ewes showed serological evidence of acquired infection and all lambed satisfactorily.     

Epididymitis Caused by Brucella ovis in a Southern Ontario Sheep Flock

Epididymitis was diagnosed in three rams in a commercial sheep flock in southern Ontario. The affected rams had palpably enlarged epididymides and two rams had semen which contained inflammatory cells and was of poor quality. Serum compliment fixation titers for Brucella ovis were 1:20, 1:80 and 1:90. Five other rams in the flock were clinically normal and without titers. Two of the affected rams had lesions similar to those produced by experimental infection with B. ovis. The infection in the rams had no apparent affect on ewe performance. The source of the infection remains unknown, but the rams were purchased from a flock which had imported ewes from the western U.S.A.     

Persistence, serodiagnosis and effects on semen characteristics of artificial Brucella ovis infection in red deer stags

AIMS: To investigate the persistence of infection and serum antibody titres after infection of red deer (Cervus elaphus) stags with Brucella ovis, and compare these with those of rams. To assess the effects of recent and chronic infection on semen characteristics of stags. METHODS: Fourteen stags and eight rams were artificially infected with B. ovis by intravenous inoculation. Semen and blood samples were collected at approximately monthly intervals for 649 days. Semen samples were subjected to bacterial culture, and sera were tested for B. ovis antibodies using a complement fixation test (CFT) and an enzyme-linked immunosorbent assay (ELISA). At the end of the study, animals were slaughtered and reproductive organs subjected to bacterial culture. During the first and second breeding seasons, three and five semen samples, respectively, were evaluated from each stag for sperm motility and morphology. RESULTS: Twelve of 14 (86%) stags and 6/8 (75%) rams developed a patent B. ovis infection and shed the organism in semen. All six infected rams continued to shed B. ovis in semen throughout the 649-day study period, and at slaughter B. ovis was isolated from the reproductive tract and urinary bladder. In contrast, 10/12 (83%) infected stags stopped shedding B. ovis in semen 103-342 days after inoculation, and the organism could not be isolated from their reproductive tracts at slaughter. The remaining two infected stags shed B. ovis in semen throughout the study period and the organism was isolated from their reproductive tracts at slaughter. All inoculated animals initially developed serum antibody titres detectable using the B. ovis CFT and ELISA. For infected stags, the diagnostic sensitivity of these tests was 100% for the first 166 days, but decreased to 50-90% after this. The diagnostic sensitivity for the infected rams was 100% throughout the study period. Infection in stags resulted in variable effects on semen characteristics. Eight of 12 (67%) infected stags had a mean sperm motility of < 50%, and < 60% mean normal sperm in the first year of infection. Seven of these stags had resolved the infection by the following breeding season, and there was a significant improvement in sperm motility and morphology. CONCLUSIONS: Stags are as susceptible as rams to experimental B. ovis infection. However, the majority of infected stags resolved the infection within a year, whereas rams remained infected for at least 649 days (22 months). Serology, using CFT and ELISA, was effective at detecting infection during the first 166 days in both species, but after this time was less effective at detecting infection in stags than in rams. Infection with B. ovis had variable but generally deleterious effects on the semen characteristics of stags, which resolved following resolution of the infection. Differences in the characteristics of the disease in stags compared with rams mean that different control methods are warranted for the two species. CLINICAL RELEVANCE: Most stags infected with B. ovis are likely to resolve the infection within a year, and semen characteristics return to levels acceptable for breeding. Serology is useful for detection of infection in the early stages of the disease, but once disease has been present in the herd for some time false-negative reactions are likely to occur in individual stags.     

The response of vaccinated rams to experimental challenge using Brucella ovis

One hundred and thirty eight rams were allocated to four experimental groups. An inactivated Br. ovis vaccine was administered either once by the intraperitoneal route (1 i/p), twice by the intraperitoneal route (2 i/p), or twice by the subcutaneous route (2 s/c), and the last group was left unvaccinated. They were then challenged by the intravenous inoculation of between 123 and 1.23 × 10⁸ live Br. ovis bacteria. The number of rams that succumbed to infection within the four groups was 4/35 (11%) for the 2 s/c, 7/33 (21%) for the 2 i/p, 9/35 (26%) for the 1 i/p and 18/35 (51%) for the unvaccinated rams. Vaccination reduced the number of rams that succumbed to experimental challenge and although there were differences between the vaccinated groups, these were not statistically significant.

Following challenge, unvaccinated rams were the first to excrete Br. ovis in their semen; three weeks following inoculation. Next, those vaccinated by either one or two doses by the intraperitoneal technique began to excrete the organism (five weeks) and then finally those rams vaccinated twice by the subcutaneous route (seven weeks).     

