Growth responses to lime and fertilizers and critical concentrations in herbage of white clover in Scottish hill soils

The responses in dry matter (DM) production and changes in nutrient concentration in the shoots of white clover (cv. New Zealand Grasslands Huia) to additions of lime, N, P, K and Mg were investigated in pot and field experiments in a deep peat soil and to additions of N, P, K in two other hill soils in pot experiments. DM production and nutrient concentrations were assessed also for perennial ryegrass in the field experiment. There was no response by white clover to N, but in all soils, and in particular a deep peat, production of shoot DM was increased greatly by lime, P and K, and slightly by Mg. Interactions between lime and P and between P and K were observed. Critical concentrations of nutrients (g kg⁻¹) for white clover appeared to be about 2.0 for P, 10·15 for K and 20 for Ca. Herbage production and nutrient contents of ryegrass and white clover grown on a deep peat in the field suggests that critical concentrations may possibly help to diagnose the need fur maintenance fertilizer dressings.     

Lime and major nutrient fertilizers required to establish a perennial ryegrass/white clover pasture on a non-calcareous gley in the Scottish uplands

A field experiment with mixed swards of perennial ryegrass and while clover carded out in 1982–83 using small cut plots is described. With perennial ryegrass, lime slightly decreased annual dry matter (DM) production in 1982 (the sowing year) but increased it in 1983 (the first harvest year) by about 1 t ha^-1. Applications of N and P produced small increases in DM in 1982 and greater increases in 1983. In the latter season annual DM production varied from an average of 3·5 to about 10 t ha^-1 with 0 or 480 kg N ha^-1 applied in three equal-sized dressings throughout the growing season. Application of 40 kg P ha^-1 in 1982 increased DM production by about 2·5 t ha^-1 in 1983 but higher rates had little effect. Fifteen mg extractable P kg^-1 soil seemed sufficient to support levels of production normally expected from ryegrass pastures in upland Scotland, Applications of K did not affect DM production. N increased tiller weight and sward height of ryegrass; lime and P tended to increase tiller weight but this effect was not statistically significant. Leaf appearance and tiller number were not affected by treatments.
The white clover content of the pasture was decreased 10-fold by application of N and increased by lime and P (1·45 and 1·46-fold. respectively). The DM response to P was most apparent in limed soil and was also affected by the siting of the plots in the experimental area. Effects of lime and P on growth of white clover were to increase the number of stolon growing points and root nodule numbers per unit area.
The results emphasize the importance of lime and P fertilizer for establishment and growth of pasture in this soil and the differences between white clover and ryegrass in their responses to these.     

Proper adjuvant selection to enhance the activity of triclopyr combined with metsulfuron on the control of Hedyotis verticillata

A study was conducted to evaluate the combined activity of a tank mixture of triclopyr plus metsulfuron with non-ionic surfactant (NIS), crop oil concentrate (COC), and organosilicon (OS) adjuvants on the control of Hedyotis verticillata under glasshouse and field conditions. The results of both the glasshouse and field experiments showed that 160 g ai ha⁻¹ triclopyr plus 0.2 g ai ha⁻¹ metsulfuron and 320 g ai ha⁻¹ triclopyr plus 0.4 g ai ha⁻¹ metsulfuron, with the addition of 0.25% NIS, 0.05% COC, or 0.05% OS, were effective in controlling H. verticillata . A comparison of the cost revealed that the most cost-effective combination for controlling H. verticillata is 160 g ai ha⁻¹ triclopyr plus 0.2 g ai ha⁻¹ metsulfuron combined with 0.25% NIS.     

Replication of infectious pancreatic necrosis virus in trout leucocytes and detection of the carrier state

Abstract. The exact cellular site of replication of infectious pancreatic necrosis virus (IPNV) in carrier fish is unknown. In order to determine if IPNV replicates in trout leucocytes, we purified leucocytes from normal (non-carrier) trout and separated the cells into an adherent and a non-adherent population. IPNV replicated in less than 0-01 % of the adherent leucocytes with a yield of about 400 p.f.u./cell. IPNV also became associated with less than 0.07% of the non-adherent leucocytes; either IPNV did not replicate in these cells or the yield was, at best, only a few p.f.u./cell. Trout persistently infected with IPNV (carrier fish) were tested for the presence of IPNV in leucocytes by co-cultivating with a sensitive fish cell line; this same population of trout was also tested for IPNV by organ sampling using standard methods. Ninety-eight per cent of the trout were positive for IPNV by organ sampling, but only 75 % yielded IPNV from leucocytes. Thus a blood sample from a living fish can be used to detect the presence of IPNV.     

