Field evaluation of the single intradermal cervical tuberculin test and the interferon-gamma assay for detection and eradication of bovine tuberculosis in Spain

A field comparison of the interferon-gamma (IFN-gamma) assay and the single intradermal cervical tuberculin (SICT) test for the diagnosis of bovine tuberculosis was conducted. A total of 1136 cattle belonging to 85 herds placed in 'Castilla y León' (northwestern Spain) were chosen, and 21 of these herds were subjected to the diagnostic assays two or three times at intervals of at least 4 months. All the animals positive to any of the tests were slaughtered and tuberculosis was confirmed by culture isolation method (CIM) and further identification by means of PCR. Only 10.6% of cattle reacted with the bovine PPD in the SICT test, a percentage that increased to 12.8% in the IFN-gamma assay. The sensitivity of the IFN-gamma assay compared to CIM was shown to be higher (84.9%) than that of the SICT test (80.2%), but the combination of both tests offered the highest sensitivity (92.9%). The number of false positive reactors (those animals in which CIM was negative) was considerably higher for the IFN-gamma assay than for the SICT test and, conversely, the number of false negative animals (M. bovis isolation but negative immunological result) was higher for the skin test than for the interferon assay. In the herds tested twice, tuberculosis was eradicated after the second cycle of testing in 50%, and in 75% after the third cycle in herds tested three times. The combination of these two techniques instead of separately seems, therefore, to be useful in eradication programmes against bovine tuberculosis.     

Freezing of stallion semen with addition of glycine betaine

The effect of addition of glycine betaine to a lactose-EDTA freezing medium on the post-thaw motility of stallion semen was determined. The first three semen-rich fractions of nine stallions were collected with an open-end Krakow artificial vagina on consecutive weekdays. Semen was frozen using the Hannover method with freezing media containing glycine betaine in various concentrations from 0 to 5%. After thawing, sperm motility was analysed both by a light microscope and by a Hamilton-Thorn Motility Analyser. Total and progressive post-thaw motilities of semen containing 0.25-3% glycine betaine did not differ significantly from the total and progressive post-thaw motilities of semen frozen without glycine betaine. The total and progressive post-thaw motilities of semen containing 4 or 5% glycine betaine were significantly lower (P < 0.001) than those of semen without glycine betaine. In conclusion, glycine betaine did not show any beneficial effect on the post-thaw motility of stallion semen when semen was frozen using the Hannover method.     

Behavior of a Virulent Strain Derived from Agrobacterium radiobacter Strain K84 After Spontaneous Ti Plasmid Acquisition

ABSTRACT The behavior of the virulent transconjugant K84N6 derived from Agrobacterium radiobacter strain K84 after spontaneous Ti plasmid transfer in crown gall tissue in a biocontrol experiment was studied and compared with the behavior of the wild-type A. tumefaciens donor of the Ti plasmid. The main difference between the strains was a greatly reduced ability of the transconjugant to catabolize nopaline. Host range, ability to induce tumors in several fruit trees, and stability of the pathogenic determinants in isolates from tumors did not differ between the strains. Nevertheless, in a biocontrol experiment, the transconjugant was not controlled by strain K84 or K1026 in peach x almond hybrids and survived in the plant rhizo-sphere for 9 months with larger population densities than the wild strain. The appearance and persistence in soil of strains harboring a Ti plasmid in the K84 chromosomal background could represent a risk in the medium term, if they show good competitive ability.     

Ultrastructural identification of small granule prolactin (PRL) cells in goat adenohypophysis by the colloidal-gold method

We describe ultrastructural characteristics of PRL cells with small secretory granules, immunostained with ovine antiserum, in adult Murciano-Granadina milking goats during anoestrus, the last third of gestation and lactation. This cell subtype is considered to comprise a stable population that decreases numerically during gestation and lactation, and that may change during these stages to show large granules.     