EVALUATION OF PROCEDURES FOR THE DIAGNOSIS OF BRUCELLA OVIS INFECTION IN RAMS

Procedures for the diagnosis of Br. ovis infection in rams were evaluated by examining 10 rams artificially infected by preputial inoculation. Observations were undertaken at weekly intervals for 1 year to follow changes in clinical, bacteriological and serological findings. Clinical lesions were detected in 1 ram 3 weeks after inoculation and in all rams by 8 weeks; lesions were undetectable in 3 rams at the completion of the trial. The presence of inflammatory cells in semen samples was the earliest indication of infection being demonstrated in 2 rams at 2 weeks and in all rams by 8 weeks; subsequently 86% of samples were positive. Br. ovis was detected in semen smears from 3 rams at 4 weeks but only once in all rams (at 27 weeks); overall 52% of semen smears were positive from 4 weeks onwards. Br. ovis was cultured from semen of 5 rams after 4 weeks and from all rams at 5 weeks; thereafter 97% of samples were positive. All rams developed significant titres to the CFT between 2 and 9 weeks; thereafter the CFT was a reliable indication of infection in 6 rams, highly suggestive in 3 and unreliable in one. By 8–10 weeks all rams developed significant titres to the IHA which were then maintained in all rams for the remainder of the trial.     

Effects of faunation and type of dietary protein on gastric solubility and liver content of copper in sheep

Three experiments were conducted to determine the influence of the presence of protozoa on copper (Cu) metabolism in sheep fed corn silage or corn silage supplemented with casein, fish meal or soybean meal. For each diet, eight rams were kept fauna-free; eight additional rams were faunated and housed separately from them. The faunated rams in all treatments grew faster and consumed more feed and, consequently, more Cu. However, they had a lower (P less than .01) ruminal Cu solubility and accumulated less Cu in their livers than the fauna-free rams when fed corn silage alone or in combination with soybean meal (insoluble, ruminally degraded protein). Such effects were not significant when corn silage was supplemented with fish meal (protein resistant to ruminal degradation). The presence of ciliate protozoa in the rumen had no effect on the accumulation of Cu in the liver of sheep fed corn silage supplemented with casein (soluble, ruminally degraded protein) and produced conflicting results on ruminal Cu solubility. Hence, the effect of protozoa on Cu metabolism is indirect and depends on the type of protein present in the diet.     

A comparison of three serological tests for the diagnosis of B. ovis infection in rams

The complement fixation test (CFT), the enzyme labelled immunosorbent assay (ELISA) and the gel diffusion precipitin test (GD) were compared, for the diagnosis of Brucella ovis infection in rams. The sensitivities of the tests in 109 rams which were shedding B. ovis in their semen were: CFT 96.3%; ELISA 97.2%; GD 91.7%. The specificities of the tests in 141 rams from non-infected flocks were: CFI 99.3%; ELISA 98.6%; GD 100%. Predictive values of the three tests were measured in 285 rams from infected flocks. Thirty-eight percent of these rams were shedding B. ovis in their semen. Predictive values of positive tests were: CFT 75.5%; ELISA 66.7%; GD 72.5%. Predictive values of negative tests were: CFI 97.1%; ELISA 97.6%; GD 93.8%.     

Correlation of the presence of seminal white blood cells and the prevalence of separated spermatozoal heads with subclinical Brucella ovis infection in rams

A breeding soundness evaluation was conducted on 824 Colorado range rams. These rams were determined to be free from epididymitis via testicular palpation. Semen evaluation included microscopic observation for the presence of WBC. Of the 824 rams, 15.5% failed the breeding soundness evaluation on the basis of the semen evaluation: 10.6% had WBC in the semen and 4.9% had poor sperm morphology. The prevalence of Brucella ovis isolation varied from 0% to 16.2% within flocks. The prevalence of subclinical B ovis infection was 10% in the control flocks. Brucella ovis was isolated from 71.9% of the rams that had WBC in their semen. From this study, it appeared that palpation and vaccination may be inadequate for control of ram epididymitis.     

The relationship of scrotal circumference to testicular weight in rams

Scrotal circumference (SC), testicular diameter (TD) and testicular weight (TW) were measured at necropsy of 148 Merino rams of varying age (yearling: 110, 2- to 3-year-old: 5, 4-year-old: 28, greater than 7-year-old: 5). These rams, although culled from flocks in north western Queensland for poor conformation or advancing age, had no clinically palpable or gross necropsy lesions of the genitalia. Despite the fact that SC measurement was performed at necropsy on scrota with greatly varying wool cover and its diverse content of plant material (burrs and grass seeds), the correlation of SC with TW was positive, high and significant (r = 0.92, P less than 0.01). This correlation was greater than that between TD and TW (r = 0.91, P less than 0.01) even though both were measured after dissection of the scrotal contents. The clinically convenient SC measurement deserves wider application as an estimate of testicular weight and therefore fertility in rams.     

Actinobacillus seminis infection in sheep in the Republic of South Africa. II. Incidence and geographical distribution

To obtain information on the incidence and distribution of Actinobacillus seminis infection in the Republic of South Africa, a clinical and serological survey was carried out on 409 farms situated in 29 districts. All rams submitted for certification to the Regional Laboratory from 1/1/69 to 31/1/74 were included in a separate investigation. These particular rams represented different breeds and originated from farms in over 48 districts. Examinations were also carried out on all rams on 11 stud farms in the Middelburg and adjacent districts with a high incidence of epididymitis, despite regular immunization with Elberg Rev. 1 vaccine. These investigations confirmed that genital infection of rams still presents a major problem in the main sheep breeds and the main sheep farming areas of South Africa. A high incidence of infection with A. seminis, an organism which appear to be the most important one associated with genital infection in this country, was also established. Genital infection due to A. seminis is geographically also very widespread.