Residue management for reducing evaporation in relation to soil type and evaporativity1

Abstract. Usual residue-management options are to remove the residue, use it as mulch with or without undercutting or to incorporate it into the soil. While the role of surface mulch in evaporation has been widely studied, the information on the effect on evaporation of mulch with undercutting or residue incorporated into soil, particularly in relation to soil type and evaporativity (E_o) is lacking. We studied the effect of wheat straw used in various ways on the course of evaporation loss from soil columns with three soils at Ludhiana, India and one soil at Bushland, Texas, USA, under two E_o's Energy-limited evaporation rates under mulch (E_om) followed the soil-specific relation E_om/E_o= a e^(bRes+cEo), where Res is residue rate t/ha and a, b and c are constants; E_o, is expressed in mm/d. In an effort to model the total evaporation (CE) during the energy-limited stage ‘U’ was obtained from appropriate CE versus time curves and (CE-U) was regressed over (t - ti)^0.5 to obtain the slope ‘α’ (Ritchie 1972) for the soil-limited evaporation stage. The observed ‘U’ was independent of mulch rate and E_o but was strongly affected by soil type, Values of ‘α’ decreased with increase in mulch rate and decrease in E_o and coarseness of soil. The otherwise short lived benefit of evaporation reduction with mulch per se, which peaked after a few days was maintained when residue was mixed with soil at the stage when evaporation reduction reached a maximum; this benefit continued for several weeks. Cumulative evaporation values computed from ‘U’ and ‘α’ agreed closely with the observed values under straw mulch for loamy sand and clay loam soils and for ‘undercut’ and ‘residue mixed’ treatments on all soils regardless of E_o, and for all situations under small E_o. However, for sandy loam and silt loam soils under E_o of 10 mm/d, the modified square root of the time function of Jalota et al. (1988) gave a better fit.     

Water transport in the kidney and nephrogenic diabetes insipidus

Nephrogenic diabetes insipidus is caused by an inability of the kidney to concentrate urine despite adequate concentration of vasopressin in blood and is characterized by polyuria, polydipsia, and hyposthenuria in the presence of plasma hyperosmolality. Nephrogenic diabetes insipidus is the result of defects in water homeostasis in the kidney. Nephrogenic diabetes insipidus occurs when the kidneys cannot or do not respond to vasopressin. There are 2 categories of nephrogenic diabetes insipidus. Congenital nephrogenic diabetes insipidus is a rare, inherited, irreversible cause of polyuria and polydipsia in humans that is even rarer in animals. Acquired nephrogenic diabetes insipidus is more common and is often secondary to illness or medication that interferes with the action of vasopressin in the renal tubules. Unlike congenital nephrogenic diabetes insipidus, acquired or secondary nephrogenic diabetes insipidus is often reversible with correction of the associated or causative problem.     

Presumptive fenbendazole toxicosis in North American porcupines

CASE DESCRIPTION: 4 North American porcupines were evaluated because of diarrhea or neutropenia (or both) that developed after treatment with fenbendazole for intestinal parasites. CLINICAL FINDINGS: Complete blood cell count abnormalities included severe neutropenia in all affected porcupines and mild anemia in some of them. In 2 porcupines, postmortem findings included bone marrow hypoplasia and intestinal crypt cell necrosis. TREATMENT AND OUTCOME: Affected porcupines received supportive care including fluid supplementation and broad-spectrum antimicrobials. The 2 surviving animals recovered after 9 to 33 days of treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Fenbendazole is an anthelminthic that may be used in an extralabel manner for the treatment of intestinal parasitism in wildlife species. The drug inhibits mitosis and can affect rapidly dividing cell lines, such as those in the bone marrow and intestinal crypt mucosa. Fenbendazole may not be an appropriate anthelminthic choice in North American porcupines.     

Intestinal cellular reaction of cattle after infection by Fasciola hepatica]