Magnetic Motor Evoked Potentials for Assessing Spinal Cord Integrity in Dogs with Intervertebral Disc Disease

Magnetically elicited transcranial motor evoked potentials (MEPs) were studied in 37 dogs with type 1 intervertebral disc (IVD) disease. The waveforms were recorded from both cranial tibial muscles before and after surgery. The latencies and amplitudes obtained were compared to those of a control population (n = 14). MEPs were recordable in all dogs with mild or no neurologic deficits, but they were recordable in only 50% of ambulatory dogs that were severely ataxic. MEPs could not be elicited from nonambulatory dogs. There was a significant attenuation of the amplitudes in all clinical cases, even if the dogs demonstrated back pain alone. Significantly prolonged latencies were associated with neurologic deficits. MEPs were not good predictors of neurologic recovery. The responses obtained from the side where the disc material was found were not different from those recorded from the opposite side. MEPs were very sensitive to lesions of the spinal cord, as indicated by the significant changes in the waves in patients with mild or no neurologic deficits and in the loss of response in dogs that still demonstrated purposeful movement. Neurologic exams provided more accurate diagnoses and prognoses than did MEPs in dogs with IVD disease.     

Chlorhexidine Diacetate and Povidone-iodine Cytotoxicity to Canine Embryonic Fibroblasts and Staphylococcus aureus

Chlorhexidine diacetate and povidone-iodine were evaluated for fibroblast toxicity on a primary line of canine embryonic fibroblasts, and for bactericidal efficacy against Staphylococcus aureus. The cultured fibroblasts or S. aureus were exposed for 30 minutes to incremental dilutions of 0.5 and 0.0005% chlorhexidine diacetate, 5.0 to 0.05% povidone-iodine, or physiologic buffered saline as a control. To determine survival, fibroblasts were trypsinized and counted; S. aureus colonies were counted on brain-heart infusion agar. Survival for both groups was expressed by calculating the number of living cells in test dilutions as a percentage of the number in control cultures. Fibroblast survival occurred at chlorhexidine concentrations less than 0.013% and at povidone-iodine concentrations less than 0.5% (p less than 0.05). Significant S. aureus survival (p less than 0.05) was noted at chlorhexidine concentrations less than 0.05% and povidone-iodine concentrations less than 1.0%. These data showed that all bactericidal concentrations of chlorhexidine diacetate and povidone-iodine were lethal to canine embryonic fibroblasts in vitro, whereas non-lethal concentrations allowed significant bacterial survival.     

Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphylococci in the UK, 1980–96

