Increased litter size in Rambouillet sheep: II. Expected responses from alternative selection criteria.

The variance and covariance components estimated from an experimental flock of Rambouillet sheep were used to predict response in litter size to direct and indirect selection. Indirect traits considered were ovulation rate and scrotal circumference. Ovulation rate was the most useful indirect selection criterion for genetic improvement of litter size. Expected response in litter size to indirect selection on ovulation rate was 93% as large as the expected response to direct selection on litter size. Selection based on an index of litter size and ovulation rate was estimated to produce 123% as much response in litter size as selection on litter size alone, and selection on an index of litter size, ovulation rate, and scrotal circumference resulted in 133% as much response in litter size as direct selection on litter size.     

Effect of calflhood morbidity on age at first calving in New York Holstein herds

The effect of calhood morbidity on age at first calving was investigated in 948 heifer calves in 21 herds in the vicinity of Cornell University. Heifers were born from July 1983 to April 1985 and neither died nor were sold prior to 90 days of age. All calvings occurred on or before 31 May 1987.

The specific calfhood morbidity variables of interest were the first occurrences of the following clinical signs as diagnosed by farmers on check-off forms: scours/diarrhea within 14 days of birth and from 15 to 90 days of age; dull, listless, droopy ears, or off of feed within 90 days of birth; cough, runny nose or eyes, or trouble with breathing within 90 days of birth. The Kaplan-Meier product-limit life-table technique and Cox's proportional hazards model were used to evaluate the effect of calfhood morbidity on the age distribution of first calving. Season and year of birth were included (forced) into the Cox's proportional hazards model as possible confounding variables. The model was stratified on herd (allowing a different survival function for each herd) in order to account for herd effects.

The final Cox's proportional hazards model included season and year of birth, signs of respiratory illness within 90 days of birth and dullness within 90 days of birth. Heifers without respiratory illness as calves were twice as likely subsequently to calve and calved 6 months earlier when compared to those with respiratory illness as calves. Heifers with dullness as calves were 1.6 × more likely to calve and calved 2 months earlier when compared to calves without dullness as calves.     

Risk factors for Clostridium piliforme infection in foals

OBJECTIVE: To determine risk factors for Clostridium piliforme infection in neonatal foals on a Thoroughbred breeding farm in California. DESIGN: Case-control and retrospective cohort studies. ANIMALS: 322 neonatal Thoroughbred foals either born on the study farm or born elsewhere but traveled to the farm with their dam during the 1998, 1999, and 2000 breeding seasons. PROCEDURE: Mare and foal records from 1998, 1999, and 2000 were examined, using case-control design methods to determine variables associated with increased risk of C. piliforme infection in foals. Important risk factors identified in the case-control study were then reevaluated by use of a retrospective cohort design, using data from all neonatal foals present on the farm during the 3-year study period. RESULTS: Foals born between March 13 and April 13 were 7.2 times as likely to develop C. piliforme infection as were those born at any other time of the foaling season. Foals of nonresident (visiting) mares were 3.4 times as likely to develop disease as were foals born to mares that were permanent residents of the study farm. Foals of mares < 6 years of age were 2.9 times as likely to develop disease as were foals born to older mares. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this research can be used to better understand the epidemiologic factors of C. piliforme infection in horses. High-risk foals can be closely monitored to aid in early diagnosis and treatment, resulting in the best possible clinical outcome for affected individuals.     

EFFECT OF SELENIUM ON WOOL PRODUCTION, BODY WEIGHT AND MORTALITY OF YOUNG SHEEP IN WESTERN AUSTRALIA

The effect of regular selenium supplementation on the body weight, wool production and mortality of young Merino sheep was investigated. Groups of Se-treated and control sheep involving from 260–500 on each of 15 farms were observed from six weeks to 19 months of age. Ten mg Se as sodium hydrogen selenite was administered orally to the treated sheep at two-monthly intervals. Treated and control sheep grazed together throughout the trial period. Statistically significant responses to selenium were recorded in body weight gains on four farms, in decreased mortality on five farms and as an increase in fleece weight on eight farms. The response in fleece weight varied from 2.9-7.6% and could not be explained as a result of increased body weight. The increase in fleece weight was not due to an increase of grease in the wool but appeared to be due to an increase in fibre diameter and to a lesser extent an increase in staple length. A statistically significant decrease in the incidence of tender fleeces as a result of selenium supplementation was also recorded. All farms on which responses to selenium were obtained were in areas with average annual rainfall more than 20 inches. On two farms selenium caused statistically significant depressions in the parameters measured. Both farms were in areas with less than 20 inches average annual rainfall.     

