Crop and soil response to subsoil loosening, deep incorporation of phosphorus and potassium fertilizer and subsequent soil management on a range of soil types.: Part 2: Soil structural conditions

Abstract. In a series of experiments on 16 sites both a power-driven rotary-tine Wye Double Digger and a rigid tine winged subsoiler produced significant subsoil loosening and fissuring. The Double Digger consistently produced the greatest clod breakdown together with the least soil bulk densities and cone penetration resistances. Management strategies after loosening had an important influence on the longevity of the loosening effect. The rate of recompaction was least with controlled traffic and bed systems and increased with random traffic and with the growing of root crops. No significant differences in crop response were monitored between the two loosening treatments, yield response depending largely on the extent of moisture stress experienced by the crop. Loosening on silty soils reduced yields in wet seasons and this was associated with soil structural instability. Visual soil profile examination is necessary to support bulk density and cone penetration resistance measurements when assessing soil compaction.     

Suppression of ovarian progesterone production in dairy cows using an implant of GnRH-agonist (deslorelin) for the purpose of evaluating progesterone metabolism

OBJECTIVE: To evaluate the potential of an implant of a GnRH-agonist (deslorelin) to create a progesterone free animal suitable for studying progesterone (P4) metabolism in intact cows by measuring blood P4 and faecal P4 metabolites. METHODS: Experiment 1: Eighteen non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to one of three groups to study plasma P4 concentrations preceding an intravaginal insert. These groups comprised: i) a deslorelin group (GnRH-agonist implanted); ii) a PGF group receiving two injections of prostaglandin (PGF2alpha) 12 days apart; and, iii) an ovariectomised (OVX) group. An intravaginal device (CIDR) was inserted into the vagina of each animal and left in place for 11 days. Plasma P4 concentrations were measured during the study period. Experiment 2: Twelve non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to two groups: i) a deslorelin group (GnRH-agonist implanted); and ii) an ovariectomised group. Plasma P4 and faecal P4 metabolites (20-oxo-pregnanes, 20alpha-OH and 20beta-OH) were monitored for a period of 5 weeks. RESULTS: Experiment 1: Average plasma P4 concentration did not differ between the three groups (1.28, 1.43 and 1.55 ng/mL for deslorelin, OVX and PGF cows, respectively, P = 0.8) during the period of supplementation. Experiment 2: There was no difference in plasma P4 (mean plasma P4 < 0.02 ng/mL, P = 0.9) and faecal P4 metabolites between deslorelin and OVX cows 2 weeks after the implantation (P = 0.7). CONCLUSIONS: These data showed that a GnRH-agonist (deslorelin) implant may be used as an alternative to ovariectomy to create a progesterone free animal suitable for studying the metabolism of administered P4.     

Evaluation of four point-of-care meters for rapid determination of blood lactate concentrations in dogs

OBJECTIVE: To determine whether blood lactate values determined in dogs with 4 commercially available point-of-care meters were in agreement with values determined with a critical care laboratory blood analyzer. DESIGN: Prospective study. ANIMALS: 50 dogs evaluated for emergency treatment. PROCEDURES: Blood samples were collected at initial evaluation and processed on 4 point-of-care meters and on a critical care laboratory blood analyzer. RESULTS: All 4 point-of-care lactate meters generated measurements that were in agreement with the hospital's critical care analyzer. Values for agreement (bias) between the 4 point-of-care meters and the critical care analyzer were -0.652 (limits of agreement [LA], -1.958 to 0.654]), -0.670 (LA, -2.110 to 0.769), -0.096 (LA, -2.071 to 1.879), and -0.498 (LA, -2.616 to 1.620), respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Despite its prognostic and therapeutic relevance, blood lactate measurement in dogs has been hampered by the inability to perform the test in a timely fashion. Results of the present study indicated that several handheld point-of-care lactate meters provided results that were in agreement with a laboratory critical care blood analyzer.     

Measuring statistical agreement between four point of care (POC) lactate meters and a laboratory blood analyzer in cats

The use of blood lactate concentrations as a prognostic indicator and therapeutic gauge in feline medicine has been hindered by the inability to obtain values in a timely manner with minimal quantities of blood. Recently, hand-held point-of-care (POC) lactate meters have become commercially available. The objective of this prospective study was to determine if lactate values produced by three commercially available and one medical grade POC meter were in agreement with a laboratory blood analyzer. Blood samples from 47 cats were collected on presentation to an emergency service and processed on four POC meters and a Stat Profile Critical Care Xpress blood analyzer. The results were analyzed using the Bland-Altman method. The blood lactate values produced by the hospital grade POC meter and one of the commercially POC meters were in good agreement with the Critical Care Xpress blood analyzer. Other commercially available POC meters produced acceptable agreement.