Abstract Disc sensitivity tests were carried out on 2296 isolates of non-pigmented, coagulase-positive staphylococcal isolates from dogs in referral practice over the period 1980–96. Ninety-eight isolates were from the ears, 1089 from other skin regions and 37 from mucosae. Resistance to penicillin increased from 69.0 to 89.3%. Oxytetracycline resistance remained at about 40%; resistance to erythromycin and lincomycin, and to co-trimoxazole peaked at about 20 and 15%, respectively, in 1987–89 but has since fallen. Only a single isolate resistant to cephalexin was found between 1986 and 1996. No resistance to co-amoxyclav, oxacillin, methicillin and enrofloxacin was demonstrated. Resistance of mucosal isolates was higher than those from skin. Multiple isolates from 90 dogs showed different resistance spectra in 56% of cases indicating that single swab samples are of limited value in determining optimal therapeutic antibiotics. Resumé 2296 souches de staphylocoques coagulase positifs, isolées á partir de chiens présentés en consultation référée entre 1980 et 1996, subirent des tests de sensibilité sur disques. 98 souches étaient d'origine auriculaire, 1098 d'autres origines cutanées, et 37 d'origine muqueuse. La résistance á la pénicilline augmenta de 69, 0 á 89, 3 pour cent. La résistance a l'oxytetracyline resta stable á environ 40 pour cent; les résistances á l'erythromycine et á la lincomycine, et au co-trimoxazole atteignirent 20 pour cent et 15 pour cent respectivement de 1987 á 1989 mais baissèrent ensuite. Une seule souche resistante á la cephalexine fut isolée entre 1986 et 1996. Aucune résistance á l'amoxycilline-acide clavulanique, Foxacilline, la methicilline, et l'enrofloxacine se fürent découvertes. Les résistances des souches d'origine muqueuse étaient plus nombreuses que celles des souches d'origine cutaneé. Des souches isolées par prelevement multiples chez 90 chiens montraient des spectres de résistance différents dans 56 pour cent des cas ce qui montre que des écouvillonages uniques ont un interèt limité pour le choix de la meilleure antibiotherapie. [Lloyd, D.H., Lamport, A.I., Feeney, C. Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphyloccoci in the United Kingdom, 1980–96 (Antibiosensibilité de souches de staphylocoques pathogènes canins d'origines cutanee et muqueuse au Royaume Uni de 1980 a 1996). Veterinary Dermatology 1996; 7 : 171–175.] Resumen A continuación el autor describe como discos de antibiograma fueron utilizados en 2.296 aislamientos caninos de no pigmentados estafilococos coagulasa positiva durante el periodo de 1980 a 1996; 98 aislamientos a partir del oido, 1098 de otras partes de la piel y 37 de mucosas. Se observó que las resistencias a la penicilina aumentaron de 69, 0 a 89,3 por ciento; a la oxitetraciclina permanecieron constantes, alrededor del 40 por ciento. Con respecto a la eritromicina y lincomicina asi como al cotrimoxazol, el nivel de resistencias alcanzó un pico máximo de alrededor 20 y 15 por ciento respectivamente en 1987–1989 para disminuir desde entonces. Solo un solo aislamiento desarolló resistencias a la cefalexina desde 1986 a 1996. No se han encontrado resistencias frente a la asociación amoxicilina-clavulanico, oxicilina, meticilina y enrofloxacina. Se demostró una resistencia superior en los aislamientos a partir de mucosa que aquellos a partir de piel. Diversos aislamientos realizados en 90 perros mostraron espectros de resistencias differentes en 56 por ciento de los casos, lo cual indica que únicamente muestras recogidas a partir de escobillon son de valor limitado a la hora de determinar una terapia antibiótica optima. [Lloyd, D.H., Lamport, A.I., Feeney, C. Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphyloccoci in the United Kingdom, 1980–96 (Sensibilidad a los antibioticós entre aislamientos cutanéos y mucosos de estafilococos patogénico en el Reino Unido, 1980–96). Veterinary Dermatology 1996; 7 : 171–175.] Zusammenfassung— Es wurden Resistenztests mit Antibiotika-Plättchen bei 2.296 nicht-pigmentierten, koagulase-positiven Staphylokokken-Stämmen durchgeführt, die von Hunden in einer Überweisungspraxis im Zeitraum von 1980 bis 1996 gewonnen worden waren. 98 Isolate kamen von den Ohren, 1089 von anderen Hautgebieten und 37 von den Schleimhäuten. Resistenzen gegenüber Penizillinen stiegen von 69,0 auf 89, 3%. Resistenzen gegenüber Oxytetracyclin blieben bei etwa 40%; Resistenzen auf Erythromycin bzw. Lincomycin und Co-Trimazole waren in den Jahren 1987 bis 1989 am höchsten mit 20 und 15%, sind seither jedoch weniger geworden. Nur ein einziges Isolat mit Resistenz gegenüber Cephalexin wurde zwischen 1986 und 1996 gefunden. Es zeigte sich keine Resistenz auf Co-Amoxyclaf, Oxacillin, Methicillin und Enrofloxacin. Die Resistenzen von Schleimhaut-Isolaten waren höher als die von der Haut. Mehrfachisolate von 90 Hunden zeigten Spektren mit unterschiedlichen Resistenzen in 56% der Fälle. Dies ist ein Hinweis, daß Einzelabstriche von begrenztem Wert sind, um optimal wirksame Antibiotika zu ermitteln. [Lloyd, D.H., Lamport, A.I., Feeney, C. Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphyloccoci in the United Kingdom, 1980–96 (Sensitivität auf Antibiotika bei kutanen und Schleimhaut-Isolaten von pathogenen Staphylokokken des Hundes im Vereinigten Königreich, 1980 bis 1996). Veterinary Dermatology 1996; 7 : 171–175.]     