Defence reactions of cattle against Fasciola hepatica take place not only in the liver but also on a prehepatic level. The aim of the present experiments is to identify and quantify the cellular response in the small intestine. Five groups of two bulls (Simmental x Red Holstein, 6 months old) were infected by oesophageal probe with metacercariae of F. hepatica (MC) according to two experimental procedures. Two groups of bulls served as controls. In the first experiment both infected groups received 1000 MC once or twice at an interval of five weeks. The intestinal tissue was taken before infection and 5, 10 and 19 weeks p.i., respectively 5 and 14 weeks p. reinf. (p.ri.). In the second experiment, three infected groups received 400, 2 x 400 MC (at an interval of five weeks) and 800 MC respectively. Biopsies were taken one week ante infectionem, 6, 11 and 19 weeks p.i., respectively 1, 6 and 14 weeks post reinfectionem (p. ri.). The biopsies of the small intestine were prepared for histology and the tissue sections stained as follows: Astra blue for mucosal mast cells (MMC), Lendrum for eosinophils (EOS) and Periodic Acid Schiff (PAS) for goblet cells (GC). The density of the three cell populations in the mucosa was determined microscopically and quantified. In both experiments the density of the MMC and EOS increased with each reinfection and depended on the infectious dose. There was no significant variation of the GC-numbers. The described intestinal cellular reactions suggest a participation of the small intestinal wall in the immunity against the common liver fluke.     

Diagnosis of pancreatitis.

In summary, pancreatitis is common in dogs and cats, but it seems that most cases remain undiagnosed. Serum amylase and lipase activities are useful as a quick screening test for pancreatitis in the dog only. Serum amylase or lipase activity must be at least three to five times the upper limit of the reference range to suggest a diagnosis of pancreatitis. Furthermore, the diagnosis must be confirmed by other diagnostic modalities, and normal test results do not eliminate the possibility of pancreatitis. Abdominal ultrasound is highly specific for pancreatitis in dogs and cats but is not particularly sensitive, especially in cats. Serum cPLI concentration is highly specific for exocrine pancreatic function and is also highly sensitive for pancreatitis. Similarly, initial data would suggest that serum fPLI is the most sensitive and specific diagnostic test for feline pancreatitis. Until further data are available, however, serum fPLI should be used in conjunction with other diagnostic tests to arrive at a diagnosis of feline pancreatitis. Histopathologic evidence of pancreatitis is conclusive for a diagnosis of pancreatitis. In most cases, however, lesions are localized, and the lack of histopathologic evidence of pancreatitis does not eliminate a diagnosis of pancreatitis.     

Kinetics and postmucosal effects on urinary recovery of 5 intravenously administered sugars in healthy cats

The objective of this study was to describe the kinetics of urinary recovery and to evaluate the effects of postmucosal factors on urinary recovery of 5 intravenously administered saccharides. Ten cats received an isotonic sugar solution containing lactulose, rhamnose, xylose, methylglucose, and sucrose intravenously. These sugars were selected because of their prior use for intestinal permeability and mucosal function testing in humans and dogs. Urethral catheterization with a closed collection system was used for collection of cumulative urine samples prior to and 2, 4, 6, 8, 10, 12, and 24 h after administration of the sugar solution. High-pressure anion exchange liquid chromatography with pulsed amperometric detection was used to measure the concentrations of each sugar in the urine and calculate urinary recovery. Twenty-four hour cumulative urinary recovery for each sugar from the cats, was lower than expected compared to dogs and humans. All 5 sugars had the highest percentage of urinary recovery during the first 2 h after administration. Mean sugar elimination rate constants and half-lives ranged from 0.268/h for methylglucose to 0.415/h for lactulose and 1.67 h for lactulose to 2.59 h for methylglucose, respectively. Metabolism and incomplete urine collection are possible reasons for lower cumulative urinary recoveries of these 5 sugars in cats compared with dogs. Although these 5 sugars are not ideal marker molecules, they may still be useful for intestinal permeability and mucosal function testing in cats.     

Identification of unreported putative new bovine papillomavirus types in Brazilian cattle herds

The amplification by degenerate primers FAP59/FAP64 and sequencing allowed the detection of 15 putative new BPV types in cutaneous warts as well as in healthy skin. Four of these isolates were recently recognized as new BPV types (BPV-7, -8, -9, and -10) after determination of their complete genome sequences. In Brazil, investigations involving the definition of BPV types present in skin warts are still rare. The aim of the current study was to identify the BPV types associated with cutaneous papillomatosis observed in Brazilian cattle herds. Twenty-two cutaneous papilloma specimens were submitted to PCR assay employing the FAP primer pair. All PCR products with approximately 480 bp were submitted to direct sequencing. Cloning was performed for the amplicons which prior analysis revealed as putative new BPV types. From 16 cutaneous lesions, BPV-1, -2, and -6 were identified in two, six, and eight papilloma specimens, respectively. In addition, four putative new BPV types were identified in other six skin warts, and then designated as BPV/BR-UEL2 to -5. The detection of the BPV-1, -2, and -6 types in skin wart specimens supports the existence of these BPV types throughout the Brazilian cattle herd. In addition, the identification of four putative new BPV types is the first report of the presence of different BPV types in the American continent.