Bovine intestinal cellular responses following primary and challenge infections with Calicophoron microbothrium metacercariae

This study was carried out to establish whether cattle can develop resistance to re-infection by Calicophoron microbothrium by assessing the response of intestinal mucosal globule leukocytes, eosinophils, mast cells and basophils, and the establishment of the parasite in the host. A total of 24 1-year-old Tuli steers were randomly divided into four groups of six animals each and infected with C. microbothrium metacercariae. On the first day of the study, animals in Groups I and II were immunized with 5000 metacercariae and then challenged with 15,000 metacercariae on Day 150 post-immunization. Animals in Group III were immunized with 15,000 metacercariae at the same time that Groups I and II animals were challenged to act as a positive control group. Animals in Group IV were left uninfected and acted as a negative control group. Three animals from each group were slaughtered on Day 28 post-challenge and the remainder were slaughtered on Day 42 post-challenge. The established amphistomes were recovered and histopathological and cytological examinations were done on the jejunum, duodenum, abomasum and the rumen. The establishment rates of the challenge infection in the immunized and challenged groups were lower and ranged from 0 to 0.2% as compared to 6% from naive animals infected as positive controls. Animals immunized and then challenged with C. microbothrium had significantly higher eosinophil, mast cell and globule leukocytes counts in the intestinal mucosa (P < 0.05) as compared to those of the control group. The study indicates that cattle can develop resistance to C. microbothrium re-infection and that eosinophils and mast cells may be important cells in the rejection of the parasite.     

Strategic use of anthelmintics to prevent parasitic gastroenteritis in cow-calf herds in California

On the basis of the hypothesis that the peak numbers of infective nematode third-stage larvae (L3) on herbage in winter months results from fall contamination of pastures, 2 methods to reduce fall contamination were tested. In trial 1, morantal sustained-release boluses were administered to 15 fall-calving cows on Sept 7, 1982. Fifteen untreated cows (controls) were placed on separate pastures. Numbers of L3 on herbage during the winter and spring were assessed by use of worm-free tracer calves. In trial 2, 19 cattle due to calve in the fall were administered 200 micrograms of invermectin/kg of body weight, SC, on Sept 2, 1983. Also, 17 cattle similarly were given a placebo injection and served as control animals. Treated cattle were placed on the pasture used by control cattle in trial 1 and control cattle on the pasture used by treated cattle in trial 1. Worm-free tracer calves were again used to assess numbers of L3 on herbage. In trial 1, tracer calves grazing the control animal pasture from January 14 to 28 acquired 37 times as many nematodes as did those grazing the treated animal pasture. In trial 2, the greatest difference observed was a 10-fold increase of nematodes in calves grazing control animal pastures, compared with worm numbers in tracer calves grazing the treated animal pasture.     

Increased pulmonary secretion of tumor necrosis factor-alpha in calves experimentally infected with bovine respiratory syncytial virus

Bovine respiratory syncytial virus (BRSV) is an important cause of respiratory disease among calves in the Danish cattle industry. An experimental BRSV infection model was used to study the pathogenesis of the disease in calves. Broncho alveolar lung lavage (BAL) was performed on 28 Jersey calves, of which 23 were experimentally infected with BRSV and five were given a mock inoculum. The presence of the cytokine tumor necrosis factor alpha (TNF-alpha) in the BAL fluids was detected and quantified by a capture ELISA. TNF-alpha was detected in 21 of the infected animals. The amount of TNF-alpha in the BAL fluid of calves killed post inoculation day (PID) 2 and 4 was at the same very low level as in the uninfected control animals. Large amounts of TNF-alpha were detected on PID 6, maximum levels of TNF-alpha were reached on PID 7, and smaller amounts of TNF-alpha were seen on PID 8. The high levels of TNF-alpha appeared on the days where severe lung lesions and clinical signs were obvious and the amounts of BRSV-antigen were at their greatest. Although Pasteurellaceae were isolated from some of the BRSV-infected calves, calves treated with antibiotics before and through the whole period of the infection, as well as BRSV-infected calves free of bacteria reached the same level of TNF-alpha as animals from which bacteria were isolated from the lungs. It is concluded that significant quantities of TNF-alpha are produced in the lungs of the calves on PID 6-7 of BRSV infection. The involvement of TNF-alpha in the pathogenesis of, as well as the anti-viral immune response against, BRSV infection is discussed.     

