Comparison of fecal samples collected per rectum and off the ground for estimation of environmental contamination attributable to beef cattle.

OBJECTIVES: To determine whether sampling feces off the ground replicates prevalence estimates for specific pathogens obtained from fecal samples collected per rectum of adult cows, and to determine characteristics of feces on the ground (fecal pats) that are associated with subsequent identification of Campylobacter spp, Cryptosporidium parvum, and Giardia duodenalis. ANIMALS: A random sample of adult beef cattle from 25 herds located throughout California. PROCEDURE: 1,115 rectal and ground fecal samples were obtained. Samples were submitted for culture of Campylobacter spp and examined, using a direct fluorescent antibody assay, to detect C parvum oocysts and G duodenalis cysts. Characteristics of fecal pats, such as volume and consistency, were recorded. RESULTS: Prevalence of Campylobacter spp was 5.0% (20/401) for rectal fecal samples, which was significantly greater than prevalence determined for ground fecal samples (2/402; 0.5%). Most isolates were C jejuni subsp jejuni. Prevalence of C parvum was higher in rectal fecal samples (6/557; 1.1%) than in ground fecal samples (1/558; 0.2%), but this difference was not significant. Prevalence of G duodenalis did not differ for rectal (36/557; 6.5%) versus ground (26/558; 4.7%) fecal samples. CONCLUSIONS AND CLINICAL RELEVANCE: Evaluation of ground fecal samples may not accurately indicate the prevalence of Campylobacter spp or C parvum in cattle but may reflect prevalence of G duodenalis. Differences in prevalence estimates between the 2 methods suggest inactivation of pathogens in feces after cattle have defecated. Prevalence estimates generated by evaluation of ground fecal samples, however, may more accurately estimate environmental pathogen burden.

Evaluation of North American antibody detection tests for diagnosis of brucellosis in goats.

The sensitivities and specificities of 17 antibody detection tests for brucellosis in goats were estimated. Tests evaluated included the U.S. Department of Agriculture (USDA) card test with 8% cell concentration (8%Card), USDA rapid automated presumptive test (RAP), Mexican rose bengal plate tests with 8 and 3% cell concentrations (8%RB and 3%RB), French rose bengal plate test with 4.5% cell concentration (4.5%RB), USDA standard plate test (SPT), USDA buffered acidified plate agglutination test (BAPA), USDA and Mexican rivanol tests (URIV and MRIV), USDA standard tube tests with Brucella abortus and Brucella melitensis antigens (SATA and SATM), serum enzyme-linked immunosorbent assay (ELISA), USDA cold-fixation complement fixation tests with B. abortus and B. melitensis antigens (CFA and CFM), USDA and Mexican milk ring tests (UBRT and MBRT), and a milk ELISA. Test sensitivity was evaluated by using two groups of 10 goats experimentally infected with B. melitensis or B. abortus and monitored for 24 weeks. Specificity was evaluated by using 200 brucellosis-free nonvaccinated goats from 10 California herds. The 3%RB was considered a good screening test because of high sensitivity at week 24 postinfection (90%), ease of performance, and low cost. The cold-fixation CFA and CFM had 100% specificity in the field study and were considered appropriate confirmatory tests. The milk ELISA was significantly more sensitive (P < 0.05) than the UBRT and significantly more specific (P < 0.05) than the MBRT. The milk ELISA also had the advantage of objectivity and ease of interpretation.

Reproductive cycles and pregnancy in interspecific sheep<==>goat chimaeras.

The objectives of the current study were to determine whether interspecific sheep<==>goat chimaeras exhibited reproductive cycles of their component species and were capable of maintaining ovine and caprine pregnancies to term. All chimaeras had oestrous cycles and several exhibited characteristics of both ewes and does, including short, 6-7-day cycles. Sixteen caprine pregnancies were confirmed in eight sheep<==>goat and one hybrid<==>sheep chimaera from 21 embryo transfers; of these, six appeared normal by ultrasonographic examination during Weeks 5 or 6, but none progressed beyond Week 8. Three apparent pseudopregnancies developed in two animals. In contrast, eight of 11 pregnancies in chimaeras resulted in term ovine offspring after transfer of ovine embryos or natural matings with rams. By comparison, interspecific (caprine or hybrid) pregnancies in ewes were lost in Week 4 (n = 8) or Weeks 5-6 (n = 2). First interspecific (ovine or hybrid) pregnancies in does were maintained longer (Weeks 6-12, n = 7) than second interspecific pregnancies (Weeks 4-5, n = 5) (P < 0.05) or interspecific pregnancies in ewes (P < 0.05). The results suggest that abnormal fetomaternal interactions during the early stages of implantation are responsible for termination of caprine pregnancies in the ovine or chimaeric uterus, whereas ovine conceptuses are able to implant successfully in the chimaeric uterus. All chimaeras were fertile, since each carried at least one ovine pregnancy to term following natural matings with rams.