Validation of a Rapid Parathyroid Hormone Assay and Intraoperative Measurement of Parathyroid Hormone in Dogs with Benign Naturally Occurring Primary Hyperparathyroidism

Objectives— To (1) validate a rapid chemiluminescent parathyroid hormone (PTH) assay, (2) determine it's usefulness locating a parathyroid nodule(s), and (3) determine if >50% decrease in PTH corresponds with excision of autonomously functioning parathyroid tissue. Study Design— Prospective cohort study. Animals— Dogs (n=12) with naturally occurring primary hyperparathyroidism and 25 healthy dogs. Methods— The assay was validated with linearity, precision, and intermethod comparison. Preoperative and postoperative systemic plasma PTH concentrations, measured from saphenous venous blood, were compared. Intraoperative local PTH concentrations were measured in right and left jugular venous blood before and after surgical excision of the grossly abnormal parathyroid gland(s). Results— Within run and day‐to‐day precisions were acceptable (coefficient of variation <15%). Dilutional parallelism was used to demonstrate high correlation between measured and calculated PTH concentrations (R²=0.99). The assay methods had good correlation but numerical results of the rapid assay were usually lower than the immunoradiometric assay. Seven of 12 dogs had uniglandular disease and five had multiglandular disease. Systemic and local PTH concentrations decreased >50% in all the dogs after excision of the parathyroid gland(s). Mean preoperative systemic plasma PTH concentrations were significantly higher than mean postoperative systemic concentrations. Local PTH concentrations could not be used reliably to differentiate the side of the autonomously functioning gland(s). Hypercalcemia resolved postoperatively in all the dogs. Conclusion— This assay measures PTH in dogs. Rapid PTH measurement provided documentation of decreased PTH concentration after removal of autonomously functioning parathyroid tissue. Clinical Relevance— Use of this assay allows documentation of a significant decrease in PTH concentration after excision of autonomously functioning parathyroid tissue.     

A bath challenge model for furunculosis in rainbow trout, Salmo gairdneri Richardson, and Atlantic salmon, Salmo salar L.

Abstract. A natural bath challenge method has been developed for furunculosis using Atlantic salmon, Salmo salar L., and rainbow trout, Salmo gairdneri Richardson. Fish were placed in an enclosed, continuously circulating tank system, supplemented with additional oxygen, the temperature raised gradually (overnight) to 15–16°C, a low dose of Aeromonas salmonicida (strain 184/186) introduced into the tank and the challenge maintained for 14 days. The challenge strain was characterized with respect to possible virulence factors and possessed an A-layer, ability to auto-agglutinate, haemagglutinate, adhere to Atlantic salmon cells and resist destruction by serum. No caseinase activity was detected. LD₅₀ for salmon using this method was 1.8×10³ cells per millilitre while trout had an LD₅₀ of 9.5×10⁴ cells per millilitre. Onset of the disease appeared to depend on fish size with larger trout (50 g) taking up to 10 days to show signs of the disease while mortalities in smaller trout (8.5g) commenced on day 1 post-challenge.     

Cohort survival patterns of walleye pollock, Theragra chalcogramma, in Shelikof Strait, Alaska: a critical factor analysis

A series of age-specific life tables for walleye pollock ( Theragra chalcogramma ) in the western Gulf of Alaska was compiled for the 1980-91 year classes. The life tables were utilized to perform an exploratory key factor analysis to examine the timing of critical periods in the recruitment process, evidence of density-dependence at different stages and trends in mortality rates. Early larval mortality was significantly correlated with generational mortality (In recruits/spawning bio-mass), but patterns in juvenile mortality also were similar to generational mortality and in some years were clearly dominant in determining the fate of a cohort. Density-dependent mortality, based on the correlation between mortality and initial abundance, was indicated only for the late larval to early juvenile stage. Time trends were marginally significant for juvenile mortality. It is speculated that the observed increase in juvenile mortality is associated with increasing abundance of arrowtooth flounder. Weaknesses in the data base are discussed; these along with the short time series involved make our conclusions tentative and subject to further study. We hypothesize that pollock recruitment levels can be established at any life stage depending on sufficient supply from prior stages, a type of dynamics which can be termed supply dependent multiple life stage control.