Risk factors associated with the seroprevalence of leptospirosis among students at the veterinary school of Zaragoza University

The prevalence and risk factors associated with leptospirosis were studied in veterinary students in Zaragoza. Sera were collected at the beginning and end of the academic year 1994 to 1995 and were tested by ELISA against a pool of Leptospira interrogans serovars bratislava, canicola, grippotyphosa, hardjo, icterohaemorrhagiae and pomona antigens. At the beginning of the study the prevalence was 8.14 per cent and at the end it was 11.4 per cent. The incidence of the disease during the study was 0.0394. Risk factors associated with leptospirosis included: taking the course specialising in food inspection and technology, on-farm work, contact with pets in general, and particularly carnivores, and contact with animal traders. The symptoms associated with the disease were myalgia and fever, and the treatment of the symptoms provided some protection.     

IgE responses to bluetongue virus (BTV) serotype 11 after immunization with inactivated BTV and challenge infection

To test the hypothesis that development of a BTV-specific IgE response plays a role in clinical disease manifestation, the humoral immune response of cattle to inactivated and virulent BTV was studied. Three calves received three sensitizing immunizations of inactivated BTV, 3 weeks apart. The BTV-sensitized animals, two non-sensitized BTV-seropositive and 4 BTV-seronegative control cattle. were challenge-exposed with BTV-11, UC8 strain. All cattle inoculated with inactivated BTV developed group-specific non-neutralizing and serotype-specific neutralizing antibodies. The development of post-challenge-exposure neutralizing antibody titers was inversely correlated with protective immunity. None of the BTV-challenged animals showed clinical disease. The levels of IgE were greatest in the sensitized calves after virus challenge in comparison with control groups. The sequential development, specificity and intensity of virus protein-specific humoral responses were evaluated using immunostaining. After challenge exposure of BTV-sensitized and non-sensitized cattle, total and IgE antibodies reacted consistently within BTV structural proteins VP2, VP5 and VP7. Although no correlation was found between clinical disease and IgE, results add support to the hypothesis that IgE may be involved in the pathogenesis of clinical disease, since infection with BTV causes an increase in serum IgE levels. However, these results suggest that the levels of virus-specific reactivity may be an important factor in determining whether or not clinical disease manifestation occurs.     

Use of protected methionine (Mepron M 85) in cattle

The ruminal stability of Mepron M 85 and the effect of supplementation with Mepron M 85 on free methionine level of blood were studied in rumen-fistulated cows and rumen- and duodenum-fistulated growing bulls. In five rumen-fistulated cows in situ 69.5% and 64.6% of the methionine content of Mepron M 85 was found after ruminal incubation of 16 h and 24 h, respectively. Daily rations of the rumen-fistulated cows were supplemented with 15.0 g DL-methionine and 17.7 g Mepron M 85, which increased the free methionine level of blood from 13.64 mumol/L to 15.35 and 20.46 mumol/L, respectively, three hours after feeding. In the four rumen- and duodenum-fistulated growing bulls, supplementation with 15.0 g DL-methionine and 17.7 g Mepron M 85 increased the total methionine getting into the duodenum during 24 h from 14.99 g to 16.84 and 20.84 g, respectively. The influence of Mepron M 85 on milk production was studied in 35 pairs of Hungarian Fleckvieh x Holstein-Friesian cows. The animals were coupled on the basis of the number of finished lactations, milk production in the previous lactation, and the date of calving. Daily supplementation of 18.0 g Mepron M 85 increased daily milk production significantly (p < 0.05), by 1.24 litres. Milk fat content also increased significantly (from 3.10% to 3.19%, p < 0.05) in the experimental group. The supplementation did not influence milk protein content.     