Transstadial and attempted transovarial transmission of Anaplasma marginale by Dermacentor variabilis

Transstadial and transovarial transmission of Anaplasma marginale by Dermacentor variabilis were attempted with with ticks exposed to the organism once by feeding as larvae or nymphs, and twice by feeding as larvae and nymphs. Typical colonies of A marginale were in gut tissues of adults that were infected as larvae, larvae and nymphs, and as nymphs; repeated exposure of ticks did not appear to result in an increase in the number of colonies in the gut of subsequently molted adults nor did it affect severity of the clinical disease that developed in cattle they fed on. In contrast, colonies of A marginale were not found in the midgut epithelium of unfed nymphs exposed as larvae, even though companion nymphs transmitted the parasite, causing severe clinical anaplasmosis in susceptible calves. The organism was not transmitted transovarially by F1 larvae or nymphs from the groups exposed as parent larvae, nymphs, larvae and nymphs, and as adults. Some of the calves fed on by F1 progeny had a few erythrocytic marginale bodies that looked suspiciously like A marginale, as well as postchallenge exposure prepatent periods that were longer than other calves in the transovarial transmission study. Sera from these calves were tested for antibody to A marginale, using a highly sensitive immunoblot technique. Antibodies were not detected in any of the sera.     

Longitudinal study of veterinarians from entry to the veterinary course to ten years after graduation: career paths

OBJECTIVE: To map out the career paths of veterinarians during their first 10 years after graduation, and to determine if this could have been predicted at entry to the veterinary course. DESIGN: Longitudinal study of students who started their course at The University of Queensland in 1985 and 1986, and who completed questionnaires in their first and fifth year as students, and in their second, sixth and eleventh year as veterinarians. METHODS: Data from 129 (96%) questionnaires completed during the eleventh year after graduation were coded numerically then analysed, together with data from previous questionnaires, with SAS System 7 for Windows 95. RESULTS: Ten years after they graduated, 80% were doing veterinary work, 60% were in private practice, 40% in small animal practice and 18% in mixed practice. The equivalent of 25% of the working time of all females was taken up by family duties. When part-time work was taken into account, veterinary work constituted the equivalent of 66% of the group working full-time. That 66% consisted of 52% on small animals, 7% on horses, 6% on cattle/sheep and 1% on pigs/poultry. Those who had grown up on farms with animals were twice as likely to be working with farm animals as were those from other backgrounds. Forecasts made on entry to the veterinary course were of no value in predicting who would remain in mixed practice. CONCLUSIONS: Fewer than one-fifth of graduates were in mixed practice after 10 years, but the number was higher for those who grew up on farms with animals. Forecasts that may be made at interview before entry to the course were of little value in predicting the likelihood of remaining in mixed veterinary practice.     

Intracellular distribution and destruction of liposomes after in vitro phagocytosis by alveolar macrophages

Electron microscopy was used to watch and monitor free as well as phagosomically incorporated multilamellar vesicles (MLV) which were considered to be signs of rapid recycling of phagosomal membranes. Close relations were found to exist between lysosomes, on the one hand, and MLV in phagosomes, on the other. The same applied to MLV and mitochondria or nuclear membranes. Destruction of MLV was highly differentiated. Hints are given in this paper on the kinetics of such processes. These results are considered to be of some relevance to the suitability of liposomes as carriers of pharmaceutical substances.     

Influence of dietary mineral imbalance on the incidence of urolithiasis in Egyptian calves

The influence of certain dietary elements on the urolithiasis syndrome in cattle calves was elucidated. Calcium, phosphorus, and magnesium measurements were conducted on feed rations as well as on serum and urine samples collected from affected and normal calves. Analysis of the rations given to the animals showed phosphorus at higher levels than calcium, indicating mineral imbalance. Serum and urine of urolithic calves were characterised by high phosphorus, calcium, magnesium, urea, and creatinine levels. Physical examination of urine of affected animals showed a high degree of turbidity, a large amount of calcium carbonate, and triple phosphate as well as abundant amount of pus cells and red blood cells. The characteristic clinical symptoms of urine retention were observed. Moreover, some animals were found to urinate through an opening in front of the scrotal region.     