Inter- and intraspecific placentae in sheep, goats and sheep-goat chimaeras.

These studies compared inter- and intraspecific placentae during implantation and at full-term in sheep, goats and interspecific sheep-goat chimaeras. Histological sections prepared from intra- and interspecific day-26, 32 and 36 placentae in ewes and does indicated an altered ability of the trophoblast to invade the maternal caruncle in interspecific pregnancies. Two sheep-in-goat pregnancies were less, and two goat-in-sheep pregnancies were more, invasive than homologous pregnancies. Caprine pregnancies in chimaeras generally terminated before timed samples could be obtained, but biopsy samples collected at laparotomy between days 42 and 48 demonstrated both normal and abnormal placentation in chimaeras after breedings to rams. In six of 11 full-term fetal placentae from ovine pregnancies in chimaeras, there was abnormal retention of maternal caruncular tissue to the extent that macroscopic lesions were visible on the surface of the fetal cotyledons. Histological observations indicated that proliferation of maternal septa and hyalinization of maternal vessels had occurred at the expense of the fetal villi. Overall, the results suggested that the physiological events that regulate implantation are different in the two species, despite anatomical similarities between the ovine and caprine placenta. The caprine conceptus is likely to be rejected in the ovine or chimaeric uterus because of its over-invasiveness in the early stages of implantation, whereas the ovine conceptus can survive in the potentially chimaeric uterus.

Maternal serum reactivity to species-specific antigens in sheep-goat interspecific pregnancy.

Three models were used to test the hypothesis that interspecific pregnancy failure between the sheep and goat is due to a species-specific, maternal antibody response. Interspecific pregnancies were established in ewes and does, sheep in equilibrium goat chimeric conceptuses produced by injection of ovine blastocysts were transferred to ovine recipients, and ovine and caprine pregnancies were established in interspecific chimeras. Complement-mediated lymphocytotoxic and hemolytic assays were used to monitor onset and titer of antibodies. Sera from 3 of 8 injection-chimera recipients reacted with all caprine peripheral blood lymphocytes (PBL) and red blood cells (RBC) tested (n = 18). Sera from 3 of 6 ewes and 7 of 7 does also were pancytotoxic to PBL of the other species (n greater than or equal to 20). Absorptions with xenogeneic RBC generally removed the reactivity. The data were consistent with responses to species-specific, monomorphic antigens expressed on PBL and RBC, and probably trophoblast. The response preceded or coincided with interspecific pregnancy failure in does, but not in ewes. Accordingly, no xenoreactivity was observed in chimera sera but caprine pregnancies were resorbed (n = 16) and ovine pregnancies developed to term (n = 11). The data did not support the hypothesis that failure of caprine pregnancy in ewes or chimeras is due to a species-specific, maternal antibody response. In contrast, a maternal, cytotoxic antibody response to species-specific antigen(s) may contribute to failure of hybrid or ovine pregnancy in does.

Survival analysis for evaluation of corneal ulcer healing times in calves with naturally acquired infectious bovine keratoconjunctivitis.

A clinical trial examining the efficacy of 2 drugs for treatment of a natural epizootic of infectious bovine keratoconjunctivitis was performed. The study was conducted in 103 grazing Hereford calves during the summer of 1985. The calves were prospectively and randomly assigned to 1 of 3 groups at the beginning of the study on June 17, and were examined 3 times weekly thereafter until the final observation on August 6. Calves in group 1 (n = 34) were not treated and were used as controls. Calves of group 2 (n = 34) with corneal ulcers were treated with a long-acting oxytetracycline formulation (OTC group). The parenteral treatment was repeated in 72 hours. Affected calves of group 3 (n = 35) were treated topically with furazolidone spray when they developed new corneal ulcers, or when existing lesions worsened during subsequent examination periods (NFZ group). Healing times of the corneal ulcers were reported in 3 ways: the combined times for ulcers present in both eyes of a calf simultaneously (method A), independent times of each ulcer on a calf (method B), and time of the first ulcer for each calf (method C). Censored healing times were examined as left censored (ulcer present at the beginning of the study), right censored (ulcer not healed at the end of the study), or uncensored (true) healing times. The effect that the treatments had on healing times were investigated by use of notched box and whisker plots, life tables, and Cox regression models. The analysis indicated that treatment of calves with either antimicrobial reduced the healing time of corneal ulcers, compared with untreated controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Corynebacterium pyogenes mastitis outbreak in inbred heifers in a California dairy.

An outbreak of Corynebacterium pyogenes mastitis ("Summer Mastitis") was observed in a group of 96 heifers. The outbreak affected 8 animals, of which 7 were too young for breeding. The disease incidence was highest in calves 2 to 4 months old. Cases were observed over an initial estimated 14 day period with a further case being detected 14 days subsequently. Corynebacterium pyogenes mastitis has not been reported in calves this age. Factors postulated to influence the outbreak include the presence of large numbers of flies, intersucking of calves, and possible viral disease.