Relationships between bulk-tank antibodies to Ostertagia ostertagi and herd-management practices and measures of milk production in Nova Scotia dairy herds

Monthly bulk-tank milk samples were obtained from 415 Nova Scotia dairy herds in each of the months of July-September 1998 and tested using an indirect microtitre ELISA against a crude saline-extract, whole-worm Ostertagia ostertagi antigen. ELISA results (optical densities (ODs)) were consistent across months (r=0.85) but there was considerable variation among herds. A questionnaire was sent by mail to all producers; information on management factors that would potentially influence parasite burdens in the herds was obtained from 239 farms. Data on annual milk production, summer milk production (July-September) and seasonal decline in milk production were obtained from the Animal Productivity and Health Information Network (APHIN) database. Associations between management practices and ODs, and between ODs and milk-production parameters were studied. Some management practices known to be associated with parasite burdens had expected directions of association with the ODs, giving supporting evidence that the ELISA is a reasonable measure of parasite burden. Most notably, ODs were increased with greater exposure of heifers or milking cows to pasture. ODs were not associated with either annual milk production or seasonal decline in milk production. However, there was a substantial relationship between the herd OD value and the level of milk production during the summer. An increase in the OD from 0.58 to 0.83 (the interquartile range of ODs) was associated with a reduction in production of 1.25kg/cow/day.     

Regulation by gonadal steroids of estrogen and progesterone receptors along the reproductive tract in female lambs.

The regulation of estrogen and progesterone receptor (ER, PR) expression by estradiol (E2) and progesterone (P4) in the oviduct, uterus and cervix of female lambs was studied. The animals received three intramuscular injections of E2, P4 or vehicle with an interval of 24 h and they were slaugthered 24 h after the third injection. Determinations of ER and PR were performed by binding assays and mRNAs of ER alpha and PR by solution hybridization. High levels of ER and PR in both cervix and oviduct were found in the female lamb, differing from other mammalian species. No significant effects by either E2 or P4 treatment on ER and PR levels in the cervix and oviduct could be observed. E2 treatment increased the mRNA levels of ERa and PR more than 3-fold in the cervix, while P4 treatment increased the mRNA levels of ERa and PR in the uterus. The results show differential effects of gonadal steroids on sex steroid receptor expression along the reproductive tract in female lambs, suggesting that steroid target tissues can modulate responses to the same circulating levels of steroid hormones.     

Litter Size and Vagina–cervix Catheter Penetration Length in Gilts

As in other species, the reproductive tract in pigs increases in size with age and body weight, and the development of the reproductive tract depends on a balance between development of the pituitary–ovarian axis and the influence of metabolic hormones. Two experiments were conducted in prepubertal Duroc gilts, 150–180 days of age, to determine whether litter size is related to vaginal–cervix catheter penetration length during insemination. In experiment 1, oestrus was induced in 452 gilts with a combined dose of 400 IU Pregnant Mare Serum Gonadotrophine (PMSG) + 200 IU human chorionic gonadotropin (hCG). The gilts were classified into three catheter penetration length groups: Ih, ≤ 21 cm; IIh, > 21 and < 28 cm; IIIh, > 28 cm. The litter size was lowest in group Ih (7.35 ± 0.15) compared with groups IIh (7.81 ± 0.12; p < 0.05) and IIIh (10.0 ± 0.36; p < 0.001). In experiment 2, first oestrus was induced in 162 gilts by boar exposure. The gilts were classified into three catheter penetration length groups at insemination during their second oestrus: In, ≤ 24 cm; IIn, > 24 and < 26 cm; IIIn, > 26 cm. As in experiment 1, the litter size was lowest in the group with the shortest catheter penetration length (8.32 ± 0.19). The litter size was not different among gilts of groups IIn and IIIn (8.84 ± 0.35 and 9.56 ± 0.46, respectively), but litter size was lower (p < 0.05) in group In than in group IIn. Based on the combined data from both experiments, the correlation between the catheter penetration length and total number of piglets born was expressed as: y=5.346 ± 0.104x; r=0.361 (p < 0.05). Fertility rate was not different among the groups of gilts induced into oestrus by hormone treatment or inseminated in the second oestrus; however, the total fertility rate of boar‐exposed gilts was higher (p < 0.0001) than PMSG/hCG treated animals. Thus, it is possible to conclude that litter size at first farrowing is associated with vaginal–cervix catheter penetration length during insemination of the gilt.