Effect of noise on the physiological functions in fowl. 1. Effect of primary strong noise on the 11-OHKS level in broilers and leghorns]

The effects of first noises on broilers and white leghorns were tested by plasma levels on 11-hydroxycorticosteroid (11-OHKS). The noises were 100 dB, 60 to 8,00 Hz, and applied 30 minutss to one group of broilers, aged 14, 28, and 56 days, and to another group of broilers and white leghorns in adult age. The reactions were compared. Acoustic stimulation was followed by temporary activation of the hypothalamic pituitary-suprarenal system. The rise of the plasma glucocorticosteroid level in leghorns was three times as high as that in adult broilers, which was interpreted as a reflection of stronger organic stress. Reactions differed in intensity, depending on age as well. Plasma-11-OHKS levels went up by 32 per cent maximum in broilers aged 56 days or by 73 per cent in animals aged 14 days or 120 per cent in those aged 28 days. The above results seemed to support the conclusion that noises of the above quantity and quality represented stress on fowl.     

Lysozyme in calves

Relatively high lysozyme concentrations, depending on age, were recorded from intestinal content, spleen, liver, kidney, lung, lymph nodes, and mucosa of calves. Yet, only minor quantities of lysozyme were found in blood serum or plasma and in granulocytes. Physicochemical characterisation, precipitation, using polyclonal antisera, and crosswise neutralisation of lysis reaction were likely to suggest occurrence of immunological relationship reactions as well as differences between organ lysozymes, on the one hand, and intestinal lysozymes, on the other.     

Metabolic disturbances induced by organotins through subchronic treatment in chickens. First communication: growth dynamics, carbohydrate and protein metabolism

Four organotin derivatives (tributyltin acid, dibutyltin chloride, triphenyltinchloride, and triphenyltin-bis (diethyl) dithiophosphate) were tested through subchronic treatment on 19 days old chickens. Growth dynamics as well as carbohydrate and protein metabolism were investigated, in order to evaluate their effects on metabolic activity. Biochemical liver and blood constituents revealed growth retardation and general depression of metabolic activity in experimental groups. Some correlations were found to exist chemical structure, dose use for compound, and effects. Butyltins were more toxic than phenylderivatives and their effects were proportionale to the dose.     

Concanavalin A binding sites on the cell membrane and other membrane structures of alveolar macrophages

Concanavalin-A points of linkage were positively detected on cell membranes of alveolar and peritoneal macrophages by means of Con-A ferritin conjugate. Quantitative conclusions were drawn from these findings with regard to the number of mannose and glucose residues per 1 micron 2 of membrane area. With different incubation periods, 15, 25, and 45 minutes, various distribution patterns of ferritin molecules were recorded. They were diffusely distributed in cytoplasma as well as on the outer nuclear membrane. Ferritin particles were identified also on vacuolar membranes and in direct contact with lysosomes.     

The epidemiology of Mycobacterium bovis infection in brushtail possums (Trichosurus vulpecula Kerr) in the Hauhungaroa Ranges, New Zealand

The prevalence of Mycobacterium bovis infection in the wild possum population around the perimeter of the Hauhungaroa Ranges, New Zealand, was determined by a cross-sectional study, and risk factors associated with tuberculosis were identified. Of 6083 possums necropsied, 128 (2.1%) showed gross lesions suggestive of tuberculosis infection, and 76 (1.25%) were subsequently confirmed as tuberculous on histopathological examination. Considering only traplines where tuberculosis was detected, adult possums were 1.9 times as likely to be infected as immature animals, and the total prevalence was 5.4% in males compared with 3.9% in females. Adult females were 3.64 times as likely to be infected as immature females, whereas there was no significant age difference for males (odds ratio = 1.46, p=O.29). Immature males were 3.12 times as likely to be infected as immature females. Possums in poor condition were more likely to be found infected than possums in good condition. Tuberculous possums were found in 27 local clusters of infection. The correlation between the prevalence of tuberculosis in possums in zones and the incidence of tuberculosis in cattle on adjoining properties was 0.4 (p相似文献   

Influence of selenium on antibody production in sheep

Three experiments were carried out, using sheep fed a marginally low selenium diet, to study the effect of selenium supplementation on the antibody response to tetanus toxoid and on the serum IgG concentration. Six groups of three six-month-old lambs were fed a basal diet containing 0.13 mg Se kg-1 supplemented with either 0.1, 0.5 or 1.0 mg Se kg-1, as sodium selenite or as selenomethionine. These animals generally showed enhanced antibody response to tetanus toxoid, parainfluenza-3 virus and Corynebacterium pseudotuberculosis, and their total serum IgG concentrations were higher than in unsupplemented control animals although few responses were statistically significant. In two field studies significantly higher titres to tetanus toxoid were detected in ewes injected with 100 mg selenium as barium selenate, although no influence on serum IgG concentrations was detected. Lambs from selenium supplemented ewes had significantly higher titres to tetanus toxoid than lambs from ewes in the control group. Dietary vitamin E supplementation had a similar effect on the antibody response to tetanus toxoid in ewes, though no additive effect was seen when vitamin E was given together with selenium.     

Epidemiology of Haemophilus somnus in young rams

The prevalence of Haemophilus somnus in the prepuce of young rams was examined. Of 473 rams entering Record of Performance (ROP) stations at 50 days of age, 43 (9.1%) were positive. Average daily gain was not affected by Haemophilus status, but was influenced by breed of ram. Suffolks were predicted to gain 0.515 kg daily compared to 0.427 kg for a group combining all other breeds. Using logistic regression to identify risk factors for individual H. somnus infection, rams in 1989 were 0.382 times as likely to be infected as rams in 1988, and Suffolks were 0.314 times as likely to be infected as the other breeds group, but these factors were not significant at the flock level. Of 80 eligible flocks of origin, 22 (27.5%) were classified as infected with H. somnus, based on rams submitted to the ROP station. Infected flocks contributed 133 rams, 43 (32.3%) of which were positive. There was no association between H. somnus status and lambing percent of the percent of abortions and stillbirths, but there was a statistically significant association with the percent of ewes which failed to lamb. In the model developed, 6% of the bred ewes in noninfected flocks failed to lamb, compared to a rate of 12% in infected flocks. These results suggest H. somnus may influence ewe fertility earlier, rather than later in gestation. Purchasing replacement animals and having cattle on the farm were risk factors for Haemophilus infection in the flock. Where replacements had been purchased within the previous year, the risk of flock infection rose 8.5 times, and on farms having cattle as well as sheep, the risk rose 13.2 times.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pathologic changes in chickens caused by intravenous inoculation with fowlpox virus

Twenty chickens were inoculated intravenously with fowlpox (FP) virus, and clinical and pathological examinations were carried out chronologically. Upon gross examination, miliary nodules scattered in the kidneys were observed from 10 to 18 days postinoculation (PI), as were papules on the skin and diphtheritic lesions on the mucous membrane of the upper respiratory tract. Microscopically, characteristic FP lesions, composed of swelling and proliferation of cells with formation of Bollinger bodies, were observed in the epithelial cells of renal tubules from 4 to 14 days PI and in the epithelial reticular cells of the thymic medulla from 4 to 10 days PI, as well as in the skin and mucous membrane. Immunofluorescent and electron microscopic observations confirmed the presence of viral antigen and virus particles in the characteristic lesions of FP.     

The synergism of Actinobacillus pleuropneumoniae and influenza A virus in experimentally-infected mice

Models for infecting mice with Influenza A-Virus (A/PR 8/34, H0N1) and Actinobacillus pleuropneumoniae (serotype 9) were developed in Han: NMRI-mice. After infecting mice with sublethal doses of one of the infectious agents, or both together as a mixed infection, animals were subsequently exsanguinated and the lungs washed by bronchoalveolar lavage. Clinical symptoms were recorded daily, examination of lung lavage fluid and sera as well as histology of the lungs were done. An increase in mortality, weight reduction and total cell yield of lung lavage fluid was observed after mixed infection. Compared to mixed infections total protein content and elastase in sera and lung lavage fluid after singular ones were raised not as much. In lung lavage fluid the total cell yield was increased more marked. These alterations indicate a synergistic effect of viruses and bacteria, developed by mixed infection as well as a bacterial infection on top of a viral one. Histopathologically the lung alterations were found to depend on the infectious agent and the mode of infection.